[cfe-commits] r162109 - in /cfe/trunk: include/clang/Basic/DiagnosticGroups.td include/clang/Basic/DiagnosticSemaKinds.td lib/Sema/SemaCast.cpp test/Sema/warn-bad-function-cast.c

Matt Beaumont-Gay matthewbg at google.com
Fri Aug 17 11:11:47 PDT 2012


Can you explain the rationale behind this warning a little bit? It
fires on some more-or-less reasonable code like this snippet from the
Python Imaging Library:

libImaging/Draw.c:448:51: error: cast from function call of type
'double' to non-matching type 'int' [-Werror,-Wbad-function-cast]
                hline8(im, CEIL(xx[0]-0.5), ymin, FLOOR(xx[1]+0.5), ink);
                                                  ^~~~~~~~~~~~~~~~
libImaging/Draw.c:40:50: note: expanded from macro 'FLOOR'
#define FLOOR(v) ((v) >= 0.0 ? (int) (v) : (int) floor(v))
                                                 ^~~~~~~~

On Fri, Aug 17, 2012 at 10:22 AM, Fariborz Jahanian <fjahanian at apple.com> wrote:
> Author: fjahanian
> Date: Fri Aug 17 12:22:34 2012
> New Revision: 162109
>
> URL: http://llvm.org/viewvc/llvm-project?rev=162109&view=rev
> Log:
> c: implement gcc's -Wbad-function-cast which warns
> on unsafe cast of a c-function call. This is
> a C-only option.
>
> Added:
>     cfe/trunk/test/Sema/warn-bad-function-cast.c
> Modified:
>     cfe/trunk/include/clang/Basic/DiagnosticGroups.td
>     cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>     cfe/trunk/lib/Sema/SemaCast.cpp
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=162109&r1=162108&r2=162109&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Fri Aug 17 12:22:34 2012
> @@ -157,6 +157,7 @@
>  def OverloadedVirtual : DiagGroup<"overloaded-virtual">;
>  def PrivateExtern : DiagGroup<"private-extern">;
>  def SelTypeCast : DiagGroup<"cast-of-sel-type">;
> +def BadFunctionCast : DiagGroup<"bad-function-cast">;
>  def ObjCPropertyImpl : DiagGroup<"objc-property-implementation">;
>  def ObjCPropertyNoAttribute : DiagGroup<"objc-property-no-attribute">;
>  def ObjCMissingSuperCalls : DiagGroup<"objc-missing-super-calls">;
> @@ -377,7 +378,8 @@
>      ObjCMissingSuperCalls,
>      OverloadedVirtual,
>      PrivateExtern,
> -    SelTypeCast
> +    SelTypeCast,
> +    BadFunctionCast
>   ]>;
>
>  // Thread Safety warnings
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=162109&r1=162108&r2=162109&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Fri Aug 17 12:22:34 2012
> @@ -4968,6 +4968,9 @@
>  def warn_cast_pointer_from_sel : Warning<
>    "cast of type %0 to %1 is deprecated; use sel_getName instead">,
>    InGroup<SelTypeCast>;
> +def warn_bad_function_cast : Warning<
> +  "cast from function call of type %0 to non-matching type %1">,
> +  InGroup<BadFunctionCast>, DefaultIgnore;
>  def err_cast_pointer_to_non_pointer_int : Error<
>    "pointer cannot be cast to type %0">;
>  def err_typecheck_expect_scalar_operand : Error<
>
> Modified: cfe/trunk/lib/Sema/SemaCast.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaCast.cpp?rev=162109&r1=162108&r2=162109&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaCast.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaCast.cpp Fri Aug 17 12:22:34 2012
> @@ -1903,6 +1903,43 @@
>      SrcExpr = ExprError();
>  }
>
> +/// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a
> +///  non-matching type. Such as enum function call to int, int call to
> +/// pointer; etc. Cast to 'void' is an exception.
> +static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr,
> +                                  QualType DestType) {
> +  if (Self.Diags.getDiagnosticLevel(diag::warn_bad_function_cast,
> +                                    SrcExpr.get()->getExprLoc())
> +        == DiagnosticsEngine::Ignored)
> +    return;
> +
> +  if (!isa<CallExpr>(SrcExpr.get()))
> +    return;
> +
> +  QualType SrcType = SrcExpr.get()->getType();
> +  if (DestType.getUnqualifiedType()->isVoidType())
> +    return;
> +  if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType())
> +      && (DestType->isAnyPointerType() || DestType->isBlockPointerType()))
> +    return;
> +  if (SrcType->isIntegerType() && DestType->isIntegerType() &&
> +      (SrcType->isBooleanType() == DestType->isBooleanType()) &&
> +      (SrcType->isEnumeralType() == DestType->isEnumeralType()))
> +    return;
> +  if (SrcType->isRealFloatingType() && DestType->isRealFloatingType())
> +    return;
> +  if (SrcType->isEnumeralType() && DestType->isEnumeralType())
> +    return;
> +  if (SrcType->isComplexType() && DestType->isComplexType())
> +    return;
> +  if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType())
> +    return;
> +
> +  Self.Diag(SrcExpr.get()->getExprLoc(),
> +            diag::warn_bad_function_cast)
> +            << SrcType << DestType << SrcExpr.get()->getSourceRange();
> +}
> +
>  /// Check the semantics of a C-style cast operation, in C.
>  void CastOperation::CheckCStyleCast() {
>    assert(!Self.getLangOpts().CPlusPlus);
> @@ -2076,7 +2113,7 @@
>      }
>    }
>    DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
> -
> +  DiagnoseBadFunctionCast(Self, SrcExpr, DestType);
>    Kind = Self.PrepareScalarCast(SrcExpr, DestType);
>    if (SrcExpr.isInvalid())
>      return;
>
> Added: cfe/trunk/test/Sema/warn-bad-function-cast.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-bad-function-cast.c?rev=162109&view=auto
> ==============================================================================
> --- cfe/trunk/test/Sema/warn-bad-function-cast.c (added)
> +++ cfe/trunk/test/Sema/warn-bad-function-cast.c Fri Aug 17 12:22:34 2012
> @@ -0,0 +1,47 @@
> +// RUN: %clang_cc1 %s -fsyntax-only -Wno-unused-value -Wbad-function-cast -verify
> +// rdar://9103192
> +
> +void vf(void);
> +int if1(void);
> +char if2(void);
> +long if3(void);
> +float rf1(void);
> +double rf2(void);
> +_Complex double cf(void);
> +enum e { E1 } ef(void);
> +_Bool bf(void);
> +char *pf1(void);
> +int *pf2(void);
> +
> +void
> +foo(void)
> +{
> +  /* Casts to void types are always OK.  */
> +  (void)vf();
> +  (void)if1();
> +  (void)cf();
> +  (const void)bf();
> +  /* Casts to the same type or similar types are OK.  */
> +  (int)if1();
> +  (long)if2();
> +  (char)if3();
> +  (float)rf1();
> +  (long double)rf2();
> +  (_Complex float)cf();
> +  (enum f { F1 })ef();
> +  (_Bool)bf();
> +  (void *)pf1();
> +  (char *)pf2();
> +  /* All following casts issue warning */
> +  (float)if1(); /* expected-warning {{cast from function call of type 'int' to non-matching type 'float'}} */
> +  (double)if2(); /* expected-warning {{cast from function call of type 'char' to non-matching type 'double'}} */
> +  (_Bool)if3(); /* expected-warning {{cast from function call of type 'long' to non-matching type '_Bool'}} */
> +  (int)rf1(); /* expected-warning {{cast from function call of type 'float' to non-matching type 'int'}} */
> +  (long)rf2(); /* expected-warning {{cast from function call of type 'double' to non-matching type 'long'}} */
> +  (double)cf(); /* expected-warning {{cast from function call of type '_Complex double' to non-matching type 'double'}} */
> +  (int)ef(); /* expected-warning {{cast from function call of type 'enum e' to non-matching type 'int'}} */
> +  (int)bf(); /* expected-warning {{cast from function call of type '_Bool' to non-matching type 'int'}} */
> +  (__SIZE_TYPE__)pf1(); /* expected-warning {{cast from function call of type 'char *' to non-matching type 'unsigned long'}} */
> +  (__PTRDIFF_TYPE__)pf2(); /* expected-warning {{cast from function call of type 'int *' to non-matching type 'long'}} */
> +}
> +
>
>
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits



More information about the cfe-commits mailing list