Assume that we have isinf().

Windows has this, and so do all other live platforms according to the
buildfarm, so remove the configure probe and src/port/ substitution.

This also lets us get rid of some configure probes that existed only
to support src/port/isinf.c.  I kept the port.h hack to force using
__builtin_isinf() on clang, though.

This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code.  I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.

Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us

configure

@@ -12762,7 +12762,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
 fi
 
 
-for ac_header in atomic.h copyfile.h execinfo.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/event.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
+for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/event.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"
@@ -15485,63 +15485,6 @@ $as_echo "#define HAVE_PS_STRINGS 1" >>confdefs.h
 
 fi
 
-
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for isinf" >&5
-$as_echo_n "checking for isinf... " >&6; }
-if ${ac_cv_func_isinf+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-
-#include <math.h>
-double glob_double;
-
-int
-main ()
-{
-return isinf(glob_double) ? 0 : 1;
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_func_isinf=yes
-else
-  ac_cv_func_isinf=no
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_func_isinf" >&5
-$as_echo "$ac_cv_func_isinf" >&6; }
-
-if test $ac_cv_func_isinf = yes ; then
-
-$as_echo "#define HAVE_ISINF 1" >>confdefs.h
-
-else
-  case " $LIBOBJS " in
-  *" isinf.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS isinf.$ac_objext"
- ;;
-esac
-
-  # Look for a way to implement a substitute for isinf()
-  for ac_func in fpclass fp_class fp_class_d class
-do :
-  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
-ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
-if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
-_ACEOF
- break
-fi
-done
-
-fi
-
 ac_fn_c_check_func "$LINENO" "dlopen" "ac_cv_func_dlopen"
 if test "x$ac_cv_func_dlopen" = xyes; then :
   $as_echo "#define HAVE_DLOPEN 1" >>confdefs.h

configure.in

@@ -1280,9 +1280,7 @@ AC_CHECK_HEADERS(m4_normalize([
 	atomic.h
 	copyfile.h
 	execinfo.h
-	fp_class.h
 	getopt.h
-	ieeefp.h
 	ifaddrs.h
 	langinfo.h
 	mbarrier.h
@@ -1699,25 +1697,6 @@ if test "$pgac_cv_var_PS_STRINGS" = yes ; then
   AC_DEFINE([HAVE_PS_STRINGS], 1, [Define to 1 if the PS_STRINGS thing exists.])
 fi
 
-
-dnl Cannot use AC_CHECK_FUNC because isinf may be a macro
-AC_CACHE_CHECK([for isinf], ac_cv_func_isinf,
-[AC_LINK_IFELSE([AC_LANG_PROGRAM([
-#include <math.h>
-double glob_double;
-],
-[return isinf(glob_double) ? 0 : 1;])],
-[ac_cv_func_isinf=yes],
-[ac_cv_func_isinf=no])])
-
-if test $ac_cv_func_isinf = yes ; then
-  AC_DEFINE(HAVE_ISINF, 1, [Define to 1 if you have isinf().])
-else
-  AC_LIBOBJ(isinf)
-  # Look for a way to implement a substitute for isinf()
-  AC_CHECK_FUNCS([fpclass fp_class fp_class_d class], [break])
-fi
-
 AC_REPLACE_FUNCS(m4_normalize([
 	dlopen
 	explicit_bzero

src/include/pg_config.h.in

@@ -104,9 +104,6 @@
 /* Define to 1 if you have the `cbrt' function. */
 #undef HAVE_CBRT
 
-/* Define to 1 if you have the `class' function. */
-#undef HAVE_CLASS
-
 /* Define to 1 if you have the `clock_gettime' function. */
 #undef HAVE_CLOCK_GETTIME
 
@@ -206,18 +203,6 @@
 /* Define to 1 if you have the `fls' function. */
 #undef HAVE_FLS
 
-/* Define to 1 if you have the `fpclass' function. */
-#undef HAVE_FPCLASS
-
-/* Define to 1 if you have the `fp_class' function. */
-#undef HAVE_FP_CLASS
-
-/* Define to 1 if you have the `fp_class_d' function. */
-#undef HAVE_FP_CLASS_D
-
-/* Define to 1 if you have the <fp_class.h> header file. */
-#undef HAVE_FP_CLASS_H
-
 /* Define to 1 if fseeko (and presumably ftello) exists and is declared. */
 #undef HAVE_FSEEKO
 
@@ -295,9 +280,6 @@
 /* Define to 1 if you have the `history_truncate_file' function. */
 #undef HAVE_HISTORY_TRUNCATE_FILE
 
-/* Define to 1 if you have the <ieeefp.h> header file. */
-#undef HAVE_IEEEFP_H
-
 /* Define to 1 if you have the <ifaddrs.h> header file. */
 #undef HAVE_IFADDRS_H
 
@@ -325,9 +307,6 @@
 /* Define to 1 if you have support for IPv6. */
 #undef HAVE_IPV6
 
-/* Define to 1 if you have isinf(). */
-#undef HAVE_ISINF
-
 /* Define to 1 if __builtin_constant_p(x) implies "i"(x) acceptance. */
 #undef HAVE_I_CONSTRAINT__BUILTIN_CONSTANT_P
 

src/include/port.h

@@ -352,9 +352,6 @@ extern int	getpeereid(int sock, uid_t *uid, gid_t *gid);
 #endif
 #endif
 
-#ifndef HAVE_ISINF
-extern int	isinf(double x);
-#else
 /*
  * Glibc doesn't use the builtin for clang due to a *gcc* bug in a version
  * newer than the gcc compatibility clang claims to have. This would cause a
@@ -370,7 +367,6 @@ extern int	isinf(double x);
 #define isinf __builtin_isinf
 #endif							/* __has_builtin(isinf) */
 #endif							/* __clang__ && !__cplusplus */
-#endif							/* !HAVE_ISINF */
 
 #ifndef HAVE_EXPLICIT_BZERO
 extern void explicit_bzero(void *buf, size_t len);

src/port/isinf.c

@@ -1,81 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * isinf.c
- *
- * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- *	  src/port/isinf.c
- *
- *-------------------------------------------------------------------------
- */
-
-#include "c.h"
-
-#include <float.h>
-#include <math.h>
-
-#if HAVE_FPCLASS				/* this is _not_ HAVE_FP_CLASS, and not typo */
-
-#if HAVE_IEEEFP_H
-#include <ieeefp.h>
-#endif
-
-int
-isinf(double d)
-{
-	fpclass_t	type = fpclass(d);
-
-	switch (type)
-	{
-		case FP_NINF:
-		case FP_PINF:
-			return 1;
-		default:
-			break;
-	}
-	return 0;
-}
-#else
-
-#if defined(HAVE_FP_CLASS) || defined(HAVE_FP_CLASS_D)
-
-#if HAVE_FP_CLASS_H
-#include <fp_class.h>
-#endif
-
-int
-isinf(double x)
-{
-#if HAVE_FP_CLASS
-	int			fpclass = fp_class(x);
-#else
-	int			fpclass = fp_class_d(x);
-#endif
-
-	if (fpclass == FP_POS_INF)
-		return 1;
-	if (fpclass == FP_NEG_INF)
-		return -1;
-	return 0;
-}
-
-#elif defined(HAVE_CLASS)
-
-int
-isinf(double x)
-{
-	int			fpclass = class(x);
-
-	if (fpclass == FP_PLUS_INF)
-		return 1;
-	if (fpclass == FP_MINUS_INF)
-		return -1;
-	return 0;
-}
-
-#endif
-
-#endif

src/tools/msvc/Solution.pm

@@ -211,7 +211,6 @@ sub GenerateFiles
 		HAVE_BIO_GET_DATA          => undef,
 		HAVE_BIO_METH_NEW          => undef,
 		HAVE_CBRT                  => undef,
-		HAVE_CLASS                 => undef,
 		HAVE_CLOCK_GETTIME         => undef,
 		HAVE_COMPUTED_GOTO         => undef,
 		HAVE_COPYFILE              => undef,
@@ -240,10 +239,6 @@ sub GenerateFiles
 		HAVE_EXPLICIT_BZERO                         => undef,
 		HAVE_FDATASYNC                              => undef,
 		HAVE_FLS                                    => undef,
-		HAVE_FPCLASS                                => undef,
-		HAVE_FP_CLASS                               => undef,
-		HAVE_FP_CLASS_D                             => undef,
-		HAVE_FP_CLASS_H                             => undef,
 		HAVE_FSEEKO                                 => 1,
 		HAVE_FUNCNAME__FUNC                         => undef,
 		HAVE_FUNCNAME__FUNCTION                     => 1,
@@ -269,7 +264,6 @@ sub GenerateFiles
 		HAVE_GSSAPI_H                               => undef,
 		HAVE_HISTORY_H                              => undef,
 		HAVE_HISTORY_TRUNCATE_FILE                  => undef,
-		HAVE_IEEEFP_H                               => undef,
 		HAVE_IFADDRS_H                              => undef,
 		HAVE_INET_ATON                              => undef,
 		HAVE_INT_TIMEZONE                           => 1,
@@ -279,7 +273,6 @@ sub GenerateFiles
 		HAVE_INT_OPTERR                             => undef,
 		HAVE_INT_OPTRESET                           => undef,
 		HAVE_IPV6                                   => 1,
-		HAVE_ISINF                                  => 1,
 		HAVE_I_CONSTRAINT__BUILTIN_CONSTANT_P       => undef,
 		HAVE_KQUEUE                                 => undef,
 		HAVE_LANGINFO_H                             => undef,