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fix(fingerprint): Hackily keep --remap-path-prefix binaries reproducible

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This commit is contained in:
Ed Page 2024-12-05 16:30:09 -06:00
parent 306d515c08
commit 29a267a143
3 changed files with 32 additions and 10 deletions
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31
src/cargo/core/compiler/build_runner/compilation_files.rs
View File

@ -703,14 +703,19 @@ fn compute_metadata(
// Avoid trashing the caches on RUSTFLAGS changing via `c_extra_filename`
//
// Limited to `c_extra_filename` to help with reproducible build / PGO issues.
build_runner
.bcx
.extra_args_for(unit)
.hash(&mut c_extra_filename_hasher);
let default = Vec::new();
let extra_args = build_runner.bcx.extra_args_for(unit).unwrap_or(&default);
if !has_remap_path_prefix(&extra_args) {
extra_args.hash(&mut c_extra_filename_hasher);
}
if unit.mode.is_doc() || unit.mode.is_doc_scrape() {
unit.rustdocflags.hash(&mut c_extra_filename_hasher);
if !has_remap_path_prefix(&unit.rustdocflags) {
unit.rustdocflags.hash(&mut c_extra_filename_hasher);
}
} else {
unit.rustflags.hash(&mut c_extra_filename_hasher);
if !has_remap_path_prefix(&unit.rustflags) {
unit.rustflags.hash(&mut c_extra_filename_hasher);
}
}
let c_metadata = UnitHash(c_metadata_hasher.finish());
@ -726,6 +731,20 @@ fn compute_metadata(
}
}
/// HACK: Detect the *potential* presence of `--remap-path-prefix`
///
/// As CLI parsing is contextual and dependent on the CLI definition to understand the context, we
/// can't say for sure whether `--remap-path-prefix` is present, so we guess if anything looks like
/// it.
/// If we could, we'd strip it out for hashing.
/// Instead, we use this to avoid hashing rustflags if it might be present to avoid the risk of taking
/// a flag that is trying to make things reproducible and making things less reproducible by the
/// `-Cextra-filename` showing up in the rlib, even with `split-debuginfo`.
fn has_remap_path_prefix(args: &[String]) -> bool {
args.iter()
.any(|s| s.starts_with("--remap-path-prefix=") || s == "--remap-path-prefix")
}
/// Hash the version of rustc being used during the build process.
fn hash_rustc_version(bcx: &BuildContext<'_, '_>, hasher: &mut StableHasher, unit: &Unit) {
let vers = &bcx.rustc().version;

7
src/cargo/core/compiler/fingerprint/mod.rs
View File

@ -68,7 +68,7 @@
//! -------------------------------------------|-------------|---------------------|------------------------|----------
//! rustc | ✓ | ✓ | ✓ | ✓
//! [`Profile`] | ✓ | ✓ | ✓ | ✓
//! `cargo rustc` extra args | ✓ | ✓ | | ✓
//! `cargo rustc` extra args | ✓ | ✓[^7] | | ✓[^7]
//! [`CompileMode`] | ✓ | ✓ | ✓ | ✓
//! Target Name | ✓ | ✓ | ✓ | ✓
//! `TargetKind` (bin/lib/etc.) | ✓ | ✓ | ✓ | ✓
@ -83,7 +83,7 @@
//! Target flags (test/bench/for_host/edition) | ✓ | | |
//! -C incremental=… flag | ✓ | | |
//! mtime of sources | ✓[^3] | | |
//! RUSTFLAGS/RUSTDOCFLAGS | ✓ | ✓ | | ✓
//! RUSTFLAGS/RUSTDOCFLAGS | ✓ | ✓[^7] | | ✓[^7]
//! [`Lto`] flags | ✓ | ✓ | ✓ | ✓
//! config settings[^5] | ✓ | | |
//! `is_std` | | ✓ | ✓ | ✓
@ -102,6 +102,9 @@
//!
//! [^6]: Via [`Manifest::lint_rustflags`][crate::core::Manifest::lint_rustflags]
//!
//! [^7]: extra-flags and RUSTFLAGS are conditionally excluded when `--remap-path-prefix` is
//! present to avoid breaking build reproducibility while we wait for trim-paths
//!
//! When deciding what should go in the Metadata vs the Fingerprint, consider
//! that some files (like dylibs) do not have a hash in their filename. Thus,
//! if a value changes, only the fingerprint will detect the change (consider,

4
tests/testsuite/rustflags.rs
View File

@ -1592,7 +1592,7 @@ fn rustflags_remap_path_prefix_ignored_for_c_extra_filename() {
.run();
let second_c_extra_filename = dbg!(get_c_extra_filename(build_output));
assert_ne!(first_c_extra_filename, second_c_extra_filename);
assert_data_eq!(first_c_extra_filename, second_c_extra_filename);
}
// `--remap-path-prefix` is meant to take two different binaries and make them the same but the
@ -1613,7 +1613,7 @@ fn rustc_remap_path_prefix_ignored_for_c_extra_filename() {
.run();
let second_c_extra_filename = dbg!(get_c_extra_filename(build_output));
assert_ne!(first_c_extra_filename, second_c_extra_filename);
assert_data_eq!(first_c_extra_filename, second_c_extra_filename);
}
fn get_c_metadata(output: RawOutput) -> String {