Regression: localized MSVC linker progress messages are emitted as linker stdout warnings

[gifnksm]

Code

I tried this code:

Cargo.toml

[package]
name = "foo"
version = "0.1.0"
edition = "2024"

[lib]
crate-type = ["cdylib"]

src/lib.rs (empty)

Build with:

cargo build

I expected to see this happen:

The build should complete without any warnings.

Instead, this happened:

warning: linker stdout: ライブラリ C:\Users\...\foo.dll.lib とオブジェクト C:\Users\...\foo.dll.exp を作成中
  |
  = note: `#[warn(linker_messages)]` on by default

The warning is emitted on every build.

According to the Rust 1.97 release notes, common linker messages that have been diagnosed as false positives or intentional behavior are filtered out by rustc.

The linker message:

ライブラリ ... とオブジェクト ... を作成中

translates to:

Creating library ... and object ...

This appears to be the localized equivalent of one of those common linker messages.

Version it worked on

It most recently worked on: 1.96.0

Version with regression

rustc --version --verbose:

rustc 1.97.0 (2d8144b78 2026-07-07)
binary: rustc
commit-hash: 2d8144b7880597b6e6d3dfd63a9a9efae3f533d3
commit-date: 2026-07-07
host: x86_64-pc-windows-msvc
release: 1.97.0
LLVM version: 22.1.6

rustc +nightly --version --verbose:

rustc 1.99.0-nightly (375b1431b 2026-07-10)
binary: rustc
commit-hash: 375b1431b7d89d1c2e2bc168c011848ae12b7d14
commit-date: 2026-07-10
host: x86_64-pc-windows-msvc
release: 1.99.0-nightly
LLVM version: 22.1.8

Backtrace

N/A (no crash)

Additional information

Environment:

• Windows 11 (display language: Japanese)
• Target: x86_64-pc-windows-msvc
• Visual Studio Build Tools 2022
• link.exe version 14.44.35228.0

The issue reproduces consistently with the minimal example above.

The linker is localized. For example, invoking link.exe without arguments displays Japanese help text.

Looking at compiler/rustc_codegen_ssa/src/back/link.rs, the linker message filter appears to recognize English messages such as "Creating library", but not the localized equivalent.

@rustbot modify labels: +regression-from-stable-to-stable -regression-untriaged

[ChrisDenton]

We do also attempt to force English output

rust/compiler/rustc_codegen_ssa/src/back/linker.rs

Line 43 in 3b58636

linker.env("VSLANG", "1033");

However, that only works if the English language pack is installed.

[gifnksm]

Additional finding: I believe the mechanism is now clear.

In my environment, the issue is caused by link.exe emitting localized (Japanese) progress text.
rustc sets VSLANG=1033 when invoking link.exe, but this only has effect if the English language resources are installed in Visual Studio Build Tools.

What I observed:

• Without English language pack:
  • link.exe output remains Japanese
  • rustc reports the localized progress line as warning: linker stdout
• After installing English language pack:
  • VSLANG=1033 takes effect
  • link.exe output becomes English
  • warning disappears (intended behavior)

So this issue seems to depend on whether English language resources are present, not just on VSLANG being set.

Question for maintainers: should rustc treat “no English language pack installed” as supported and still suppress this known-benign message, or is requiring English linker resources acceptable?