From 41add82f1750e4c477b941cd076ad12e3a150a99 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Wed, 4 Feb 2026 02:32:33 +0000
Subject: [PATCH 01/21] WIP test for new build system design

---
 Cargo.lock                                | 15 ++++++
 Cargo.toml                                |  2 +-
 Makefile.pre.in                           |  3 +-
 Modules/_base64/Cargo.toml                |  6 ++-
 Modules/_base64/build.rs                  |  5 ++
 Modules/cpython-build-helper/Cargo.toml   |  7 +++
 Modules/cpython-build-helper/README.md    |  4 ++
 Modules/cpython-build-helper/src/lib.rs   | 17 +++++++
 Modules/cpython-rust-staticlib/Cargo.toml | 11 +++++
 Modules/cpython-rust-staticlib/src/lib.rs |  1 +
 Modules/makesetup                         | 60 +++++++++++------------
 configure                                 | 43 +++++++++++-----
 configure.ac                              | 40 ++++++++++-----
 13 files changed, 153 insertions(+), 61 deletions(-)
 create mode 100644 Modules/_base64/build.rs
 create mode 100644 Modules/cpython-build-helper/Cargo.toml
 create mode 100644 Modules/cpython-build-helper/README.md
 create mode 100644 Modules/cpython-build-helper/src/lib.rs
 create mode 100644 Modules/cpython-rust-staticlib/Cargo.toml
 create mode 100644 Modules/cpython-rust-staticlib/src/lib.rs

diff --git a/Cargo.lock b/Cargo.lock
index afc3744abd1cb6..b2080d8d0da80b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6,6 +6,7 @@ version = 4
 name = "_base64"
 version = "0.1.0"
 dependencies = [
+ "cpython-build-helper",
  "cpython-sys",
 ]
 
@@ -70,6 +71,20 @@ dependencies = [
  "libloading",
 ]
 
+[[package]]
+name = "cpython-build-helper"
+version = "0.1.0"
+dependencies = [
+ "shlex",
+]
+
+[[package]]
+name = "cpython-rust-staticlib"
+version = "0.1.0"
+dependencies = [
+ "_base64",
+]
+
 [[package]]
 name = "cpython-sys"
 version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 8b75182b7a596a..768d289fd77653 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [workspace]
 resolver = "3"
 members = [
-    "Modules/_base64",
+    "Modules/_base64", "Modules/cpython-build-helper", "Modules/cpython-rust-staticlib",
     "Modules/cpython-sys"
 ]
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 10f299819cd40f..0f2553f1fcf737 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -178,7 +178,8 @@ CONFINCLUDEPY=	$(CONFINCLUDEDIR)/python$(LDVERSION)
 SHLIB_SUFFIX=	@SHLIB_SUFFIX@
 EXT_SUFFIX=	@EXT_SUFFIX@
 LDSHARED=	@LDSHARED@ $(PY_LDFLAGS)
-BLDSHARED=	@BLDSHARED@ $(PY_CORE_LDFLAGS)
+BLDSHARED_EXE= @BLDSHARED_EXE@
+BLDSHARED_ARGS=	@BLDSHARED_ARGS@ $(PY_CORE_LDFLAGS)
 LDCXXSHARED=	@LDCXXSHARED@ $(PY_LDFLAGS)
 DESTSHARED=	$(BINLIBDEST)/lib-dynload
 
diff --git a/Modules/_base64/Cargo.toml b/Modules/_base64/Cargo.toml
index 0810b787ab2773..f90350624729d6 100644
--- a/Modules/_base64/Cargo.toml
+++ b/Modules/_base64/Cargo.toml
@@ -6,6 +6,10 @@ edition = "2024"
 [dependencies]
 cpython-sys ={ path = "../cpython-sys" }
 
+[build-dependencies]
+cpython-build-helper = { path = "../cpython-build-helper" }
+
 [lib]
 name = "_base64"
-crate-type = ["staticlib"]
+# For shared builds, we generate a c dynamic library. Static builds use the rlib
+crate-type = ["cdylib", "rlib"]
diff --git a/Modules/_base64/build.rs b/Modules/_base64/build.rs
new file mode 100644
index 00000000000000..8cca32f8f8c3df
--- /dev/null
+++ b/Modules/_base64/build.rs
@@ -0,0 +1,5 @@
+use cpython_build_helper::print_linker_args;
+
+fn main() {
+    print_linker_args();
+}
diff --git a/Modules/cpython-build-helper/Cargo.toml b/Modules/cpython-build-helper/Cargo.toml
new file mode 100644
index 00000000000000..1369020965012a
--- /dev/null
+++ b/Modules/cpython-build-helper/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "cpython-build-helper"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+shlex = "1.3"
diff --git a/Modules/cpython-build-helper/README.md b/Modules/cpython-build-helper/README.md
new file mode 100644
index 00000000000000..f42946cfefc31c
--- /dev/null
+++ b/Modules/cpython-build-helper/README.md
@@ -0,0 +1,4 @@
+# cpython-build-helper
+
+This crate is used in Rust modules `build.rs` files to help do common tasks such
+as passing necessary link arguments.
\ No newline at end of file
diff --git a/Modules/cpython-build-helper/src/lib.rs b/Modules/cpython-build-helper/src/lib.rs
new file mode 100644
index 00000000000000..f9fc5b2e77fc46
--- /dev/null
+++ b/Modules/cpython-build-helper/src/lib.rs
@@ -0,0 +1,17 @@
+use std::env;
+
+/// Print necessary link arguments for the library depending on the build
+/// configuration (static or shared)
+pub fn print_linker_args() {
+    let shared_build = env::var("RUST_SHARED_BUILD").expect("RUST_SHARED_BUILD not set in Makefile?");
+    if shared_build == "1" {
+        let build_shared_args =
+            env::var("BLDSHARED_ARGS").expect("BLDSHARED_ARGS not set in Makefile?");
+        // TODO(emmatyping): Ideally, we would not need to split the args here and take shlex
+        // as a dependency.
+        for arg in shlex::split(&build_shared_args).expect("Invalid BUILDSHARED_ARGS") {
+            println!("cargo:rustc-link-arg={}", arg);
+        }
+    }
+    // Static linker configuration is in cpython-rust-staticlib
+}
diff --git a/Modules/cpython-rust-staticlib/Cargo.toml b/Modules/cpython-rust-staticlib/Cargo.toml
new file mode 100644
index 00000000000000..d7f52b0f3e9602
--- /dev/null
+++ b/Modules/cpython-rust-staticlib/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "cpython-rust-staticlib"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+_base64 ={ path = "../_base64" }
+
+[lib]
+name = "cpython_rust_staticlib"
+crate-type = ["staticlib"]
diff --git a/Modules/cpython-rust-staticlib/src/lib.rs b/Modules/cpython-rust-staticlib/src/lib.rs
new file mode 100644
index 00000000000000..a440707833f65d
--- /dev/null
+++ b/Modules/cpython-rust-staticlib/src/lib.rs
@@ -0,0 +1 @@
+pub use _base64::PyInit__base64;
diff --git a/Modules/makesetup b/Modules/makesetup
index bd33c8fb2804c7..25b091cde689c1 100755
--- a/Modules/makesetup
+++ b/Modules/makesetup
@@ -232,7 +232,6 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 		yes)	continue;;
 		esac
 		objs=''
-		custom_ldflags=''
 		if test "x$rust" = "x"; then
 			for src in $srcs
 			do
@@ -272,6 +271,22 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 				esac
 				echo "$rule" >>$rulesf
 			done
+			case $doconfig in
+			yes)	OBJS="$OBJS $objs";;
+			esac
+			for mod in $mods
+			do
+				file="$srcdir/$mod\$(EXT_SUFFIX)"
+				case $doconfig in
+				no)
+					SHAREDMODS="$SHAREDMODS $file"
+					BUILT_SHARED="$BUILT_SHARED $mod"
+					;;
+				esac
+				rule="$file: $objs \$(MODULE_${mods_upper}_LDEPS)"
+				rule="$rule; \$(BLDSHARED_EXE) \$(BLDSHARED_ARGS) $objs $libs \$(LIBPYTHON) -o $file"
+				echo "$rule" >>$rulesf
+			done
 		else
 			prefixed_srcs=
 			for src in $srcs
@@ -279,44 +294,25 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 				prefixed_srcs="$prefixed_srcs $srcdir/$src"
 			done
 			objs=
-			# there's actually only one obj, so just set it to the lib
-			for lib in $libs
-			do
-				objs="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/$lib"
-			done
 			libs=
-			# depends on the headers through cpython-sys
-			rule="$objs: cpython-sys \$(srcdir)/Cargo.toml \$(srcdir)/Cargo.lock \$(srcdir)/$srcdir/$manifest $prefixed_srcs \$(PYTHON_HEADERS)"
-			rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) \$(CARGO_HOME)/bin/cargo build --lib --locked --package ${mods} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
-			echo "$rule" >>$rulesf
+
 			for mod in $mods
 			do
-				case $UNAME_SYSTEM in
-				Darwin*)
-					custom_ldflags="$custom_ldflags -Wl,-u,_PyInit_$mod"
-					;;
-				*)
-					custom_ldflags="$custom_ldflags -Wl,--defsym=PyInit_$mod=PyInit_$mod"
+				rust_shared="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/lib$mod\$(SHLIB_SUFFIX)"
+				file="$srcdir/$mod\$(EXT_SUFFIX)"
+				case $doconfig in
+				no)
+					SHAREDMODS="$SHAREDMODS $file"
+					BUILT_SHARED="$BUILT_SHARED $mod"
 					;;
 				esac
+				# depends on the headers through cpython-sys
+				rule="$rust_shared: cpython-sys \$(srcdir)/Cargo.toml \$(srcdir)/Cargo.lock \$(srcdir)/$srcdir/$manifest $prefixed_srcs \$(PYTHON_HEADERS) \$(MODULE_${mods_upper}_LDEPS) \$(LIBRARY)"
+				rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) RUST_SHARED_BUILD=\$(PY_ENABLE_SHARED) \$(CARGO_HOME)/bin/cargo build -vvv --lib --locked --package ${mod} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
+				echo "$rule" >>$rulesf
+				echo "$file: $rust_shared; mv $rust_shared $file" >>$rulesf
 			done
 		fi
-		case $doconfig in
-		yes)	OBJS="$OBJS $objs";;
-		esac
-		for mod in $mods
-		do
-			file="$srcdir/$mod\$(EXT_SUFFIX)"
-			case $doconfig in
-			no)
-				SHAREDMODS="$SHAREDMODS $file"
-				BUILT_SHARED="$BUILT_SHARED $mod"
-				;;
-			esac
-			rule="$file: $objs \$(MODULE_${mods_upper}_LDEPS)"
-			rule="$rule; \$(BLDSHARED) $custom_ldflags $objs $libs \$(LIBPYTHON) -o $file"
-			echo "$rule" >>$rulesf
-		done
 	done
 
 	case $SHAREDMODS in
diff --git a/configure b/configure
index 5b09de36f9a0b8..911577c444b79c 100755
--- a/configure
+++ b/configure
@@ -908,7 +908,8 @@ SHLIBS
 CFLAGSFORSHARED
 LINKFORSHARED
 CCSHARED
-BLDSHARED
+BLDSHARED_ARGS
+BLDSHARED_EXE
 LDCXXSHARED
 LDSHARED
 SHLIB_SUFFIX
@@ -13503,6 +13504,7 @@ fi
 
 
 
+
 # SHLIB_SUFFIX is the extension of shared libraries `(including the dot!)
 # -- usually .so, .sl on HP-UX, .dll on Cygwin
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking the extension of shared libraries" >&5
@@ -13532,7 +13534,8 @@ if test -z "$LDSHARED"
 then
 	case $ac_sys_system/$ac_sys_release in
 	AIX*)
-		BLDSHARED="Modules/ld_so_aix \$(CC) -bI:Modules/python.exp"
+		BLDSHARED_EXE="Modules/ld_so_aix"
+    BLDSHARED_ARGS="\$(CC) -bI:Modules/python.exp"
 		LDSHARED="\$(LIBPL)/ld_so_aix \$(CC) -bI:\$(LIBPL)/python.exp"
 		;;
 	SunOS/5*)
@@ -13556,7 +13559,8 @@ then
 		LDCXXSHARED='$(CXX) -bundle'
 		if test "$enable_framework" ; then
 			# Link against the framework. All externals should be defined.
-			BLDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
+      BLDSHARED_EXE="$LDSHARED"
+      BLDSHARED_ARGS='$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDCXXSHARED="$LDCXXSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 		else
@@ -13567,14 +13571,15 @@ then
 	Darwin/1.4*|Darwin/5.*|Darwin/6.*)
 		LDSHARED='$(CC) -bundle'
 		LDCXXSHARED='$(CXX) -bundle'
+    BLDSHARED_EXE="$LDSHARED"
 		if test "$enable_framework" ; then
 			# Link against the framework. All externals should be defined.
-			BLDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
+      BLDSHARED_ARGS='$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDCXXSHARED="$LDCXXSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 		else
 			# No framework, use the Python app as bundle-loader
-			BLDSHARED="$LDSHARED "'-bundle_loader $(BUILDPYTHON)'
+			BLDSHARED_ARGS='-bundle_loader $(BUILDPYTHON)'
 			LDSHARED="$LDSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
 			LDCXXSHARED="$LDCXXSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
 		fi ;;
@@ -13595,13 +13600,15 @@ then
 			# building for OS X 10.3 and later
 			LDSHARED='$(CC) -bundle -undefined dynamic_lookup'
 			LDCXXSHARED='$(CXX) -bundle -undefined dynamic_lookup'
-			BLDSHARED="$LDSHARED"
+			BLDSHARED_EXE="$LDSHARED"
+      BLDSHARED_ARGS=""
 		fi
 		;;
 	iOS/*)
 		LDSHARED='$(CC) -dynamiclib -F . -framework $(PYTHONFRAMEWORK)'
 		LDCXXSHARED='$(CXX) -dynamiclib -F . -framework $(PYTHONFRAMEWORK)'
-		BLDSHARED="$LDSHARED"
+		BLDSHARED_EXE="$LDSHARED"
+    BLDSHARED_ARGS=""
 		;;
 	Emscripten*|WASI*)
 		LDSHARED='$(CC) -shared'
@@ -13661,18 +13668,25 @@ fi;;
 fi
 
 if test "$enable_wasm_dynamic_linking" = "yes" -a "$ac_sys_system" = "Emscripten"; then
-  BLDSHARED='$(CC) -shared -sSIDE_MODULE=1'
+  BLDSHARED_EXE='$(CC) -shared'
+  BLDSHARED_ARGS='-sSIDE_MODULE=1'
 fi
 
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $LDSHARED" >&5
 printf "%s\n" "$LDSHARED" >&6; }
 LDCXXSHARED=${LDCXXSHARED-$LDSHARED}
 
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking BLDSHARED flags" >&5
-printf %s "checking BLDSHARED flags... " >&6; }
-BLDSHARED=${BLDSHARED-$LDSHARED}
-{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $BLDSHARED" >&5
-printf "%s\n" "$BLDSHARED" >&6; }
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking BLDSHARED_EXE executable" >&5
+printf %s "checking BLDSHARED_EXE executable... " >&6; }
+BLDSHARED_EXE=${BLDSHARED_EXE-$LDSHARED}
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $BLDSHARED_EXE" >&5
+printf "%s\n" "$BLDSHARED_EXE" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking BLDSHARED_ARGS flags" >&5
+printf %s "checking BLDSHARED_ARGS flags... " >&6; }
+BLDSHARED_ARGS=${BLDSHARED_ARGS-}
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $BLDSHARED_ARGS" >&5
+printf "%s\n" "$BLDSHARED_ARGS" >&6; }
 
 # CCSHARED are the C *flags* used to create objects to go into a shared
 # library (module) -- this is only needed for a few systems
@@ -16106,6 +16120,8 @@ else
     CARGO_PROFILE='dev'
   fi
   # Set CARGO_TARGET for cross-compilation
+  # TODO(emmatyping): derive this in platform-triplet.c and set the Rust triple
+  # higher up
   case "$host" in
     aarch64-apple-ios-simulator)
       CARGO_TARGET="aarch64-apple-ios-sim"
@@ -36187,3 +36203,4 @@ if test "$ac_cv_header_stdatomic_h" != "yes"; then
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: Your compiler or platform does have a working C11 stdatomic.h. A future version of Python may require stdatomic.h." >&5
 printf "%s\n" "$as_me: Your compiler or platform does have a working C11 stdatomic.h. A future version of Python may require stdatomic.h." >&6;}
 fi
+
diff --git a/configure.ac b/configure.ac
index 1561c6f9b2e99f..852d7c83718d21 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3379,7 +3379,8 @@ with_tsan="no"
 AC_SUBST([SHLIB_SUFFIX])
 AC_SUBST([LDSHARED])
 AC_SUBST([LDCXXSHARED])
-AC_SUBST([BLDSHARED])
+AC_SUBST([BLDSHARED_EXE])
+AC_SUBST([BLDSHARED_ARGS])
 AC_SUBST([CCSHARED])
 AC_SUBST([LINKFORSHARED])
 
@@ -3409,7 +3410,8 @@ if test -z "$LDSHARED"
 then
 	case $ac_sys_system/$ac_sys_release in
 	AIX*)
-		BLDSHARED="Modules/ld_so_aix \$(CC) -bI:Modules/python.exp"
+		BLDSHARED_EXE="Modules/ld_so_aix"
+    BLDSHARED_ARGS="\$(CC) -bI:Modules/python.exp"
 		LDSHARED="\$(LIBPL)/ld_so_aix \$(CC) -bI:\$(LIBPL)/python.exp"
 		;;
 	SunOS/5*)
@@ -3433,7 +3435,8 @@ then
 		LDCXXSHARED='$(CXX) -bundle'
 		if test "$enable_framework" ; then
 			# Link against the framework. All externals should be defined.
-			BLDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
+      BLDSHARED_EXE="$LDSHARED"
+      BLDSHARED_ARGS='$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDCXXSHARED="$LDCXXSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 		else
@@ -3444,14 +3447,15 @@ then
 	Darwin/1.4*|Darwin/5.*|Darwin/6.*)
 		LDSHARED='$(CC) -bundle'
 		LDCXXSHARED='$(CXX) -bundle'
+    BLDSHARED_EXE="$LDSHARED"
 		if test "$enable_framework" ; then
 			# Link against the framework. All externals should be defined.
-			BLDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
+      BLDSHARED_ARGS='$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDSHARED="$LDSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 			LDCXXSHARED="$LDCXXSHARED "'$(PYTHONFRAMEWORKPREFIX)/$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK)'
 		else
 			# No framework, use the Python app as bundle-loader
-			BLDSHARED="$LDSHARED "'-bundle_loader $(BUILDPYTHON)'
+			BLDSHARED_ARGS='-bundle_loader $(BUILDPYTHON)'
 			LDSHARED="$LDSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
 			LDCXXSHARED="$LDCXXSHARED "'-bundle_loader $(BINDIR)/python$(VERSION)$(EXE)'
 		fi ;;
@@ -3472,13 +3476,15 @@ then
 			# building for OS X 10.3 and later
 			LDSHARED='$(CC) -bundle -undefined dynamic_lookup'
 			LDCXXSHARED='$(CXX) -bundle -undefined dynamic_lookup'
-			BLDSHARED="$LDSHARED"
+			BLDSHARED_EXE="$LDSHARED"
+      BLDSHARED_ARGS=""
 		fi
 		;;
 	iOS/*)
 		LDSHARED='$(CC) -dynamiclib -F . -framework $(PYTHONFRAMEWORK)'
 		LDCXXSHARED='$(CXX) -dynamiclib -F . -framework $(PYTHONFRAMEWORK)'
-		BLDSHARED="$LDSHARED"
+		BLDSHARED_EXE="$LDSHARED"
+    BLDSHARED_ARGS=""
 		;;
 	Emscripten*|WASI*)
 		LDSHARED='$(CC) -shared'
@@ -3535,18 +3541,24 @@ then
 	esac
 fi
 
-dnl Emscripten's emconfigure sets LDSHARED. Set BLDSHARED outside the
-dnl test -z $LDSHARED block to configure BLDSHARED for side module support.
+dnl Emscripten's emconfigure sets LDSHARED. Set BLDSHARED_EXE and BLDSHARED_ARGS
+dnl outside the test -z $LDSHARED block to configure BLDSHARED for side module
+dnl support.
 if test "$enable_wasm_dynamic_linking" = "yes" -a "$ac_sys_system" = "Emscripten"; then
-  BLDSHARED='$(CC) -shared -sSIDE_MODULE=1'
+  BLDSHARED_EXE='$(CC) -shared'
+  BLDSHARED_ARGS='-sSIDE_MODULE=1'
 fi
 
 AC_MSG_RESULT([$LDSHARED])
 LDCXXSHARED=${LDCXXSHARED-$LDSHARED}
 
-AC_MSG_CHECKING([BLDSHARED flags])
-BLDSHARED=${BLDSHARED-$LDSHARED}
-AC_MSG_RESULT([$BLDSHARED])
+AC_MSG_CHECKING([BLDSHARED_EXE executable])
+BLDSHARED_EXE=${BLDSHARED_EXE-$LDSHARED}
+AC_MSG_RESULT([$BLDSHARED_EXE])
+
+AC_MSG_CHECKING([BLDSHARED_ARGS flags])
+BLDSHARED_ARGS=${BLDSHARED_ARGS-}
+AC_MSG_RESULT([$BLDSHARED_ARGS])
 
 # CCSHARED are the C *flags* used to create objects to go into a shared
 # library (module) -- this is only needed for a few systems
@@ -4329,6 +4341,8 @@ else
     CARGO_PROFILE='dev'
   fi
   # Set CARGO_TARGET for cross-compilation
+  # TODO(emmatyping): derive this in platform-triplet.c and set the Rust triple
+  # higher up
   case "$host" in
     aarch64-apple-ios-simulator)
       CARGO_TARGET="aarch64-apple-ios-sim"

From 363f9acf35461ae5e265608188b149e864eec875 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Wed, 4 Feb 2026 05:15:23 +0000
Subject: [PATCH 02/21] Also pass whether or not the build is shared to
 cpython-sys

---
 Cargo.lock                     | 1 +
 Makefile.pre.in                | 2 +-
 Modules/cpython-sys/Cargo.toml | 3 ++-
 Modules/cpython-sys/build.rs   | 3 +++
 4 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index b2080d8d0da80b..f6a41e2ba1b555 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -90,6 +90,7 @@ name = "cpython-sys"
 version = "0.1.0"
 dependencies = [
  "bindgen",
+ "cpython-build-helper",
 ]
 
 [[package]]
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 0f2553f1fcf737..d41e5c1c320aa6 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -3375,7 +3375,7 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 # Module dependencies and platform-specific files
 
 cpython-sys: Modules/cpython-sys/Cargo.toml Modules/cpython-sys/build.rs Modules/cpython-sys/wrapper.h Modules/cpython-sys/parser.h
-	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) \$(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) RUST_SHARED_BUILD=\$(PY_ENABLE_SHARED) \$(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
 
 # force rebuild when header file or module build flavor (static/shared) is changed
 MODULE_DEPS_STATIC=Modules/config.c
diff --git a/Modules/cpython-sys/Cargo.toml b/Modules/cpython-sys/Cargo.toml
index de0b88d5d5b723..f0e9b5bc888b79 100644
--- a/Modules/cpython-sys/Cargo.toml
+++ b/Modules/cpython-sys/Cargo.toml
@@ -6,4 +6,5 @@ edition = "2024"
 [dependencies]
 
 [build-dependencies]
-bindgen = "0.72.1"
\ No newline at end of file
+bindgen = "0.72.1"
+cpython-build-helper = { path = "../cpython-build-helper" }
\ No newline at end of file
diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index a681e498171675..ae71f9c0aebe4b 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -1,7 +1,10 @@
 use std::env;
 use std::path::{Path, PathBuf};
 
+use cpython_build_helper::print_linker_args;
+
 fn main() {
+    print_linker_args();
     let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
     let srcdir = manifest_dir
         .parent()

From e40d3aa4114c7b10dff5ae45632bde70e694a521 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Sun, 1 Mar 2026 21:51:39 +0000
Subject: [PATCH 03/21] Properly pass linker arguments and set up static
 library building

---
 Cargo.lock                     |  1 -
 Makefile.pre.in                | 11 +++++++++--
 Modules/_base64/src/lib.rs     |  3 ---
 Modules/cpython-sys/Cargo.toml |  3 +--
 Modules/cpython-sys/build.rs   |  3 ---
 Modules/makesetup              | 36 +++++++++++++++++++++-------------
 configure                      | 15 ++++++++++++++
 configure.ac                   | 17 ++++++++++++++++
 8 files changed, 64 insertions(+), 25 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f6a41e2ba1b555..b2080d8d0da80b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -90,7 +90,6 @@ name = "cpython-sys"
 version = "0.1.0"
 dependencies = [
  "bindgen",
- "cpython-build-helper",
 ]
 
 [[package]]
diff --git a/Makefile.pre.in b/Makefile.pre.in
index d41e5c1c320aa6..a26bff47da7ef9 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -62,6 +62,8 @@ CARGO_HOME=@CARGO_HOME@
 CARGO_TARGET_DIR=@CARGO_TARGET_DIR@
 CARGO_PROFILE=@CARGO_PROFILE@
 CARGO_TARGET=@CARGO_TARGET@
+CARGO_TARGET_LINKER_ENV=@CARGO_TARGET_LINKER_ENV@
+RUST_STATICLIB_DEP=@RUST_STATICLIB_DEP@
 
 GNULD=		@GNULD@
 
@@ -989,7 +991,7 @@ clinic-tests: check-clean-src $(srcdir)/Lib/test/clinic.test.c
 	$(PYTHON_FOR_REGEN) $(srcdir)/Tools/clinic/clinic.py -f $(srcdir)/Lib/test/clinic.test.c
 
 # Build the interpreter
-$(BUILDPYTHON):	Programs/python.o $(LINK_PYTHON_DEPS)
+$(BUILDPYTHON):	Programs/python.o $(LINK_PYTHON_DEPS) $(RUST_STATICLIB_DEP)
 	$(LINKCC) $(PY_CORE_LDFLAGS) $(LINKFORSHARED) -o $@ Programs/python.o $(LINK_PYTHON_OBJS) $(LIBS) $(MODLIBS) $(SYSLIBS)
 
 platform: $(PYTHON_FOR_BUILD_DEPS) pybuilddir.txt
@@ -3375,7 +3377,12 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 # Module dependencies and platform-specific files
 
 cpython-sys: Modules/cpython-sys/Cargo.toml Modules/cpython-sys/build.rs Modules/cpython-sys/wrapper.h Modules/cpython-sys/parser.h
-	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) RUST_SHARED_BUILD=\$(PY_ENABLE_SHARED) \$(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
+
+RUST_STATICLIB_A= target/$(if $(CARGO_TARGET),$(CARGO_TARGET)/$(CARGO_TARGET_DIR),$(CARGO_TARGET_DIR))/libcpython_rust_staticlib.a
+
+cpython-rust-staticlib: cpython-sys
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-rust-staticlib --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
 
 # force rebuild when header file or module build flavor (static/shared) is changed
 MODULE_DEPS_STATIC=Modules/config.c
diff --git a/Modules/_base64/src/lib.rs b/Modules/_base64/src/lib.rs
index 7e13438ca21c6f..64e4d718789372 100644
--- a/Modules/_base64/src/lib.rs
+++ b/Modules/_base64/src/lib.rs
@@ -115,7 +115,6 @@ impl Drop for BorrowedBuffer {
 /// # Safety
 /// `module` must be a valid pointer of PyObject representing the module.
 /// `args` must be a valid pointer to an array of valid PyObject pointers with length `nargs`.
-#[unsafe(no_mangle)]
 pub unsafe extern "C" fn standard_b64encode(
     _module: *mut PyObject,
     args: *mut *mut PyObject,
@@ -193,13 +192,11 @@ fn standard_b64encode_impl(source: &PyObject) -> Result<*mut PyObject, ()> {
     Ok(result)
 }
 
-#[unsafe(no_mangle)]
 pub extern "C" fn _base64_clear(_obj: *mut PyObject) -> c_int {
     //TODO
     0
 }
 
-#[unsafe(no_mangle)]
 pub extern "C" fn _base64_free(_o: *mut c_void) {
     //TODO
 }
diff --git a/Modules/cpython-sys/Cargo.toml b/Modules/cpython-sys/Cargo.toml
index f0e9b5bc888b79..de0b88d5d5b723 100644
--- a/Modules/cpython-sys/Cargo.toml
+++ b/Modules/cpython-sys/Cargo.toml
@@ -6,5 +6,4 @@ edition = "2024"
 [dependencies]
 
 [build-dependencies]
-bindgen = "0.72.1"
-cpython-build-helper = { path = "../cpython-build-helper" }
\ No newline at end of file
+bindgen = "0.72.1"
\ No newline at end of file
diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index ae71f9c0aebe4b..a681e498171675 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -1,10 +1,7 @@
 use std::env;
 use std::path::{Path, PathBuf};
 
-use cpython_build_helper::print_linker_args;
-
 fn main() {
-    print_linker_args();
     let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
     let srcdir = manifest_dir
         .parent()
diff --git a/Modules/makesetup b/Modules/makesetup
index 25b091cde689c1..c8e68e96c34880 100755
--- a/Modules/makesetup
+++ b/Modules/makesetup
@@ -296,22 +296,30 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 			objs=
 			libs=
 
-			for mod in $mods
-			do
-				rust_shared="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/lib$mod\$(SHLIB_SUFFIX)"
-				file="$srcdir/$mod\$(EXT_SUFFIX)"
-				case $doconfig in
-				no)
+			case $doconfig in
+			no)
+				# Shared build: build each Rust module as a cdylib (.so)
+				for mod in $mods
+				do
+					rust_shared="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/lib$mod\$(SHLIB_SUFFIX)"
+					file="$srcdir/$mod\$(EXT_SUFFIX)"
 					SHAREDMODS="$SHAREDMODS $file"
 					BUILT_SHARED="$BUILT_SHARED $mod"
-					;;
-				esac
-				# depends on the headers through cpython-sys
-				rule="$rust_shared: cpython-sys \$(srcdir)/Cargo.toml \$(srcdir)/Cargo.lock \$(srcdir)/$srcdir/$manifest $prefixed_srcs \$(PYTHON_HEADERS) \$(MODULE_${mods_upper}_LDEPS) \$(LIBRARY)"
-				rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) RUST_SHARED_BUILD=\$(PY_ENABLE_SHARED) \$(CARGO_HOME)/bin/cargo build -vvv --lib --locked --package ${mod} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
-				echo "$rule" >>$rulesf
-				echo "$file: $rust_shared; mv $rust_shared $file" >>$rulesf
-			done
+					# depends on the headers through cpython-sys
+					rule="$rust_shared: cpython-sys \$(srcdir)/Cargo.toml \$(srcdir)/Cargo.lock \$(srcdir)/$srcdir/$manifest $prefixed_srcs \$(PYTHON_HEADERS) \$(MODULE_${mods_upper}_LDEPS) \$(LIBRARY)"
+					rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) RUST_SHARED_BUILD=\$(PY_ENABLE_SHARED) BLDSHARED_ARGS=\"\$(BLDSHARED_ARGS)\" \$(if \$(CARGO_TARGET_LINKER_ENV),\$(CARGO_TARGET_LINKER_ENV)=\$(CC)) \$(CARGO_HOME)/bin/cargo build -vvv --lib --locked --package ${mod} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
+					echo "$rule" >>$rulesf
+					echo "$file: $rust_shared; mv $rust_shared $file" >>$rulesf
+				done
+				;;
+			yes)
+				# Static build: Rust modules are built as part of cpython-rust-staticlib.
+				# The dependency on cpython-rust-staticlib is in Makefile.pre.in
+				# (via RUST_STATICLIB_DEP on the BUILDPYTHON rule).
+				rust_staticlib="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/libcpython_rust_staticlib.a"
+				LIBS="$LIBS $rust_staticlib"
+				;;
+			esac
 		fi
 	done
 
diff --git a/configure b/configure
index 911577c444b79c..944c18f499eecd 100755
--- a/configure
+++ b/configure
@@ -824,6 +824,7 @@ MODULE_TIME_FALSE
 MODULE_TIME_TRUE
 MODULE__IO_FALSE
 MODULE__IO_TRUE
+RUST_STATICLIB_DEP
 MODULE_BUILDTYPE
 _PYTHREAD_NAME_MAXLEN
 TEST_MODULES
@@ -887,6 +888,7 @@ TCLTK_LIBS
 TCLTK_CFLAGS
 LIBSQLITE3_LIBS
 LIBSQLITE3_CFLAGS
+CARGO_TARGET_LINKER_ENV
 CARGO_TARGET
 CARGO_PROFILE
 CARGO_TARGET_DIR
@@ -16143,6 +16145,12 @@ else
       ;;
   esac
 fi
+if test -n "$CARGO_TARGET"; then
+  CARGO_TARGET_LINKER_ENV="CARGO_TARGET_$(echo "$CARGO_TARGET" | tr 'a-z-' 'A-Z_')_LINKER"
+else
+  CARGO_TARGET_LINKER_ENV=""
+fi
+
 
 
 
@@ -31378,6 +31386,13 @@ case $host_cpu in #(
 esac
 
 
+if test "$HAVE_CARGO" != "no" -a "$MODULE_BUILDTYPE" = "static"; then
+  RUST_STATICLIB_DEP=cpython-rust-staticlib
+else
+  RUST_STATICLIB_DEP=
+fi
+
+
 
 MODULE_BLOCK=
 
diff --git a/configure.ac b/configure.ac
index 852d7c83718d21..2eec993e841cb0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4364,10 +4364,18 @@ else
       ;;
   esac
 fi
+dnl Compute the CARGO_TARGET_<triple>_LINKER env var name so we can
+dnl tell Cargo which linker to use for the target platform.
+if test -n "$CARGO_TARGET"; then
+  CARGO_TARGET_LINKER_ENV="CARGO_TARGET_$(echo "$CARGO_TARGET" | tr 'a-z-' 'A-Z_')_LINKER"
+else
+  CARGO_TARGET_LINKER_ENV=""
+fi
 AC_SUBST([CARGO_HOME])
 AC_SUBST([CARGO_TARGET_DIR])
 AC_SUBST([CARGO_PROFILE])
 AC_SUBST([CARGO_TARGET])
+AC_SUBST([CARGO_TARGET_LINKER_ENV])
 
 
 dnl detect sqlite3 from Emscripten emport
@@ -7882,6 +7890,15 @@ AS_CASE([$host_cpu],
 )
 AC_SUBST([MODULE_BUILDTYPE])
 
+dnl Set RUST_STATICLIB_DEP to cpython-rust-staticlib when building Rust
+dnl modules statically so that the python binary depends on it.
+if test "$HAVE_CARGO" != "no" -a "$MODULE_BUILDTYPE" = "static"; then
+  RUST_STATICLIB_DEP=cpython-rust-staticlib
+else
+  RUST_STATICLIB_DEP=
+fi
+AC_SUBST([RUST_STATICLIB_DEP])
+
 dnl _MODULE_BLOCK_ADD([VAR], [VALUE])
 dnl internal: adds $1=quote($2) to MODULE_BLOCK
 AC_DEFUN([_MODULE_BLOCK_ADD], [AS_VAR_APPEND([MODULE_BLOCK], ["$1=_AS_QUOTE([$2])$as_nl"])])

From e24aa53e5112ed3b7c430c89a015ea1d456eea47 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Sun, 1 Mar 2026 22:04:45 +0000
Subject: [PATCH 04/21] Modify build helper to handle differences in how Python
 symbols are linked in

---
 Modules/cpython-build-helper/src/lib.rs | 43 ++++++++++++++++++++-----
 Modules/makesetup                       |  2 +-
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/Modules/cpython-build-helper/src/lib.rs b/Modules/cpython-build-helper/src/lib.rs
index f9fc5b2e77fc46..1f96750afa3d81 100644
--- a/Modules/cpython-build-helper/src/lib.rs
+++ b/Modules/cpython-build-helper/src/lib.rs
@@ -3,15 +3,42 @@ use std::env;
 /// Print necessary link arguments for the library depending on the build
 /// configuration (static or shared)
 pub fn print_linker_args() {
-    let shared_build = env::var("RUST_SHARED_BUILD").expect("RUST_SHARED_BUILD not set in Makefile?");
-    if shared_build == "1" {
-        let build_shared_args =
-            env::var("BLDSHARED_ARGS").expect("BLDSHARED_ARGS not set in Makefile?");
-        // TODO(emmatyping): Ideally, we would not need to split the args here and take shlex
-        // as a dependency.
-        for arg in shlex::split(&build_shared_args).expect("Invalid BUILDSHARED_ARGS") {
-            println!("cargo:rustc-link-arg={}", arg);
+    let target = env::var("TARGET").unwrap_or_default();
+
+    // On Apple platforms (macOS, iOS), Cargo's cdylib produces a Mach-O
+    // dynamiclib (via -dynamiclib), but CPython's C extensions are built as
+    // bundles (via -bundle). Unlike bundles, dynamiclibs require all symbols
+    // to be resolved at link time. Pass -undefined dynamic_lookup so that
+    // Python C API symbols are resolved at load time by the interpreter.
+    if target.contains("apple") {
+        println!("cargo:rustc-cdylib-link-arg=-undefined");
+        println!("cargo:rustc-cdylib-link-arg=dynamic_lookup");
+    }
+
+    // Pass platform-specific shared link arguments (e.g. PY_CORE_LDFLAGS)
+    // from the CPython build system.
+    if let Ok(args) = env::var("BLDSHARED_ARGS") {
+        let args = shlex::split(&args).expect("Invalid BLDSHARED_ARGS");
+        let mut iter = args.iter();
+        while let Some(arg) = iter.next() {
+            // -bundle_loader is incompatible with Cargo's cdylib on macOS
+            // (it only works with -bundle, not -dynamiclib). Skip it and
+            // its argument.
+            if arg == "-bundle_loader" {
+                iter.next(); // skip the path argument
+                continue;
+            }
+            println!("cargo:rustc-cdylib-link-arg={}", arg);
         }
     }
+
+    // On Android (and Cygwin), extension modules must link against libpython.
+    // LIBPYTHON is set by the CPython build system on these platforms.
+    if let Ok(libpython) = env::var("LIBPYTHON") {
+        for arg in shlex::split(&libpython).expect("Invalid LIBPYTHON") {
+            println!("cargo:rustc-cdylib-link-arg={}", arg);
+        }
+    }
+
     // Static linker configuration is in cpython-rust-staticlib
 }
diff --git a/Modules/makesetup b/Modules/makesetup
index c8e68e96c34880..27758a133b65eb 100755
--- a/Modules/makesetup
+++ b/Modules/makesetup
@@ -307,7 +307,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 					BUILT_SHARED="$BUILT_SHARED $mod"
 					# depends on the headers through cpython-sys
 					rule="$rust_shared: cpython-sys \$(srcdir)/Cargo.toml \$(srcdir)/Cargo.lock \$(srcdir)/$srcdir/$manifest $prefixed_srcs \$(PYTHON_HEADERS) \$(MODULE_${mods_upper}_LDEPS) \$(LIBRARY)"
-					rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) RUST_SHARED_BUILD=\$(PY_ENABLE_SHARED) BLDSHARED_ARGS=\"\$(BLDSHARED_ARGS)\" \$(if \$(CARGO_TARGET_LINKER_ENV),\$(CARGO_TARGET_LINKER_ENV)=\$(CC)) \$(CARGO_HOME)/bin/cargo build -vvv --lib --locked --package ${mod} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
+					rule="$rule; CARGO_TARGET_DIR=\$(abs_builddir)/target PYTHON_BUILD_DIR=\$(abs_builddir) BLDSHARED_ARGS=\"\$(BLDSHARED_ARGS)\" LIBPYTHON=\"\$(LIBPYTHON)\" \$(if \$(CARGO_TARGET_LINKER_ENV),\$(CARGO_TARGET_LINKER_ENV)=\$(CC)) \$(CARGO_HOME)/bin/cargo build -vvv --lib --locked --package ${mod} --profile \$(CARGO_PROFILE) \$(if \$(CARGO_TARGET),--target=\$(CARGO_TARGET)) --manifest-path \$(srcdir)/Cargo.toml"
 					echo "$rule" >>$rulesf
 					echo "$file: $rust_shared; mv $rust_shared $file" >>$rulesf
 				done

From 025f3fcd99f5b47cc13d50f77dccff2f47a19318 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Sun, 1 Mar 2026 22:18:47 +0000
Subject: [PATCH 05/21] Modify cdylib suffix on macOS

---
 Makefile.pre.in   | 1 +
 Modules/makesetup | 2 +-
 configure         | 6 ++++++
 configure.ac      | 8 ++++++++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Makefile.pre.in b/Makefile.pre.in
index a26bff47da7ef9..33dc645fb9c230 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -63,6 +63,7 @@ CARGO_TARGET_DIR=@CARGO_TARGET_DIR@
 CARGO_PROFILE=@CARGO_PROFILE@
 CARGO_TARGET=@CARGO_TARGET@
 CARGO_TARGET_LINKER_ENV=@CARGO_TARGET_LINKER_ENV@
+CARGO_DYLIB_SUFFIX=@CARGO_DYLIB_SUFFIX@
 RUST_STATICLIB_DEP=@RUST_STATICLIB_DEP@
 
 GNULD=		@GNULD@
diff --git a/Modules/makesetup b/Modules/makesetup
index 27758a133b65eb..4b5085d843f1e7 100755
--- a/Modules/makesetup
+++ b/Modules/makesetup
@@ -301,7 +301,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 				# Shared build: build each Rust module as a cdylib (.so)
 				for mod in $mods
 				do
-					rust_shared="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/lib$mod\$(SHLIB_SUFFIX)"
+					rust_shared="target/\$(if \$(CARGO_TARGET),\$(CARGO_TARGET)/\$(CARGO_TARGET_DIR),\$(CARGO_TARGET_DIR))/lib$mod\$(CARGO_DYLIB_SUFFIX)"
 					file="$srcdir/$mod\$(EXT_SUFFIX)"
 					SHAREDMODS="$SHAREDMODS $file"
 					BUILT_SHARED="$BUILT_SHARED $mod"
diff --git a/configure b/configure
index 944c18f499eecd..00b93c838a4bb3 100755
--- a/configure
+++ b/configure
@@ -888,6 +888,7 @@ TCLTK_LIBS
 TCLTK_CFLAGS
 LIBSQLITE3_LIBS
 LIBSQLITE3_CFLAGS
+CARGO_DYLIB_SUFFIX
 CARGO_TARGET_LINKER_ENV
 CARGO_TARGET
 CARGO_PROFILE
@@ -16150,6 +16151,11 @@ if test -n "$CARGO_TARGET"; then
 else
   CARGO_TARGET_LINKER_ENV=""
 fi
+case "$host" in
+  *-apple-*)  CARGO_DYLIB_SUFFIX=".dylib";;
+  *)          CARGO_DYLIB_SUFFIX="$SHLIB_SUFFIX";;
+esac
+
 
 
 
diff --git a/configure.ac b/configure.ac
index 2eec993e841cb0..ccdd55802ba2bb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4371,11 +4371,19 @@ if test -n "$CARGO_TARGET"; then
 else
   CARGO_TARGET_LINKER_ENV=""
 fi
+dnl Cargo's cdylib crate type uses the platform's native shared library
+dnl extension, which differs from CPython's SHLIB_SUFFIX on macOS/iOS
+dnl (CPython uses .so, Cargo uses .dylib).
+case "$host" in
+  *-apple-*)  CARGO_DYLIB_SUFFIX=".dylib";;
+  *)          CARGO_DYLIB_SUFFIX="$SHLIB_SUFFIX";;
+esac
 AC_SUBST([CARGO_HOME])
 AC_SUBST([CARGO_TARGET_DIR])
 AC_SUBST([CARGO_PROFILE])
 AC_SUBST([CARGO_TARGET])
 AC_SUBST([CARGO_TARGET_LINKER_ENV])
+AC_SUBST([CARGO_DYLIB_SUFFIX])
 
 
 dnl detect sqlite3 from Emscripten emport

From 5ce8a5fd2e20e88ca36ef0e4d091ffdcfce3f696 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 04:31:55 +0000
Subject: [PATCH 06/21] Calculate Rust target from Misc/platform_triplet.c

---
 Misc/platform_triplet.c | 90 +++++++++++++++++++++++++++++++++++++++++
 configure               | 34 +++++-----------
 configure.ac            | 34 +++++-----------
 3 files changed, 112 insertions(+), 46 deletions(-)

diff --git a/Misc/platform_triplet.c b/Misc/platform_triplet.c
index f5cd73bdea8333..13da020b84f2e3 100644
--- a/Misc/platform_triplet.c
+++ b/Misc/platform_triplet.c
@@ -1,5 +1,8 @@
 /* Detect platform triplet from builtin defines
  * cc -E Misc/platform_triplet.c | grep '^PLATFORM_TRIPLET=' | tr -d ' '
+ *
+ * Also detects the closest Rust target triple for cargo/rustc:
+ * cc -E Misc/platform_triplet.c | grep '^RUST_TARGET=' | tr -d ' '
  */
 #undef bfin
 #undef cris
@@ -16,12 +19,16 @@
 #if defined(__ANDROID__)
 #  if defined(__x86_64__)
 PLATFORM_TRIPLET=x86_64-linux-android
+RUST_TARGET=x86_64-linux-android
 #  elif defined(__i386__)
 PLATFORM_TRIPLET=i686-linux-android
+RUST_TARGET=i686-linux-android
 #  elif defined(__aarch64__)
 PLATFORM_TRIPLET=aarch64-linux-android
+RUST_TARGET=aarch64-linux-android
 #  elif defined(__arm__)
 PLATFORM_TRIPLET=arm-linux-androideabi
+RUST_TARGET=arm-linux-androideabi
 #  else
 #    error unknown Android platform
 #  endif
@@ -39,18 +46,25 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 # elif defined(__GLIBC__)
 #  define LIBC gnu
 #  define LIBC_X32 gnux32
+#  define RUST_LIBC gnu
+#  define RUST_LIBC_X32 gnux32
 #  if defined(__ARM_PCS_VFP)
 #   define LIBC_ARM gnueabihf
+#   define RUST_LIBC_ARM gnueabihf
 #  else
 #   define LIBC_ARM gnueabi
+#   define RUST_LIBC_ARM gnueabi
 #  endif
 #  if defined(__loongarch__)
 #   if defined(__loongarch_soft_float)
 #    define LIBC_LA gnusf
+#    define RUST_LIBC_LA unknown
 #   elif defined(__loongarch_single_float)
 #    define LIBC_LA gnuf32
+#    define RUST_LIBC_LA unknown
 #   elif defined(__loongarch_double_float)
 #    define LIBC_LA gnu
+#    define RUST_LIBC_LA gnu
 #   else
 #    error unknown loongarch floating-point base abi
 #   endif
@@ -59,20 +73,26 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 #   if defined(__mips_hard_float)
 #    if defined(_ABIO32) && _MIPS_SIM == _ABIO32
 #     define LIBC_MIPS gnu
+#     define RUST_LIBC_MIPS gnu
 #    elif defined(_ABIN32) && _MIPS_SIM == _ABIN32
 #     define LIBC_MIPS gnuabin32
+#     define RUST_LIBC_MIPS unknown
 #    elif defined(_ABI64) && _MIPS_SIM == _ABI64
 #     define LIBC_MIPS gnuabi64
+#     define RUST_LIBC_MIPS gnuabi64
 #    else
 #     error unknown mips sim value
 #    endif
 #   else
 #    if defined(_ABIO32) && _MIPS_SIM == _ABIO32
 #     define LIBC_MIPS gnusf
+#     define RUST_LIBC_MIPS unknown
 #    elif defined(_ABIN32) && _MIPS_SIM == _ABIN32
 #     define LIBC_MIPS gnuabin32sf
+#     define RUST_LIBC_MIPS unknown
 #    elif defined(_ABI64) && _MIPS_SIM == _ABI64
 #     define LIBC_MIPS gnuabi64sf
+#     define RUST_LIBC_MIPS unknown
 #    else
 #     error unknown mips sim value
 #    endif
@@ -80,8 +100,10 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 #  endif
 #  if defined(__SPE__)
 #   define LIBC_PPC gnuspe
+#   define RUST_LIBC_PPC gnuspe
 #  else
 #   define LIBC_PPC gnu
+#   define RUST_LIBC_PPC gnu
 #  endif
 # else
 // Heuristic to detect musl libc
@@ -89,18 +111,25 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 #  ifdef __DEFINED_va_list
 #   define LIBC musl
 #   define LIBC_X32 muslx32
+#   define RUST_LIBC musl
+#   define RUST_LIBC_X32 unknown
 #   if defined(__ARM_PCS_VFP)
 #    define LIBC_ARM musleabihf
+#    define RUST_LIBC_ARM musleabihf
 #   else
 #    define LIBC_ARM musleabi
+#    define RUST_LIBC_ARM musleabi
 #   endif
 #   if defined(__loongarch__)
 #    if defined(__loongarch_soft_float)
 #     define LIBC_LA muslsf
+#     define RUST_LIBC_LA unknown
 #    elif defined(__loongarch_single_float)
 #     define LIBC_LA muslf32
+#     define RUST_LIBC_LA unknown
 #    elif defined(__loongarch_double_float)
 #     define LIBC_LA musl
+#     define RUST_LIBC_LA musl
 #    else
 #     error unknown loongarch floating-point base abi
 #    endif
@@ -109,20 +138,26 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 #    if defined(__mips_hard_float)
 #     if defined(_ABIO32) && _MIPS_SIM == _ABIO32
 #      define LIBC_MIPS musl
+#      define RUST_LIBC_MIPS musl
 #     elif defined(_ABIN32) && _MIPS_SIM == _ABIN32
 #      define LIBC_MIPS musln32
+#      define RUST_LIBC_MIPS unknown
 #     elif defined(_ABI64) && _MIPS_SIM == _ABI64
 #      define LIBC_MIPS musl
+#      define RUST_LIBC_MIPS muslabi64
 #     else
 #      error unknown mips sim value
 #     endif
 #    else
 #     if defined(_ABIO32) && _MIPS_SIM == _ABIO32
 #      define LIBC_MIPS muslsf
+#      define RUST_LIBC_MIPS unknown
 #     elif defined(_ABIN32) && _MIPS_SIM == _ABIN32
 #      define LIBC_MIPS musln32sf
+#      define RUST_LIBC_MIPS unknown
 #     elif defined(_ABI64) && _MIPS_SIM == _ABI64
 #      define LIBC_MIPS muslsf
+#      define RUST_LIBC_MIPS unknown
 #     else
 #      error unknown mips sim value
 #     endif
@@ -130,8 +165,10 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 #   endif
 #   if defined(_SOFT_FLOAT) || defined(__NO_FPRS__)
 #    define LIBC_PPC muslsf
+#    define RUST_LIBC_PPC unknown
 #   else
 #    define LIBC_PPC musl
+#    define RUST_LIBC_PPC musl
 #   endif
 #  else
 #   error unknown libc
@@ -140,85 +177,118 @@ PLATFORM_TRIPLET=arm-linux-androideabi
 
 # if defined(__x86_64__) && defined(__LP64__)
 PLATFORM_TRIPLET=x86_64-linux-LIBC
+RUST_TARGET=x86_64-unknown-linux-RUST_LIBC
 # elif defined(__x86_64__) && defined(__ILP32__)
 PLATFORM_TRIPLET=x86_64-linux-LIBC_X32
+RUST_TARGET=x86_64-unknown-linux-RUST_LIBC_X32
 # elif defined(__i386__)
 PLATFORM_TRIPLET=i386-linux-LIBC
+RUST_TARGET=i686-unknown-linux-RUST_LIBC
 # elif defined(__aarch64__) && defined(__AARCH64EL__)
 #  if defined(__ILP32__)
 PLATFORM_TRIPLET=aarch64_ilp32-linux-LIBC
+RUST_TARGET=unknown
 #  else
 PLATFORM_TRIPLET=aarch64-linux-LIBC
+RUST_TARGET=aarch64-unknown-linux-RUST_LIBC
 #  endif
 # elif defined(__aarch64__) && defined(__AARCH64EB__)
 #  if defined(__ILP32__)
 PLATFORM_TRIPLET=aarch64_be_ilp32-linux-LIBC
+RUST_TARGET=unknown
 #  else
 PLATFORM_TRIPLET=aarch64_be-linux-LIBC
+RUST_TARGET=aarch64_be-unknown-linux-RUST_LIBC
 #  endif
 # elif defined(__alpha__)
 PLATFORM_TRIPLET=alpha-linux-LIBC
+RUST_TARGET=unknown
 # elif defined(__ARM_EABI__)
 #  if defined(__ARMEL__)
 PLATFORM_TRIPLET=arm-linux-LIBC_ARM
+RUST_TARGET=arm-unknown-linux-RUST_LIBC_ARM
 #  else
 PLATFORM_TRIPLET=armeb-linux-LIBC_ARM
+RUST_TARGET=armeb-unknown-linux-RUST_LIBC_ARM
 #  endif
 # elif defined(__hppa__)
 PLATFORM_TRIPLET=hppa-linux-LIBC
+RUST_TARGET=unknown
 # elif defined(__ia64__)
 PLATFORM_TRIPLET=ia64-linux-LIBC
+RUST_TARGET=unknown
 # elif defined(__loongarch__) && defined(__loongarch_lp64)
 PLATFORM_TRIPLET=loongarch64-linux-LIBC_LA
+RUST_TARGET=loongarch64-unknown-linux-RUST_LIBC_LA
 # elif defined(__m68k__) && !defined(__mcoldfire__)
 PLATFORM_TRIPLET=m68k-linux-LIBC
+RUST_TARGET=m68k-unknown-linux-RUST_LIBC
 # elif defined(__mips__)
 #  if defined(__mips_isa_rev) && (__mips_isa_rev >=6)
 #   if defined(_MIPSEL) && defined(__mips64)
 PLATFORM_TRIPLET=mipsisa64r6el-linux-LIBC_MIPS
+RUST_TARGET=mipsisa64r6el-unknown-linux-RUST_LIBC_MIPS
 #   elif defined(_MIPSEL)
 PLATFORM_TRIPLET=mipsisa32r6el-linux-LIBC_MIPS
+RUST_TARGET=mipsisa32r6el-unknown-linux-RUST_LIBC_MIPS
 #   elif defined(__mips64)
 PLATFORM_TRIPLET=mipsisa64r6-linux-LIBC_MIPS
+RUST_TARGET=mipsisa64r6-unknown-linux-RUST_LIBC_MIPS
 #   else
 PLATFORM_TRIPLET=mipsisa32r6-linux-LIBC_MIPS
+RUST_TARGET=mipsisa32r6-unknown-linux-RUST_LIBC_MIPS
 #   endif
 #  else
 #   if defined(_MIPSEL) && defined(__mips64)
 PLATFORM_TRIPLET=mips64el-linux-LIBC_MIPS
+RUST_TARGET=mips64el-unknown-linux-RUST_LIBC_MIPS
 #   elif defined(_MIPSEL)
 PLATFORM_TRIPLET=mipsel-linux-LIBC_MIPS
+RUST_TARGET=mipsel-unknown-linux-RUST_LIBC_MIPS
 #   elif defined(__mips64)
 PLATFORM_TRIPLET=mips64-linux-LIBC_MIPS
+RUST_TARGET=mips64-unknown-linux-RUST_LIBC_MIPS
 #   else
 PLATFORM_TRIPLET=mips-linux-LIBC_MIPS
+RUST_TARGET=mips-unknown-linux-RUST_LIBC_MIPS
 #   endif
 #  endif
 # elif defined(__or1k__)
 PLATFORM_TRIPLET=or1k-linux-LIBC
+RUST_TARGET=unknown
 # elif defined(__powerpc64__)
 #  if defined(__LITTLE_ENDIAN__)
 PLATFORM_TRIPLET=powerpc64le-linux-LIBC
+RUST_TARGET=powerpc64le-unknown-linux-RUST_LIBC
 #  else
 PLATFORM_TRIPLET=powerpc64-linux-LIBC
+RUST_TARGET=powerpc64-unknown-linux-RUST_LIBC
 #  endif
 # elif defined(__powerpc__)
 PLATFORM_TRIPLET=powerpc-linux-LIBC_PPC
+RUST_TARGET=powerpc-unknown-linux-RUST_LIBC_PPC
 # elif defined(__s390x__)
 PLATFORM_TRIPLET=s390x-linux-LIBC
+RUST_TARGET=s390x-unknown-linux-RUST_LIBC
 # elif defined(__s390__)
 PLATFORM_TRIPLET=s390-linux-LIBC
+RUST_TARGET=unknown
 # elif defined(__sh__) && defined(__LITTLE_ENDIAN__)
 PLATFORM_TRIPLET=sh4-linux-LIBC
+RUST_TARGET=unknown
 # elif defined(__sparc__) && defined(__arch64__)
 PLATFORM_TRIPLET=sparc64-linux-LIBC
+RUST_TARGET=sparc64-unknown-linux-RUST_LIBC
 # elif defined(__sparc__)
 PLATFORM_TRIPLET=sparc-linux-LIBC
+RUST_TARGET=sparc-unknown-linux-RUST_LIBC
 # elif defined(__riscv)
 #  if __riscv_xlen == 32
 PLATFORM_TRIPLET=riscv32-linux-LIBC
+RUST_TARGET=riscv32gc-unknown-linux-RUST_LIBC
 #  elif __riscv_xlen == 64
 PLATFORM_TRIPLET=riscv64-linux-LIBC
+RUST_TARGET=riscv64gc-unknown-linux-RUST_LIBC
 #  else
 #   error unknown platform triplet
 #  endif
@@ -231,16 +301,20 @@ PLATFORM_TRIPLET=riscv64-linux-LIBC
 #elif defined(__FreeBSD_kernel__)
 # if defined(__LP64__)
 PLATFORM_TRIPLET=x86_64-kfreebsd-gnu
+RUST_TARGET=unknown
 # elif defined(__i386__)
 PLATFORM_TRIPLET=i386-kfreebsd-gnu
+RUST_TARGET=unknown
 # else
 #   error unknown platform triplet
 # endif
 #elif defined(__gnu_hurd__)
 # if defined(__x86_64__) && defined(__LP64__)
 PLATFORM_TRIPLET=x86_64-gnu
+RUST_TARGET=x86_64-unknown-hurd-gnu
 # elif defined(__i386__)
 PLATFORM_TRIPLET=i386-gnu
+RUST_TARGET=i686-unknown-hurd-gnu
 # else
 #   error unknown platform triplet
 # endif
@@ -251,28 +325,42 @@ PLATFORM_TRIPLET=i386-gnu
 #    if defined(TARGET_OS_SIMULATOR) && TARGET_OS_SIMULATOR
 #      if __x86_64__
 PLATFORM_TRIPLET=x86_64-iphonesimulator
+RUST_TARGET=x86_64-apple-ios
 #      else
 PLATFORM_TRIPLET=arm64-iphonesimulator
+RUST_TARGET=aarch64-apple-ios-sim
 #      endif
 #    else
 PLATFORM_TRIPLET=arm64-iphoneos
+RUST_TARGET=aarch64-apple-ios
 #    endif
 // Older macOS SDKs do not define TARGET_OS_OSX
 #  elif !defined(TARGET_OS_OSX) || TARGET_OS_OSX
 PLATFORM_TRIPLET=darwin
+#    if defined(__x86_64__)
+RUST_TARGET=x86_64-apple-darwin
+#    elif defined(__aarch64__)
+RUST_TARGET=aarch64-apple-darwin
+#    else
+RUST_TARGET=unknown
+#    endif
 #  else
 #    error unknown Apple platform
 #  endif
 #elif defined(__VXWORKS__)
 PLATFORM_TRIPLET=vxworks
+RUST_TARGET=unknown
 #elif defined(__wasm32__)
 #  if defined(__EMSCRIPTEN__)
 PLATFORM_TRIPLET=wasm32-emscripten
+RUST_TARGET=wasm32-unknown-emscripten
 #  elif defined(__wasi__)
 #    if defined(_REENTRANT)
 PLATFORM_TRIPLET=wasm32-wasi-threads
+RUST_TARGET=wasm32-wasip1-threads
 #    else
 PLATFORM_TRIPLET=wasm32-wasi
+RUST_TARGET=wasm32-wasip1
 #    endif
 #  else
 #    error unknown wasm32 platform
@@ -280,8 +368,10 @@ PLATFORM_TRIPLET=wasm32-wasi
 #elif defined(__wasm64__)
 #  if defined(__EMSCRIPTEN__)
 PLATFORM_TRIPLET=wasm64-emscripten
+RUST_TARGET=unknown
 #  elif defined(__wasi__)
 PLATFORM_TRIPLET=wasm64-wasi
+RUST_TARGET=unknown
 #  else
 #    error unknown wasm64 platform
 #  endif
diff --git a/configure b/configure
index 00b93c838a4bb3..a74a40722c39e3 100755
--- a/configure
+++ b/configure
@@ -7177,6 +7177,8 @@ printf %s "checking for the platform triplet based on compiler characteristics..
 if $CPP $CPPFLAGS $srcdir/Misc/platform_triplet.c >conftest.out 2>/dev/null; then
   PLATFORM_TRIPLET=`grep '^PLATFORM_TRIPLET=' conftest.out | tr -d ' 	'`
   PLATFORM_TRIPLET="${PLATFORM_TRIPLET#PLATFORM_TRIPLET=}"
+  RUST_TARGET=`grep '^RUST_TARGET=' conftest.out | tr -d ' 	'`
+  RUST_TARGET="${RUST_TARGET#RUST_TARGET=}"
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PLATFORM_TRIPLET" >&5
 printf "%s\n" "$PLATFORM_TRIPLET" >&6; }
 else
@@ -16122,29 +16124,15 @@ else
     CARGO_TARGET_DIR='debug'
     CARGO_PROFILE='dev'
   fi
-  # Set CARGO_TARGET for cross-compilation
-  # TODO(emmatyping): derive this in platform-triplet.c and set the Rust triple
-  # higher up
-  case "$host" in
-    aarch64-apple-ios-simulator)
-      CARGO_TARGET="aarch64-apple-ios-sim"
-      ;;
-    *-apple-darwin*)
-      cargo_host="$host"
-      case "$cargo_host" in
-        arm64-apple-*)
-          cargo_host="aarch64${cargo_host#arm64}"
-          ;;
-      esac
-      CARGO_TARGET="${cargo_host%%-apple-darwin*}-apple-darwin"
-      ;;
-    *-pc-linux-*)
-      CARGO_TARGET=$(echo "$host" | sed 's/-pc-linux-/-unknown-linux-/')
-      ;;
-    *)
-      CARGO_TARGET="$host"
-      ;;
-  esac
+  # RUST_TARGET is detected from Misc/platform_triplet.c using the
+  # C preprocessor, giving us the correct Rust target triple for the
+  # platform being compiled for.
+  CARGO_TARGET="$RUST_TARGET"
+  if test -z "$CARGO_TARGET" || test "$CARGO_TARGET" = "unknown"; then
+    as_fn_error $? "Could not determine a Rust target triple for this platform.
+      Rust may not support this target. Set CARGO_TARGET manually or
+      disable Rust support." "$LINENO" 5
+  fi
 fi
 if test -n "$CARGO_TARGET"; then
   CARGO_TARGET_LINKER_ENV="CARGO_TARGET_$(echo "$CARGO_TARGET" | tr 'a-z-' 'A-Z_')_LINKER"
diff --git a/configure.ac b/configure.ac
index ccdd55802ba2bb..554a33af76c536 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1154,6 +1154,8 @@ AC_MSG_CHECKING([for the platform triplet based on compiler characteristics])
 if $CPP $CPPFLAGS $srcdir/Misc/platform_triplet.c >conftest.out 2>/dev/null; then
   PLATFORM_TRIPLET=`grep '^PLATFORM_TRIPLET=' conftest.out | tr -d ' 	'`
   PLATFORM_TRIPLET="${PLATFORM_TRIPLET@%:@PLATFORM_TRIPLET=}"
+  RUST_TARGET=`grep '^RUST_TARGET=' conftest.out | tr -d ' 	'`
+  RUST_TARGET="${RUST_TARGET@%:@RUST_TARGET=}"
   AC_MSG_RESULT([$PLATFORM_TRIPLET])
 else
   AC_MSG_RESULT([none])
@@ -4340,29 +4342,15 @@ else
     CARGO_TARGET_DIR='debug'
     CARGO_PROFILE='dev'
   fi
-  # Set CARGO_TARGET for cross-compilation
-  # TODO(emmatyping): derive this in platform-triplet.c and set the Rust triple
-  # higher up
-  case "$host" in
-    aarch64-apple-ios-simulator)
-      CARGO_TARGET="aarch64-apple-ios-sim"
-      ;;
-    *-apple-darwin*)
-      cargo_host="$host"
-      case "$cargo_host" in
-        arm64-apple-*)
-          cargo_host="aarch64${cargo_host#arm64}"
-          ;;
-      esac
-      CARGO_TARGET="${cargo_host%%-apple-darwin*}-apple-darwin"
-      ;;
-    *-pc-linux-*)
-      CARGO_TARGET=$(echo "$host" | sed 's/-pc-linux-/-unknown-linux-/')
-      ;;
-    *)
-      CARGO_TARGET="$host"
-      ;;
-  esac
+  # RUST_TARGET is detected from Misc/platform_triplet.c using the
+  # C preprocessor, giving us the correct Rust target triple for the
+  # platform being compiled for.
+  CARGO_TARGET="$RUST_TARGET"
+  if test -z "$CARGO_TARGET" || test "$CARGO_TARGET" = "unknown"; then
+    AC_MSG_ERROR([Could not determine a Rust target triple for this platform.
+      Rust may not support this target. Set CARGO_TARGET manually or
+      disable Rust support.])
+  fi
 fi
 dnl Compute the CARGO_TARGET_<triple>_LINKER env var name so we can
 dnl tell Cargo which linker to use for the target platform.

From cb43e5b961aad18e7186bdc0f2b15dbfd6879313 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 04:47:52 +0000
Subject: [PATCH 07/21] Pass CPPFLAGS to cpython-sys and set target

---
 Cargo.lock                     |  1 +
 Makefile.pre.in                |  2 +-
 Modules/cpython-sys/Cargo.toml |  3 ++-
 Modules/cpython-sys/build.rs   | 35 ++++++++++++++++++++++++++++++----
 4 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index b2080d8d0da80b..132b913b06d5e5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -90,6 +90,7 @@ name = "cpython-sys"
 version = "0.1.0"
 dependencies = [
  "bindgen",
+ "shlex",
 ]
 
 [[package]]
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 33dc645fb9c230..489b5cf6a45170 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -3378,7 +3378,7 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 # Module dependencies and platform-specific files
 
 cpython-sys: Modules/cpython-sys/Cargo.toml Modules/cpython-sys/build.rs Modules/cpython-sys/wrapper.h Modules/cpython-sys/parser.h
-	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) PY_CPPFLAGS="$(CPPFLAGS)" $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
 
 RUST_STATICLIB_A= target/$(if $(CARGO_TARGET),$(CARGO_TARGET)/$(CARGO_TARGET_DIR),$(CARGO_TARGET_DIR))/libcpython_rust_staticlib.a
 
diff --git a/Modules/cpython-sys/Cargo.toml b/Modules/cpython-sys/Cargo.toml
index de0b88d5d5b723..8919965d031eba 100644
--- a/Modules/cpython-sys/Cargo.toml
+++ b/Modules/cpython-sys/Cargo.toml
@@ -6,4 +6,5 @@ edition = "2024"
 [dependencies]
 
 [build-dependencies]
-bindgen = "0.72.1"
\ No newline at end of file
+bindgen = "0.72.1"
+shlex = "1.3"
\ No newline at end of file
diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index a681e498171675..84c98dfb263d79 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -12,11 +12,8 @@ fn main() {
     if gil_disabled(srcdir, builddir.as_deref()) {
         println!("cargo:rustc-cfg=py_gil_disabled");
     }
+    println!("cargo::rustc-check-cfg=cfg(py_gil_disabled)");
     generate_c_api_bindings(srcdir, builddir.as_deref(), out_path.as_path());
-    // TODO(emmatyping): generate bindings to the internal parser API
-    // The parser includes things slightly differently, so we should generate
-    // it's bindings independently
-    //generate_parser_bindings(srcdir, &out_path.as_path());
 }
 
 fn gil_disabled(srcdir: &Path, builddir: Option<&str>) -> bool {
@@ -39,6 +36,36 @@ fn gil_disabled(srcdir: &Path, builddir: Option<&str>) -> bool {
 fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Path) {
     let mut builder = bindgen::Builder::default().header("wrapper.h");
 
+    // Suppress all clang warnings (deprecation warnings, etc.)
+    builder = builder.clang_arg("-w");
+
+    // Tell clang the correct target triple for cross-compilation.
+    // Without this, bindgen uses the host target which causes errors like
+    // "thread-local storage is not supported" on iOS or missing headers
+    // on Android/WASI.
+    if let Ok(target) = env::var("TARGET") {
+        builder = builder.clang_arg(format!("--target={}", target));
+    }
+
+    // Forward cross-compilation flags (include paths, defines, sysroot)
+    // from CPython's CPPFLAGS. These are needed so bindgen's clang can
+    // find system headers (e.g. assert.h) when cross-compiling for
+    // Android NDK, WASI, etc.
+    if let Ok(cppflags) = env::var("PY_CPPFLAGS") {
+        if let Some(flags) = shlex::split(&cppflags) {
+            for flag in &flags {
+                if flag.starts_with("-I")
+                    || flag.starts_with("-D")
+                    || flag.starts_with("--sysroot")
+                    || flag.starts_with("-isysroot")
+                    || flag.starts_with("-isystem")
+                {
+                    builder = builder.clang_arg(flag);
+                }
+            }
+        }
+    }
+
     // Always search the source dir and the public headers.
     let mut include_dirs = vec![srcdir.to_path_buf(), srcdir.join("Include")];
     // Include the build directory if provided; out-of-tree builds place

From 8c593c8864f9501874fd1c14f752ed0a858cb803 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 05:13:25 +0000
Subject: [PATCH 08/21] Detect LLVM triple and handle NDK sysroot

---
 Makefile.pre.in              |  3 +-
 Misc/platform_triplet.c      | 19 +++++++++
 Modules/cpython-sys/build.rs | 79 ++++++++++++++++++++++++++++--------
 configure                    |  7 ++++
 configure.ac                 |  7 ++++
 5 files changed, 96 insertions(+), 19 deletions(-)

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 489b5cf6a45170..2ca8b45ce792fb 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -64,6 +64,7 @@ CARGO_PROFILE=@CARGO_PROFILE@
 CARGO_TARGET=@CARGO_TARGET@
 CARGO_TARGET_LINKER_ENV=@CARGO_TARGET_LINKER_ENV@
 CARGO_DYLIB_SUFFIX=@CARGO_DYLIB_SUFFIX@
+LLVM_TARGET=@LLVM_TARGET@
 RUST_STATICLIB_DEP=@RUST_STATICLIB_DEP@
 
 GNULD=		@GNULD@
@@ -3378,7 +3379,7 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 # Module dependencies and platform-specific files
 
 cpython-sys: Modules/cpython-sys/Cargo.toml Modules/cpython-sys/build.rs Modules/cpython-sys/wrapper.h Modules/cpython-sys/parser.h
-	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) PY_CPPFLAGS="$(CPPFLAGS)" $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) PY_CC="$(CC)" PY_CPPFLAGS="$(CPPFLAGS)" LLVM_TARGET="$(LLVM_TARGET)" $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
 
 RUST_STATICLIB_A= target/$(if $(CARGO_TARGET),$(CARGO_TARGET)/$(CARGO_TARGET_DIR),$(CARGO_TARGET_DIR))/libcpython_rust_staticlib.a
 
diff --git a/Misc/platform_triplet.c b/Misc/platform_triplet.c
index 13da020b84f2e3..f6d584189eb4ec 100644
--- a/Misc/platform_triplet.c
+++ b/Misc/platform_triplet.c
@@ -3,6 +3,10 @@
  *
  * Also detects the closest Rust target triple for cargo/rustc:
  * cc -E Misc/platform_triplet.c | grep '^RUST_TARGET=' | tr -d ' '
+ *
+ * And the LLVM/clang target triple (for bindgen), only when it differs
+ * from RUST_TARGET:
+ * cc -E Misc/platform_triplet.c | grep '^LLVM_TARGET=' | tr -d ' '
  */
 #undef bfin
 #undef cris
@@ -145,6 +149,7 @@ RUST_TARGET=arm-linux-androideabi
 #     elif defined(_ABI64) && _MIPS_SIM == _ABI64
 #      define LIBC_MIPS musl
 #      define RUST_LIBC_MIPS muslabi64
+#      define LLVM_LIBC_MIPS musl
 #     else
 #      error unknown mips sim value
 #     endif
@@ -242,12 +247,18 @@ RUST_TARGET=mipsisa32r6-unknown-linux-RUST_LIBC_MIPS
 #   if defined(_MIPSEL) && defined(__mips64)
 PLATFORM_TRIPLET=mips64el-linux-LIBC_MIPS
 RUST_TARGET=mips64el-unknown-linux-RUST_LIBC_MIPS
+#    ifdef LLVM_LIBC_MIPS
+LLVM_TARGET=mips64el-unknown-linux-LLVM_LIBC_MIPS
+#    endif
 #   elif defined(_MIPSEL)
 PLATFORM_TRIPLET=mipsel-linux-LIBC_MIPS
 RUST_TARGET=mipsel-unknown-linux-RUST_LIBC_MIPS
 #   elif defined(__mips64)
 PLATFORM_TRIPLET=mips64-linux-LIBC_MIPS
 RUST_TARGET=mips64-unknown-linux-RUST_LIBC_MIPS
+#    ifdef LLVM_LIBC_MIPS
+LLVM_TARGET=mips64-unknown-linux-LLVM_LIBC_MIPS
+#    endif
 #   else
 PLATFORM_TRIPLET=mips-linux-LIBC_MIPS
 RUST_TARGET=mips-unknown-linux-RUST_LIBC_MIPS
@@ -286,9 +297,11 @@ RUST_TARGET=sparc-unknown-linux-RUST_LIBC
 #  if __riscv_xlen == 32
 PLATFORM_TRIPLET=riscv32-linux-LIBC
 RUST_TARGET=riscv32gc-unknown-linux-RUST_LIBC
+LLVM_TARGET=riscv32-unknown-linux-RUST_LIBC
 #  elif __riscv_xlen == 64
 PLATFORM_TRIPLET=riscv64-linux-LIBC
 RUST_TARGET=riscv64gc-unknown-linux-RUST_LIBC
+LLVM_TARGET=riscv64-unknown-linux-RUST_LIBC
 #  else
 #   error unknown platform triplet
 #  endif
@@ -326,21 +339,26 @@ RUST_TARGET=i686-unknown-hurd-gnu
 #      if __x86_64__
 PLATFORM_TRIPLET=x86_64-iphonesimulator
 RUST_TARGET=x86_64-apple-ios
+LLVM_TARGET=x86_64-apple-ios-simulator
 #      else
 PLATFORM_TRIPLET=arm64-iphonesimulator
 RUST_TARGET=aarch64-apple-ios-sim
+LLVM_TARGET=arm64-apple-ios-simulator
 #      endif
 #    else
 PLATFORM_TRIPLET=arm64-iphoneos
 RUST_TARGET=aarch64-apple-ios
+LLVM_TARGET=arm64-apple-ios
 #    endif
 // Older macOS SDKs do not define TARGET_OS_OSX
 #  elif !defined(TARGET_OS_OSX) || TARGET_OS_OSX
 PLATFORM_TRIPLET=darwin
 #    if defined(__x86_64__)
 RUST_TARGET=x86_64-apple-darwin
+LLVM_TARGET=x86_64-apple-macosx
 #    elif defined(__aarch64__)
 RUST_TARGET=aarch64-apple-darwin
+LLVM_TARGET=arm64-apple-macosx
 #    else
 RUST_TARGET=unknown
 #    endif
@@ -358,6 +376,7 @@ RUST_TARGET=wasm32-unknown-emscripten
 #    if defined(_REENTRANT)
 PLATFORM_TRIPLET=wasm32-wasi-threads
 RUST_TARGET=wasm32-wasip1-threads
+LLVM_TARGET=wasm32-wasi
 #    else
 PLATFORM_TRIPLET=wasm32-wasi
 RUST_TARGET=wasm32-wasip1
diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index 84c98dfb263d79..cc47b8b8819822 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -40,27 +40,70 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
     builder = builder.clang_arg("-w");
 
     // Tell clang the correct target triple for cross-compilation.
-    // Without this, bindgen uses the host target which causes errors like
-    // "thread-local storage is not supported" on iOS or missing headers
-    // on Android/WASI.
-    if let Ok(target) = env::var("TARGET") {
+    // LLVM_TARGET is the clang/LLVM triple which may differ from the Rust
+    // target (e.g. arm64-apple-macosx vs aarch64-apple-darwin, or
+    // riscv64-unknown-linux-gnu vs riscv64gc-unknown-linux-gnu).
+    // Falls back to Cargo's TARGET if LLVM_TARGET is not set.
+    let target = env::var("LLVM_TARGET")
+        .or_else(|_| env::var("TARGET"))
+        .unwrap_or_default();
+    if !target.is_empty() {
         builder = builder.clang_arg(format!("--target={}", target));
     }
 
-    // Forward cross-compilation flags (include paths, defines, sysroot)
-    // from CPython's CPPFLAGS. These are needed so bindgen's clang can
-    // find system headers (e.g. assert.h) when cross-compiling for
-    // Android NDK, WASI, etc.
-    if let Ok(cppflags) = env::var("PY_CPPFLAGS") {
-        if let Some(flags) = shlex::split(&cppflags) {
-            for flag in &flags {
-                if flag.starts_with("-I")
-                    || flag.starts_with("-D")
-                    || flag.starts_with("--sysroot")
-                    || flag.starts_with("-isysroot")
-                    || flag.starts_with("-isystem")
-                {
-                    builder = builder.clang_arg(flag);
+    // Extract cross-compilation flags from the C compiler command (PY_CC)
+    // and preprocessor flags (PY_CPPFLAGS). These provide the sysroot and
+    // include paths that bindgen's clang needs to find system headers when
+    // cross-compiling.
+    //
+    // - WASI: the sysroot is embedded in CC ("clang --sysroot=...")
+    // - iOS: -isysroot in CPPFLAGS points to the SDK
+    let mut have_sysroot = false;
+    for env_name in ["PY_CC", "PY_CPPFLAGS"] {
+        if let Ok(value) = env::var(env_name) {
+            if let Some(flags) = shlex::split(&value) {
+                let mut iter = flags.iter().peekable();
+                while let Some(flag) = iter.next() {
+                    if flag.starts_with("--sysroot")
+                        || flag.starts_with("-isysroot")
+                    {
+                        builder = builder.clang_arg(flag);
+                        have_sysroot = true;
+                        // Handle "-isysroot <path>" (space-separated)
+                        if flag == "-isysroot" || flag == "--sysroot" {
+                            if let Some(path) = iter.next() {
+                                builder = builder.clang_arg(path);
+                            }
+                        }
+                    } else if flag.starts_with("-I")
+                        || flag.starts_with("-D")
+                        || flag.starts_with("-isystem")
+                    {
+                        builder = builder.clang_arg(flag);
+                    }
+                }
+            }
+        }
+    }
+
+    // Android NDK: the cross-compiler binary knows its own sysroot
+    // implicitly, but bindgen's libclang does not. The NDK sysroot is
+    // at .../toolchains/llvm/prebuilt/<host>/sysroot, which is a sibling
+    // of the bin/ directory containing the compiler.
+    if !have_sysroot && target.contains("android") {
+        if let Ok(cc) = env::var("PY_CC") {
+            if let Some(parts) = shlex::split(&cc) {
+                if let Some(binary) = parts.first() {
+                    let cc_path = Path::new(binary);
+                    if let Some(bin_dir) = cc_path.parent() {
+                        let sysroot = bin_dir.with_file_name("sysroot");
+                        if sysroot.is_dir() {
+                            builder = builder.clang_arg(format!(
+                                "--sysroot={}",
+                                sysroot.display()
+                            ));
+                        }
+                    }
                 }
             }
         }
diff --git a/configure b/configure
index a74a40722c39e3..16db4f9593cd47 100755
--- a/configure
+++ b/configure
@@ -888,6 +888,7 @@ TCLTK_LIBS
 TCLTK_CFLAGS
 LIBSQLITE3_LIBS
 LIBSQLITE3_CFLAGS
+LLVM_TARGET
 CARGO_DYLIB_SUFFIX
 CARGO_TARGET_LINKER_ENV
 CARGO_TARGET
@@ -7179,6 +7180,11 @@ if $CPP $CPPFLAGS $srcdir/Misc/platform_triplet.c >conftest.out 2>/dev/null; the
   PLATFORM_TRIPLET="${PLATFORM_TRIPLET#PLATFORM_TRIPLET=}"
   RUST_TARGET=`grep '^RUST_TARGET=' conftest.out | tr -d ' 	'`
   RUST_TARGET="${RUST_TARGET#RUST_TARGET=}"
+    LLVM_TARGET=`grep '^LLVM_TARGET=' conftest.out | tr -d ' 	'`
+  LLVM_TARGET="${LLVM_TARGET#LLVM_TARGET=}"
+  if test -z "$LLVM_TARGET"; then
+    LLVM_TARGET="$RUST_TARGET"
+  fi
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $PLATFORM_TRIPLET" >&5
 printf "%s\n" "$PLATFORM_TRIPLET" >&6; }
 else
@@ -16154,6 +16160,7 @@ esac
 
 
 
+
   if test "$ac_sys_system" = "Emscripten" -a -z "$LIBSQLITE3_CFLAGS" -a -z "$LIBSQLITE3_LIBS"
 then :
 
diff --git a/configure.ac b/configure.ac
index 554a33af76c536..dd202d193a6da1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1156,6 +1156,12 @@ if $CPP $CPPFLAGS $srcdir/Misc/platform_triplet.c >conftest.out 2>/dev/null; the
   PLATFORM_TRIPLET="${PLATFORM_TRIPLET@%:@PLATFORM_TRIPLET=}"
   RUST_TARGET=`grep '^RUST_TARGET=' conftest.out | tr -d ' 	'`
   RUST_TARGET="${RUST_TARGET@%:@RUST_TARGET=}"
+  dnl LLVM_TARGET is only emitted when it differs from RUST_TARGET
+  LLVM_TARGET=`grep '^LLVM_TARGET=' conftest.out | tr -d ' 	'`
+  LLVM_TARGET="${LLVM_TARGET@%:@LLVM_TARGET=}"
+  if test -z "$LLVM_TARGET"; then
+    LLVM_TARGET="$RUST_TARGET"
+  fi
   AC_MSG_RESULT([$PLATFORM_TRIPLET])
 else
   AC_MSG_RESULT([none])
@@ -4372,6 +4378,7 @@ AC_SUBST([CARGO_PROFILE])
 AC_SUBST([CARGO_TARGET])
 AC_SUBST([CARGO_TARGET_LINKER_ENV])
 AC_SUBST([CARGO_DYLIB_SUFFIX])
+AC_SUBST([LLVM_TARGET])
 
 
 dnl detect sqlite3 from Emscripten emport

From a5fb908e8f2cc64e694ef678c2b585d3a7fb2447 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 07:31:03 +0000
Subject: [PATCH 09/21] Add targets for WASI, Android, and iOS

---
 .github/workflows/build.yml         | 7 ++++++-
 .github/workflows/reusable-wasi.yml | 3 +++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a0f60c30ac8a60..42ce10fd340eba 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -383,6 +383,9 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          targets: ${{ matrix.arch }}-linux-android
       - name: Build and test
         run: ./Android/android.py ci --fast-ci ${{ matrix.arch }}-linux-android
 
@@ -396,7 +399,9 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          targets: aarch64-apple-ios-sim
       # GitHub recommends explicitly selecting the desired Xcode version:
       # https://github.com/actions/runner-images/issues/12541#issuecomment-3083850140
       # This became a necessity as a result of
diff --git a/.github/workflows/reusable-wasi.yml b/.github/workflows/reusable-wasi.yml
index 8f412288f530bc..dc6366cb106e92 100644
--- a/.github/workflows/reusable-wasi.yml
+++ b/.github/workflows/reusable-wasi.yml
@@ -48,6 +48,9 @@ jobs:
       uses: actions/setup-python@v5
       with:
         python-version: '3.x'
+    - uses: dtolnay/rust-toolchain@master
+      with:
+        targets: wasm32-wasip1
     - name: "Runner image version"
       run: echo "IMAGE_OS_VERSION=${ImageOS}-${ImageVersion}" >> "$GITHUB_ENV"
     - name: "Configure build Python"

From b170c1b899d52cb008af02ae2b783f5481406ecb Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 07:31:20 +0000
Subject: [PATCH 10/21] Tweak WASI and Android sysroot searching

---
 Modules/cpython-sys/build.rs | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index cc47b8b8819822..addebd2ed878dd 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -86,16 +86,33 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
         }
     }
 
-    // Android NDK: the cross-compiler binary knows its own sysroot
-    // implicitly, but bindgen's libclang does not. The NDK sysroot is
-    // at .../toolchains/llvm/prebuilt/<host>/sysroot, which is a sibling
-    // of the bin/ directory containing the compiler.
+    // WASI SDK: WASI_SDK_PATH is set by Tools/wasm/wasi/__main__.py.
+    // The sysroot is at $WASI_SDK_PATH/share/wasi-sysroot.
+    if !have_sysroot && target.contains("wasi") {
+        if let Ok(sdk_path) = env::var("WASI_SDK_PATH") {
+            let sysroot = PathBuf::from(&sdk_path)
+                .join("share")
+                .join("wasi-sysroot");
+            if sysroot.is_dir() {
+                builder = builder.clang_arg(format!(
+                    "--sysroot={}",
+                    sysroot.display()
+                ));
+                have_sysroot = true;
+            }
+        }
+    }
+
+    // Android NDK: ANDROID_HOME is set by the CI/user environment, and
+    // Android/android-env.sh sets CC to the NDK clang binary at:
+    //   $ANDROID_HOME/ndk/<ver>/toolchains/llvm/prebuilt/<host>/bin/<triple>-clang
+    // The sysroot is a sibling of bin/:
+    //   .../toolchains/llvm/prebuilt/<host>/sysroot
     if !have_sysroot && target.contains("android") {
         if let Ok(cc) = env::var("PY_CC") {
             if let Some(parts) = shlex::split(&cc) {
                 if let Some(binary) = parts.first() {
-                    let cc_path = Path::new(binary);
-                    if let Some(bin_dir) = cc_path.parent() {
+                    if let Some(bin_dir) = Path::new(binary).parent() {
                         let sysroot = bin_dir.with_file_name("sysroot");
                         if sysroot.is_dir() {
                             builder = builder.clang_arg(format!(

From b85f67e56847bce0c7aa324bdd00bcb24c22f696 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 07:35:55 +0000
Subject: [PATCH 11/21] Pin to 1.91.1 toolchain for CI

---
 .github/workflows/build.yml         | 4 ++--
 .github/workflows/reusable-wasi.yml | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 42ce10fd340eba..ab9a73627ae1df 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -383,7 +383,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@1.91.1
         with:
           targets: ${{ matrix.arch }}-linux-android
       - name: Build and test
@@ -399,7 +399,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           persist-credentials: false
-      - uses: dtolnay/rust-toolchain@master
+      - uses: dtolnay/rust-toolchain@1.91.1
         with:
           targets: aarch64-apple-ios-sim
       # GitHub recommends explicitly selecting the desired Xcode version:
diff --git a/.github/workflows/reusable-wasi.yml b/.github/workflows/reusable-wasi.yml
index dc6366cb106e92..b0462a82ed34a1 100644
--- a/.github/workflows/reusable-wasi.yml
+++ b/.github/workflows/reusable-wasi.yml
@@ -48,7 +48,7 @@ jobs:
       uses: actions/setup-python@v5
       with:
         python-version: '3.x'
-    - uses: dtolnay/rust-toolchain@master
+    - uses: dtolnay/rust-toolchain@1.91.1
       with:
         targets: wasm32-wasip1
     - name: "Runner image version"

From 98ed04788a5acda7282cc5d8ae9af20301dd5c79 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 07:51:20 +0000
Subject: [PATCH 12/21] Fix bindings for 32bit (e.g. WASI) platforms

---
 Modules/cpython-sys/src/lib.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/Modules/cpython-sys/src/lib.rs b/Modules/cpython-sys/src/lib.rs
index 5180762fbef6bf..17924f0e5fb00a 100644
--- a/Modules/cpython-sys/src/lib.rs
+++ b/Modules/cpython-sys/src/lib.rs
@@ -55,7 +55,7 @@ pub const _Py_STATIC_FLAG_BITS: Py_ssize_t =
 pub const _Py_STATIC_IMMORTAL_INITIAL_REFCNT: Py_ssize_t =
     (_Py_IMMORTAL_INITIAL_REFCNT as Py_ssize_t) | (_Py_STATIC_FLAG_BITS << 48);
 #[cfg(not(target_pointer_width = "64"))]
-pub const _Py_STATIC_IMMORTAL_INITIAL_REFCNT: Py_ssize_t = 7u32 << 28;
+pub const _Py_STATIC_IMMORTAL_INITIAL_REFCNT: Py_ssize_t = (7u32 << 28) as Py_ssize_t;
 
 #[repr(transparent)]
 pub struct PyObject(std::cell::UnsafeCell<_object>);
@@ -129,7 +129,7 @@ pub const PyObject_HEAD_INIT: PyObject = {
     PyObject(std::cell::UnsafeCell::new(obj))
 };
 
-#[cfg(not(py_gil_disabled))]
+#[cfg(all(not(py_gil_disabled), target_pointer_width = "64"))]
 pub const PyObject_HEAD_INIT: PyObject = PyObject(std::cell::UnsafeCell::new(_object {
     __bindgen_anon_1: _object__bindgen_ty_1 {
         ob_refcnt_full: _Py_STATIC_IMMORTAL_INITIAL_REFCNT as i64,
@@ -137,6 +137,15 @@ pub const PyObject_HEAD_INIT: PyObject = PyObject(std::cell::UnsafeCell::new(_ob
     ob_type: std::ptr::null_mut(),
 }));
 
+// On 32-bit platforms, the refcount union only has ob_refcnt (no ob_refcnt_split).
+#[cfg(all(not(py_gil_disabled), not(target_pointer_width = "64")))]
+pub const PyObject_HEAD_INIT: PyObject = PyObject(std::cell::UnsafeCell::new(_object {
+    __bindgen_anon_1: _object__bindgen_ty_1 {
+        ob_refcnt: _Py_STATIC_IMMORTAL_INITIAL_REFCNT,
+    },
+    ob_type: std::ptr::null_mut(),
+}));
+
 pub const PyModuleDef_HEAD_INIT: PyModuleDef_Base = PyModuleDef_Base {
     ob_base: PyObject_HEAD_INIT,
     m_init: None,

From 4979e92b648c34004ade0f7f950d28ea46954531 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 07:51:54 +0000
Subject: [PATCH 13/21] Fix remaining BLDSHARED references

---
 Makefile.pre.in | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 2ca8b45ce792fb..c69a032107ecc6 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1026,16 +1026,16 @@ $(LIBRARY): $(LIBRARY_OBJS)
 libpython$(LDVERSION).so: $(LIBRARY_OBJS) $(DTRACE_OBJS)
 	# AIX Linker don't support "-h" option
 	if test "$(MACHDEP)" != "aix"; then \
-		$(BLDSHARED) -Wl,-h$(INSTSONAME) -o $(INSTSONAME) $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
+		$(BLDSHARED_EXE) $(BLDSHARED_ARGS) -Wl,-h$(INSTSONAME) -o $(INSTSONAME) $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
 	else \
-		$(BLDSHARED) -o $@ $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
+		$(BLDSHARED_EXE) $(BLDSHARED_ARGS) -o $@ $(LIBRARY_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
 	fi
 	if test $(INSTSONAME) != $@; then \
 		$(LN) -f $(INSTSONAME) $@; \
 	fi
 
 libpython3.so:	libpython$(LDVERSION).so
-	$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^
+	$(BLDSHARED_EXE) $(BLDSHARED_ARGS) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^
 
 libpython$(LDVERSION).dylib: $(LIBRARY_OBJS)
 	 $(CC) -dynamiclib $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(SHLIBS) $(LIBC) $(LIBM); \

From 5c40dc8df23232910f9d1da472cf51041c16fdd8 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 08:55:32 +0000
Subject: [PATCH 14/21] Add LIBPYTHON search path for Android

---
 Modules/cpython-build-helper/src/lib.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/Modules/cpython-build-helper/src/lib.rs b/Modules/cpython-build-helper/src/lib.rs
index 1f96750afa3d81..1362e383606142 100644
--- a/Modules/cpython-build-helper/src/lib.rs
+++ b/Modules/cpython-build-helper/src/lib.rs
@@ -33,9 +33,19 @@ pub fn print_linker_args() {
     }
 
     // On Android (and Cygwin), extension modules must link against libpython.
-    // LIBPYTHON is set by the CPython build system on these platforms.
+    // LIBPYTHON is set by the CPython build system on these platforms and
+    // typically contains "-L. -lpython3.X". The "-L." is relative to the
+    // make build directory, so resolve it to an absolute path using
+    // PYTHON_BUILD_DIR.
     if let Ok(libpython) = env::var("LIBPYTHON") {
+        let builddir = env::var("PYTHON_BUILD_DIR").ok();
         for arg in shlex::split(&libpython).expect("Invalid LIBPYTHON") {
+            if arg == "-L." {
+                if let Some(ref dir) = builddir {
+                    println!("cargo:rustc-cdylib-link-arg=-L{}", dir);
+                    continue;
+                }
+            }
             println!("cargo:rustc-cdylib-link-arg={}", arg);
         }
     }

From dfb19036ddfdface9c17dc48e3db24b1f067d83d Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 08:56:44 +0000
Subject: [PATCH 15/21] Get WASI working?

---
 Makefile.pre.in              |  2 +-
 Modules/Setup.stdlib.in      |  2 +-
 Modules/cpython-sys/build.rs | 24 +++++++++++++-----------
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/Makefile.pre.in b/Makefile.pre.in
index c69a032107ecc6..03c894268fea72 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -3379,7 +3379,7 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 # Module dependencies and platform-specific files
 
 cpython-sys: Modules/cpython-sys/Cargo.toml Modules/cpython-sys/build.rs Modules/cpython-sys/wrapper.h Modules/cpython-sys/parser.h
-	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) PY_CC="$(CC)" PY_CPPFLAGS="$(CPPFLAGS)" LLVM_TARGET="$(LLVM_TARGET)" $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
+	CARGO_TARGET_DIR=$(abs_builddir)/target PYTHON_BUILD_DIR=$(abs_builddir) PY_CC="$(CC)" PY_CPPFLAGS="$(CPPFLAGS)" PY_CFLAGS="$(CFLAGS)" LLVM_TARGET="$(LLVM_TARGET)" $(CARGO_HOME)/bin/cargo build --lib --locked --package cpython-sys --profile $(CARGO_PROFILE) $(if $(CARGO_TARGET),--target=$(CARGO_TARGET)) --manifest-path $(srcdir)/Cargo.toml
 
 RUST_STATICLIB_A= target/$(if $(CARGO_TARGET),$(CARGO_TARGET)/$(CARGO_TARGET_DIR),$(CARGO_TARGET_DIR))/libcpython_rust_staticlib.a
 
diff --git a/Modules/Setup.stdlib.in b/Modules/Setup.stdlib.in
index 635be3cbe8dbc0..6b56dd858ce585 100644
--- a/Modules/Setup.stdlib.in
+++ b/Modules/Setup.stdlib.in
@@ -120,7 +120,7 @@
 ############################################################################
 # Rust modules
 #
-@MODULE__BASE64_TRUE@_base64 _base64/Cargo.toml _base64/src/lib.rs lib_base64.a
+@MODULE__BASE64_TRUE@_base64 _base64/Cargo.toml _base64/src/lib.rs
 
 ############################################################################
 # Modules with some UNIX dependencies
diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index addebd2ed878dd..d370f40b13d199 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -51,15 +51,15 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
         builder = builder.clang_arg(format!("--target={}", target));
     }
 
-    // Extract cross-compilation flags from the C compiler command (PY_CC)
-    // and preprocessor flags (PY_CPPFLAGS). These provide the sysroot and
-    // include paths that bindgen's clang needs to find system headers when
-    // cross-compiling.
+    // Extract cross-compilation flags from the C compiler command (PY_CC),
+    // preprocessor flags (PY_CPPFLAGS), and compiler flags (PY_CFLAGS).
+    // These provide the sysroot, include paths, and defines that bindgen's
+    // clang needs when cross-compiling.
     //
-    // - WASI: the sysroot is embedded in CC ("clang --sysroot=...")
-    // - iOS: -isysroot in CPPFLAGS points to the SDK
+    // - WASI: sysroot in CC, -D_WASI_EMULATED_SIGNAL in CFLAGS
+    // - iOS: -isysroot in CPPFLAGS
     let mut have_sysroot = false;
-    for env_name in ["PY_CC", "PY_CPPFLAGS"] {
+    for env_name in ["PY_CC", "PY_CPPFLAGS", "PY_CFLAGS"] {
         if let Ok(value) = env::var(env_name) {
             if let Some(flags) = shlex::split(&value) {
                 let mut iter = flags.iter().peekable();
@@ -126,13 +126,15 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
         }
     }
 
-    // Always search the source dir and the public headers.
-    let mut include_dirs = vec![srcdir.to_path_buf(), srcdir.join("Include")];
-    // Include the build directory if provided; out-of-tree builds place
-    // the generated pyconfig.h there.
+    // Include the build directory first so that cross-build pyconfig.h
+    // takes precedence over any pyconfig.h in the source tree (which may
+    // be from a native build with different settings like LONG_BIT).
+    let mut include_dirs = Vec::new();
     if let Some(build) = builddir {
         include_dirs.push(PathBuf::from(build));
     }
+    include_dirs.push(srcdir.to_path_buf());
+    include_dirs.push(srcdir.join("Include"));
 
     for dir in include_dirs {
         builder = builder.clang_arg(format!("-I{}", dir.display()));

From 2c08857308bab9ac37234ae14ea38a231f38a038 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 09:10:41 +0000
Subject: [PATCH 16/21] Try adding a fallback mapping of Rust->LLVM triples

---
 Modules/cpython-sys/build.rs | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index d370f40b13d199..8d1f99fe5e0890 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -33,6 +33,32 @@ fn gil_disabled(srcdir: &Path, builddir: Option<&str>) -> bool {
     false
 }
 
+/// Map a Rust target triple to the corresponding LLVM/clang target triple.
+/// Most are identical, but some platforms differ:
+/// - Apple: aarch64 → arm64, darwin → macosx, ios-sim → ios-simulator
+/// - RISC-V: riscv64gc → riscv64, riscv32gc → riscv32
+/// - WASI threads: wasip1-threads → wasi
+fn rust_target_to_llvm(rust_target: &str) -> String {
+    match rust_target {
+        "aarch64-apple-darwin" => "arm64-apple-macosx".into(),
+        "x86_64-apple-darwin" => "x86_64-apple-macosx".into(),
+        "aarch64-apple-ios" => "arm64-apple-ios".into(),
+        "aarch64-apple-ios-sim" => "arm64-apple-ios-simulator".into(),
+        "x86_64-apple-ios" => "x86_64-apple-ios-simulator".into(),
+        "wasm32-wasip1-threads" => "wasm32-wasi".into(),
+        other => {
+            // riscv64gc-* → riscv64-*, riscv32gc-* → riscv32-*
+            if let Some(rest) = other.strip_prefix("riscv64gc-") {
+                return format!("riscv64-{rest}");
+            }
+            if let Some(rest) = other.strip_prefix("riscv32gc-") {
+                return format!("riscv32-{rest}");
+            }
+            other.into()
+        }
+    }
+}
+
 fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Path) {
     let mut builder = bindgen::Builder::default().header("wrapper.h");
 
@@ -43,9 +69,13 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
     // LLVM_TARGET is the clang/LLVM triple which may differ from the Rust
     // target (e.g. arm64-apple-macosx vs aarch64-apple-darwin, or
     // riscv64-unknown-linux-gnu vs riscv64gc-unknown-linux-gnu).
-    // Falls back to Cargo's TARGET if LLVM_TARGET is not set.
+    // Falls back to Cargo's TARGET with known Rust→LLVM mappings.
     let target = env::var("LLVM_TARGET")
-        .or_else(|_| env::var("TARGET"))
+        .ok()
+        .filter(|s| !s.is_empty())
+        .or_else(|| {
+            env::var("TARGET").ok().map(|t| rust_target_to_llvm(&t))
+        })
         .unwrap_or_default();
     if !target.is_empty() {
         builder = builder.clang_arg(format!("--target={}", target));

From caf1f9fa2e91266de7d1a9c999ba5fd6177f89a6 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Mon, 2 Mar 2026 09:25:25 +0000
Subject: [PATCH 17/21] Revert "Try adding a fallback mapping of Rust->LLVM
 triples"

This reverts commit 2c08857308bab9ac37234ae14ea38a231f38a038.
---
 Modules/cpython-sys/build.rs | 34 ++--------------------------------
 1 file changed, 2 insertions(+), 32 deletions(-)

diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index 8d1f99fe5e0890..d370f40b13d199 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -33,32 +33,6 @@ fn gil_disabled(srcdir: &Path, builddir: Option<&str>) -> bool {
     false
 }
 
-/// Map a Rust target triple to the corresponding LLVM/clang target triple.
-/// Most are identical, but some platforms differ:
-/// - Apple: aarch64 → arm64, darwin → macosx, ios-sim → ios-simulator
-/// - RISC-V: riscv64gc → riscv64, riscv32gc → riscv32
-/// - WASI threads: wasip1-threads → wasi
-fn rust_target_to_llvm(rust_target: &str) -> String {
-    match rust_target {
-        "aarch64-apple-darwin" => "arm64-apple-macosx".into(),
-        "x86_64-apple-darwin" => "x86_64-apple-macosx".into(),
-        "aarch64-apple-ios" => "arm64-apple-ios".into(),
-        "aarch64-apple-ios-sim" => "arm64-apple-ios-simulator".into(),
-        "x86_64-apple-ios" => "x86_64-apple-ios-simulator".into(),
-        "wasm32-wasip1-threads" => "wasm32-wasi".into(),
-        other => {
-            // riscv64gc-* → riscv64-*, riscv32gc-* → riscv32-*
-            if let Some(rest) = other.strip_prefix("riscv64gc-") {
-                return format!("riscv64-{rest}");
-            }
-            if let Some(rest) = other.strip_prefix("riscv32gc-") {
-                return format!("riscv32-{rest}");
-            }
-            other.into()
-        }
-    }
-}
-
 fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Path) {
     let mut builder = bindgen::Builder::default().header("wrapper.h");
 
@@ -69,13 +43,9 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
     // LLVM_TARGET is the clang/LLVM triple which may differ from the Rust
     // target (e.g. arm64-apple-macosx vs aarch64-apple-darwin, or
     // riscv64-unknown-linux-gnu vs riscv64gc-unknown-linux-gnu).
-    // Falls back to Cargo's TARGET with known Rust→LLVM mappings.
+    // Falls back to Cargo's TARGET if LLVM_TARGET is not set.
     let target = env::var("LLVM_TARGET")
-        .ok()
-        .filter(|s| !s.is_empty())
-        .or_else(|| {
-            env::var("TARGET").ok().map(|t| rust_target_to_llvm(&t))
-        })
+        .or_else(|_| env::var("TARGET"))
         .unwrap_or_default();
     if !target.is_empty() {
         builder = builder.clang_arg(format!("--target={}", target));

From e1936b8b62b9716b85ff0518aee9682f9131106e Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Tue, 3 Mar 2026 01:06:39 +0000
Subject: [PATCH 18/21] Ignore Rust build support dirs in
 generate_stdlib_module_names.py

---
 Tools/build/generate_stdlib_module_names.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Tools/build/generate_stdlib_module_names.py b/Tools/build/generate_stdlib_module_names.py
index 646f31b49761c1..f7a4166415a4a5 100644
--- a/Tools/build/generate_stdlib_module_names.py
+++ b/Tools/build/generate_stdlib_module_names.py
@@ -22,6 +22,10 @@
     '__pycache__',
     'site-packages',
 
+    # Rust build-system support modules
+    'cpython-build-helper',
+    'cpython-rust-staticlib',
+
     # Test modules and packages
     '__hello__',
     '__phello__',

From a59b30007c63867c349c4a1fd278c3c2c5107b84 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Tue, 3 Mar 2026 01:07:07 +0000
Subject: [PATCH 19/21] Run cargo fmt && clippy

---
 Modules/cpython-build-helper/src/lib.rs | 10 +--
 Modules/cpython-sys/build.rs            | 81 +++++++++++--------------
 2 files changed, 40 insertions(+), 51 deletions(-)

diff --git a/Modules/cpython-build-helper/src/lib.rs b/Modules/cpython-build-helper/src/lib.rs
index 1362e383606142..94883aaf4f8d82 100644
--- a/Modules/cpython-build-helper/src/lib.rs
+++ b/Modules/cpython-build-helper/src/lib.rs
@@ -40,11 +40,11 @@ pub fn print_linker_args() {
     if let Ok(libpython) = env::var("LIBPYTHON") {
         let builddir = env::var("PYTHON_BUILD_DIR").ok();
         for arg in shlex::split(&libpython).expect("Invalid LIBPYTHON") {
-            if arg == "-L." {
-                if let Some(ref dir) = builddir {
-                    println!("cargo:rustc-cdylib-link-arg=-L{}", dir);
-                    continue;
-                }
+            if arg == "-L."
+                && let Some(ref dir) = builddir
+            {
+                println!("cargo:rustc-cdylib-link-arg=-L{}", dir);
+                continue;
             }
             println!("cargo:rustc-cdylib-link-arg={}", arg);
         }
diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index d370f40b13d199..5d45d58239709d 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -60,27 +60,25 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
     // - iOS: -isysroot in CPPFLAGS
     let mut have_sysroot = false;
     for env_name in ["PY_CC", "PY_CPPFLAGS", "PY_CFLAGS"] {
-        if let Ok(value) = env::var(env_name) {
-            if let Some(flags) = shlex::split(&value) {
-                let mut iter = flags.iter().peekable();
-                while let Some(flag) = iter.next() {
-                    if flag.starts_with("--sysroot")
-                        || flag.starts_with("-isysroot")
-                    {
-                        builder = builder.clang_arg(flag);
-                        have_sysroot = true;
-                        // Handle "-isysroot <path>" (space-separated)
-                        if flag == "-isysroot" || flag == "--sysroot" {
-                            if let Some(path) = iter.next() {
-                                builder = builder.clang_arg(path);
-                            }
-                        }
-                    } else if flag.starts_with("-I")
-                        || flag.starts_with("-D")
-                        || flag.starts_with("-isystem")
+        if let Ok(value) = env::var(env_name)
+            && let Some(flags) = shlex::split(&value)
+        {
+            let mut iter = flags.iter().peekable();
+            while let Some(flag) = iter.next() {
+                if flag.starts_with("--sysroot") || flag.starts_with("-isysroot") {
+                    builder = builder.clang_arg(flag);
+                    have_sysroot = true;
+                    // Handle "-isysroot <path>" (space-separated)
+                    if (flag == "-isysroot" || flag == "--sysroot")
+                        && let Some(path) = iter.next()
                     {
-                        builder = builder.clang_arg(flag);
+                        builder = builder.clang_arg(path);
                     }
+                } else if flag.starts_with("-I")
+                    || flag.starts_with("-D")
+                    || flag.starts_with("-isystem")
+                {
+                    builder = builder.clang_arg(flag);
                 }
             }
         }
@@ -88,18 +86,14 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
 
     // WASI SDK: WASI_SDK_PATH is set by Tools/wasm/wasi/__main__.py.
     // The sysroot is at $WASI_SDK_PATH/share/wasi-sysroot.
-    if !have_sysroot && target.contains("wasi") {
-        if let Ok(sdk_path) = env::var("WASI_SDK_PATH") {
-            let sysroot = PathBuf::from(&sdk_path)
-                .join("share")
-                .join("wasi-sysroot");
-            if sysroot.is_dir() {
-                builder = builder.clang_arg(format!(
-                    "--sysroot={}",
-                    sysroot.display()
-                ));
-                have_sysroot = true;
-            }
+    if !have_sysroot
+        && target.contains("wasi")
+        && let Ok(sdk_path) = env::var("WASI_SDK_PATH")
+    {
+        let sysroot = PathBuf::from(&sdk_path).join("share").join("wasi-sysroot");
+        if sysroot.is_dir() {
+            builder = builder.clang_arg(format!("--sysroot={}", sysroot.display()));
+            have_sysroot = true;
         }
     }
 
@@ -108,21 +102,16 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
     //   $ANDROID_HOME/ndk/<ver>/toolchains/llvm/prebuilt/<host>/bin/<triple>-clang
     // The sysroot is a sibling of bin/:
     //   .../toolchains/llvm/prebuilt/<host>/sysroot
-    if !have_sysroot && target.contains("android") {
-        if let Ok(cc) = env::var("PY_CC") {
-            if let Some(parts) = shlex::split(&cc) {
-                if let Some(binary) = parts.first() {
-                    if let Some(bin_dir) = Path::new(binary).parent() {
-                        let sysroot = bin_dir.with_file_name("sysroot");
-                        if sysroot.is_dir() {
-                            builder = builder.clang_arg(format!(
-                                "--sysroot={}",
-                                sysroot.display()
-                            ));
-                        }
-                    }
-                }
-            }
+    if !have_sysroot
+        && target.contains("android")
+        && let Ok(cc) = env::var("PY_CC")
+        && let Some(parts) = shlex::split(&cc)
+        && let Some(binary) = parts.first()
+        && let Some(bin_dir) = Path::new(binary).parent()
+    {
+        let sysroot = bin_dir.with_file_name("sysroot");
+        if sysroot.is_dir() {
+            builder = builder.clang_arg(format!("--sysroot={}", sysroot.display()));
         }
     }
 

From 9b338488e3ee3290a7e4e3b84bc1f671ea917bd5 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Tue, 3 Mar 2026 01:13:49 +0000
Subject: [PATCH 20/21] Pass through C standard flag to libclang for sanitizers

---
 Modules/cpython-sys/build.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Modules/cpython-sys/build.rs b/Modules/cpython-sys/build.rs
index 5d45d58239709d..701a3be550ae0b 100644
--- a/Modules/cpython-sys/build.rs
+++ b/Modules/cpython-sys/build.rs
@@ -76,6 +76,7 @@ fn generate_c_api_bindings(srcdir: &Path, builddir: Option<&str>, out_path: &Pat
                     }
                 } else if flag.starts_with("-I")
                     || flag.starts_with("-D")
+                    || flag.starts_with("-std=")
                     || flag.starts_with("-isystem")
                 {
                     builder = builder.clang_arg(flag);

From 74f6e7ecd626fc272b5733addc2ee2a6932f5eb0 Mon Sep 17 00:00:00 2001
From: Emma Harper Smith <emma@emmatyping.dev>
Date: Tue, 3 Mar 2026 02:21:26 +0000
Subject: [PATCH 21/21] Add newline to end of cpython-sys/Cargo.toml

---
 Modules/cpython-sys/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Modules/cpython-sys/Cargo.toml b/Modules/cpython-sys/Cargo.toml
index 8919965d031eba..a12556c6e305a1 100644
--- a/Modules/cpython-sys/Cargo.toml
+++ b/Modules/cpython-sys/Cargo.toml
@@ -7,4 +7,4 @@ edition = "2024"
 
 [build-dependencies]
 bindgen = "0.72.1"
-shlex = "1.3"
\ No newline at end of file
+shlex = "1.3"