[cfe-dev] macro_begin()/macro_end()

[Richard Smith]

On Wed, Jul 29, 2015 at 10:43 AM, Sean Callanan <scallanan at apple.com> wrote:

> LLDB’s module support (implemented here:
> http://llvm.org/svn/llvm-project/lldb/trunk/source/Expression/ClangModulesDeclVendor.cpp
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_svn_llvm-2Dproject_lldb_trunk_source_Expression_ClangModulesDeclVendor.cpp&d=AwMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=CnzuN65ENJ1H9py9XLiRvC_UQz6u3oG6GUNn7_wosSM&m=qJ7PzNcXqcUiCKOoFs9S4BDpb3TOf64WitZDB3JoLdM&s=WSvUUkZckMbgeN5UAaJKYWcqxxQzarzUBnC0_xfDRZ4&e=>)
> sets up its own CompilerInstance and then loads modules into it.
>
> The way we import macros from modules into expressions is by textual
> inclusion – we iterate across the macros like this:
>
> –
> if (m_compiler_instance->getPreprocessor().getExternalSource())
> {
>   m_compiler_instance->getPreprocessor().getExternalSource()->
> ReadDefinedMacros();
> }
>
>
> for (clang::Preprocessor::macro_iterator mi = m_compiler_instance->
> getPreprocessor().macro_begin(),
>                                          me = m_compiler_instance->
> getPreprocessor().macro_end();
>      mi != me; ++mi)
> {
>   // ...
>   clang::MacroInfo *macro_info = nullptr;
>
>
>   for (clang::ModuleMacro *module_macro : m_compiler_instance->
> getPreprocessor().getLeafModuleMacros(ii))
>   {
>     // pick the macro_info from the module we care most about; that might
> be NULL
>   }
>
>
>   if (macro_info)
>   {
>     // make a string from the macro
>   }
> }
> –
>
> What Im noticing is that a macro (say, “MAX”) doesn’t appear in the
> macro_begin() list at all.  Only later, after I’ve done a name lookup for
> “MAX" (on the assumption that it might be a variable, see
> ClangModulesDeclVendorImpl::FindDecls()), does it appear in the list.
>
> Is there something else I need to tickle here, or is this a bug in the API?
>

Does this help:

Index: lib/Serialization/ASTReader.cpp
===================================================================
--- lib/Serialization/ASTReader.cpp     (revision 243368)
+++ lib/Serialization/ASTReader.cpp     (working copy)
@@ -1623,7 +1623,7 @@

         case PP_MACRO_OBJECT_LIKE:
         case PP_MACRO_FUNCTION_LIKE:
-          getLocalIdentifier(**I, Record[0]);
+          updateOutOfDateIdentifier(*getLocalIdentifier(**I, Record[0]));
           break;

         case PP_TOKEN:
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