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Disambiguate Windows run-times when using clang to compile. #825

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merged 2 commits into from
Jul 21, 2023
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Disambiguate Windows run-times when using clang to compile. #825

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1a356d9
Disambiguate Windows run-times when using clang to compile.
dot-asm Jul 18, 2023
f368cb4
Soften warning language about GNU compiler in MSVC environment.
dot-asm Jul 21, 2023
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11 changes: 11 additions & 0 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1619,6 +1619,13 @@ impl Build {
cmd.push_opt_unless_duplicate(format!("-O{}", opt_level).into());
}

if cmd.family == ToolFamily::Clang && target.contains("windows") {
// Disambiguate mingw and msvc on Windows. Problem is that
// depending on the origin clang can default to a mismatchig
// run-time.
cmd.push_cc_arg(format!("--target={}", target).into());
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Does this still work if there's a mismatch between the clang target name and rust target name?

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To my knowledge, there is no mismatch between Rust and clang. Which shouldn't really come as surprise, both are llvm-based.

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Oh! Maybe you refer to aarch64-pc-windows-llvm, or what was it called? Fair enough, I'll double-check...

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Oh! Maybe you refer to aarch64-pc-windows-llvm,

It's *-pc-windows-gnullvm, i.e. not just aarch64, and there is "gnu" in the name. Surprisingly enough clang appears to accept gnullvm and even do arguably right thing. It appears to be due to a pattern matching, because it also accepts gnufoobar, gnu-foobar, and even msvcfoobar and msvc-foobar. And it generates code targeting mingw runtime if there is gnu somewhere in the target name, and vc runtime otherwise.

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Yes, clang accepts far more target triples than rustc, which only accepts a finite set (clang, due to compatibility with GCC, does quite a bit of massaging of the value).

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To summarize, the answer to the original question is "yes, it still works."

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We can presumably check that it continues to work with official targets. My only concern would be third party rustc targets (which can be named anything). But we can either say they aren't supported or require setting the target to a llvm compatible one.

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We can presumably check that it continues to work with official targets.

That's what "yes, it still works" effectively mean. It still works with official targets.

}

if cmd.family == ToolFamily::Clang && target.contains("android") {
// For compatibility with code that doesn't use pre-defined `__ANDROID__` macro.
// If compiler used via ndk-build or cmake (officially supported build methods)
Expand Down Expand Up @@ -2541,6 +2548,10 @@ impl Build {
}
}

if target.contains("msvc") && tool.family == ToolFamily::Gnu {
println!("cargo:warning=GNU compiler is not supported for this target");
}

Ok(tool)
}

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