[cfe-commits] r99939 - in /cfe/trunk: lib/Parse/ParseCXXInlineMethods.cpp test/Parser/cxx-default-args.cpp

[Douglas Gregor]

On Mar 30, 2010, at 3:14 PM, Argiris Kirtzidis wrote:

> Author: akirtzidis
> Date: Tue Mar 30 17:14:32 2010
> New Revision: 99939
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=99939&view=rev
> Log:
> When "delayed parsing" C++ default arguments, if there is an error, there may be tokens left in the token stream
> that will interfere (they will be parsed as if they are after the class' '}') and a crash will occur because
> the CachedTokens that holds them will be deleted while the lexer is still using them.
> 
> Make sure that the tokens of default args are removed from the token stream.
> Fixes PR6647.

Isn't there the potential for having this same problem in ParseLexedMethodDefs, where we've cached the tokens for the function body?

> Added:
>    cfe/trunk/test/Parser/cxx-default-args.cpp
> Modified:
>    cfe/trunk/lib/Parse/ParseCXXInlineMethods.cpp
> 
> Modified: cfe/trunk/lib/Parse/ParseCXXInlineMethods.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Parse/ParseCXXInlineMethods.cpp?rev=99939&r1=99938&r2=99939&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Parse/ParseCXXInlineMethods.cpp (original)
> +++ cfe/trunk/lib/Parse/ParseCXXInlineMethods.cpp Tue Mar 30 17:14:32 2010
> @@ -122,6 +122,9 @@
>       Actions.ActOnDelayedCXXMethodParameter(CurScope, LM.DefaultArgs[I].Param);
> 
>       if (CachedTokens *Toks = LM.DefaultArgs[I].Toks) {
> +        // Save the current token position.
> +        SourceLocation origLoc = Tok.getLocation();
> +
>         // Parse the default argument from its saved token stream.
>         Toks->push_back(Tok); // So that the current token doesn't get lost
>         PP.EnterTokenStream(&Toks->front(), Toks->size(), true, false);
> @@ -139,6 +142,15 @@
>         else
>           Actions.ActOnParamDefaultArgument(LM.DefaultArgs[I].Param, EqualLoc,
>                                             move(DefArgResult));
> +
> +        assert(!PP.getSourceManager().isBeforeInTranslationUnit(origLoc,
> +                                                           Tok.getLocation()) &&
> +               "ParseAssignmentExpression went over the default arg tokens!");
> +        // There could be leftover tokens (e.g. because of an error).
> +        // Skip through until we reach the original token position.
> +        while (Tok.getLocation() != origLoc)
> +          ConsumeAnyToken();
> +
>         delete Toks;
>         LM.DefaultArgs[I].Toks = 0;
>       }
> 
> Added: cfe/trunk/test/Parser/cxx-default-args.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Parser/cxx-default-args.cpp?rev=99939&view=auto
> ==============================================================================
> --- cfe/trunk/test/Parser/cxx-default-args.cpp (added)
> +++ cfe/trunk/test/Parser/cxx-default-args.cpp Tue Mar 30 17:14:32 2010
> @@ -0,0 +1,9 @@
> +// RUN: %clang_cc1 -fsyntax-only -verify %s
> +
> +// PR6647
> +class C {
> +  // After the error, the rest of the tokens inside the default arg should be
> +  // skipped, avoiding a "expected ';' after class" after 'undecl'.
> +  void m(int x = undecl + 0); // expected-error {{use of undeclared identifier 'undecl'}}
> +};
> +
> 
> 
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