[LLVMdev] Incomplete X86MachineFunctionInfo type

[Howard Hinnant]

In lib/Target/X86/X86COFFMachineModuleInfo.h we have:

   class X86MachineFunctionInfo;
   ...

   class X86COFFMachineModuleInfo : public MachineModuleInfoImpl {
     ...
     typedef std::map<const Function*, X86MachineFunctionInfo>  
FMFInfoMap;
     FMFInfoMap FunctionInfoMap;
     ...
   };

At this point in the translation unit X86MachineFunctionInfo is an  
incomplete type, yet it is being used to instantiate std::map.  This  
is undefined behavior in C++03 (and C++0X) according to:

    17.4.3.6 - Other functions [lib.res.on.functions], p2, b5

Unfortunately I am not familiar enough with this code to recommend a  
fix.  However I do know that this will create portability problems  
with llvm.  X86MachineFunctionInfo must not be incomplete at the point  
it is used to instantiate std::map.

-Howard