[cfe-dev] -ast-print-xml hasUninstantiatedDefaultArg assert

[Garrison Venn]

Well, it looks like I need more hand holding. While at frame 6 in gdb, executing:

print (argDecl->Loc).dump((argDecl->getASTContext()).getSourceManager())

gives: /usr/include/c++/4.2.1/bits/basic_string.h:254:36

Looking at the source code for SourceLocation::print(...), it looks like the above
should be interpreted as the filename:line#:col#. However the source line: 
<space+>_CharT* neither has a 36th column nor is a method decl
containing a param with a default arg. So I think I'm in never never land. Is this
because the use of getPresumedLoc(...) in the implementation of SourceLocation::
print(...) is not returning the correct location? Or is it because _CharT type is a 
template arg, and somehow that involves method instantiations behind the 
scene? Or is it ...? :-)

I think the real request is that I need more pointers if you have time. I do not believe 
the doc covers this kind of debugging for clang, but I've not been thorough, and 
regardless I believe we have an -ast-print-xml bug. If you agree, I'll file it, though
I was really hoping for better understanding of how parts of clang work. 

Thanks in advance again

Garrison

On Nov 1, 2010, at 16:37, Douglas Gregor wrote:

> 
> On Nov 1, 2010, at 1:07 PM, Garrison Venn wrote:
> 
>> On OS X (10.6.x) when running (with trunk revision: 117928):
>> 
>> clang++ -cc1 -ast-print-xml unparsedDefaultArg.cc 
>> 
>> produces the following partial stack dump with:
>> 
>> Assertion failed: (!hasUninstantiatedDefaultArg() && "Default argument is not yet instantiated!"), function getDefaultArg, file llvm/tools/clang/lib/AST/Decl.cpp, line 1092.
>> 0  clang++           0x000000010120978b PrintStackTrace(void*) + 38
>> 1  clang++           0x0000000101209d46 SignalHandler(int) + 254
>> 2  libSystem.B.dylib 0x00007fff812e635a _sigtramp + 26
>> 3  libSystem.B.dylib 0x0000000104c4dc65 _sigtramp + 2207676709
>> 4  clang++           0x000000010002099f raise + 27
>> 5  clang++           0x00000001000209af abort + 14
>> 6  clang++           0x0000000100020a3c __gnu_cxx::new_allocator<std::pair<void (*)(void*), void*> >::new_allocator() + 0
>> 7  clang++           0x00000001006bbda8 clang::ParmVarDecl::getDefaultArg() + 138
>> 8  clang++           0x0000000100079831 clang::DocumentXML::DeclPrinter::addSubNodes(clang::ParmVarDecl*) + 25
>> 9  clang++           0x000000010007994f clang::DocumentXML::DeclPrinter::VisitParmVarDecl(clang::ParmVarDecl*) + 249
>> 10 clang++           0x0000000100079eab clang::DeclVisitor<clang::DocumentXML::DeclPrinter, void>::Visit(clang::Decl*) + 1055
>> 11 clang++           0x000000010007a803 clang::DocumentXML::DeclPrinter::addSubNodes(clang::FunctionDecl*) + 61
>> 12 clang++           0x000000010007aee2 clang::DocumentXML::DeclPrinter::VisitCXXMethodDecl(clang::CXXMethodDecl*) + 858
>> ...
>> 
>> 
>> such that unparsedDefaultArg.cc ==
>> 
>> ---------------------- START --------------------------------
>> #include <string>
>> 
>> int main (int argc, char* argv[])
>> {
>>   return(0);
>> }
>> ----------------------- END -------------------------------
>> 
>> Same result occurs with a release build, and when building on Linux (32bit on ec2, clang+llvm
>> built with gcc4.2.1 and -m686).
>> 
>> I do not yet have the proficiency in Clang internals to debug this, but pointers 
>> in this direction would help mitigate my time. Specifically given that I need to
>> search for a parameter with a default arg, is there a symbol one could give
>> me which I could use in gdb to dump the current source (SourceLocation/SourceRange?)
>> at frame 7 above?
> 
> SourceLocation::dump(SourceManager&) will dump a source location in a human-readable format.
> 
> 	- Doug