Unchecked function assigned to safe typedef

[kyleheadley]

In this simplification of a vsftpd error:

typedef void (*fp)(int *i); // given checked type

void simplefunc(int *i) {
  i = (int*)1; // unsafe - function will not be _Checked
}

void test(void) {
  fp func = simplefunc; // fail compilation: assign unchecked to checked
}

3C completes but clang won't accept the function pointer initialization in test. If simplefunc were checked, or even declared but undefined, clang would accept it. This may be another case for having an unchecked variant of a typedef (see #389).

[john-h-kastner]

Does this work if you explicitly take the address of simplefunc? I think this might be a Checked C compiler bug where it doesn't handle implicit conversion from function to function pointer correctly.

[kyleheadley]

if I change the line to fp func = &simplefunc; then, yes it will compile.