[cfe-commits] r58100 - in /cfe/trunk: lib/Sema/SemaDecl.cpp test/SemaCXX/fntype-decl.cpp

[Argiris Kirtzidis]

Hi Doug,

Two points:
--Would it be better if the C++ semantic checks were modified to work on 
the param types of the function type ?
ParmVarDecls are not strictly needed except in the case of default args.

--The test case (along with some others) now crashes on both C++ and C 
on Windows. This is what happens:
-ParmVarDecls are added to the FunctionDecl that has typedef as type.
-When it's time to destroy the FunctionDecl, the destructor enters the 
ParmVarDecl-destroying-loop
-FunctionDecl::param_end() sees that there are actually ParmVarDecls 
stored so it tries to return the correct iterator (before your commit it 
would just return 0x0 for a typedef'ed FunctionDecl).
-FunctionDecl::getNumParams() tries to return the number of parameters.
-Getting the param number involves first getting at the underlying 
FunctionType of the TypedefType.
-In order to get at its unsugared type, the TypedefType needs to get the 
TypedefDecl::UnderlyingType
-The TypedefDecl was previously destroyed and... crash!


-Argiris


Douglas Gregor wrote:
> Author: dgregor
> Date: Fri Oct 24 13:09:54 2008
> New Revision: 58100
>
> URL: http://llvm.org/viewvc/llvm-project?rev=58100&view=rev
> Log:
> PR2942: FunctionDecls by typedef crash the C++ front-end
>
> Added:
>     cfe/trunk/test/SemaCXX/fntype-decl.cpp
> Modified:
>     cfe/trunk/lib/Sema/SemaDecl.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=58100&r1=58099&r2=58100&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Fri Oct 24 13:09:54 2008
> @@ -781,13 +781,42 @@
>              Param->getType().getUnqualifiedType() != Context.VoidTy) {
>            Diag(Param->getLocation(), diag::ext_param_typedef_of_void);
>          }
> -
>        } else if (FTI.NumArgs > 0 && FTI.ArgInfo[0].Param != 0) {
>          for (unsigned i = 0, e = FTI.NumArgs; i != e; ++i)
>            Params.push_back((ParmVarDecl *)FTI.ArgInfo[i].Param);
>        }
>    
>        NewFD->setParams(&Params[0], Params.size());
> +    } else if (R->getAsTypedefType()) {
> +      // When we're declaring a function with a typedef, as in the
> +      // following example, we'll need to synthesize (unnamed)
> +      // parameters for use in the declaration.
> +      //
> +      // @code
> +      // typedef void fn(int);
> +      // fn f;
> +      // @endcode
> +      const FunctionTypeProto *FT = R->getAsFunctionTypeProto();
> +      if (!FT) {
> +        // This is a typedef of a function with no prototype, so we
> +        // don't need to do anything.
> +      } else if ((FT->getNumArgs() == 0) ||
> +          (FT->getNumArgs() == 1 && !FT->isVariadic() &&
> +           FT->getArgType(0)->isVoidType())) {
> +        // This is a zero-argument function. We don't need to do anything.
> +      } else {
> +        // Synthesize a parameter for each argument type.
> +        llvm::SmallVector<ParmVarDecl*, 16> Params;
> +        for (FunctionTypeProto::arg_type_iterator ArgType = FT->arg_type_begin();
> +             ArgType != FT->arg_type_end(); ++ArgType) {
> +          Params.push_back(ParmVarDecl::Create(Context, CurContext,
> +                                               SourceLocation(), 0,
> +                                               *ArgType, VarDecl::None,
> +                                               0, 0));
> +        }
> +
> +        NewFD->setParams(&Params[0], Params.size());
> +      }
>      }
>  
>      // Merge the decl with the existing one if appropriate. Since C functions
>
> Added: cfe/trunk/test/SemaCXX/fntype-decl.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/fntype-decl.cpp?rev=58100&view=auto
>
> ==============================================================================
> --- cfe/trunk/test/SemaCXX/fntype-decl.cpp (added)
> +++ cfe/trunk/test/SemaCXX/fntype-decl.cpp Fri Oct 24 13:09:54 2008
> @@ -0,0 +1,5 @@
> +// RUN: clang -fsyntax-only -verify %s
> +
> +// PR2942
> +typedef void fn(int);
> +fn f;
>
>
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