Consider the following source code saved in file "bar.c": --------------------------- 8< --------------------------- extern int * (__attribute__((stdcall)) *fooPtr)( void); int * __attribute__((stdcall)) myFn01( void) { return 0; } void snafu( void) { fooPtr = myFn01; } --------------------------- 8< --------------------------- Running "g++ -c bar.c" gives: --------------------------- 8< --------------------------- bar.c: In function `void snafu()': bar.c:7: invalid conversion from `int*(*)()' to `int*(*)()' --------------------------- 8< --------------------------- However, running "gcc -c bar.c" creates no such problems. With reference to the source code given above, here're a few more observations: 1. This problem is not shown by the 2.95.3 g++. 2. If the definition of myFn01 above is changed to a declaration or if a declaration for the same is added before it, the problem disappears. 3. The problem appears only if the return type is of the kind "xyz *" - if there's a "typedef int *intptr;" and we use "intptr" instead of "int *" for myFn01, the problem disappears. 4. The problem can also be circumvented by putting the attribute and the function name together in parentheses like "int * (__attribute__((stdcall)) myFn01)( void)". 5. The problem does not come if all the "stdcall" instances are replaced by "cdecl", but it reappears if they are replaced by "fastcall". 6. Both Borland C/C++ 5.5 and MSVC++ 6.2 compile this code perfectly (after using the MS equivalent "__stdcall"). Lastly, this looks very similar to PR 6626, but IMHO is different - the syntax and semantics are perfectly valid in this case as far as I can see. Release: GCC 3.2 Environment: MinGW, Cygwin and Linux(x86) (and possibly other x86-32 targets) How-To-Repeat: Just save the sample code given above as file "bar.c" (or whatever) and run "g++ -c" on it.
State-Changed-From-To: open->analyzed State-Changed-Why: I'm not sure if this is a bug or nor. The problem is that the types actually differ because the attribute applies to different parts of the declaration. In int * __attribute__((stdcall)) F (void) {}; the attribute is applied to the return type not to the function type. In the extern declaration extern int * (__attribute__((stdcall)) * f) (void); the attribute is applied to the function type. I'm not 100% sure if this is intended or a parser error but I suspect it is intended. As a result of this the error itself is justified because calling conventions for the function and the function pointer differ. The text of the error however isn't helful at all. Workaround: Put explicit parenthesis around the attribute and the function name: int * (__attribute__(stdcall)) F) (void) {}; regards Christian
Fixed in GCC 3.3.2 and GCC 3.4.