Hello, The following code is rejected by one compiler, while it is accepted by gcc without any warning. Several people in comp.lang.c seem to think that it is a bug in the first compiler which should ***not*** reject the program.
Message-ID: <h63e5s$ec...@aioe.org> http://groups.google.com/group/comp.lang.c/browse_frm/thread/2858a1c9ccdcd741 I'd like to ask what you think. typedef int fun_t(int *p); int foo1( int * p) { return *p; } int foo2(const int * p) { return *p; } int foo3( int *const p) { return *p; } int foo4(const int *const p) { return *p; } void zozo(void) { fun_t *fp; fp = foo1; fp = foo2; /* GCC WARNS */ fp = foo3; fp = foo4; /* GCC WARNS */ } (I run gcc 4.3.2 under cygwin.) $ gcc -std=c89 -pedantic -Wall -Wextra -O2 -c mu2.c mu2.c: In function 'zozo': mu2.c:12: warning: assignment from incompatible pointer type mu2.c:14: warning: assignment from incompatible pointer type $ cc -c mu2.c E "mu2.c",L12/C8(#416): foo2 | Type `int(const int * p)' ("mu2.c",L4/C5) can't be converted to type `fun_t(*)'. | (See also type `fun_t' (= `int(int * p)') ("mu2.c",L1/C13)). E "mu2.c",L13/C8(#416): foo3 | Type `int(int *const p)' ("mu2.c",L5/C5) can't be converted to type `fun_t(*)'. | (See also type `fun_t' (= `int(int * p)') ("mu2.c",L1/C13)). E "mu2.c",L14/C8(#416): foo4 | Type `int(const int *const p)' ("mu2.c",L6/C5) can't be converted to type `fun_t(*)'. | (See also type `fun_t' (= `int(int * p)') ("mu2.c",L1/C13)). 3 user errors No warnings The relevant line is line 13 i.e. fp = foo3; (cc's warnings are cosmetically different if I write fp = &foo3;) E "mu2.c",L13/C8(#416): | Type `int(*)(int *const p)' can't be converted to type `fun_t(*)'. | (See also type `int(int *const p)' ("mu2.c",L5/C5)). | (See also type `fun_t' (= `int(int * p)') ("mu2.c",L1/C13)). In short, cc refuses to convert an "int (*)(int *const)" pointer to an "int (*)(int *)" pointer. Would you say this is a bug in cc? -- Regards.
