new clang report

The lastest clang svn tip (2.9-to-be, I guess) builds PostgreSQL out of
the box and most tests pass. Specifically, it no longer chokes on
-D_GNU_SOURCE on Linux, which was the previously reported blocker.

Warnings:

Lots of these:
clang: warning: argument unused during compilation: '-mthreads'
clang: warning: argument unused during compilation: '-mt'

Possible fix, check both link and compile invocations for warnings in
configure:

diff --git i/config/acx_pthread.m4 w/config/acx_pthread.m4
index ceb161a..ee181f9 100644
--- i/config/acx_pthread.m4
+++ w/config/acx_pthread.m4
@@ -142,7 +142,7 @@ main (int argc, char **argv)
}
_ACEOF
rm -f conftest.$ac_objext conftest$ac_exeext
- if test "`(eval $ac_link 2>&1 1>&5)`" = ""; then
+ if test "`(eval $ac_link 2>&1 1>&5)`" = "" && test "`(eval $ac_compile 2>&1 1>&5)`" = ""; then
# we continue with more flags because Linux needs -lpthread
# for libpq builds on PostgreSQL. The test above only
# tests for building binaries, not shared libraries.

The usual flex warning:

In file included from gram.y:12460:
scan.c:16256:23: warning: unused variable 'yyg' [-Wunused-variable]
struct yyguts_t * yyg = (struct yyguts_t*)yyscanner; /* This var may be unused depending upon options. */

And then only these two:

fe-exec.c:2408:13: warning: comparison of unsigned enum expression < 0 is always false [-Wtautological-compare]
if (status < 0 || status >= sizeof pgresStatus / sizeof pgresStatus[0])
~~~~~~ ^ ~

pg_standby.c:347:22: warning: comparison of unsigned expression >= 0 is always true [-Wtautological-compare]
if (tli > 0 && log >= 0 && seg > 0)
~~~ ^ ~

Regression tests (world):

--- src/test/regress/expected/float8.out
+++ src/test/regress/results/float8.out
@@ -384,7 +384,15 @@
SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
ERROR: value out of range: overflow
SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
-ERROR: value out of range: overflow
+ bad | ?column?
+-----+----------
+ | 0
+ | NaN
+ | NaN
+ | NaN
+ | NaN
+(5 rows)
+
SELECT 0 ^ 0 + 0 ^ 1 + 0 ^ 0.0 + 0 ^ 0.5;
?column?
----------

PL/Python test crashes. I was able to make it work either by using -O0
or by applying the following patch:

diff --git i/src/pl/plpython/plpython.c w/src/pl/plpython/plpython.c
index fff7de7..8eaee36 100644
--- i/src/pl/plpython/plpython.c
+++ w/src/pl/plpython/plpython.c
@@ -1019,12 +1019,13 @@ PLy_trigger_build_args(FunctionCallInfo fcinfo, PLyProcedure *proc, HeapTuple *r

/* function handler and friends */
static Datum
-PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *proc)
+PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *proc2)
{
Datum rv;
PyObject *volatile plargs = NULL;
PyObject *volatile plrv = NULL;
ErrorContextCallback plerrcontext;
+ PLyProcedure *volatile proc = proc2;

PG_TRY();
{

Hmmm.