[cfe-commits] r150128 - in /cfe/trunk: include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/SemaDecl.cpp test/SemaCXX/function-extern-c.cpp

[Chandler Carruth]

On Thu, Feb 9, 2012 at 12:42 PM, Matt Beaumont-Gay <matthewbg at google.com>wrote:

> On a different note, what do you think about not warning when the
> return type is incomplete? It's a little surprising that we warn on
> this:
>
> struct foo;
> extern "C" { struct foo get_foo(void); }
> struct foo { };
>

I think that's a bug. Incomplete struct types are relatively common as
"opaque" return types.


>
> On Wed, Feb 8, 2012 at 17:21, Aaron Ballman <aaron at aaronballman.com>
> wrote:
> > Author: aaronballman
> > Date: Wed Feb  8 19:21:34 2012
> > New Revision: 150128
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=150128&view=rev
> > Log:
> > Adding support for warning when a non-C compatible user-defined type is
> returned from an extern "C" function.
> >
> > Fixes bug 6143
> >
> > Added:
> >    cfe/trunk/test/SemaCXX/function-extern-c.cpp   (with props)
> > Modified:
> >    cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> >    cfe/trunk/lib/Sema/SemaDecl.cpp
> >
> > Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> > URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=150128&r1=150127&r2=150128&view=diff
> >
> ==============================================================================
> > --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> > +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed Feb  8
> 19:21:34 2012
> > @@ -163,7 +163,9 @@
> >  def warn_return_value_size: Warning<
> >   "return value of %0 is a large (%1 bytes) pass-by-value object; "
> >   "pass it by reference instead ?">, InGroup<LargeByValueCopy>;
> > -
> > +def warn_return_value_udt: Warning<
> > +  "%0 has C-linkage specified, but returns user-defined type %1 which
> is "
> > +  "incompatible with C">, InGroup<ReturnType>;
> >  def warn_implicit_function_decl : Warning<
> >   "implicit declaration of function %0">,
> >   InGroup<ImplicitFunctionDeclare>, DefaultIgnore;
> >
> > Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=150128&r1=150127&r2=150128&view=diff
> >
> ==============================================================================
> > --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> > +++ cfe/trunk/lib/Sema/SemaDecl.cpp Wed Feb  8 19:21:34 2012
> > @@ -5774,6 +5774,17 @@
> >         Context.BuiltinInfo.ForgetBuiltin(BuiltinID, Context.Idents);
> >       }
> >     }
> > +
> > +    // If this function is declared as being extern "C", then check to
> see if
> > +    // the function returns a UDT (class, struct, or union type) that
> is not C
> > +    // compatible, and if it does, warn the user.
> > +    if (NewFD->isExternC()) {
> > +      QualType R = NewFD->getResultType();
> > +      if (!R.isPODType(Context) &&
> > +          !R->isVoidType())
> > +        Diag( NewFD->getLocation(), diag::warn_return_value_udt )
> > +          << NewFD << R;
> > +    }
> >   }
> >   return Redeclaration;
> >  }
> >
> > Added: cfe/trunk/test/SemaCXX/function-extern-c.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/function-extern-c.cpp?rev=150128&view=auto
> >
> ==============================================================================
> > --- cfe/trunk/test/SemaCXX/function-extern-c.cpp (added)
> > +++ cfe/trunk/test/SemaCXX/function-extern-c.cpp Wed Feb  8 19:21:34 2012
> > @@ -0,0 +1,38 @@
> > +// RUN: %clang_cc1 -Wreturn-type -fsyntax-only -std=c++11 -verify %s
> > +
> > +class A {
> > +public:
> > +  A(const A&);
> > +};
> > +
> > +struct S {
> > +  int i;
> > +  double d;
> > +
> > +  virtual void B() {}
> > +};
> > +
> > +union U {
> > +  struct {
> > +    int i;
> > +    virtual void B() {} // Can only do this in C++11
> > +  } t;
> > +};
> > +
> > +struct S2 {
> > +  int i;
> > +  double d;
> > +};
> > +
> > +extern "C" U f3( void ); // expected-warning {{'f3' has C-linkage
> specified, but returns user-defined type 'U' which is incompatible with C}}
> > +extern "C" S f0(void); // expected-warning {{'f0' has C-linkage
> specified, but returns user-defined type 'S' which is incompatible with C}}
> > +extern "C" A f4( void ); // expected-warning {{'f4' has C-linkage
> specified, but returns user-defined type 'A' which is incompatible with C}}
> > +
> > +// These should all be fine
> > +extern "C" S2 f5( void );
> > +extern "C" void f2( A x );
> > +extern "C" void f6( S s );
> > +extern "C" void f7( U u );
> > +extern "C" double f8(void);
> > +extern "C" long long f11( void );
> > +extern "C" A *f10( void );
> >
> > Propchange: cfe/trunk/test/SemaCXX/function-extern-c.cpp
> >
> ------------------------------------------------------------------------------
> >    svn:eol-style = native
> >
> >
> > _______________________________________________
> > cfe-commits mailing list
> > cfe-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20120209/91fbe64c/attachment.html>