Extend fallthrough safety to LLVM in gmpy2_mpmath.c #502
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This seems to be gcc/clang-specific.
Not a surprise, this will break CI on Windows:
D:\a\gmpy\gmpy\src\gmpy2_mpmath.c(290): warning C4013: '__attribute__' undefined; assuming extern returning int
D:\a\gmpy\gmpy\src\gmpy2_mpmath.c(290): error C2065: 'fallthrough': undeclared identifier
D:\a\gmpy\gmpy\src\gmpy2_mpmath.c(297): error C2065: 'fallthrough': undeclared identifier
D:\a\gmpy\gmpy\src\gmpy2_mpmath.c(300): error C2065: 'fallthrough': undeclared identifier
src/gmpy2_mpmath.c
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| @@ -287,17 +287,17 @@ Pympz_mpmath_create_fast(PyObject *self, PyObject *const *args, Py_ssize_t nargs | |||
| switch (nargs) { | |||
| case 4: | |||
| rnd = PyString_1Char(args[3]); | |||
| /* fallthrough */ | |||
| __attribute__((fallthrough)); | |||
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attribute
Could you point on page in C99 or C11 where this keyword was defined?
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GCC talks about the fallthrough attribute here. clang also supports it, but see my message below.
The current fallthrough comments only suppress warnings for GCC. `__attribute__((fallthrough));` works for both GCC (>=7) and LLVM. C23 will introduce `[[fallthrough]]`.
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@skirpichev - Most projects I've worked with have opted to use a preprocessor macro to handle compatibility issues. I've added one here, but note that you'll only get the benefits of the protections by using |
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@skirpichev - clang does not recognize comments as having semantics, so the code as-is will fail to compile using clang with |
Ah, then it makes some sense.
(only with -Werror) |
The current fallthrough comments only suppress warnings for GCC.
__attribute__((fallthrough));works for both GCC (>=7) and LLVM. C23 will introduce[[fallthrough]].