fix: incorrect error message for string literal suffixes

[notJoon]

Description

Fixes #144161

When a raw string literal has an invalid suffix (like r#"test"#suffix), the compiler was not reporting the appropriate error message "suffixes on string literals are invalid". This was particularly problematic when the suffix was immediately followed by another token, as in r#" \\ "#r"\\ ".

Changes

Modified parse_expr_lit to handle raw string literals with suffixes by:

1. Checking if a token is a raw string literal with a suffix before general literal parsing
2. Using the existing LitKind::from_token_lit to validate and get the appropriate error

To prevent cascading errors, consume the next token if it's another string literal after an error is reported.

[rustbot]

r? @petrochenkov

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[petrochenkov]

This is incorrect, the string literal suffix is a semantic error, not a parsing error, and this code

#[cfg(false)]
fn check() {
    let _ = r#"raw"#suffix;
}

should compile successfully.

@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[bors]

☔ The latest upstream changes (presumably #144689) made this pull request unmergeable. Please resolve the merge conflicts.

[Dylan-DPC]

@notJoon any updates on this? thanks

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rustbot]

⚠️ Warning ⚠️

• The following commits have merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.

  • 92a62e8

  You can start a rebase with the following commands:

  $ # rebase
  $ git pull --rebase https://github.com/rust-lang/rust.git master
  $ git push --force-with-lease
  

[notJoon]

@Dylan-DPC sorry for the delay, I'll take a look this asap. thanks for the remind

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [ui] tests/ui/parser/bad-lit-suffixes.rs stdout ----
Saved the actual stderr to `/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/parser/bad-lit-suffixes/bad-lit-suffixes.stderr`
diff of stderr:

16 LL |     r#""#suffix;
17    |     ^^^^^^^^^^^ invalid suffix `suffix`
18 
- error: suffixes on string literals are invalid
-   --> $DIR/bad-lit-suffixes.rs:30:17
-    |
- LL | #[rustc_dummy = "string"suffix]
-    |                 ^^^^^^^^^^^^^^ invalid suffix `suffix`
- 
- error: suffixes on string literals are invalid
-   --> $DIR/bad-lit-suffixes.rs:34:14
-    |
- LL | #[must_use = "string"suffix]
-    |              ^^^^^^^^^^^^^^ invalid suffix `suffix`
- 
- error: suffixes on string literals are invalid
-   --> $DIR/bad-lit-suffixes.rs:39:15
-    |
- LL | #[link(name = "string"suffix)]
-    |               ^^^^^^^^^^^^^^ invalid suffix `suffix`
- 
- error: invalid suffix `suffix` for number literal
-   --> $DIR/bad-lit-suffixes.rs:43:41
-    |
- LL | #[rustc_layout_scalar_valid_range_start(0suffix)]
-    |                                         ^^^^^^^ invalid suffix `suffix`
-    |
-    = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)
- 
45 warning: `extern` declarations without an explicit ABI are deprecated
46   --> $DIR/bad-lit-suffixes.rs:3:1
47    |


The actual stderr differed from the expected stderr
To update references, rerun the tests and pass the `--bless` flag
To only update this specific test, also pass `--test-args parser/bad-lit-suffixes.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/parser/bad-lit-suffixes.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/parser/bad-lit-suffixes" "-A" "unused" "-A" "internal_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers"
stdout: none
--- stderr -------------------------------
error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:4:5
   |
LL |     "C"suffix //~ ERROR suffixes on string literals are invalid
   |     ^^^^^^^^^ invalid suffix `suffix`

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:8:5
   |
LL |     "C"suffix //~ ERROR suffixes on string literals are invalid
   |     ^^^^^^^^^ invalid suffix `suffix`

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:14:5
   |
LL |     r#""#suffix; //~ ERROR suffixes on string literals are invalid
   |     ^^^^^^^^^^^ invalid suffix `suffix`

warning: `extern` declarations without an explicit ABI are deprecated
##[warning]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:3:1
   |
LL | extern //~ WARN missing_abi
   | ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`
   |
   = note: `#[warn(missing_abi)]` on by default

warning: `extern` declarations without an explicit ABI are deprecated
##[warning]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:7:1
   |
LL | extern //~ WARN missing_abi
   | ^^^^^^ help: explicitly specify the "C" ABI: `extern "C"`

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:12:5
   |
LL |     ""suffix; //~ ERROR suffixes on string literals are invalid
   |     ^^^^^^^^ invalid suffix `suffix`

error: suffixes on byte string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:13:5
   |
LL |     b""suffix; //~ ERROR suffixes on byte string literals are invalid
   |     ^^^^^^^^^ invalid suffix `suffix`

error: suffixes on byte string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:15:5
   |
LL |     br#""#suffix; //~ ERROR suffixes on byte string literals are invalid
   |     ^^^^^^^^^^^^ invalid suffix `suffix`

error: suffixes on char literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:16:5
   |
LL |     'a'suffix; //~ ERROR suffixes on char literals are invalid
   |     ^^^^^^^^^ invalid suffix `suffix`

error: suffixes on byte literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:17:5
   |
LL |     b'a'suffix; //~ ERROR suffixes on byte literals are invalid
   |     ^^^^^^^^^^ invalid suffix `suffix`

error: invalid width `1024` for integer literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:19:5
   |
LL |     1234u1024; //~ ERROR invalid width `1024` for integer literal
   |     ^^^^^^^^^
   |
   = help: valid widths are 8, 16, 32, 64 and 128

error: invalid width `1024` for integer literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:20:5
   |
LL |     1234i1024; //~ ERROR invalid width `1024` for integer literal
   |     ^^^^^^^^^
   |
   = help: valid widths are 8, 16, 32, 64 and 128

error: invalid width `1024` for float literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:21:5
   |
LL |     1234f1024; //~ ERROR invalid width `1024` for float literal
   |     ^^^^^^^^^
   |
   = help: valid widths are 32 and 64

error: invalid width `1024` for float literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:22:5
   |
LL |     1234.5f1024; //~ ERROR invalid width `1024` for float literal
   |     ^^^^^^^^^^^
   |
   = help: valid widths are 32 and 64

error: invalid suffix `suffix` for number literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:24:5
   |
LL |     1234suffix; //~ ERROR invalid suffix `suffix` for number literal
   |     ^^^^^^^^^^ invalid suffix `suffix`
   |
   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)

error: invalid suffix `suffix` for number literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:25:5
   |
LL |     0b101suffix; //~ ERROR invalid suffix `suffix` for number literal
   |     ^^^^^^^^^^^ invalid suffix `suffix`
   |
   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)

error: invalid suffix `suffix` for float literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:26:5
   |
LL |     1.0suffix; //~ ERROR invalid suffix `suffix` for float literal
   |     ^^^^^^^^^ invalid suffix `suffix`
   |
   = help: valid suffixes are `f32` and `f64`

error: invalid suffix `suffix` for float literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:27:5
   |
LL |     1.0e10suffix; //~ ERROR invalid suffix `suffix` for float literal
   |     ^^^^^^^^^^^^ invalid suffix `suffix`
   |
   = help: valid suffixes are `f32` and `f64`

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:30:17
   |
LL | #[rustc_dummy = "string"suffix]
   |                 ^^^^^^^^^^^^^^ invalid suffix `suffix`

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:34:14
   |
LL | #[must_use = "string"suffix]
   |              ^^^^^^^^^^^^^^ invalid suffix `suffix`

error[E0539]: malformed `must_use` attribute input
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:34:1
   |
LL | #[must_use = "string"suffix]
   | ^^^^^^^^^^^^^--------------^
   |              |
   |              expected a string literal here
   |
   = note: for more information, visit <https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute>
help: try changing it to one of the following valid forms of the attribute
   |
LL - #[must_use = "string"suffix]
LL + #[must_use = "reason"]
   |
LL - #[must_use = "string"suffix]
LL + #[must_use]
   |

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:39:15
   |
LL | #[link(name = "string"suffix)]
   |               ^^^^^^^^^^^^^^ invalid suffix `suffix`

error: invalid suffix `suffix` for number literal
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:43:41
   |
LL | #[rustc_layout_scalar_valid_range_start(0suffix)]
   |                                         ^^^^^^^ invalid suffix `suffix`
   |
   = help: the suffix must be one of the numeric types (`u32`, `isize`, `f32`, etc.)

error: suffixes on string literals are invalid
##[error]  --> /checkout/tests/ui/parser/bad-lit-suffixes.rs:48:25
   |
LL |     #[rustc_confusables("blah"suffix)]
   |                         ^^^^^^^^^^^^ invalid suffix `suffix`

error: aborting due to 22 previous errors; 2 warnings emitted

For more information about this error, try `rustc --explain E0539`.
------------------------------------------

[reddevilmidzy]

@notJoon
Triage: I'm closing this due to inactivity. Please reopen when you are ready to continue with this. Thanks for your contribution.
@rustbot label: +S-inactive