On Mon, 12 Jul 2021 at 12:02, Richard Biener wrote:
> Somebody with more C++ knowledge than me needs to approve the
> vec.h changes - I don't feel competent to assess all effects of the change.
They look OK to me except for:
-extern vnull vNULL;
+static constexpr vnull vNULL{ };
Making vNULL have static linkage can make it an ODR violation to use
vNULL in templates and inline functions, because different
instantiations will refer to a different "vNULL" in each translation
unit. The extern object avoids that problem. It probably won't cause
real problems in practice but it's still technically UB.
If avoiding the extern variable is desirable, you can make it inline
when compiled by a C++17 compiler (such as GCC 11):
#if __cpp_inline_variables
inline constexpr vnull vNULL{ };
#else
extern const vnull vNULL;
#endif
and then define it in vec.c:
#if ! __cpp_inline_variables
const vnull vNULL{ };
#endif
