link.exe: Don't embed full path to PDB file in binary.

[michaelwoerister]

This PR makes rustc unconditionally pass /PDBALTPATH:%_PDB% to MSVC-style linkers, causing the linker to only embed the filename of the PDB in the binary instead of the full path. This will help implement the trim-paths RFC for *-msvc targets.

Passing /PDBALTPATH:%_PDB% to the linker is already done by many projects that need reproducible builds and debugger's should still be able to find the PDB if it is in the same directory as the binary.

r? @ghost

Fixes #87825

[michaelwoerister]

#122306 updated backtrace-rs to a version that includes rust-lang/backtrace-rs#584, so this is unblocked now.

@rustbot ping windows

r? compiler

[rustbot]

Hey Windows Group! This bug has been identified as a good "Windows candidate".
In case it's useful, here are some instructions for tackling these sorts of
bugs. Maybe take a look?
Thanks! <3

cc @albertlarsan68 @arlosi @ChrisDenton @danielframpton @gdr-at-ms @kennykerr @luqmana @lzybkr @nico-abram @retep998 @sivadeilra @wesleywiser

[michaelwoerister]

@bors rollup=never since this touching an *-msvc-only run-make test.

[kennykerr]

Looks good!

[lcnr]

r? compiler

[wesleywiser]

Thanks @michaelwoerister for fixing this and landing that fix to backtrace-rs to unblock it!

@bors r+

[bors]

📌 Commit c37a824 has been approved by wesleywiser

It is now in the queue for this repository.

[workingjubilee]

However, backtrace-rs currently does not find the PDB. Consequently, this PR is blocked until rust-lang/backtrace-rs#584 is merged.

Merged and backtrace has been updated, so this can land, yep.

[bors]

⌛ Testing commit c37a824 with merge 4026a87...

[bors]

💔 Test failed - checks-actions

[michaelwoerister]

r? @wesleywiser

Let's see if this is the same i686 backtracing issue already encountered in rust-lang/backtrace-rs#584, where backtracing was pretty flaky without frame pointers enabled.

[michaelwoerister]

@bors r=wesleywiser

[bors]

📌 Commit d3af77c has been approved by wesleywiser

It is now in the queue for this repository.

[bors]

⌛ Testing commit d3af77c with merge 3f79023...

[bors]

💔 Test failed - checks-actions

[michaelwoerister]

I modified the test code in 0a094ba, so that unwinding will more reliably produce a stack trace that actually contains frames from the test. Unwinding not always working is a pre-existing issue on i686-pc-windows-msvc and unrelated to the change in this PR.

[wesleywiser]

@bors r+

[bors]

📌 Commit 0a094ba has been approved by wesleywiser

It is now in the queue for this repository.

[bors]

⌛ Testing commit 0a094ba with merge c5b5713...

[bors]

☀️ Test successful - checks-actions
Approved by: wesleywiser
Pushing c5b5713 to master...

[rust-timer]

Finished benchmarking commit (c5b5713): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.2%	[2.2%, 2.2%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.8%	[-4.8%, -1.0%]	14
Improvements ✅ (secondary)	-2.5%	[-5.7%, -0.5%]	52
All ❌✅ (primary)	-2.5%	[-4.8%, 2.2%]	15

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 671.321s -> 670.605s (-0.11%)
Artifact size: 311.51 MiB -> 311.47 MiB (-0.01%)