Re: Compiler warning in costsize.c

Michael Paquier <michael.paquier@gmail.com> writes:
> In builds where USE_ASSERT_CHECKING is not enabled, costsize.c can
> generate warnings. Here is for example with MSVC:
>   src/backend/optimizer/path/costsize.c(4520): warning C4101: 'rte' : unreferenced local variable
[C:\Users\ioltas\git\postgres\postgres.vcxproj]
>   src/backend/optimizer/path/costsize.c(4640): warning C4101: 'rte' : unreferenced local variable
[C:\Users\ioltas\git\postgres\postgres.vcxproj]

> a9c074ba7 has done an effort, but a bit more is needed as the attached.

That doesn't look right at all:

+#ifdef USE_ASSERT_CHECKING    RangeTblEntry *rte PG_USED_FOR_ASSERTS_ONLY;
+#endif

The entire point of the PG_USED_FOR_ASSERTS_ONLY annotation is to suppress
this type of warning without a need for an explicit #ifdef like that one.

We should either fix PG_USED_FOR_ASSERTS_ONLY to work on MSVC as well,
or decide that we don't care about suppressing such warnings on MSVC,
or give up on PG_USED_FOR_ASSERTS_ONLY and remove it everywhere in
favor of plain #ifdefs.

(I'm personally not that much in love with PG_USED_FOR_ASSERTS_ONLY,
because it tends to confuse pgindent.)
        regards, tom lane