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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
@@ -5229,7 +5229,7 @@ else
52295229
fi
52305230

52315231
# When generating bitcode (for inlining) we always want to use -O2
5232-
# even when --enable-debug is specified. The bitcode it's not going to
5232+
# even when --enable-debug is specified. The bitcode is not going to
52335233
# be used for line-by-line debugging, and JIT inlining doesn't work
52345234
# without at least -O1 (otherwise clang will emit 'noinline'
52355235
# attributes everywhere), which is bad for testing. Still allow the
@@ -5988,9 +5988,14 @@ if test x"$pgac_cv_prog_CC_cflags__ftree_vectorize" = x"yes"; then
59885988
fi
59895989

59905990

5991-
# We want to suppress clang's unhelpful unused-command-line-argument warnings
5992-
# but gcc won't complain about unrecognized -Wno-foo switches, so we have to
5993-
# test for the positive form and if that works, add the negative form
5991+
#
5992+
# The following tests want to suppress various unhelpful warnings by adding
5993+
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
5994+
# switches, so we have to test for the positive form and if that works,
5995+
# add the negative form. Note that tests of this form typically need to
5996+
# be duplicated in the BITCODE_CFLAGS setup stanza below.
5997+
#
5998+
# Suppress clang's unhelpful unused-command-line-argument warnings.
59945999
NOT_THE_CFLAGS=""
59956000
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS" >&5
59966001
$as_echo_n "checking whether ${CC} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS... " >&6; }
@@ -6035,8 +6040,7 @@ fi
60356040
CFLAGS="$CFLAGS -Wno-unused-command-line-argument"
60366041
fi
60376042
# Remove clang 12+'s compound-token-split-by-macro, as this causes a lot
6038-
# of warnings when building plperl because of Perl. Like previously, test
6039-
# for the positive form and add the negative form
6043+
# of warnings when building plperl because of usages in the Perl headers.
60406044
NOT_THE_CFLAGS=""
60416045
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS" >&5
60426046
$as_echo_n "checking whether ${CC} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS... " >&6; }
@@ -6635,9 +6639,12 @@ fi
66356639

66366640

66376641

6638-
# Determine flags used to emit bitcode for JIT inlining. Need to test
6639-
# for behaviour changing compiler flags, to keep compatibility with
6640-
# compiler used for normal postgres code.
6642+
# Determine flags used to emit bitcode for JIT inlining.
6643+
# 1. We must duplicate any behaviour-changing compiler flags used above,
6644+
# to keep compatibility with the compiler used for normal Postgres code.
6645+
# 2. We don't bother to duplicate extra-warnings switches --- seeing a
6646+
# warning in the main build is enough.
6647+
# 3. But we must duplicate -Wno-warning flags, else we'll see those anyway.
66416648
if test "$with_llvm" = yes ; then
66426649
CLANGXX="$CLANG -xc++"
66436650

@@ -6905,6 +6912,175 @@ if test x"$pgac_cv_prog_CLANGXX_cxxflags__fexcess_precision_standard" = x"yes";
69056912
BITCODE_CXXFLAGS="${BITCODE_CXXFLAGS} -fexcess-precision=standard"
69066913
fi
69076914

6915+
6916+
NOT_THE_CFLAGS=""
6917+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS" >&5
6918+
$as_echo_n "checking whether ${CLANG} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS... " >&6; }
6919+
if ${pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument+:} false; then :
6920+
$as_echo_n "(cached) " >&6
6921+
else
6922+
pgac_save_CFLAGS=$CFLAGS
6923+
pgac_save_CC=$CC
6924+
CC=${CLANG}
6925+
CFLAGS="${NOT_THE_CFLAGS} -Wunused-command-line-argument"
6926+
ac_save_c_werror_flag=$ac_c_werror_flag
6927+
ac_c_werror_flag=yes
6928+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
6929+
/* end confdefs.h. */
6930+
6931+
int
6932+
main ()
6933+
{
6934+
6935+
;
6936+
return 0;
6937+
}
6938+
_ACEOF
6939+
if ac_fn_c_try_compile "$LINENO"; then :
6940+
pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument=yes
6941+
else
6942+
pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument=no
6943+
fi
6944+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
6945+
ac_c_werror_flag=$ac_save_c_werror_flag
6946+
CFLAGS="$pgac_save_CFLAGS"
6947+
CC="$pgac_save_CC"
6948+
fi
6949+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument" >&5
6950+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument" >&6; }
6951+
if test x"$pgac_cv_prog_CLANG_cflags__Wunused_command_line_argument" = x"yes"; then
6952+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wunused-command-line-argument"
6953+
fi
6954+
6955+
if test -n "$NOT_THE_CFLAGS"; then
6956+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-unused-command-line-argument"
6957+
fi
6958+
NOT_THE_CFLAGS=""
6959+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS" >&5
6960+
$as_echo_n "checking whether ${CLANG} supports -Wcompound-token-split-by-macro, for NOT_THE_CFLAGS... " >&6; }
6961+
if ${pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro+:} false; then :
6962+
$as_echo_n "(cached) " >&6
6963+
else
6964+
pgac_save_CFLAGS=$CFLAGS
6965+
pgac_save_CC=$CC
6966+
CC=${CLANG}
6967+
CFLAGS="${NOT_THE_CFLAGS} -Wcompound-token-split-by-macro"
6968+
ac_save_c_werror_flag=$ac_c_werror_flag
6969+
ac_c_werror_flag=yes
6970+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
6971+
/* end confdefs.h. */
6972+
6973+
int
6974+
main ()
6975+
{
6976+
6977+
;
6978+
return 0;
6979+
}
6980+
_ACEOF
6981+
if ac_fn_c_try_compile "$LINENO"; then :
6982+
pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro=yes
6983+
else
6984+
pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro=no
6985+
fi
6986+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
6987+
ac_c_werror_flag=$ac_save_c_werror_flag
6988+
CFLAGS="$pgac_save_CFLAGS"
6989+
CC="$pgac_save_CC"
6990+
fi
6991+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro" >&5
6992+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro" >&6; }
6993+
if test x"$pgac_cv_prog_CLANG_cflags__Wcompound_token_split_by_macro" = x"yes"; then
6994+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wcompound-token-split-by-macro"
6995+
fi
6996+
6997+
if test -n "$NOT_THE_CFLAGS"; then
6998+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-compound-token-split-by-macro"
6999+
fi
7000+
NOT_THE_CFLAGS=""
7001+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wformat-truncation, for NOT_THE_CFLAGS" >&5
7002+
$as_echo_n "checking whether ${CLANG} supports -Wformat-truncation, for NOT_THE_CFLAGS... " >&6; }
7003+
if ${pgac_cv_prog_CLANG_cflags__Wformat_truncation+:} false; then :
7004+
$as_echo_n "(cached) " >&6
7005+
else
7006+
pgac_save_CFLAGS=$CFLAGS
7007+
pgac_save_CC=$CC
7008+
CC=${CLANG}
7009+
CFLAGS="${NOT_THE_CFLAGS} -Wformat-truncation"
7010+
ac_save_c_werror_flag=$ac_c_werror_flag
7011+
ac_c_werror_flag=yes
7012+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
7013+
/* end confdefs.h. */
7014+
7015+
int
7016+
main ()
7017+
{
7018+
7019+
;
7020+
return 0;
7021+
}
7022+
_ACEOF
7023+
if ac_fn_c_try_compile "$LINENO"; then :
7024+
pgac_cv_prog_CLANG_cflags__Wformat_truncation=yes
7025+
else
7026+
pgac_cv_prog_CLANG_cflags__Wformat_truncation=no
7027+
fi
7028+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
7029+
ac_c_werror_flag=$ac_save_c_werror_flag
7030+
CFLAGS="$pgac_save_CFLAGS"
7031+
CC="$pgac_save_CC"
7032+
fi
7033+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wformat_truncation" >&5
7034+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wformat_truncation" >&6; }
7035+
if test x"$pgac_cv_prog_CLANG_cflags__Wformat_truncation" = x"yes"; then
7036+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wformat-truncation"
7037+
fi
7038+
7039+
if test -n "$NOT_THE_CFLAGS"; then
7040+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-format-truncation"
7041+
fi
7042+
NOT_THE_CFLAGS=""
7043+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CLANG} supports -Wstringop-truncation, for NOT_THE_CFLAGS" >&5
7044+
$as_echo_n "checking whether ${CLANG} supports -Wstringop-truncation, for NOT_THE_CFLAGS... " >&6; }
7045+
if ${pgac_cv_prog_CLANG_cflags__Wstringop_truncation+:} false; then :
7046+
$as_echo_n "(cached) " >&6
7047+
else
7048+
pgac_save_CFLAGS=$CFLAGS
7049+
pgac_save_CC=$CC
7050+
CC=${CLANG}
7051+
CFLAGS="${NOT_THE_CFLAGS} -Wstringop-truncation"
7052+
ac_save_c_werror_flag=$ac_c_werror_flag
7053+
ac_c_werror_flag=yes
7054+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
7055+
/* end confdefs.h. */
7056+
7057+
int
7058+
main ()
7059+
{
7060+
7061+
;
7062+
return 0;
7063+
}
7064+
_ACEOF
7065+
if ac_fn_c_try_compile "$LINENO"; then :
7066+
pgac_cv_prog_CLANG_cflags__Wstringop_truncation=yes
7067+
else
7068+
pgac_cv_prog_CLANG_cflags__Wstringop_truncation=no
7069+
fi
7070+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
7071+
ac_c_werror_flag=$ac_save_c_werror_flag
7072+
CFLAGS="$pgac_save_CFLAGS"
7073+
CC="$pgac_save_CC"
7074+
fi
7075+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CLANG_cflags__Wstringop_truncation" >&5
7076+
$as_echo "$pgac_cv_prog_CLANG_cflags__Wstringop_truncation" >&6; }
7077+
if test x"$pgac_cv_prog_CLANG_cflags__Wstringop_truncation" = x"yes"; then
7078+
NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wstringop-truncation"
7079+
fi
7080+
7081+
if test -n "$NOT_THE_CFLAGS"; then
7082+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-stringop-truncation"
7083+
fi
69087084
fi
69097085

69107086
# supply -g if --enable-debug

‎configure.in

Lines changed: 37 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -436,7 +436,7 @@ else
436436
fi
437437

438438
# When generating bitcode (for inlining) we always want to use -O2
439-
# even when --enable-debug is specified. The bitcode it's not going to
439+
# even when --enable-debug is specified. The bitcode is not going to
440440
# be used for line-by-line debugging, and JIT inlining doesn't work
441441
# without at least -O1 (otherwise clang will emit 'noinline'
442442
# attributes everywhere), which is bad for testing. Still allow the
@@ -507,17 +507,21 @@ if test "$GCC" = yes -a "$ICC" = no; then
507507
# Optimization flags for specific files that benefit from vectorization
508508
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-funroll-loops])
509509
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-ftree-vectorize])
510-
# We want to suppress clang's unhelpful unused-command-line-argument warnings
511-
# but gcc won't complain about unrecognized -Wno-foo switches, so we have to
512-
# test for the positive form and if that works, add the negative form
510+
#
511+
# The following tests want to suppress various unhelpful warnings by adding
512+
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
513+
# switches, so we have to test for the positive form and if that works,
514+
# add the negative form. Note that tests of this form typically need to
515+
# be duplicated in the BITCODE_CFLAGS setup stanza below.
516+
#
517+
# Suppress clang's unhelpful unused-command-line-argument warnings.
513518
NOT_THE_CFLAGS=""
514519
PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wunused-command-line-argument])
515520
if test -n "$NOT_THE_CFLAGS"; then
516521
CFLAGS="$CFLAGS -Wno-unused-command-line-argument"
517522
fi
518523
# Remove clang 12+'s compound-token-split-by-macro, as this causes a lot
519-
# of warnings when building plperl because of Perl. Like previously, test
520-
# for the positive form and add the negative form
524+
# of warnings when building plperl because of usages in the Perl headers.
521525
NOT_THE_CFLAGS=""
522526
PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wcompound-token-split-by-macro])
523527
if test -n "$NOT_THE_CFLAGS"; then
@@ -557,9 +561,12 @@ fi
557561

558562
AC_SUBST(CFLAGS_VECTOR)
559563

560-
# Determine flags used to emit bitcode for JIT inlining. Need to test
561-
# for behaviour changing compiler flags, to keep compatibility with
562-
# compiler used for normal postgres code.
564+
# Determine flags used to emit bitcode for JIT inlining.
565+
# 1. We must duplicate any behaviour-changing compiler flags used above,
566+
# to keep compatibility with the compiler used for normal Postgres code.
567+
# 2. We don't bother to duplicate extra-warnings switches --- seeing a
568+
# warning in the main build is enough.
569+
# 3. But we must duplicate -Wno-warning flags, else we'll see those anyway.
563570
if test "$with_llvm" = yes ; then
564571
CLANGXX="$CLANG -xc++"
565572

@@ -569,6 +576,27 @@ if test "$with_llvm" = yes ; then
569576
PGAC_PROG_VARCXX_VARFLAGS_OPT(CLANGXX, BITCODE_CXXFLAGS, [-fwrapv])
570577
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, BITCODE_CFLAGS, [-fexcess-precision=standard])
571578
PGAC_PROG_VARCXX_VARFLAGS_OPT(CLANGXX, BITCODE_CXXFLAGS, [-fexcess-precision=standard])
579+
580+
NOT_THE_CFLAGS=""
581+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wunused-command-line-argument])
582+
if test -n "$NOT_THE_CFLAGS"; then
583+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-unused-command-line-argument"
584+
fi
585+
NOT_THE_CFLAGS=""
586+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wcompound-token-split-by-macro])
587+
if test -n "$NOT_THE_CFLAGS"; then
588+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-compound-token-split-by-macro"
589+
fi
590+
NOT_THE_CFLAGS=""
591+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wformat-truncation])
592+
if test -n "$NOT_THE_CFLAGS"; then
593+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-format-truncation"
594+
fi
595+
NOT_THE_CFLAGS=""
596+
PGAC_PROG_VARCC_VARFLAGS_OPT(CLANG, NOT_THE_CFLAGS, [-Wstringop-truncation])
597+
if test -n "$NOT_THE_CFLAGS"; then
598+
BITCODE_CFLAGS="$BITCODE_CFLAGS -Wno-stringop-truncation"
599+
fi
572600
fi
573601

574602
# supply -g if --enable-debug

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