Why can't bindgen find libclang.dll?

[Boscop]

Why can't bindgen find libclang.dll?

D:\3rdparty\reaper_extension_sdk\jmde>bindgen reaper_plugin_functions.h -o reaper.rs
thread 'main' panicked at 'Unable to find libclang: "the `libclang` shared libra
ry at D:\\Program Files\\LLVM\\bin\\libclang.dll could not be opened: %1 is not
a valid Win32 application. (os error 193)"', libcore\result.rs:945:5
stack backtrace:
   0: <unknown>
   1: <unknown>
   2: <unknown>
   3: <unknown>
   4: <unknown>
   5: <unknown>
   6: <unknown>
   7: <unknown>
   8: <unknown>
   9: <unknown>
  10: <unknown>
  11: <unknown>
  12: <unknown>
  13: <unknown>
  14: BaseThreadInitThunk
  15: RtlInitializeExceptionChain
  16: RtlInitializeExceptionChain

Btw, the file "D:\Program Files\LLVM\bin\libclang.dll" exists and has version 4.0.0.0.
An earlier version of bindgen cli was working without problems on this system.

[emilio]

If this is a regression, could you please try different versions to figure out which regressed?

This should probably be reported upstream to the clang-sys crate, though looks like your DLL is borked in some way.

[emilio]

This may even be a regression in libloading itself I guess.

[Boscop]

Thanks for the quick reply. I tried version 0.30.0 (cargo install -f --vers 0.30.0 bindgen, it seems to load libclang.dll but fails on C++ constructs.. Do I have to pass a flag to enable C++ support?

D:\3rdparty\reaper_extension_sdk\jmde>bindgen reaper_plugin_functions.h -o reaper.rs
./reaper_plugin.h:149:1: error: unknown type name 'class'
./reaper_plugin.h:149:26: error: expected ';' after top level declarator
./reaper_plugin.h:174:1: error: unknown type name 'class'
./reaper_plugin.h:174:21: error: expected ';' after top level declarator
./reaper_plugin.h:204:3: error: unknown type name 'MIDI_eventlist'
./reaper_plugin.h:248:3: error: unknown type name 'MIDI_eventlist'
./reaper_plugin.h:258:1: error: unknown type name 'class'
./reaper_plugin.h:258:17: error: expected ';' after top level declarator
./reaper_plugin.h:302:3: error: unknown type name 'bool'
./reaper_plugin.h:309:3: error: unknown type name 'PCM_source'
./reaper_plugin.h:375:3: error: unknown type name 'PCM_source'
./reaper_plugin.h:376:3: error: unknown type name 'PCM_source'
./reaper_plugin.h:389:1: error: unknown type name 'class'
./reaper_plugin.h:389:26: error: expected ';' after top level declarator
./reaper_plugin.h:439:3: error: unknown type name 'bool'
./reaper_plugin.h:449:1: error: unknown type name 'class'
./reaper_plugin.h:449:15: error: expected ';' after top level declarator
./reaper_plugin.h:490:3: error: unknown type name 'PCM_sink'
./reaper_plugin.h:490:91: error: unknown type name 'bool'
fatal error: too many errors emitted, stopping now [-ferror-limit=]
./reaper_plugin.h:149:1: error: unknown type name 'class', err: true
./reaper_plugin.h:149:26: error: expected ';' after top level declarator, err: t
rue
./reaper_plugin.h:174:1: error: unknown type name 'class', err: true
./reaper_plugin.h:174:21: error: expected ';' after top level declarator, err: t
rue
./reaper_plugin.h:204:3: error: unknown type name 'MIDI_eventlist', err: true
./reaper_plugin.h:248:3: error: unknown type name 'MIDI_eventlist', err: true
./reaper_plugin.h:258:1: error: unknown type name 'class', err: true
./reaper_plugin.h:258:17: error: expected ';' after top level declarator, err: t
rue
./reaper_plugin.h:302:3: error: unknown type name 'bool', err: true
./reaper_plugin.h:309:3: error: unknown type name 'PCM_source', err: true
./reaper_plugin.h:375:3: error: unknown type name 'PCM_source', err: true
./reaper_plugin.h:376:3: error: unknown type name 'PCM_source', err: true
./reaper_plugin.h:389:1: error: unknown type name 'class', err: true
./reaper_plugin.h:389:26: error: expected ';' after top level declarator, err: t
rue
./reaper_plugin.h:439:3: error: unknown type name 'bool', err: true
./reaper_plugin.h:449:1: error: unknown type name 'class', err: true
./reaper_plugin.h:449:15: error: expected ';' after top level declarator, err: t
rue
./reaper_plugin.h:490:3: error: unknown type name 'PCM_sink', err: true
./reaper_plugin.h:490:91: error: unknown type name 'bool', err: true
fatal error: too many errors emitted, stopping now [-ferror-limit=], err: true
thread 'main' panicked at 'Unable to generate bindings: ()', libcore\result.rs:9
45:5
stack backtrace:
   0: <unknown>
   1: <unknown>
   2: <unknown>
   3: <unknown>
   4: <unknown>
   5: <unknown>
   6: <unknown>
   7: <unknown>
   8: <unknown>
   9: <unknown>
  10: <unknown>
  11: <unknown>
  12: <unknown>
  13: <unknown>
  14: <unknown>
  15: <unknown>
  16: <unknown>
  17: BaseThreadInitThunk
  18: RtlUserThreadStart

Update: same behavior with v0.32.0

[Boscop]

Just tried with v0.33.0, it shows this:

[Michael-F-Bryan]

I just encountered this at work. I know clang itself is installed, but every time I try to run bindgen it fails saying %1 is not a valid Win32 application.

C:\Users\mbryan> bindgen --version
thread 'main' panicked at 'Unable to find libclang: "the `libclang` shared library at C:\\Program Files (x86)\\LLVM\\bin\\libclang.dll could not be opened: %1 is not a valid Win32 application. (os error 193)"', libcore\result.rs:945:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
C:\Users\mbryan> clang --version
clang version 5.0.1 (tags/RELEASE_501/final)
Target: i686-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files (x86)\LLVM\bin

I tried re-running with RUST_BACKTRACE="full" but it's a release build without debug symbols available, so the backtrace is essentially useless.

EDIT: I just added bindgen as a build script and managed to get a backtrace.

errors.txt

[emilio]

So, the error comes from here:

https://github.com/KyleMayes/clang-sys/blob/e6948cb8e7d6d67d6eb409aa788699b401ef9585/src/link.rs#L122

I don't have a machine that reproduces the issue but if it worked before chances are that this is a libloading regression (cc @nagisa). Probably an issue should be filed there.

[Michael-F-Bryan]

I just noticed that under clang --version it says Target: i686-pc-windows-msvc. It may be the case that I installed clang as a 32-bit program (the application I'm interfacing with is 32-bit) and then I've told rustup to target 64-bit during development.

I'm not sure whether this is actually the case, but when I'm back at work on Monday I'll check whether that DLL is 32-bit or 64-bit. It could be that the "%1 is not a valid Win32 application" error is a red herring or not the root cause, and the actual issue is you can't load the DLL because it's got a different wrong word size to the build script/bindgen program.

@Boscop, does any of this sound familiar?

[Boscop]

But I didn't change the libclang.dll since bindgen worked, and the old bindgen was installed the same way so it must also have been 64 bit..
Is there a way I can cargo install the 32 bit version to test?

[KyleMayes]

v0.23.0 of clang-sys has been released to address this issue.

The issue was indeed the selection of 32-bit DLLs for a 64-bit build (or vice-versa) and the fix was to skip DLLs for the incorrect architecture while searching for clang.dll / libclang.dll.