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Merge pull request #154 from amyspark/fix-windows-library-detection
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Fix Windows static library detection and usage
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@sdroege
sdroege committed Jan 17, 2024
2 parents 333771e + aafa1b2 commit ed9ef8e
Showing 1 changed file with 50 additions and 27 deletions.
77 changes: 50 additions & 27 deletions src/lib.rs
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Expand Up @@ -776,34 +776,38 @@ impl Library {
}

let prefix = "lib";
if target.contains("msvc") {
// According to link.exe documentation:
// https://learn.microsoft.com/en-us/cpp/build/reference/link-input-files?view=msvc-170
//
// LINK doesn't use file extensions to make assumptions about the contents of a file.
// Instead, LINK examines each input file to determine what kind of file it is.
//
// However, rustc appends `.lib` to the string it receives from the -l command line argument,
// which it receives from Cargo via cargo:rustc-link-lib:
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L828
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L843
// So the only file extension that works for MSVC targets is `.lib`
return test_suffixes(filename, &[".lib"]);
} else if target.contains("windows") && target.contains("gnu") {
// GNU targets for Windows, including gnullvm, use `LinkerFlavor::Gcc` internally in rustc,
// which tells rustc to use the GNU linker. rustc does not prepend/append to the string it
// receives via the -l command line argument before passing it to the linker:
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L446
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L457
// GNU ld can work with more types of files than just the .lib files that MSVC's link.exe needs.
// GNU ld will prepend the `lib` prefix to the filename if necessary, so it is okay to remove
// the `lib` prefix from the filename. The `.a` suffix *requires* the `lib` prefix.
// https://sourceware.org/binutils/docs-2.39/ld.html#index-direct-linking-to-a-dll
if filename.starts_with(prefix) {
if target.contains("windows") {
if target.contains("gnu") && filename.starts_with(prefix) {
// GNU targets for Windows, including gnullvm, use `LinkerFlavor::Gcc` internally in rustc,
// which tells rustc to use the GNU linker. rustc does not prepend/append to the string it
// receives via the -l command line argument before passing it to the linker:
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L446
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L457
// GNU ld can work with more types of files than just the .lib files that MSVC's link.exe needs.
// GNU ld will prepend the `lib` prefix to the filename if necessary, so it is okay to remove
// the `lib` prefix from the filename. The `.a` suffix *requires* the `lib` prefix.
// https://sourceware.org/binutils/docs-2.39/ld.html#index-direct-linking-to-a-dll
let filename = &filename[prefix.len()..];
return test_suffixes(filename, &[".dll.a", ".dll", ".lib", ".a"]);
} else {
return test_suffixes(filename, &[".dll.a", ".dll", ".lib"]);
// According to link.exe documentation:
// https://learn.microsoft.com/en-us/cpp/build/reference/link-input-files?view=msvc-170
//
// LINK doesn't use file extensions to make assumptions about the contents of a file.
// Instead, LINK examines each input file to determine what kind of file it is.
//
// However, rustc appends `.lib` to the string it receives from the -l command line argument,
// which it receives from Cargo via cargo:rustc-link-lib:
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L828
// https://github.com/rust-lang/rust/blob/657f246812ab2684e3c3954b1c77f98fd59e0b21/compiler/rustc_codegen_ssa/src/back/linker.rs#L843
// So the only file extension that works for MSVC targets is `.lib`
// However, for externally created libraries, there's no
// guarantee that the extension is ".lib" so we need to
// consider all options.
// See:
// https://github.com/mesonbuild/meson/issues/8153
// https://github.com/rust-lang/rust/issues/114013
return test_suffixes(filename, &[".dll.a", ".dll", ".lib", ".a"]);
}
} else if target.contains("apple") {
if filename.starts_with(prefix) {
Expand Down Expand Up @@ -901,6 +905,10 @@ impl Library {
iter.next().map(|s| s.to_owned()),
);
}
"-u" => {
let meta = format!("rustc-link-arg=-Wl,-u,{}", val);
config.print_metadata(&meta);
}
_ => {}
}
}
Expand All @@ -927,6 +935,12 @@ impl Library {
self.include_paths.push(PathBuf::from(inc));
}
}
"-undefined" | "--undefined" => {
if let Some(symbol) = iter.next() {
let meta = format!("rustc-link-arg=-Wl,{},{}", part, symbol);
config.print_metadata(&meta);
}
}
_ => {
let path = std::path::Path::new(part);
if path.is_file() {
Expand Down Expand Up @@ -1000,10 +1014,19 @@ fn envify(name: &str) -> String {

/// System libraries should only be linked dynamically
fn is_static_available(name: &str, system_roots: &[PathBuf], dirs: &[PathBuf]) -> bool {
let libname = format!("lib{}.a", name);
let libnames = {
let mut names = vec![format!("lib{}.a", name)];

if cfg!(target_os = "windows") {
names.push(format!("{}.lib", name));
}

names
};

dirs.iter().any(|dir| {
!system_roots.iter().any(|sys| dir.starts_with(sys)) && dir.join(&libname).exists()
let library_exists = libnames.iter().any(|libname| dir.join(&libname).exists());
library_exists && !system_roots.iter().any(|sys| dir.starts_with(sys))
})
}

Expand Down

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