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Merged
weihanglo merged 2 commits into from
Apr 8, 2026
+62 −5
Merged

Never include use extra-filename in build scripts #16855

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e4bd2a2
test: Added regression test for new build-dir layout with __CARGO_DEF…
ranger-ross Apr 8, 2026
3cc34d6
fix: Never include use extra-filename in build scripts
ranger-ross Apr 8, 2026
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12 changes: 7 additions & 5 deletions src/cargo/core/compiler/build_runner/compilation_files.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -914,9 +914,14 @@ fn use_extra_filename(bcx: &BuildContext<'_, '_>, unit: &Unit) -> bool {
// These always use metadata.
return true;
}

if unit.target.is_custom_build() {
// Build scripts never use metadata
return false;
}
// No metadata in these cases:
//
// - dylib, cdylib, executable, build-scripts: `pkg_dir` avoids collisions for us and rustc isn't
// - dylib, cdylib, executable: `pkg_dir` avoids collisions for us and rustc isn't
// looking these up by `-Cextra-filename`
//
// The __CARGO_DEFAULT_LIB_METADATA env var is used to override this to
Expand All @@ -926,10 +931,7 @@ fn use_extra_filename(bcx: &BuildContext<'_, '_>, unit: &Unit) -> bool {
// installs. In addition it prevents accidentally loading a libstd of a
// different compiler at runtime.
// See https://github.com/rust-lang/cargo/issues/3005
if (unit.target.is_dylib()
|| unit.target.is_cdylib()
|| unit.target.is_executable()
|| unit.target.is_custom_build())
if (unit.target.is_dylib() || unit.target.is_cdylib() || unit.target.is_executable())
&& bcx.gctx.get_env("__CARGO_DEFAULT_LIB_METADATA").is_err()
{
return false;
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55 changes: 55 additions & 0 deletions tests/testsuite/build_dir.rs
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Expand Up @@ -1219,6 +1219,61 @@ CARGO_BIN_FILE_BAR_bar=[ROOT]/foo/build-dir/debug/build/bar/[HASH]/artifact/bin/
"#]]);
}

/// __CARGO_DEFAULT_LIB_METADATA is internal but used by rustc bootstrap and Miri
/// Regression test for https://github.com/rust-lang/cargo/issues/16854
#[cargo_test]
fn should_work_with_cargo_default_lib_metadata() {
let p = project()
.file("src/main.rs", r#"fn main() { println!("Hello, World!") }"#)
.file("build.rs", r#"fn main() { }"#)
.file(
".cargo/config.toml",
r#"
[build]
target-dir = "target-dir"
build-dir = "build-dir"
"#,
)
.build();

p.cargo("-Zbuild-dir-new-layout build")
.masquerade_as_nightly_cargo(&["new build-dir layout"])
.env("__CARGO_DEFAULT_LIB_METADATA", "true")
.enable_mac_dsym()
.with_stderr_data(str![[r#"
[COMPILING] foo v0.0.1 ([ROOT]/foo)
[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s

"#]])
.run();

// NOTE: build_script_build[EXE] does not contain a hash in the filename
p.root().join("build-dir").assert_build_dir_layout(str![[r#"
[ROOT]/foo/build-dir/.rustc_info.json
[ROOT]/foo/build-dir/CACHEDIR.TAG
[ROOT]/foo/build-dir/debug/.cargo-build-lock
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/bin-foo
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/bin-foo.json
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/dep-bin-foo
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/invoked.timestamp
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/out/foo[..][EXE]
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/out/foo[..].d
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/run-build-script-build-script-build
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/run-build-script-build-script-build.json
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/run/invoked.timestamp
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/run/root-output
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/run/stderr
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/run/stdout
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/build-script-build-script-build
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/build-script-build-script-build.json
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/dep-build-script-build-script-build
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/fingerprint/invoked.timestamp
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/out/build_script_build[EXE]
[ROOT]/foo/build-dir/debug/build/foo/[HASH]/out/build_script_build.d

"#]]);
}

fn parse_workspace_manifest_path_hash(hash_dir: &PathBuf) -> PathBuf {
// Since the hash will change between test runs simply find the first directories and assume
// that is the hash dir. The format is a 2 char directory followed by the remaining hash in the
Expand Down