From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
Cc: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Add some const decorations to prototypes |
Date: | 2017-11-10 16:53:27 |
Message-ID: | 31668.1510332807@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Fabien COELHO <coelho(at)cri(dot)ensmp(dot)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
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2017-11-10 17:37:29 | Re: Fix bloom WAL tap test |
Previous Message | Fabien COELHO | 2017-11-10 16:42:11 | Re: Add some const decorations to prototypes |