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Fix configure's AC_CHECK_DECLS tests to work correctly with clang.
The test case that Autoconf uses to discover whether a function has been declared doesn't work reliably with clang, because clang reports a warning not an error if the name is a known built-in function. On some platforms, this results in a lot of compile-time warnings about strlcpy and related functions not having been declared. There is a fix for this (by Noah Misch) in the upstream Autoconf sources, but since they've not made a release in years and show no indication of doing so anytime soon, let's just absorb their fix directly. We can revert this when and if we update to a newer Autoconf release. Back-patch to all supported branches. Discussion: https://postgr.es/m/26819.1542515567@sss.pgh.pa.us
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4 files changed

+223
-7
lines changed

4 files changed

+223
-7
lines changed

aclocal.m4

+1
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,7 @@ m4_include([config/ax_prog_perl_modules.m4])
44
m4_include([config/ax_pthread.m4])
55
m4_include([config/c-compiler.m4])
66
m4_include([config/c-library.m4])
7+
m4_include([config/check_decls.m4])
78
m4_include([config/docbook.m4])
89
m4_include([config/general.m4])
910
m4_include([config/libtool.m4])

config/check_decls.m4

+116
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,116 @@
1+
# config/check_decls.m4
2+
3+
# This file redefines the standard Autoconf macro _AC_CHECK_DECL_BODY,
4+
# and adds a supporting function _AC_UNDECLARED_WARNING, to make
5+
# AC_CHECK_DECLS behave correctly when checking for built-in library
6+
# functions with clang.
7+
8+
# This is based on commit 82ef7805faffa151e724aa76c245ec590d174580
9+
# in the Autoconf git repository. We can drop it if they ever get
10+
# around to releasing a new version of Autoconf. In the meantime,
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# it's distributed under Autoconf's license:
12+
13+
# This file is part of Autoconf. This program is free
14+
# software; you can redistribute it and/or modify it under the
15+
# terms of the GNU General Public License as published by the
16+
# Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# Under Section 7 of GPL version 3, you are granted additional
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# permissions described in the Autoconf Configure Script Exception,
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# version 3.0, as published by the Free Software Foundation.
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#
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# You should have received a copy of the GNU General Public License
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# and a copy of the Autoconf Configure Script Exception along with
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# this program; see the files COPYINGv3 and COPYING.EXCEPTION
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# respectively. If not, see <http://www.gnu.org/licenses/>.
32+
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# Written by David MacKenzie, with help from
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# Franc,ois Pinard, Karl Berry, Richard Pixley, Ian Lance Taylor,
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# Roland McGrath, Noah Friedman, david d zuhn, and many others.
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37+
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# _AC_UNDECLARED_WARNING
39+
# ----------------------
40+
# Set ac_[]_AC_LANG_ABBREV[]_decl_warn_flag=yes if the compiler uses a warning,
41+
# not a more-customary error, to report some undeclared identifiers. Fail when
42+
# an affected compiler warns also on valid input. _AC_PROG_PREPROC_WORKS_IFELSE
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# solves a related problem.
44+
AC_DEFUN([_AC_UNDECLARED_WARNING],
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[# The Clang compiler raises a warning for an undeclared identifier that matches
46+
# a compiler builtin function. All extant Clang versions are affected, as of
47+
# Clang 3.6.0. Test a builtin known to every version. This problem affects the
48+
# C and Objective C languages, but Clang does report an error under C++ and
49+
# Objective C++.
50+
#
51+
# Passing -fno-builtin to the compiler would suppress this problem. That
52+
# strategy would have the advantage of being insensitive to stray warnings, but
53+
# it would make tests less realistic.
54+
AC_CACHE_CHECK([how $[]_AC_CC[] reports undeclared, standard C functions],
55+
[ac_cv_[]_AC_LANG_ABBREV[]_decl_report],
56+
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [(void) strchr;])],
57+
[AS_IF([test -s conftest.err], [dnl
58+
# For AC_CHECK_DECL to react to warnings, the compiler must be silent on
59+
# valid AC_CHECK_DECL input. No library function is consistently available
60+
# on freestanding implementations, so test against a dummy declaration.
61+
# Include always-available headers on the off chance that they somehow
62+
# elicit warnings.
63+
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([dnl
64+
#include <float.h>
65+
#include <limits.h>
66+
#include <stdarg.h>
67+
#include <stddef.h>
68+
extern void ac_decl (int, char *);],
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[@%:@ifdef __cplusplus
70+
(void) ac_decl ((int) 0, (char *) 0);
71+
(void) ac_decl;
72+
@%:@else
73+
(void) ac_decl;
74+
@%:@endif
75+
])],
76+
[AS_IF([test -s conftest.err],
77+
[AC_MSG_FAILURE([cannot detect from compiler exit status or warnings])],
78+
[ac_cv_[]_AC_LANG_ABBREV[]_decl_report=warning])],
79+
[AC_MSG_FAILURE([cannot compile a simple declaration test])])],
80+
[AC_MSG_FAILURE([compiler does not report undeclared identifiers])])],
81+
[ac_cv_[]_AC_LANG_ABBREV[]_decl_report=error])])
82+
83+
case $ac_cv_[]_AC_LANG_ABBREV[]_decl_report in
84+
warning) ac_[]_AC_LANG_ABBREV[]_decl_warn_flag=yes ;;
85+
*) ac_[]_AC_LANG_ABBREV[]_decl_warn_flag= ;;
86+
esac
87+
])# _AC_UNDECLARED_WARNING
88+
89+
# _AC_CHECK_DECL_BODY
90+
# -------------------
91+
# Shell function body for AC_CHECK_DECL.
92+
m4_define([_AC_CHECK_DECL_BODY],
93+
[ AS_LINENO_PUSH([$[]1])
94+
# Initialize each $ac_[]_AC_LANG_ABBREV[]_decl_warn_flag once.
95+
AC_DEFUN([_AC_UNDECLARED_WARNING_]_AC_LANG_ABBREV,
96+
[_AC_UNDECLARED_WARNING])dnl
97+
AC_REQUIRE([_AC_UNDECLARED_WARNING_]_AC_LANG_ABBREV)dnl
98+
[as_decl_name=`echo $][2|sed 's/ *(.*//'`]
99+
[as_decl_use=`echo $][2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`]
100+
AC_CACHE_CHECK([whether $as_decl_name is declared], [$[]3],
101+
[ac_save_werror_flag=$ac_[]_AC_LANG_ABBREV[]_werror_flag
102+
ac_[]_AC_LANG_ABBREV[]_werror_flag="$ac_[]_AC_LANG_ABBREV[]_decl_warn_flag$ac_[]_AC_LANG_ABBREV[]_werror_flag"
103+
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$[]4],
104+
[@%:@ifndef $[]as_decl_name
105+
@%:@ifdef __cplusplus
106+
(void) $[]as_decl_use;
107+
@%:@else
108+
(void) $[]as_decl_name;
109+
@%:@endif
110+
@%:@endif
111+
])],
112+
[AS_VAR_SET([$[]3], [yes])],
113+
[AS_VAR_SET([$[]3], [no])])
114+
ac_[]_AC_LANG_ABBREV[]_werror_flag=$ac_save_werror_flag])
115+
AS_LINENO_POP
116+
])# _AC_CHECK_DECL_BODY

configure

+100-4
Original file line numberDiff line numberDiff line change
@@ -1756,13 +1756,16 @@ fi
17561756
ac_fn_c_check_decl ()
17571757
{
17581758
as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
1759-
as_decl_name=`echo $2|sed 's/ *(.*//'`
1759+
# Initialize each $ac_[]_AC_LANG_ABBREV[]_decl_warn_flag once.
1760+
as_decl_name=`echo $2|sed 's/ *(.*//'`
17601761
as_decl_use=`echo $2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`
17611762
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $as_decl_name is declared" >&5
17621763
$as_echo_n "checking whether $as_decl_name is declared... " >&6; }
17631764
if eval \${$3+:} false; then :
17641765
$as_echo_n "(cached) " >&6
17651766
else
1767+
ac_save_werror_flag=$ac_c_werror_flag
1768+
ac_c_werror_flag="$ac_c_decl_warn_flag$ac_c_werror_flag"
17661769
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
17671770
/* end confdefs.h. */
17681771
$4
@@ -1787,6 +1790,7 @@ else
17871790
eval "$3=no"
17881791
fi
17891792
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
1793+
ac_c_werror_flag=$ac_save_werror_flag
17901794
fi
17911795
eval ac_res=\$$3
17921796
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
@@ -4990,11 +4994,100 @@ fi
49904994
test -n "$AWK" && break
49914995
done
49924996

4997+
# The Clang compiler raises a warning for an undeclared identifier that matches
4998+
# a compiler builtin function. All extant Clang versions are affected, as of
4999+
# Clang 3.6.0. Test a builtin known to every version. This problem affects the
5000+
# C and Objective C languages, but Clang does report an error under C++ and
5001+
# Objective C++.
5002+
#
5003+
# Passing -fno-builtin to the compiler would suppress this problem. That
5004+
# strategy would have the advantage of being insensitive to stray warnings, but
5005+
# it would make tests less realistic.
5006+
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking how $CC reports undeclared, standard C functions" >&5
5007+
$as_echo_n "checking how $CC reports undeclared, standard C functions... " >&6; }
5008+
if ${ac_cv_c_decl_report+:} false; then :
5009+
$as_echo_n "(cached) " >&6
5010+
else
5011+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
5012+
/* end confdefs.h. */
5013+
5014+
int
5015+
main ()
5016+
{
5017+
(void) strchr;
5018+
;
5019+
return 0;
5020+
}
5021+
_ACEOF
5022+
if ac_fn_c_try_compile "$LINENO"; then :
5023+
if test -s conftest.err; then :
5024+
# For AC_CHECK_DECL to react to warnings, the compiler must be silent on
5025+
# valid AC_CHECK_DECL input. No library function is consistently available
5026+
# on freestanding implementations, so test against a dummy declaration.
5027+
# Include always-available headers on the off chance that they somehow
5028+
# elicit warnings.
5029+
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
5030+
/* end confdefs.h. */
5031+
#include <float.h>
5032+
#include <limits.h>
5033+
#include <stdarg.h>
5034+
#include <stddef.h>
5035+
extern void ac_decl (int, char *);
5036+
int
5037+
main ()
5038+
{
5039+
#ifdef __cplusplus
5040+
(void) ac_decl ((int) 0, (char *) 0);
5041+
(void) ac_decl;
5042+
#else
5043+
(void) ac_decl;
5044+
#endif
5045+
5046+
;
5047+
return 0;
5048+
}
5049+
_ACEOF
5050+
if ac_fn_c_try_compile "$LINENO"; then :
5051+
if test -s conftest.err; then :
5052+
{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
5053+
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
5054+
as_fn_error $? "cannot detect from compiler exit status or warnings
5055+
See \`config.log' for more details" "$LINENO" 5; }
5056+
else
5057+
ac_cv_c_decl_report=warning
5058+
fi
5059+
else
5060+
{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
5061+
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
5062+
as_fn_error $? "cannot compile a simple declaration test
5063+
See \`config.log' for more details" "$LINENO" 5; }
5064+
fi
5065+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
5066+
else
5067+
{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
5068+
$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
5069+
as_fn_error $? "compiler does not report undeclared identifiers
5070+
See \`config.log' for more details" "$LINENO" 5; }
5071+
fi
5072+
else
5073+
ac_cv_c_decl_report=error
5074+
fi
5075+
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
5076+
fi
5077+
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_c_decl_report" >&5
5078+
$as_echo "$ac_cv_c_decl_report" >&6; }
5079+
5080+
case $ac_cv_c_decl_report in
5081+
warning) ac_c_decl_warn_flag=yes ;;
5082+
*) ac_c_decl_warn_flag= ;;
5083+
esac
5084+
49935085
if test "$with_llvm" = yes; then :
49945086

49955087

49965088

49975089

5090+
49985091
if test -z "$LLVM_CONFIG"; then
49995092
for ac_prog in llvm-config llvm-config-7 llvm-config-6.0 llvm-config-5.0 llvm-config-4.0 llvm-config-3.9
50005093
do
@@ -5250,7 +5343,8 @@ _ACEOF
52505343

52515344

52525345

5253-
fi
5346+
5347+
fi # fi
52545348

52555349

52565350
unset CFLAGS
@@ -15197,7 +15291,8 @@ esac
1519715291
# posix_fadvise() is a no-op on Solaris, so don't incur function overhead
1519815292
# by calling it, 2009-04-02
1519915293
# http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libc/port/gen/posix_fadvise.c
15200-
if test "$PORTNAME" != "solaris"; then
15294+
if test "$PORTNAME" != "solaris"; then :
15295+
1520115296
for ac_func in posix_fadvise
1520215297
do :
1520315298
ac_fn_c_check_func "$LINENO" "posix_fadvise" "ac_cv_func_posix_fadvise"
@@ -15221,7 +15316,8 @@ cat >>confdefs.h <<_ACEOF
1522115316
#define HAVE_DECL_POSIX_FADVISE $ac_have_decl
1522215317
_ACEOF
1522315318

15224-
fi
15319+
15320+
fi # fi
1522515321

1522615322
ac_fn_c_check_decl "$LINENO" "fdatasync" "ac_cv_have_decl_fdatasync" "#include <unistd.h>
1522715323
"

configure.in

+6-3
Original file line numberDiff line numberDiff line change
@@ -392,7 +392,9 @@ PGAC_ARG_BOOL(with, llvm, no, [build with LLVM based JIT support],
392392
[AC_DEFINE([USE_LLVM], 1, [Define to 1 to build with LLVM based JIT support. (--with-llvm)])])
393393
AC_SUBST(with_llvm)
394394
dnl must use AS_IF here, else AC_REQUIRES inside PGAC_LLVM_SUPPORT malfunctions
395-
AS_IF([test "$with_llvm" = yes], [PGAC_LLVM_SUPPORT()])
395+
AS_IF([test "$with_llvm" = yes], [
396+
PGAC_LLVM_SUPPORT()
397+
]) # fi
396398

397399

398400
unset CFLAGS
@@ -1640,10 +1642,11 @@ esac
16401642
# posix_fadvise() is a no-op on Solaris, so don't incur function overhead
16411643
# by calling it, 2009-04-02
16421644
# http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libc/port/gen/posix_fadvise.c
1643-
if test "$PORTNAME" != "solaris"; then
1645+
dnl must use AS_IF here, else AC_REQUIRES inside AC_CHECK_DECLS malfunctions
1646+
AS_IF([test "$PORTNAME" != "solaris"], [
16441647
AC_CHECK_FUNCS(posix_fadvise)
16451648
AC_CHECK_DECLS(posix_fadvise, [], [], [#include <fcntl.h>])
1646-
fi
1649+
]) # fi
16471650

16481651
AC_CHECK_DECLS(fdatasync, [], [], [#include <unistd.h>])
16491652
AC_CHECK_DECLS([strlcat, strlcpy, strnlen])

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