[cfe-dev] Parsing gnu c++ headers/code

[Richard Smith]

On Mon, May 13, 2013 at 8:33 AM, Pascal Ognibene <pognibene at gmail.com>wrote:

> Hi all,
>
> I want to parse C++ and C headers coming from a GCC/G++ installation, with
> clang 3.2 and a recursive visitor pattern. I have difficulties to parse
> some headers with messages like:
>
> stdlib.h:863:20: error: unknown type name 'wchar_t'
> extern int mbtowc (wchar_t *__restrict __pwc,
>
> This is while parsing gcc 4.2.4 headers. I do have the wchar.h header in
> the include path.
>
> I configure my CompilerInstance the following way:
>
> ...
>
>     CompilerInstance ci;
>     if ( useCpp )
>     {
>         ci.getLangOpts().CPlusPlus = 1;
>         ci.getLangOpts().Bool = 1;
>         ci.getLangOpts().CXXExceptions = 1;
>         ci.getLangOpts().RTTI = 1;
>         //ci.getLangOpts().GNUMode = 1;
>

You also need to set WChar. But this method of setting up a
CompilerInstance is not recommended, because there's a whole big pile of
things to remember (and the set of things changes frequently). Instead,
consider using CompilerInvocation to set up your CompilerInstance.


>     }
>
>     ci.createDiagnostics ( 0, NULL );
>
>     TargetOptions to;
>     to.Triple = llvm::sys::getDefaultTargetTriple();
>     TargetInfo *pti = TargetInfo::CreateTargetInfo ( ci.getDiagnostics(),
> to );
>     ci.setTarget ( pti );
>
>     ci.createFileManager();
>     ci.createSourceManager ( ci.getFileManager() );
>     ci.createPreprocessor();
>
> //try to get the gcc built ins
> //seems to work!
> //need now the C headers in addition of C++ headers
> //for gcc 4.2
>     clang::Preprocessor &PP = ci.getPreprocessor();
>     PP.getBuiltinInfo().InitializeBuiltins(PP.getIdentifierTable(),
>                                            PP.getLangOpts());
>     HeaderSearchOptions headerSearchOptions;
>     for ( std::vector<std::string>::iterator it = includeList.begin(); it
> != includeList.end(); ++it )
>     {
>         headerSearchOptions.AddPath ( *it,
>                                       clang::frontend::Angled,
>                                       false,
>                                       false,
>                                       false );
>     }
>
>     clang::PreprocessorOptions &ppOptions = ci.getPreprocessorOpts();
>     for ( std::vector<std::string>::iterator it = macroList.begin(); it !=
> macroList.end(); ++it )
>     {
>         ppOptions.addMacroDef ( *it );
>     }
>
>     clang::InitializePreprocessor ( ci.getPreprocessor(),
>                                     ci.getPreprocessorOpts(),
>                                     headerSearchOptions,
>                                     ci.getFrontendOpts() );
>     ci.createASTContext();
>
>     MyASTConsumer *astConsumer = NULL;
>     MyASTConsumerCpp *astConsumerCpp = NULL;
>
>     if ( useCpp )
>     {
>         astConsumerCpp = new MyASTConsumerCpp ( &ci.getASTContext() );
>         ci.setASTConsumer ( astConsumerCpp );
>     }
>     else
>     {
>         astConsumer = new MyASTConsumer ( &ci.getASTContext() );
>         ci.setASTConsumer ( astConsumer );
>     }
>
>     const FileEntry *pFile = ci.getFileManager().getFile ( inputFile );
>     ci.getSourceManager().createMainFileID ( pFile );
>     ci.getDiagnosticClient().BeginSourceFile ( ci.getLangOpts(),
>             &ci.getPreprocessor() );
>
>     if ( useCpp )
>     {
>         clang::ParseAST ( ci.getPreprocessor(), astConsumerCpp,
> ci.getASTContext() );
>     }
>     else
>     {
>         clang::ParseAST ( ci.getPreprocessor(), astConsumer,
> ci.getASTContext() );
>     }
>     ci.getDiagnosticClient().EndSourceFile();
>
> ...
>
> I was hoping that this was enough to make clang 3.2 "gcc 4.2 compatible"
> but it looks like it's not the case. Any idea of the required
> options/initialization sequence for clang to understand glibc and gnu
> libC++ specificities and parse properly GNU headers?
>
> Thank you for your help!
>
> Pascal
>
> _______________________________________________
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> cfe-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>
>
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