new compiler warnings

I'm not sure if these can/should be fixed or not, but here are the
compiler warnings I'm getting on gcc and clang on ubuntu 11.10 with -O2.
The gcc ones are mostly new.

==================== GCC ========================

$ gcc --version
gcc (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is
NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

warnings generated:

execQual.c: In function ‘GetAttributeByNum’:
execQual.c:1112:11: warning: the comparison will always evaluate as
‘true’ for the address of ‘tmptup’ will never be NULL [-Waddress]
execQual.c: In function ‘GetAttributeByName’:
execQual.c:1173:11: warning: the comparison will always evaluate as
‘true’ for the address of ‘tmptup’ will never be NULL [-Waddress]
execQual.c: In function ‘ExecEvalFieldSelect’:
execQual.c:3922:11: warning: the comparison will always evaluate as
‘true’ for the address of ‘tmptup’ will never be NULL [-Waddress]
In file included from gram.y:12962:0:
scan.c: In function ‘yy_try_NUL_trans’:
scan.c:16257:23: warning: unused variable ‘yyg’ [-Wunused-variable]
elog.c: In function ‘write_pipe_chunks’:
elog.c:2479:8: warning: ignoring return value of ‘write’, declared with
attribute warn_unused_result [-Wunused-result]
elog.c:2488:7: warning: ignoring return value of ‘write’, declared with
attribute warn_unused_result [-Wunused-result]
elog.c: In function ‘write_console’:
elog.c:1797:7: warning: ignoring return value of ‘write’, declared with
attribute warn_unused_result [-Wunused-result]
tuplesort.c: In function ‘comparetup_heap’:
tuplesort.c:2751:12: warning: the comparison will always evaluate as
‘true’ for the address of ‘ltup’ will never be NULL [-Waddress]
tuplesort.c:2752:12: warning: the comparison will always evaluate as
‘true’ for the address of ‘rtup’ will never be NULL [-Waddress]
tuplesort.c: In function ‘copytup_heap’:
tuplesort.c:2783:17: warning: the comparison will always evaluate as
‘true’ for the address of ‘htup’ will never be NULL [-Waddress]
tuplesort.c: In function ‘readtup_heap’:
tuplesort.c:2835:17: warning: the comparison will always evaluate as
‘true’ for the address of ‘htup’ will never be NULL [-Waddress]
fe-connect.c: In function ‘PQconndefaults’:
fe-connect.c:832:6: warning: the comparison will always evaluate as
‘false’ for the address of ‘errorBuf’ will never be NULL [-Waddress]
fe-connect.c: In function ‘PQconninfoParse’:
fe-connect.c:3970:6: warning: the comparison will always evaluate as
‘false’ for the address of ‘errorBuf’ will never be NULL [-Waddress]
common.c: In function ‘handle_sigint’:
common.c:247:4: warning: ignoring return value of ‘write’, declared with
attribute warn_unused_result [-Wunused-result]
common.c:250:4: warning: ignoring return value of ‘write’, declared with
attribute warn_unused_result [-Wunused-result]
common.c:251:4: warning: ignoring return value of ‘write’, declared with
attribute warn_unused_result [-Wunused-result]
In file included from mainloop.c:425:0:
psqlscan.l: In function ‘evaluate_backtick’:
psqlscan.l:1677:6: warning: the comparison will always evaluate as
‘false’ for the address of ‘cmd_output’ will never be NULL [-Waddress]

==================== CLANG ========================

$ clang --version
clang version 2.9 (tags/RELEASE_29/final)
Target: x86_64-pc-linux-gnu
Thread model: posix

A lot of warnings of the form:

ruleutils.c:698:11: warning: array index of '1' indexes past the end of
an array (that contains 1 elements) [-Warray-bounds]               value = fastgetattr(ht_trig, Anum_pg_trigger_tgargs,
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
In file included from ruleutils.c:23:
In file included from ../../../../src/include/catalog/indexing.h:18:
../../../../src/include/access/htup.h:808:3: note: instantiated from:               att_isnull((attnum)-1,
(tup)->t_data->t_bits)?
 
\               ^
In file included from ruleutils.c:23:
In file included from ../../../../src/include/catalog/indexing.h:18:
In file included from ../../../../src/include/access/htup.h:18:
../../../../src/include/access/tupmacs.h:21:34: note: instantiated from:
#define att_isnull(ATT, BITS) (!((BITS)[(ATT) >> 3] & (1 << ((ATT) &
0x07))))                                ^      ~~~~~~~~~~
In file included from ruleutils.c:23:
In file included from ../../../../src/include/catalog/indexing.h:18:
../../../../src/include/access/htup.h:153:9: note: array 't_bits'
declared here       bits8           t_bits[1];              /* bitmap of NULLs --
VARIABLE LENGTH */

======================================================

Regards,Jeff Davis