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Change approach for native and cross-compilation with clang++ on FreeBSD #794

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Merged
merged 1 commit into from
Mar 21, 2023
Merged

Change approach for native and cross-compilation with clang++ on FreeBSD #794

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42 changes: 23 additions & 19 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1720,26 +1720,30 @@ impl Build {
} else if target.contains("aarch64") {
cmd.args.push("--target=aarch64-unknown-windows-gnu".into())
}
} else if target.ends_with("-freebsd") && self.get_host()?.ends_with("-freebsd")
{
// clang <= 13 on FreeBSD doesn't support a target triple without at least
// the major os version number appended; e.g. use x86_64-unknown-freebsd13
// or x86_64-unknown-freebsd13.0 instead of x86_64-unknown-freebsd.
// The current version is appended. If it doesn't align with your goals, pass
// .flag("--target=...") in the build script or adjust CXXFLAGS accordingly.
let stdout = std::process::Command::new("freebsd-version")
.output()
.map_err(|e| {
Error::new(
ErrorKind::ToolNotFound,
&format!("Error executing freebsd-version: {}", e),
)
})?
.stdout;
let stdout = String::from_utf8_lossy(&stdout);
let os_ver = stdout.split('-').next().unwrap();
} else if target.ends_with("-freebsd") {
// FreeBSD only supports C++11 and above when compiling against libc++
// (available from FreeBSD 10 onwards). Under FreeBSD, clang uses libc++ by
// default on FreeBSD 10 and newer unless `--target` is manually passed to
// the compiler, in which case its default behavior differs:
// * If --target=xxx-unknown-freebsdX(.Y) is specified and X is greater than
// or equal to 10, clang++ uses libc++
// * If --target=xxx-unknown-freebsd is specified (without a version),
// clang++ cannot assume libc++ is available and reverts to a default of
// libstdc++ (this behavior was changed in llvm 14).
//
// This breaks C++11 (or greater) builds if targeting FreeBSD with the
// generic xxx-unknown-freebsd triple on clang 13 or below *without*
// explicitly specifying that libc++ should be used.
// When cross-compiling, we can't infer from the rust/cargo target triple
// which major version of FreeBSD we are targeting, so we need to make sure
// that libc++ is used (unless the user has explicitly specified otherwise).
// There's no compelling reason to use a different approach when compiling
// natively.
if self.cpp && self.cpp_set_stdlib.is_none() {
cmd.push_cc_arg("-stdlib=libc++".into());
}

cmd.push_cc_arg(format!("--target={}{}", target, os_ver).into());
cmd.push_cc_arg(format!("--target={}", target).into());
} else {
cmd.push_cc_arg(format!("--target={}", target).into());
}
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