[Bug c/71188] missing warning converting constant integer expression zero to pointer

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71188

--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Unlike the diagnostics for values that are not constant integers, any 
diagnostic for these cases must not be a pedwarn, because converting an 
arbitrary integer constant expression with value 0 implicitly to pointer 
type is valid in ISO C.