[LLVMdev] Parsing C++ headers with Clang bindings for Python

[Elliott Slaughter]

I'd like to parse a C++ header file (say, math.h) with the Clang bindings for Python. (Yes, I know math.h is technically a C header, but for my purposes I want to pretend that it is C++.) For some reason, Clang is able to parse the file as C, but not as C++.

Here is an example session:

>>> import clang.cindex
>>> idx = clang.cindex.Index.create()
>>> tu = idx.parse('/usr/include/math.h', ['-x', 'c++-header'])
>>> c = tu.cursor
>>> for d in c.get_children():
...     print d.kind, d.spelling
...
CursorKind.TYPEDEF_DECL __int128_t
CursorKind.TYPEDEF_DECL __uint128_t
CursorKind.TYPEDEF_DECL __builtin_va_list
CursorKind.UNEXPOSED_DECL
>>> print len(tu.diagnostics)
0

Now that list clearly does not represent the contents of math.h. However, as you can see, I don't get an error, and the list of diagnostics is empty.

When I use C mode, I instead get the list of functions I'm expecting to see:

>>> tu = idx.parse('/usr/include/math.h', ['-x', 'c-header'])
>>> c = tu.cursor
>>> for d in c.get_children():
...     print d.kind, d.spelling
...
CursorKind.TYPEDEF_DECL __int128_t
CursorKind.TYPEDEF_DECL __uint128_t
CursorKind.TYPEDEF_DECL __builtin_va_list
[...]
CursorKind.FUNCTION_DECL acosf
CursorKind.FUNCTION_DECL acos
CursorKind.FUNCTION_DECL acosl
[...]

Am I doing something obviously wrong (aside from calling math.h a C++ header)? Is there any reasonable way to debug problems like this?

I'm on Mac OS X 10.8 using the Clang binaries from Xcode (Apple LLVM version 5.0 (clang-500.2.75) (based on LLVM 3.3svn)), and Python bindings from Clang 3.2, and Python 2.7.2. (I am unable to test 3.3 because clang_Cursor_isBitField seems to be missing.)

Thanks.

--
Elliott Slaughter

"Don't worry about what anybody else is going to do. The best way to predict the future is to invent it." - Alan Kay

[Elliott Slaughter]

Answering my own question:

On Fri, Oct 18, 2013 at 8:51 PM, Elliott Slaughter <elliotts...@gmail.com> wrote:

I'd like to parse a C++ header file (say, math.h) with the Clang bindings for Python. (Yes, I know math.h is technically a C header, but for my purposes I want to pretend that it is C++.) For some reason, Clang is able to parse the file as C, but not as C++.

Here is an example session:

>>> import clang.cindex
>>> idx = clang.cindex.Index.create()
>>> tu = idx.parse('/usr/include/math.h', ['-x', 'c++-header'])
>>> c = tu.cursor
>>> for d in c.get_children():
...     print d.kind, d.spelling
...
CursorKind.TYPEDEF_DECL __int128_t
CursorKind.TYPEDEF_DECL __uint128_t
CursorKind.TYPEDEF_DECL __builtin_va_list
CursorKind.UNEXPOSED_DECL

It would seem that the contents on the entire module are hidden inside this UNEXPOSED_DECL. I'd be interesting in knowing why that is, but for now at least I seem to have solved my problem.

[Mark Lacey]

Hi Elliott,

On Oct 18, 2013, at 9:29 PM, Elliott Slaughter <elliotts...@gmail.com> wrote:

Answering my own question:

On Fri, Oct 18, 2013 at 8:51 PM, Elliott Slaughter <elliotts...@gmail.com> wrote:

I'd like to parse a C++ header file (say, math.h) with the Clang bindings for Python. (Yes, I know math.h is technically a C header, but for my purposes I want to pretend that it is C++.) For some reason, Clang is able to parse the file as C, but not as C++.

Here is an example session:

>>> import clang.cindex
>>> idx = clang.cindex.Index.create()
>>> tu = idx.parse('/usr/include/math.h', ['-x', 'c++-header'])
>>> c = tu.cursor
>>> for d in c.get_children():
...     print d.kind, d.spelling
...
CursorKind.TYPEDEF_DECL __int128_t
CursorKind.TYPEDEF_DECL __uint128_t
CursorKind.TYPEDEF_DECL __builtin_va_list
CursorKind.UNEXPOSED_DECL

It would seem that the contents on the entire module are hidden inside this UNEXPOSED_DECL. I'd be interesting in knowing why that is, but for now at least I seem to have solved my problem.

I am not sure why that is, but cfe...@cs.uiuc.edu is the correct place to discuss Clang design and implementation, so you should probably try asking there.

Mark

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[Elliott Slaughter]

On Sun, Oct 20, 2013 at 3:33 PM, Mark Lacey <mark....@apple.com> wrote:

Hi Elliott,

On Oct 18, 2013, at 9:29 PM, Elliott Slaughter <elliotts...@gmail.com> wrote:

Answering my own question:

On Fri, Oct 18, 2013 at 8:51 PM, Elliott Slaughter <elliotts...@gmail.com> wrote:

I'd like to parse a C++ header file (say, math.h) with the Clang bindings for Python. (Yes, I know math.h is technically a C header, but for my purposes I want to pretend that it is C++.) For some reason, Clang is able to parse the file as C, but not as C++.

Here is an example session:

>>> import clang.cindex
>>> idx = clang.cindex.Index.create()
>>> tu = idx.parse('/usr/include/math.h', ['-x', 'c++-header'])
>>> c = tu.cursor
>>> for d in c.get_children():
...     print d.kind, d.spelling
...
CursorKind.TYPEDEF_DECL __int128_t
CursorKind.TYPEDEF_DECL __uint128_t
CursorKind.TYPEDEF_DECL __builtin_va_list
CursorKind.UNEXPOSED_DECL

It would seem that the contents on the entire module are hidden inside this UNEXPOSED_DECL. I'd be interesting in knowing why that is, but for now at least I seem to have solved my problem.

I am not sure why that is, but cfe...@cs.uiuc.edu is the correct place to discuss Clang design and implementation, so you should probably try asking there.

Thanks for the pointer. Sorry about the spam.