[LLVMbugs] [Bug 387] NEW: Need -Woverloaded-virtual To Catch Inheritance Errors

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=387

           Summary: Need -Woverloaded-virtual To Catch Inheritance Errors
           Product: Build scripts
           Version: cvs
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Makefiles
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: rspencer at x10sys.com
                CC: ghost at cs.msu.su


We need to start using the -Woverloaded-virtual option in the makefiles to catch
some inheritance bugs. Patches for this bug should first rid all of LLVM of
warnings produced by -Woverloaded-virtual option and then patch the makefiles to
turn the option on.

This idea submitted by Vladimir Prus where he made the following comments on
LLVMdev list: 

I've just had some fun, because I wanted to override 
FunctionPass::addAnalysisUsage, but forgot "const" after the method name -- 
so instead of overriding I've just created a new unrelated method.

After spending some time on this, I've decided to add -Woverloaded-virtual 
option to compiler to catch such cases. However, it also gives some warnings 
on LLVM code:

../../../include/llvm/Pass.h:264: warning: `virtual bool 
   llvm::FunctionPass::run(llvm::Module&)' was hidden
../../../include/llvm/Pass.h:326: warning:   by `bool 
   llvm::BasicBlockPass::run(llvm::BasicBlock&)'
../../../include/llvm/Pass.h:275: warning: `virtual void 
   llvm::FunctionPass::addToPassManager(llvm::PassManagerT<llvm::Module>*, 
   llvm::AnalysisUsage&)' was hidden
../../../include/llvm/Pass.h:332: warning:   by `virtual void 
   llvm::BasicBlockPass::addToPassManager(llvm::PassManagerT<llvm::BasicBlock>*,
   llvm::AnalysisUsage&)'

The problem is that "run" method is virtual in Path (with Module& as 
argument), but another version (non-virtual), which takes BasicBlock& is 
defined in BasicBlockPath.

Do you think this warning is worth fixing? One possible approach is to rename 
virtual run(Module&) to runOnModule, but that would require updating all 
derived classes :-(



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