Windows-gnullvm self-contained #147536

mati865 · 2025-10-09T18:23:31Z

No description provided.

mati865 · 2025-10-09T18:26:30Z

Tested locally on Windows but a shareable build would be useful.
@bors try jobs=dist-x86_64-linux,dist-x86_64-windows-gnullvm

Windows-gnullvm self-contained try-job: dist-x86_64-linux try-job: dist-x86_64-windows-gnullvm

mati865 · 2025-10-09T19:01:54Z

@bors try jobs=dist-x86_64-linux,dist-x86_64-windows-gnullvm

Windows-gnullvm self-contained try-job: dist-x86_64-linux try-job: dist-x86_64-windows-gnullvm

rust-bors · 2025-10-09T22:06:37Z

☀️ Try build successful (CI)
Build commit: 87a3415 (87a3415f29207b7d5add0b9bd83328ee459e7843, parent: 0b278a539440be291466ea463a9b6310eaf4d7bb)

src/bootstrap/src/core/build_steps/dist.rs

mati865 · 2025-10-28T19:04:58Z

Seems to work nicely, even with -Zbuild-std without having Clang in PATH.
What's left here is a cleanup and reconsideration of what would be the best way to move this forward.

estebank · 2025-11-04T16:49:36Z

@mati865 are there any blockers we could help you with?

compiler/rustc_codegen_ssa/src/back/link.rs

mati865 · 2025-11-05T20:50:27Z

@estebank I had a few ideas how to refactor it, but none of them turned out satisfying. I'm going to take another stab at it this week.

mati865 · 2025-11-12T16:41:59Z

@bors try jobs=dist-x86_64-linux,dist-x86_64-windows-gnullvm

Windows-gnullvm self-contained try-job: dist-x86_64-linux try-job: dist-x86_64-windows-gnullvm

rust-bors · 2025-11-12T19:53:23Z

☀️ Try build successful (CI)
Build commit: da8dd69 (da8dd699e467041c9cfdc421e44ac8758d9288e2, parent: 2fcbda6c1a70606bdb09857e01d01fc6229da712)

mati865 · 2025-11-17T18:08:27Z

compiler/rustc_codegen_ssa/src/back/link.rs

+    let self_contained_target = sess.target.os == Os::Windows
+        && sess.target.env == Env::Gnu
+        && sess.target.abi == Abi::Llvm
+        && self_contained_components.is_linker_enabled();
+    if self_contained_target
+        && let Some(ret) =
+            infer_from(sess, None, Some(LinkerFlavor::Gnu(Cc::No, Lld::Yes)), features)
+    {
+        return ret;
+    }


This doesn't feel nice, but alternatives would involve modifying the target spec to somehow allow configuring two different linkers.

rustbot · 2025-11-17T18:09:21Z

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

This PR modifies src/bootstrap/src/core/config.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

These commits modify compiler targets.
(See the Target Tier Policy.)

petrochenkov · 2025-11-18T10:20:56Z

src/bootstrap/src/core/build_steps/dist.rs

    }
 }

+fn make_win_llvm_dist(plat_root: &Path, target: TargetSelection, builder: &Builder<'_>) {


Nit: maybe put it next to fn make_win_dist? I tried to look above and below to check the difference between the two functions, but didn't find what I searched for.

petrochenkov · 2025-11-18T10:22:39Z

src/bootstrap/src/core/build_steps/dist.rs

+        "libmingw32.a",
+        "libmingwex.a",
+        "libmsvcrt.a",
+        // Windows import libs, remove them once std transitions to raw-dylib


Wait, it didn't transition yet? I clearly remember some PR doing that. Maybe not for this target specifically?

Std is still built without raw-dylib:

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

Lines 665 to 668 in c199562

if let Mode::Rustc | Mode::ToolRustcPrivate | Mode::ToolBootstrap | Mode::ToolTarget = mode

{

rustflags.arg("--cfg=windows_raw_dylib");

}

petrochenkov · 2025-11-18T10:59:52Z

compiler/rustc_codegen_ssa/src/back/link.rs

        return ret;
    }

+    // When using a supported target in self-contained linker mode, we want to use rust-lld directly.


I dislike this at pretty fundamental level.

-Clink-self-contained isn't supposed to change the linker flavor, only to change where the linker (and other things) are looked up.

If windows-gnullvm targets can be built with naked linker, without clang, then perhaps they should change the default linker and linker flavor to ld.lld?
Are windows-gnullvm targets stable enough for it to be considered a breaking change?

Also, in self-contained mode we are supposed to use ld.lld from the self-contained directory, not rust-lld.
It seems like the logic below results in that, but then the comment above is misleading.

If windows-gnullvm targets can be built with naked linker, without clang

Basically all the targets can be linked with just a linker without CC driver given you provide required objects and libraries.
Currently, Rust ships those libraries and objects for *-pc-windows-gnu (in rust-mingw component) and some musl targets (I don't know which ones exactly; definitely x86_64 and aarch64). Which means they could just pass those shipped libs to the linker directly if they are using them anyway (so we are using -Clink-self-contained).

For example, take x86_64-pc-windows-gnu. It ships x86_64-w64-mingw32-gcc.exe and ld.exe, but it doesn't really matter whether we call x86_64-w64-mingw32-gcc -l[rust objects] -l[mingw-w64 objects and libs] -o result.exe or ld -l[rust objects] -l[mingw-w64 objects and libs] -o result.exe as long as you add the flags in the correct form, i.e. prepend them with -Wl, when using GCC as the proxy. It was just easier to ship GCC binary and reuse the code.

What I'm trying to achieve here is to pass the libraries directly to LLD in self-contained-mode for windows-gnullvm hosts, so it can run similarly to windows-gnu hosts even when there is no mingw-w64 toolchain installed. But also keep the previous behaviour, which will call x86_64-w64-mingw32-clang from PATH if it finds one.
Shipping clang is difficult because of its sheer size, so writing a wrapper that just calls LLD would be more feasible.

then perhaps they should change the default linker and linker flavor to ld.lld?

This would be a groundbreaking change. That would mean it no longer uses user's toolchain and libraries. I think this would be pretty bad.

Also, in self-contained mode we are supposed to use ld.lld from the self-contained directory, not rust-lld.

There are no self-contained binaries, only lib/rustlib/x86_64-pc-windows-gnullvm/bin/gcc-ld/ which contains various wrappers over rust-lld.

petrochenkov · 2025-11-18T11:04:02Z

compiler/rustc_codegen_ssa/src/back/link.rs


-// Returns true if linker is located within sysroot
-fn detect_self_contained_mingw(sess: &Session, linker: &Path) -> bool {
-    // Assume `-C linker=rust-lld` as self-contained mode


The logic here pre-dates windows-gnullvm targets, so apparently someone used windows-gnu targets with the naked rust-lld linker, and I see some supports for that in the target specs.
But this PR removes the self-contained mode from windows-gnu + rust-lld mode, what is the reason for that?

Ah, I lost that in one of the refactors of this code.

I happen to know the person who did it: https://github.com/rust-lang/rust/pull/76167/files#diff-862130c0af71054886913befc8084094485fa7d764d95f55644e033e34acd126R1214

This comment has been minimized.

Sign in to view

rust-bors bot added a commit that referenced this pull request Oct 9, 2025

Auto merge of #147536 - mati865:gnullvm-self-contained, r=<try>

fa81451

Windows-gnullvm self-contained try-job: dist-x86_64-linux try-job: dist-x86_64-windows-gnullvm

mati865 mentioned this pull request Oct 9, 2025

[x86_64-pc-windows-gnullvm] Target doesn't ship with a linker, can't build simple test application #146634

Open

This comment was marked as resolved.

Sign in to view

This comment has been minimized.

Sign in to view

rust-bors bot added a commit that referenced this pull request Oct 9, 2025

Auto merge of #147536 - mati865:gnullvm-self-contained, r=<try>

87a3415

Windows-gnullvm self-contained try-job: dist-x86_64-linux try-job: dist-x86_64-windows-gnullvm

mati865 commented Oct 9, 2025

View reviewed changes

src/bootstrap/src/core/build_steps/dist.rs Show resolved Hide resolved

petrochenkov self-assigned this Oct 10, 2025

estebank reviewed Nov 4, 2025

View reviewed changes

compiler/rustc_codegen_ssa/src/back/link.rs Outdated Show resolved Hide resolved

mati865 force-pushed the gnullvm-self-contained branch from f3f33b7 to 9d27d77 Compare November 10, 2025 20:02

This comment has been minimized.

Sign in to view

mati865 force-pushed the gnullvm-self-contained branch from 9d27d77 to 9f92112 Compare November 11, 2025 12:45

This comment was marked as resolved.

Sign in to view

mati865 force-pushed the gnullvm-self-contained branch from 9f92112 to 48d04c8 Compare November 12, 2025 14:19

mati865 added 5 commits November 12, 2025 15:43

wip gnullvm self-contained

daa7862

Slightly refactor mingw detection

3756602

Use self-contained with windows-gnullvm

46df47f

Fix -C linker=rust-lld

0b26831

workaround for cranelift

0c43cb7

mati865 added 6 commits November 12, 2025 15:43

Revert unnecessary change

d861ad2

Fix comment

4b9ae15

Update manifest

ae0a826

refactor

3ec4b67

address review feedback

89d5fde

fix after rebase

2b5ac0b

mati865 force-pushed the gnullvm-self-contained branch from 48d04c8 to 2b5ac0b Compare November 12, 2025 14:54

This comment has been minimized.

Sign in to view

rust-bors bot added a commit that referenced this pull request Nov 12, 2025

Auto merge of #147536 - mati865:gnullvm-self-contained, r=<try>

da8dd69

Windows-gnullvm self-contained try-job: dist-x86_64-linux try-job: dist-x86_64-windows-gnullvm

mati865 commented Nov 17, 2025

View reviewed changes

mati865 marked this pull request as ready for review November 17, 2025 18:09

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 Nov 17, 2025

petrochenkov reviewed Nov 18, 2025

View reviewed changes

petrochenkov 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 Nov 18, 2025

	if let Mode::Rustc \| Mode::ToolRustcPrivate \| Mode::ToolBootstrap \| Mode::ToolTarget = mode
	{
	rustflags.arg("--cfg=windows_raw_dylib");
	}

Windows-gnullvm self-contained #147536

Are you sure you want to change the base?

Windows-gnullvm self-contained #147536

Conversation

mati865 commented Oct 9, 2025

Uh oh!

mati865 commented Oct 9, 2025

Uh oh!

This comment has been minimized.

This comment was marked as resolved.

This comment was marked as resolved.

This comment was marked as resolved.

mati865 commented Oct 9, 2025

Uh oh!

This comment has been minimized.

rust-bors bot commented Oct 9, 2025

Uh oh!

Uh oh!

mati865 commented Oct 28, 2025

Uh oh!

estebank commented Nov 4, 2025

Uh oh!

Uh oh!

mati865 commented Nov 5, 2025

Uh oh!

This comment has been minimized.

This comment was marked as resolved.

mati865 commented Nov 12, 2025

Uh oh!

This comment has been minimized.

rust-bors bot commented Nov 12, 2025

Uh oh!

Choose a reason for hiding this comment

Uh oh!

rustbot commented Nov 17, 2025

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants