Fabien COELHO <coelho@cri.ensmp.fr> writes:
>> LWLockTrancheArray = (char **)
>> MemoryContextAllocZero(TopMemoryContext,
>> LWLockTranchesAllocated * sizeof(char *));
> After your explanation, and on third thoughts, ISTM that the assignment
> should not include "const" in the explicit cast,
Can't get terribly excited about that one way or the other. I think
the statement would be OK as-is, and it would also be fine as
LWLockTrancheArray = (const char **) MemoryContextAllocZero(TopMemoryContext,
LWLockTranchesAllocated* sizeof(const char *));
The other two possible combinations are not good of course --- not that
they'd generate invalid code, but that they'd require readers to expend
brain cells convincing themselves that the code wasn't wrong.
> ... and moreover the compiler does not
> complain without the const.
Arguing on the basis of what your compiler does is a pretty shaky basis.
It's not impossible that someone else's compiler would complain if the
casted-to type isn't identical to the variable's type. I tend to agree
that a compiler *should* allow "char **" to be cast to "const char **"
silently, but that isn't necessarily what happens in the real world.
regards, tom lane
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