r184875 - Fix null pointer dereference if we redeclare an unprototyped function. Patch by

[Richard Smith]

On Tue, Jun 25, 2013 at 3:34 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
> On Tue, Jun 25, 2013 at 1:34 PM, Richard Smith <richard-llvm at metafoo.co.uk>
> wrote:
>>
>> Author: rsmith
>> Date: Tue Jun 25 15:34:17 2013
>> New Revision: 184875
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=184875&view=rev
>> Log:
>> Fix null pointer dereference if we redeclare an unprototyped function.
>> Patch by
>> WenHan Gu!
>>
>> Modified:
>>     cfe/trunk/lib/Sema/SemaDecl.cpp
>>     cfe/trunk/test/Sema/vfprintf-valid-redecl.c
>>
>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=184875&r1=184874&r2=184875&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Tue Jun 25 15:34:17 2013
>> @@ -8732,17 +8732,19 @@ Decl *Sema::ActOnStartOfFunctionDef(Scop
>>    const FunctionDecl *PossibleZeroParamPrototype = 0;
>>    if (ShouldWarnAboutMissingPrototype(FD, PossibleZeroParamPrototype)) {
>>      Diag(FD->getLocation(), diag::warn_missing_prototype) << FD;
>> -
>> +
>>      if (PossibleZeroParamPrototype) {
>> -      // We found a declaration that is not a prototype,
>> +      // We found a declaration that is not a prototype,
>>        // but that could be a zero-parameter prototype
>> -      TypeSourceInfo* TI =
>> PossibleZeroParamPrototype->getTypeSourceInfo();
>> -      TypeLoc TL = TI->getTypeLoc();
>> -      if (FunctionNoProtoTypeLoc FTL =
>> TL.getAs<FunctionNoProtoTypeLoc>())
>> -        Diag(PossibleZeroParamPrototype->getLocation(),
>> -             diag::note_declaration_not_a_prototype)
>> -          << PossibleZeroParamPrototype
>> -          << FixItHint::CreateInsertion(FTL.getRParenLoc(), "void");
>> +      if (TypeSourceInfo *TI =
>> +              PossibleZeroParamPrototype->getTypeSourceInfo()) {
>> +        TypeLoc TL = TI->getTypeLoc();
>> +        if (FunctionNoProtoTypeLoc FTL =
>> TL.getAs<FunctionNoProtoTypeLoc>())
>> +          Diag(PossibleZeroParamPrototype->getLocation(),
>> +               diag::note_declaration_not_a_prototype)
>> +            << PossibleZeroParamPrototype
>> +            << FixItHint::CreateInsertion(FTL.getRParenLoc(), "void");
>> +      }
>>      }
>>    }
>>
>>
>> Modified: cfe/trunk/test/Sema/vfprintf-valid-redecl.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/vfprintf-valid-redecl.c?rev=184875&r1=184874&r2=184875&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Sema/vfprintf-valid-redecl.c (original)
>> +++ cfe/trunk/test/Sema/vfprintf-valid-redecl.c Tue Jun 25 15:34:17 2013
>> @@ -1,7 +1,13 @@
>>  // RUN: %clang_cc1 %s -fsyntax-only -pedantic -verify
>>  // expected-no-diagnostics
>> -// PR4290
>>
>> +// PR16344
>> +// Clang has defined 'vfprint' in builtin list. If the following line
>> occurs before any other
>> +// `vfprintf' in this file, and we getPreviousDecl()->getTypeSourceInfo()
>> on it, then we will
>> +// get a null pointer since the one in builtin list doesn't has valid
>> TypeSourceInfo.
>> +int vfprintf(void) { return 0; }
>> +
>> +// PR4290
>>  // The following declaration is compatible with vfprintf, so we shouldn't
>>  // warn.
>>  int vfprintf();
>>
> This testcase isn't testing what it was originally supposed to test.

Good point. r184887.