Remap both absolute and relative paths when building `rustc` and `std` #150283

Urgau · 2025-12-22T18:18:21Z

Turns out #150110 didn't work as expected, because when the standard library sources are present, we helpfully un-remap the paths to the local directory of the user, including when we are building the compiler and standard library it-self (duh!), and since those paths are absolute (not relative), our purely relative remapping didn't pick them up.

This behavior wasn't a issue before because the un-remap logic immediately tries to remap them again, and since we had the absolute remapping we would just remap them to the the same thing.

To fix that issue I've adjusted our remapping to remap both the absolute and relative paths when building rustc and std, as well as added a run-make to make sure we don't regress it again (with a new needs-std-remap-debuginfo directive).

r? @jieyouxu

rustbot · 2025-12-22T18:18:24Z

compiletest directives have been modified. Please add or update docs for the
new or modified directive in src/doc/rustc-dev-guide/.

Some changes occurred in src/tools/compiletest

cc @jieyouxu

The rustc-dev-guide subtree was changed. If this PR only touches the dev guide consider submitting a PR directly to rust-lang/rustc-dev-guide otherwise thank you for updating the dev guide with your changes.

cc @BoxyUwU, @jieyouxu, @Kobzol, @tshepang

The run-make-support library was changed

cc @jieyouxu

Urgau · 2025-12-22T20:08:59Z

@bors try jobs=dist-x86_64-linux

Remap both absolute and relative paths when building `rustc` and `std` try-job: dist-x86_64-linux

rust-bors · 2025-12-22T23:13:54Z

☀️ Try build successful (CI)
Build commit: 859f7f2 (859f7f266bef93a6e076540b803ea08242193c84, parent: 04813e4de86a5e024e71756ef092637aa862c984)

jieyouxu

Thanks

View changes since this review

jieyouxu · 2025-12-24T01:00:45Z

src/bootstrap/src/core/builder/cargo.rs

+                        // and for working directory) so let's remap the build directory as well.
+                        format!("{}={map_to}", self.build.src.display()),
+                    ]
+                    .join("\t");


Remark: technically, I think filename parts of Windows(?)/Linux(?) paths can actually contain tabs, however, other tools have the tendency to also break on those, so I'm not worried about that possibility...

Yes, paths can contain any character on platforms that use unix paths. Well except \0.

jieyouxu · 2025-12-24T01:03:03Z

@bors r+ rollup

bors · 2025-12-24T01:03:06Z

📌 Commit 4d839da has been approved by jieyouxu

It is now in the queue for this repository.

jieyouxu · 2025-12-24T01:03:11Z

@bors rollup=never (for bisection purposes)

bors · 2025-12-24T06:23:04Z

⌛ Testing commit 4d839da with merge efa32de...

bors · 2025-12-24T09:30:43Z

☀️ Test successful - checks-actions
Approved by: jieyouxu
Pushing efa32de to main...

github-actions · 2025-12-24T09:33:46Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 5a7ad8e (parent) -> efa32de (this PR)

Test differences

Show 8 test diffs

Stage 0

directives::tests::std_remap_debuginfo: [missing] -> pass (J4)

Stage 1

[run-make] tests/run-make/remap-path-prefix-std: [missing] -> ignore (ignored if std wasn't built with remapping of debuginfo) (J3)

Stage 2

[run-make] tests/run-make/remap-path-prefix-std: [missing] -> ignore (ignored if std wasn't built with remapping of debuginfo) (J0)
[run-make] tests/run-make/remap-path-prefix-std: [missing] -> pass (J1)
[run-make] tests/run-make/remap-path-prefix-std: [missing] -> ignore (only executed when the operating system is linux) (J2)

Additionally, 3 doctest diffs were found. These are ignored, as they are noisy.

Job group index

J0: aarch64-gnu, aarch64-gnu-debug, aarch64-gnu-llvm-20-1, armhf-gnu, i686-gnu-1, i686-gnu-nopt-1, test-various, x86_64-gnu, x86_64-gnu-debug, x86_64-gnu-gcc, x86_64-gnu-llvm-20-2, x86_64-gnu-llvm-21-2, x86_64-gnu-nopt, x86_64-gnu-stable
J1: dist-i586-gnu-i586-i686-musl
J2: aarch64-apple, aarch64-msvc-1, arm-android, dist-various-1, i686-msvc-1, x86_64-mingw-1, x86_64-msvc-1
J3: x86_64-gnu-llvm-20-3, x86_64-gnu-llvm-21-3
J4: pr-check-2

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard efa32de15b394620520f24781d8c55d4df6fa106 --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

x86_64-gnu-debug: 10284.3s -> 6777.6s (-34.1%)
dist-x86_64-apple: 8687.8s -> 7154.1s (-17.7%)
aarch64-apple: 10389.6s -> 8953.7s (-13.8%)
i686-gnu-nopt-1: 8367.8s -> 7300.9s (-12.7%)
x86_64-gnu: 8344.1s -> 7325.0s (-12.2%)
x86_64-gnu-tools: 3688.9s -> 3255.0s (-11.8%)
i686-gnu-2: 6077.2s -> 5377.6s (-11.5%)
x86_64-gnu-gcc: 3402.8s -> 3033.8s (-10.8%)
x86_64-rust-for-linux: 3151.1s -> 2825.8s (-10.3%)
test-various: 7400.0s -> 6647.0s (-10.2%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2025-12-24T10:51:02Z

Finished benchmarking commit (efa32de): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.1%, secondary -2.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.0%	[1.0%, 1.0%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-2.8%	[-2.8%, -2.8%]	1
All ❌✅ (primary)	-0.1%	[-2.3%, 1.0%]	3

Cycles

Results (secondary 4.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.0%	[3.6%, 4.5%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.0%, secondary 0.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.0%]	3
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	3

Bootstrap: 482.036s -> 484.408s (0.49%)
Artifact size: 392.48 MiB -> 392.47 MiB (-0.00%)

Add needs-std-remap-debuginfo directive to compiletest & run-make

1b8ee46

rustbot assigned jieyouxu Dec 22, 2025

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Remap both absolute and relative paths when building rustc and std

4d839da

Urgau force-pushed the remap-debuginfo-absolute branch from bd16ded to 4d839da Compare December 22, 2025 18:44

rust-bors bot added a commit that referenced this pull request Dec 22, 2025

Auto merge of #150283 - Urgau:remap-debuginfo-absolute, r=<try>

859f7f2

Remap both absolute and relative paths when building `rustc` and `std` try-job: dist-x86_64-linux

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jieyouxu approved these changes Dec 24, 2025

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 24, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Dec 24, 2025

bors merged commit efa32de into rust-lang:main Dec 24, 2025
13 checks passed

rustbot added this to the 1.94.0 milestone Dec 24, 2025

Urgau mentioned this pull request Dec 24, 2025

ICE locations display regressed #150209

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Remap both absolute and relative paths when building rustc and std #150283

Remap both absolute and relative paths when building rustc and std #150283

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Test differences

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Stage 1

Stage 2

Job duration changes

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rust-timer commented Dec 24, 2025

Overall result: ❌ regressions - no action needed

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Cycles

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Remap both absolute and relative paths when building `rustc` and `std` #150283

Remap both absolute and relative paths when building `rustc` and `std` #150283

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