A few warnings on Windows

Hi,

Not sure if it's a goal to be warning free on Windows, but I was
testing some patches on that fine operating system and spotted a
couple of warnings that seemed worth asking about:


src/backend/replication/basebackup.c(1470): warning C4146: unary minus
operator applied to unsigned type, result still unsigned

Yeah, we have: if (fseek(fp, -(cnt - BLCKSZ * i), SEEK_CUR) == -1)

... where cnt is size_t.  Perhaps we should use (or cast to) off_t?


src/bin/pgbench/pgbench.c(971): warning C4307: '*' : integral constant
overflow [C:\buildfarm\buildenv\HEAD\pgsql.build\pgbench.vcxproj]

We have:     uint64      result = seed ^ (sizeof(int64) * MM2_MUL);

... where MM2_MUL is a UINT64CONST.  I checked the upstream source of
this code and it's using a runtime multiplicand while here it's a
constant so the compiler sees the overflow.  I suppose we could make
the warning go away by just defining a constant (which I make out to
be 0x35253c9ade8f4ca8).


C:\Program Files (x86)\Microsoft Visual Studio
12.0\VC\include\stdbool.h(11): warning C4005: 'false' : macro
redefinition [C:\buildfarm\buildenv\HEAD\pgsql.build\jsonb_plperl.vcxproj]
          c:\buildfarm\buildenv\head\pgsql.build\src\include\c.h(283)
: see previous definition of 'false'
C:\Program Files (x86)\Microsoft Visual Studio
12.0\VC\include\stdbool.h(12): warning C4005: 'true' : macro
redefinition [C:\buildfarm\buildenv\HEAD\pgsql.build\jsonb_plperl.vcxproj]
          c:\buildfarm\buildenv\head\pgsql.build\src\include\c.h(279)
: see previous definition of 'true'

Somehow when building jsonb_plperl and plperl we get our true/false
macros tangled up with the ones from stdbool.h on this platform.  Not
sure if this was known/expected.


There are also a bunch of other macro redefinition warnings but I
suspect those are expected (open, unlink etc).

-- 
Thomas Munro
http://www.enterprisedb.com