rust-lang / rust-lang/rust-bindgen

Problems bulding with msys2

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Description

I'm trying to build an app that needs to make use of libftdi, this makes use of bindgen to build the external library which is then static linked into the app, making it portable.

I am forced to use msys2/gnu rather than msvc.

I get the obscure error "Unable to find libclang: "the libclang shared library at C:\msys64\clang64\bin\libclang.dll could not be opened: LoadLibraryExW failed" But no indication what the cause of the failure actually is.

The file DOES exist in the location shown.

    Directory: C:\msys64\clang64\bin
Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---          04/12/2025    01:22       33602560 libclang.dll

My Cargo.toml contains

libftd2xx-ffi = { version = "~0.8.7", features = ["bindgen"] }
libftd2xx = { version = "0.33.1", features = ["static"] }

At first I got errors that bindgen could not find libclang.dll I fixed that by setting an environment variable in config.toml

I added LIBCLANG_PATH to my .cargo/config.toml

[target.x86_64-pc-windows-gnu]
linker = "C:\\msys64\\mingw64\\bin\\gcc.exe"
ar = "C:\\msys64\\mingw64\\bin\\ar.exe"

[env]
LIBCLANG_PATH = "C:\\msys64\\clang64\\bin"

The only other mentions I can find of this error are related to an embedded Rust project for ESP32. https://github.com/esp-rs/rust-build/issues/282, and they solve that by 'downgrading'.

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Research direction

Start with the stated Cargo.toml dependencies and .cargo/config.toml, then reproduce the x86_64-pc-windows-gnu build using the reported MSYS2 paths. Investigate the LoadLibraryExW failure for C:\msys64\clang64\bin\libclang.dll rather than only checking that the file exists. Done means identifying the cause of the failed library load and documenting a reproducible resolution.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
build-system
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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