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Use appropriate -Wno-warning switches when compiling bitcode.
We use "clang" to compile bitcode files for LLVM inlining. That might be different from the build's main C compiler, so it needs its own set of compiler flags. To simplify configure, we don't bother adding any -W switches to that flag set; there's little need since the main build will show us any warnings. However, if we don't want to see unwanted warnings, we still have to add any -Wno-warning switches we'd normally use with clang. This escaped notice before commit 9ff47ea, which tried to add -Wno-compound-token-split-by-macro; buildfarm animals using mismatched CC and CLANG still showed those warnings. I'm not sure why we never saw any effects from the lack of -Wno-unused-command-line-argument (maybe that's only activated by -Wall?). clang does not currently support -Wno-format-truncation or -Wno-stringop-truncation, although in the interests of future-proofing and consistency I included tests for those. Back-patch to v11 where we started building bitcode files. Discussion: https://postgr.es/m/2921539.1637254619@sss.pgh.pa.us
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‎configure

Lines changed: 185 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -5240,7 +5240,7 @@ else
52405240
fi
52415241

52425242
# When generating bitcode (for inlining) we always want to use -O2
5243-
# even when --enable-debug is specified. The bitcode it's not going to
5243+
# even when --enable-debug is specified. The bitcode is not going to
52445244
# be used for line-by-line debugging, and JIT inlining doesn't work
52455245
# without at least -O1 (otherwise clang will emit 'noinline'
52465246
# attributes everywhere), which is bad for testing. Still allow the
@@ -6090,9 +6090,14 @@ if test x"$pgac_cv_prog_CC_cflags__ftree_vectorize" = x"yes"; then
60906090
fi
60916091

60926092

6093-
# We want to suppress clang's unhelpful unused-command-line-argument warnings
6094-
# but gcc won't complain about unrecognized -Wno-foo switches, so we have to
6095-
# test for the positive form and if that works, add the negative form
6093+
#
6094+
# The following tests want to suppress various unhelpful warnings by adding
6095+
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
6096+
# switches, so we have to test for the positive form and if that works,
6097+
# add the negative form. Note that tests of this form typically need to
6098+
# be duplicated in the BITCODE_CFLAGS setup stanza below.
6099+
#
6100+
# Suppress clang's unhelpful unused-command-line-argument warnings.
60966101
NOT_THE_CFLAGS=""
60976102
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS" >&5
60986103
$as_echo_n "checking whether ${CC} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS... " >&6; }
@@ -6137,8 +6142,7 @@ fi
61376142
CFLAGS="$CFLAGS -Wno-unused-command-line-argument"
61386143
fi
61396144
# Remove clang 12+'s compound-token-split-by-macro, as this causes a lot
6140-
# of warnings when building plperl because of Perl. Like previously, test
6141-
# for the positive form and add the negative form
6145+
# of warnings when building plperl because of usages in the Perl headers.
61426146
NOT_THE_CFLAGS=""
61436147
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS" >&5
61446148
$as_echo_n "checking whether ${CC} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS... " >&6; }
@@ -6737,9 +6741,12 @@ fi
67376741

67386742

67396743

6740-
# Determine flags used to emit bitcode for JIT inlining. Need to test
6741-
# for behaviour changing compiler flags, to keep compatibility with
6742-
# compiler used for normal postgres code.
6744+
# Determine flags used to emit bitcode for JIT inlining.
6745+
# 1. We must duplicate any behaviour-changing compiler flags used above,
6746+
# to keep compatibility with the compiler used for normal Postgres code.
6747+
# 2. We don't bother to duplicate extra-warnings switches --- seeing a
6748+
# warning in the main build is enough.
6749+
# 3. But we must duplicate -Wno-warning flags, else we'll see those anyway.
67436750
if test "$with_llvm" = yes ; then
67446751
CLANGXX="$CLANG -xc++"
67456752

@@ -7007,6 +7014,175 @@ if test x"$pgac_cv_prog_CLANGXX_cxxflags__fexcess_precision_standard" = x"yes";
70077014
BITCODE_CXXFLAGS="${BITCODE_CXXFLAGS} -fexcess-precision=standard"
70087015
fi
70097016

7017+
7018+
NOT_THE_CFLAGS=""
7019+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS" >&5
7020+
$as_echo_n "checking whether ${CLANG} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS... " >&6; }
7021+
if ${pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument+:} false; then :
7022+
$as_echo_n "(cached) " >&6
7023+
else
7024+
pgac_save_CFLAGS=$CFLAGS
7025+
pgac_save_CC=$CC
7026+
CC=${CLANG}
7027+
CFLAGS="${NOT_THE_CFLAGS} -Wunused-command-line-argument"
7028+
ac_save_c_werror_flag=$ac_c_werror_flag
7029+
ac_c_werror_flag=yes
7030+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
7031+
/* end confdefs.h. */
7032+
7033+
int
7034+
main ()
7035+
{
7036+
7037+
;
7038+
return 0;
7039+
}
7040+
_ACEOF
7041+
if ac_fn_c_try_compile "$LINENO"; then :
7042+
pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument=yes
7043+
else
7044+
pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument=no
7045+
fi
7046+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
7047+
ac_c_werror_flag=$ac_save_c_werror_flag
7048+
CFLAGS="$pgac_save_CFLAGS"
7049+
CC="$pgac_save_CC"
7050+
fi
7051+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument" >&5
7052+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument" >&6; }
7053+
if test x"$pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument" = x"yes"; then
7054+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wunused-command-line-argument"
7055+
fi
7056+
7057+
if test -n "$NOT_THE_CFLAGS"; then
7058+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-unused-command-line-argument"
7059+
fi
7060+
NOT_THE_CFLAGS=""
7061+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS" >&5
7062+
$as_echo_n "checking whether ${CLANG} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS... " >&6; }
7063+
if ${pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro+:} false; then :
7064+
$as_echo_n "(cached) " >&6
7065+
else
7066+
pgac_save_CFLAGS=$CFLAGS
7067+
pgac_save_CC=$CC
7068+
CC=${CLANG}
7069+
CFLAGS="${NOT_THE_CFLAGS} -Wcompound-token-split-by-macro"
7070+
ac_save_c_werror_flag=$ac_c_werror_flag
7071+
ac_c_werror_flag=yes
7072+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
7073+
/* end confdefs.h. */
7074+
7075+
int
7076+
main ()
7077+
{
7078+
7079+
;
7080+
return 0;
7081+
}
7082+
_ACEOF
7083+
if ac_fn_c_try_compile "$LINENO"; then :
7084+
pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro=yes
7085+
else
7086+
pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro=no
7087+
fi
7088+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
7089+
ac_c_werror_flag=$ac_save_c_werror_flag
7090+
CFLAGS="$pgac_save_CFLAGS"
7091+
CC="$pgac_save_CC"
7092+
fi
7093+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro" >&5
7094+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro" >&6; }
7095+
if test x"$pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro" = x"yes"; then
7096+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wcompound-token-split-by-macro"
7097+
fi
7098+
7099+
if test -n "$NOT_THE_CFLAGS"; then
7100+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-compound-token-split-by-macro"
7101+
fi
7102+
NOT_THE_CFLAGS=""
7103+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wformat-truncation, for NOT_THE_CFLAGS" >&5
7104+
$as_echo_n "checking whether ${CLANG} supports -Wformat-truncation, for NOT_THE_CFLAGS... " >&6; }
7105+
if ${pgac_cv_prog_CLANG_cflags__Wformat_truncation+:} false; then :
7106+
$as_echo_n "(cached) " >&6
7107+
else
7108+
pgac_save_CFLAGS=$CFLAGS
7109+
pgac_save_CC=$CC
7110+
CC=${CLANG}
7111+
CFLAGS="${NOT_THE_CFLAGS} -Wformat-truncation"
7112+
ac_save_c_werror_flag=$ac_c_werror_flag
7113+
ac_c_werror_flag=yes
7114+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
7115+
/* end confdefs.h. */
7116+
7117+
int
7118+
main ()
7119+
{
7120+
7121+
;
7122+
return 0;
7123+
}
7124+
_ACEOF
7125+
if ac_fn_c_try_compile "$LINENO"; then :
7126+
pgac_cv_prog_CLANG_cflags__Wformat_truncation=yes
7127+
else
7128+
pgac_cv_prog_CLANG_cflags__Wformat_truncation=no
7129+
fi
7130+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
7131+
ac_c_werror_flag=$ac_save_c_werror_flag
7132+
CFLAGS="$pgac_save_CFLAGS"
7133+
CC="$pgac_save_CC"
7134+
fi
7135+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wformat_truncation" >&5
7136+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wformat_truncation" >&6; }
7137+
if test x"$pgac_cv_prog_CLANG_cflags__Wformat_truncation" = x"yes"; then
7138+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wformat-truncation"
7139+
fi
7140+
7141+
if test -n "$NOT_THE_CFLAGS"; then
7142+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-format-truncation"
7143+
fi
7144+
NOT_THE_CFLAGS=""
7145+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wstringop-truncation, for NOT_THE_CFLAGS" >&5
7146+
$as_echo_n "checking whether ${CLANG} supports -Wstringop-truncation, for NOT_THE_CFLAGS... " >&6; }
7147+
if ${pgac_cv_prog_CLANG_cflags__Wstringop_truncation+:} false; then :
7148+
$as_echo_n "(cached) " >&6
7149+
else
7150+
pgac_save_CFLAGS=$CFLAGS
7151+
pgac_save_CC=$CC
7152+
CC=${CLANG}
7153+
CFLAGS="${NOT_THE_CFLAGS} -Wstringop-truncation"
7154+
ac_save_c_werror_flag=$ac_c_werror_flag
7155+
ac_c_werror_flag=yes
7156+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
7157+
/* end confdefs.h. */
7158+
7159+
int
7160+
main ()
7161+
{
7162+
7163+
;
7164+
return 0;
7165+
}
7166+
_ACEOF
7167+
if ac_fn_c_try_compile "$LINENO"; then :
7168+
pgac_cv_prog_CLANG_cflags__Wstringop_truncation=yes
7169+
else
7170+
pgac_cv_prog_CLANG_cflags__Wstringop_truncation=no
7171+
fi
7172+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
7173+
ac_c_werror_flag=$ac_save_c_werror_flag
7174+
CFLAGS="$pgac_save_CFLAGS"
7175+
CC="$pgac_save_CC"
7176+
fi
7177+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wstringop_truncation" >&5
7178+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wstringop_truncation" >&6; }
7179+
if test x"$pgac_cv_prog_CLANG_cflags__Wstringop_truncation" = x"yes"; then
7180+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wstringop-truncation"
7181+
fi
7182+
7183+
if test -n "$NOT_THE_CFLAGS"; then
7184+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-stringop-truncation"
7185+
fi
70107186
fi
70117187

70127188
# supply -g if --enable-debug

‎configure.in

Lines changed: 37 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -440,7 +440,7 @@ else
440440
fi
441441

442442
# When generating bitcode (for inlining) we always want to use -O2
443-
# even when --enable-debug is specified. The bitcode it's not going to
443+
# even when --enable-debug is specified. The bitcode is not going to
444444
# be used for line-by-line debugging, and JIT inlining doesn't work
445445
# without at least -O1 (otherwise clang will emit 'noinline'
446446
# attributes everywhere), which is bad for testing. Still allow the
@@ -513,17 +513,21 @@ if test "$GCC" = yes -a "$ICC" = no; then
513513
# Optimization flags for specific files that benefit from vectorization
514514
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-funroll-loops])
515515
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-ftree-vectorize])
516-
# We want to suppress clang's unhelpful unused-command-line-argument warnings
517-
# but gcc won't complain about unrecognized -Wno-foo switches, so we have to
518-
# test for the positive form and if that works, add the negative form
516+
#
517+
# The following tests want to suppress various unhelpful warnings by adding
518+
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
519+
# switches, so we have to test for the positive form and if that works,
520+
# add the negative form. Note that tests of this form typically need to
521+
# be duplicated in the BITCODE_CFLAGS setup stanza below.
522+
#
523+
# Suppress clang's unhelpful unused-command-line-argument warnings.
519524
NOT_THE_CFLAGS=""
520525
PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wunused-command-line-argument])
521526
if test -n "$NOT_THE_CFLAGS"; then
522527
CFLAGS="$CFLAGS -Wno-unused-command-line-argument"
523528
fi
524529
# Remove clang 12+'s compound-token-split-by-macro, as this causes a lot
525-
# of warnings when building plperl because of Perl. Like previously, test
526-
# for the positive form and add the negative form
530+
# of warnings when building plperl because of usages in the Perl headers.
527531
NOT_THE_CFLAGS=""
528532
PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wcompound-token-split-by-macro])
529533
if test -n "$NOT_THE_CFLAGS"; then
@@ -563,9 +567,12 @@ fi
563567

564568
AC_SUBST(CFLAGS_VECTOR)
565569

566-
# Determine flags used to emit bitcode for JIT inlining. Need to test
567-
# for behaviour changing compiler flags, to keep compatibility with
568-
# compiler used for normal postgres code.
570+
# Determine flags used to emit bitcode for JIT inlining.
571+
# 1. We must duplicate any behaviour-changing compiler flags used above,
572+
# to keep compatibility with the compiler used for normal Postgres code.
573+
# 2. We don't bother to duplicate extra-warnings switches --- seeing a
574+
# warning in the main build is enough.
575+
# 3. But we must duplicate -Wno-warning flags, else we'll see those anyway.
569576
if test "$with_llvm" = yes ; then
570577
CLANGXX="$CLANG -xc++"
571578

@@ -575,6 +582,27 @@ if test "$with_llvm" = yes ; then
575582
PGAC_PROG_VARCXX_VARFLAGS_OPT(CLANGXX, BITCODE_CXXFLAGS, [-fwrapv])
576583
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, BITCODE_CFLAGS, [-fexcess-precision=standard])
577584
PGAC_PROG_VARCXX_VARFLAGS_OPT(CLANGXX, BITCODE_CXXFLAGS, [-fexcess-precision=standard])
585+
586+
NOT_THE_CFLAGS=""
587+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wunused-command-line-argument])
588+
if test -n "$NOT_THE_CFLAGS"; then
589+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-unused-command-line-argument"
590+
fi
591+
NOT_THE_CFLAGS=""
592+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wcompound-token-split-by-macro])
593+
if test -n "$NOT_THE_CFLAGS"; then
594+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-compound-token-split-by-macro"
595+
fi
596+
NOT_THE_CFLAGS=""
597+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wformat-truncation])
598+
if test -n "$NOT_THE_CFLAGS"; then
599+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-format-truncation"
600+
fi
601+
NOT_THE_CFLAGS=""
602+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wstringop-truncation])
603+
if test -n "$NOT_THE_CFLAGS"; then
604+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-stringop-truncation"
605+
fi
578606
fi
579607

580608
# supply -g if --enable-debug

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