Use cc-rs to detect the default linker, instead of assuming cc

Author: jamesmunns

Cargo.toml

@@ -44,6 +44,7 @@ test = ["dep:snapbox", "dep:walkdir", "clap-cargo/testing_colors"]
 anstream = "1"
 anstyle = "1.0.11"
 anyhow = "1.0.69"
+cc = "1"
 cfg-if = "1.0"
 chrono = { version = "0.4", default-features = false, features = ["std"] }
 clap = { version = "4", features = ["derive", "wrap_help", "string"] }
@@ -112,7 +113,6 @@ snapbox = { version = "1", features = ["term-svg"], optional = true }
 walkdir = { version = "2", optional = true }
 
 [target."cfg(windows)".dependencies]
-cc = "1"
 scopeguard = "1"
 windows-registry = "0.6"
 windows-result = "0.4"

src/cli/self_update.rs

@@ -828,19 +828,40 @@ fn current_install_opts(opts: &InstallOpts<'_>, process: &Process) -> String {
 
 #[cfg(unix)]
 fn warn_if_default_linker_missing(process: &Process) {
-    // Search for `cc` in PATH
+    // Search for linker in PATH
     if let Some(path) = process.var_os("PATH") {
-        let cc_binary = format!("cc{}", EXE_SUFFIX);
-
+        // If we have the host triple, attempt to determine the CC/linker path that
+        // `cc-rs` would use, as this is *usually* why we need a linker to invoke.
+        //
+        // Doing it this way allows us to correctly diagnose quirky systems like
+        // solaris and illumos that use `gcc` rather than `cc` for historical reasons.
+        let cc_binary_opt = TargetTriple::from_host(process).and_then(|triple| {
+            // Fill in some dummy settings for `Build`/`Tool` to be able to properly
+            // give us the metadata we want
+            cc::Build::new()
+                .opt_level(0)
+                .target(&triple)
+                .host(&triple)
+                .try_get_compiler()
+                .ok()
+                .and_then(|tool| tool.path().to_str().map(str::to_string))
+        });
+
+        // If we don't get info from cc-rs, fall back to just looking for the literal `cc`.
+        let cc_binary = cc_binary_opt.unwrap_or_else(|| format!("cc{}", EXE_SUFFIX));
+
+        // Search the path for the selected binary
         for mut p in env::split_paths(&path) {
             p.push(&cc_binary);
             if p.is_file() {
                 return;
             }
         }
+
+        warn!("no default linker (`{cc_binary}`) was found in your PATH");
     }
 
-    warn!("no default linker (`cc`) was found in your PATH");
+    warn!("unable to search PATH for a default linker");
     warn!("many Rust crates require a system C toolchain to build");
 }