rustc 1.82.0 doesn't add LIBPATH when invoking link.exe

[nandin-borjigin]

Rust-to-rust dynamic linking (through import library) on Windows fails with toolchain version 1.82.0.

The build log shows that 1.82.0 is not adding any /LIBPATH arguments when invoking link.exe.

I tried this code: nandin-borjigin/rustc-1.82.0-repro

I expected to see this happen: Successful build

Instead, this happened: LINK : fatal error LNK1181: cannot open input file 'mylib.dll.lib'

Meta

rustc --version --verbose:

rustc 1.82.0 (f6e511eec 2024-10-15)
binary: rustc
commit-hash: f6e511eec7342f59a25f7c0534f1dbea00d01b14
commit-date: 2024-10-15
host: x86_64-pc-windows-msvc
release: 1.82.0
LLVM version: 19.1.1

Backtrace

Possibly related

• -Clink-args=resources.res fails in 1.82 #131995

[ChrisDenton]

cc @petrochenkov, I believe there were some changes to linking with msvc?

[nandin-borjigin]

Adding this build script helps, but I think this should only be considered a workaround and rustc should emit library search path by default.

    println!("cargo:rustc-link-search=native={}/deps", out_dir.display());

[bjorn3]

I don't think this was supposed to work out of the box. Either you should make my_lib a cdylib (requiring you to build the cdylib from within the build script rather than specifying it as dependency, at least until artifact dependencies are stable) and link it like a C library (which includes adding it to the linker search path from a build script) or you should link it like a regular rust library and avoid #[link(name = "my_lib.dll")] extern "C" {}.

[petrochenkov]

This is likely from #128370.