Why can't this python script find the libclang dll?

Question

I would like to get started with using libclang with Python. I am trying to get a sample code (http://www.altdevblogaday.com/2014/03/05/implementing-a-code-generator-with-libclang/) to work on Windows, here is a part of the code I'm trying to run:

#!/usr/bin/python
# vim: set fileencoding=utf-8

import sys
import os
import clang.cindex
import itertools

...

print("Setting clang path")
# I tried multiple variations. Libclang is correctly installed in the specified location.
#clang.cindex.Config.set_library_path('C:/Program Files (x86)/LLVM/bin')
#clang.cindex.Config.set_library_path('C:/Program Files (x86)/LLVM/bin/libclang.dll')

# I also tried moving the dll into the Python installation folder.
clang.cindex.Config.set_library_file('C:/Python27/DLLs/libclang.dll')
print("Clang path set")

index = clang.cindex.Index.create()

...

I stripped all the other parts of the code, but I can post them if they are relevant. The line

index = clang.cindex.Index.create()

Throws the following error:

Setting clang path
Clang path set
Traceback (most recent call last):
  File "D:\libclangtest\boost_python_gen.py", line 60, in <module>
    index = clang.cindex.Index.create()
  File "D:\libclangtest\clang\cindex.py", line 2095, in create
    return Index(conf.lib.clang_createIndex(excludeDecls, 0))
  File "D:\libclangtest\clang\cindex.py", line 141, in __get__
    value = self.wrapped(instance)
  File "D:\libclangtest\clang\cindex.py", line 3392, in lib
    lib = self.get_cindex_library()
  File "D:\libclangtest\clang\cindex.py", line 3423, in get_cindex_library
    raise LibclangError(msg)
clang.cindex.LibclangError: [Error 193] %1 is not a valid Win32 application. To provide a path to libclang use Config.set_library_path() or Config.set_library_file().

What is the reason for this? Am I setting the dll's path wrong? I tried multiple ways, with foreslashes and backslashes, I also tried to move the dll out of Program Files to make the path contain no spaces, but nothing worked.

I am a total beginner to libclang and Python, sry if I'm asking something trivial.

Make sure both python and libclang are either 32bit or 64bit. Also, make sure a path to your libclang.dll is in the PATH environment variable. — SK-logic, Mar 29 '14 at 14:12
I added it to the PATH, but I don't think that's the problem, since I have to set its path by hand with set_library_file function. I'm gonna check whether it's 32 or 64bit, thanks for the tip! — Mark Vincze, Mar 29 '14 at 14:31

score 6 · Answer 1 · edited Nov 09 '21 at 05:40

6

I was running into a similar problem (Windows 7 x64, Anaconda3 x64). Using

import clang.cindex
clang.cindex.Config.set_library_file('C:/Program Files/LLVM/bin/libclang.dll')

fixed the problem. Please note that you need to use slashes (not antislashes), and specify path to bin/libclang.dll (not to lib/libclang.dll).

edited Nov 09 '21 at 05:40

keineahnung2345

2,635
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answered May 15 '18 at 11:27

Hope

1,051
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I have similar problem: I can find libclang.dll but, when I try to create index I receive an error that says function clang_CXXRecord_isAbstract is not found. I have python 3.6 64 bit, anaconda3 64 bit and windows 10, obviousl 64 bit. Llvm is installed by anaconda. Python-clang is 6.0.0.2, clang --version outputs 3.9.1. I'm confused. – Germano Carella Sep 02 '18 at 09:55

score 4 · Accepted Answer · answered Mar 29 '14 at 15:22

4

@SK-logic commented that I should check whether both Python and libclang are either 32bit or 64bit. Libclang was 32bit, but I couldn't find a way to check whether my Python installation is 32 or 64, so I reinstalled the 32bit version, and now it works. So the problem probably was that I had the 64 bit version of Python.

answered Mar 29 '14 at 15:22

Mark Vincze

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You can open the EXE in Dependency Walker (depends.exe) and check whether it's 32 or 64 bit. – cubuspl42 Oct 09 '14 at 23:34
You can inspect whether CPython is 32-bit or 64-bit in several ways, such as `platform.architecture()[0]`; the `sys.version` string (MSC builds); whether `sys.maxsize` is `2**31-1` or `2**63-1`; or whether the pointer size is 4 or 8 bytes via either `struct.Struct('P').size` or `ctypes.sizeof(ctypes.c_void_p)`. – Eryk Sun Oct 10 '14 at 01:45

Why can't this python script find the libclang dll?

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