llvm dev - Oct 2013 - [LLVMdev] Parsing C++ headers with Clang bindings for Python

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
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Answering my own question:

On Fri, Oct 18, 2013 at 8:51 PM, Elliott Slaughter <
elliottslaughter at 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.

> >>> 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

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

On Oct 18, 2013, at 9:29 PM, Elliott Slaughter <elliottslaughter at
gmail.com> wrote:
> Answering my own question:
> 
> On Fri, Oct 18, 2013 at 8:51 PM, Elliott Slaughter <elliottslaughter at
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-dev at cs.uiuc.edu is the correct place to
discuss Clang design and implementation, so you should probably try asking
there.

Mark
>  
> >>> 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
> 
> "Don't worry about what anybody else is going to do. The best way
to predict the future is to invent it." - Alan Kay
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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