Use .drectve for MSVC DLL exports by AsakuraMizu · Pull Request #158294 · rust-lang/rust

AsakuraMizu · 2026-06-23T09:04:46Z

This is a continuation of #142568.

This fixes the i686 MSVC issue mentioned there: .def files accept undecorated names, but .drectve /EXPORT needs decorated symbol names. The public export name is preserved with EXPORTAS.

It's worth noting that EII with defaults now also works on MSVC.

rustbot · 2026-06-23T09:04:52Z

r? @oli-obk

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AsakuraMizu · 2026-06-24T05:23:20Z

Updated :)

@rustbot ready

oli-obk

@bors r+ rollup

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rust-bors · 2026-06-24T15:22:04Z

📌 Commit 4051560 has been approved by oli-obk

It is now in the queue for this repository.

bjorn3 · 2026-06-24T16:11:27Z

Maybe rollup=iffy? Linkage related things tend to be tricky.

oli-obk · 2026-06-24T17:51:53Z

@bors rollup=iffy reason=windows linker shenanigans

…, r=oli-obk Use .drectve for MSVC DLL exports This is a continuation of rust-lang#142568. This fixes the i686 MSVC issue mentioned there: `.def` files accept undecorated names, but `.drectve` `/EXPORT` needs decorated symbol names. The public export name is preserved with `EXPORTAS`. It's worth noting that EII with defaults now also works on MSVC.

…uwer Rollup of 17 pull requests Successful merges: - #153697 (Add arg splat experiment initial tuple impl) - #158294 (Use .drectve for MSVC DLL exports) - #158253 (codegen_ssa: multiply scalable vec size by `vscale`) - #158308 (Fix bug when rustdoc "go to only result" setting is not working as expected") - #158345 (Use `transmute_neo` in `assume_init`) - #158369 (std: abort when `resume_unwind` is called inside the panic hook) - #158374 (disallow tail calling extern "rust-call" functions) - #158380 (Revert "rebuild LLVM when `bootstrap.toml` config changes") - #154398 (Add test for async Send with PhantomData<*mut ()> + unsafe impl Send + dyn Trait) - #157181 (autodiff: stop always needing an alloca) - #158278 (autodiff - typtree cleanups) - #158311 (doc(unstable-book): fix typo "earier" -> "earlier" in default-visibility flag) - #158318 (Make normalization in a test case resilient to dist compilation) - #158338 (Reorganize `tests/ui/issues` [14/N]) - #158343 (Include `Item::const_stability` info in rustdoc JSON.) - #158355 (Fixup the refactoring errors in #156246) - #158390 (Fix: auto trait, const trait bound) Failed merges: - #155535 (export symbols: support macos/windows(32/64))

JonathanBrouwer · 2026-06-25T10:18:41Z

💔 I suspect this PR failed tests as part of a rollup
@bors r-

After fixing the problem, consider running a try job for the failed job before re-approving.

Link to failure: #158391 (comment)

rust-bors · 2026-06-25T10:18:48Z

This pull request was unapproved.

This PR was contained in a rollup (#158391), which was unapproved.

View changes since this unapproval

JonathanBrouwer · 2026-06-25T10:29:30Z

@bors rollup=iffy reason=windows linker shenanigans

Thanks a lot btw, this helped in finding the pr :3

While it would be reasonable to expect the Windows linker to handle linker args in the .drectve section identical to cli arguments, as it turns out exporting weak symbols only works when the /EXPORT is in the .drectve section, not when it is a linker argument or when a .DEF file is used.

rustbot · 2026-06-29T06:19:41Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

AsakuraMizu · 2026-06-29T09:05:19Z

I've resolved the merge conflict and updated the test file. I did a simple verification on my local Windows machine, but I'm not sure if it will pass the CI completely.

@rustbot ready

oli-obk · 2026-06-29T10:30:46Z

@bors try x86_64-msvc-1

rust-bors · 2026-06-29T10:30:49Z

Unknown argument "x86_64-msvc-1". Did you mean to use @bors jobs=<jobs>|parent=<parent>? Run @bors help or go to https://bors.rust-lang.org/help to see available commands.

oli-obk · 2026-06-29T11:35:46Z

@bors try jobs=x86_64-msvc-1

Use .drectve for MSVC DLL exports try-job: x86_64-msvc-1

rust-bors · 2026-06-29T13:44:58Z

☀️ Try build successful (CI)
Build commit: fbb1950 (fbb195002ee8f5118ac156c1b0e56dd4b38aa343)
Base parent: 63f05e3 (63f05e3635171e7ac3f9ca78bad6c71052cda5a3)

oli-obk · 2026-06-29T13:46:22Z

@bors r+

rust-bors · 2026-06-29T13:46:25Z

📌 Commit c84bcbe has been approved by oli-obk

It is now in the queue for this repository.

rust-bors · 2026-06-29T14:56:37Z

⌛ Testing commit c84bcbe with merge 2523831...

Workflow: https://github.com/rust-lang/rust/actions/runs/28381305045

Use .drectve for MSVC DLL exports This is a continuation of #142568. This fixes the i686 MSVC issue mentioned there: `.def` files accept undecorated names, but `.drectve` `/EXPORT` needs decorated symbol names. The public export name is preserved with `EXPORTAS`. It's worth noting that EII with defaults now also works on MSVC.

rustbot assigned oli-obk Jun 23, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 23, 2026

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bjorn3 reviewed Jun 23, 2026

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Comment thread compiler/rustc_codegen_ssa/src/back/link.rs Outdated

bjorn3 reviewed Jun 23, 2026

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Comment thread compiler/rustc_codegen_ssa/src/back/linker.rs

oli-obk added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 23, 2026

AsakuraMizu force-pushed the windows-drectve-export branch from b0075d5 to 4051560 Compare June 24, 2026 05:22

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 24, 2026

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JonathanBrouwer mentioned this pull request Jun 25, 2026

Rollup of 18 pull requests #158386

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JonathanBrouwer mentioned this pull request Jun 25, 2026

Rollup of 17 pull requests #158389

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JonathanBrouwer mentioned this pull request Jun 25, 2026

Rollup of 17 pull requests #158391

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bjorn3 and others added 3 commits June 29, 2026 11:34

Fix MSVC drectve exports for decorated symbols

729ca3f

Use rust-lld for dll-weak-definition test

c84bcbe

AsakuraMizu force-pushed the windows-drectve-export branch from 4051560 to c84bcbe Compare June 29, 2026 06:19

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rust-bors Bot pushed a commit that referenced this pull request Jun 29, 2026

Auto merge of #158294 - AsakuraMizu:windows-drectve-export, r=<try>

fbb1950

Use .drectve for MSVC DLL exports try-job: x86_64-msvc-1

rust-bors Bot 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 Jun 29, 2026

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