[LLVMbugs] [Bug 12747] New: CallGraph Fails to List Prototype only functions

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=12747

             Bug #: 12747
           Summary: CallGraph Fails to List Prototype only functions
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Static Analyzer
        AssignedTo: kremenek at apple.com
        ReportedBy: mark.d.mccurry at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Currently the callgraph class defined at clang/lib/Analysis/CallGraph.cpp fails
to list the full callgraph when calls are made to functions without
definitions.
This problem occurs in today's version of the svn head.

To Replicate:

Use clang::CallGraph to generate a callgraph from:

---------------------------------------
//Function prototype (eg from a header)
void prototype_only(void);

void trivial_function(void)
{}

void calling_function(void)
{
    prototype_only();
    trivial_function();
}
---------------------------------------

Actual Output: [from CallGraph::dump()]
 --- Call graph Dump --- 
  Function: < root > calls: trivial_function calling_function 
  Function: trivial_function calls: 
  Function: calling_function calls: trivial_function 

Expected Output:
 --- Call graph Dump --- 
  Function: < root > calls: trivial_function calling_function 
  Function: trivial_function calls: 
  Function: calling_function calls: prototype_only trivial_function

Source of the issue:

This behavior occurs due to CallGraph::includeInGraph().
It eliminates any Declarations that are not definitions, which makes sense for
top level elements, but IMO it seems like a bug for function calls themselves.

 72 if (!FD->isThisDeclarationADefinition() ||
 73     FD->isDependentContext())
 74   return false;

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