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fix: clang-cl detect warning on MacOS #1446

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fix: clang-cl detect warning on MacOS #1446

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6cd8d1b
fix: clang-cl detect warning on MacOS
LinusChen-yf Apr 2, 2025
f15ad30
fix: missing clang-cl judgment
LinusChen-yf Apr 3, 2025
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28 changes: 14 additions & 14 deletions src/tool.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -198,22 +198,22 @@ impl Tool {
let mut compiler_detect_output = cargo_output.clone();
compiler_detect_output.warnings = compiler_detect_output.debug;

let stdout = run_output(
Command::new(path).arg("-E").arg(tmp.path()),
&compiler_detect_output,
)?;
let stdout = String::from_utf8_lossy(&stdout);

if stdout.contains("-Wslash-u-filename") {
let stdout = run_output(
Command::new(path).arg("-E").arg("--").arg(tmp.path()),
&compiler_detect_output,
)?;
let stdout = String::from_utf8_lossy(&stdout);
guess_family_from_stdout(&stdout, path, args, cargo_output)
let mut detect_cmd = Command::new(path);
// If it is clang-cl, use -- to separate the path
// to prevent confusion between the path and the parameter.
let is_clang_cl = path
.file_name()
.map_or(false, |name| name.to_string_lossy().contains("clang-cl"));
Comment on lines +204 to +206
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While this will work for many cases, checking filename isn't very robust...

@madsmtm does clang-cl --version offer anything special that we can check here?

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# On Windows
> clang-cl --version
clang version 20.1.2
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Users\crash\scoop\apps\llvm\20.1.2\bin

# On MacOS
> clang-cl --version
Homebrew clang version 19.1.7
Target: arm64-pc-windows-msvc
Thread model: posix
InstalledDir: /opt/homebrew/Cellar/llvm/19.1.7_1/bin

# On Linux
> clang-cl --version
clang version 19.1.7
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: /usr/bin

It seems that the output of clang-cl --version is not a very reliable way to determine whether it is clang-cl?

Because I saw the logic of using the file name to judge clang-cl in the original code, I referred to this part of the code.

cc-rs/src/tool.rs

Lines 242 to 244 in 5f55b01

match path.file_name().map(OsStr::to_string_lossy) {
Some(fname) if fname.contains("clang-cl") => ToolFamily::Msvc { clang_cl: true },
Some(fname) if fname.ends_with("cl") || fname == "cl.exe" => {

Or maybe it would be safer to use full characters to match clang-cl or clang-cl.exe?

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thanks, in that case I think it might be the only solution, cc @madsmtm wdyt

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With clang-cl the same warning about -Wslash-u-filename is still generated. The difference with normal clang is that the warning is output to stderr and the exit code is set to 1. Both things can be captured and checked for, allowing for a check without relying on the filename.

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When using clang-cl, you only need to add the parameter "--" before Path to avoid generating warnings, which is also the recommended way to deal with warnings.

In addition, is the reason why this PR has no follow-up now because there are not enough test cases in CI to ensure the safety of its code?

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Yes, detecting clang-cl via filename isn't very robust

if is_clang_cl {
detect_cmd.arg("-E").arg("--").arg(tmp.path());
} else {
guess_family_from_stdout(&stdout, path, args, cargo_output)
detect_cmd.arg("-E").arg(tmp.path());
}

let stdout = run_output(&mut detect_cmd, &compiler_detect_output)?;
let stdout = String::from_utf8_lossy(&stdout);

guess_family_from_stdout(&stdout, path, args, cargo_output)
}
let detect_family = |path: &Path, args: &[String]| -> Result<ToolFamily, Error> {
let cache_key = [path.as_os_str()]
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