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	vintage Linux is even more broken than we realized: a link to libreadline will succeed, and fail only at runtime. It seems that an AC_TRY_RUN test is the only reliable way to check whether this is really safe. Per report from Tatsuo.
		
			
				
	
	
		
			134 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
			
		
		
	
	
			134 lines
		
	
	
		
			4.2 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
	
	
# Macros to detect C compiler features
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# $PostgreSQL: pgsql/config/c-compiler.m4,v 1.19 2008/06/27 00:36:16 tgl Exp $
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# PGAC_C_SIGNED
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# -------------
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# Check if the C compiler understands signed types.
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AC_DEFUN([PGAC_C_SIGNED],
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[AC_CACHE_CHECK(for signed types, pgac_cv_c_signed,
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[AC_TRY_COMPILE([],
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[signed char c; signed short s; signed int i;],
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[pgac_cv_c_signed=yes],
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[pgac_cv_c_signed=no])])
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if test x"$pgac_cv_c_signed" = xno ; then
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  AC_DEFINE(signed,, [Define to empty if the C compiler does not understand signed types.])
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fi])# PGAC_C_SIGNED
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# PGAC_TYPE_64BIT_INT(TYPE)
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# -------------------------
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# Check if TYPE is a working 64 bit integer type. Set HAVE_TYPE_64 to
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# yes or no respectively, and define HAVE_TYPE_64 if yes.
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AC_DEFUN([PGAC_TYPE_64BIT_INT],
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[define([Ac_define], [translit([have_$1_64], [a-z *], [A-Z_P])])dnl
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define([Ac_cachevar], [translit([pgac_cv_type_$1_64], [ *], [_p])])dnl
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AC_CACHE_CHECK([whether $1 is 64 bits], [Ac_cachevar],
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[AC_TRY_RUN(
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[typedef $1 ac_int64;
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/*
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 * These are globals to discourage the compiler from folding all the
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 * arithmetic tests down to compile-time constants.
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 */
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ac_int64 a = 20000001;
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ac_int64 b = 40000005;
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int does_int64_work()
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{
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  ac_int64 c,d;
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  if (sizeof(ac_int64) != 8)
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    return 0;			/* definitely not the right size */
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  /* Do perfunctory checks to see if 64-bit arithmetic seems to work */
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  c = a * b;
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  d = (c + b) / b;
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  if (d != a+1)
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    return 0;
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  return 1;
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}
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main() {
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  exit(! does_int64_work());
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}],
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[Ac_cachevar=yes],
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[Ac_cachevar=no],
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[# If cross-compiling, check the size reported by the compiler and
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# trust that the arithmetic works.
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AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([], [sizeof($1) == 8])],
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                  Ac_cachevar=yes,
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                  Ac_cachevar=no)])])
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Ac_define=$Ac_cachevar
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if test x"$Ac_cachevar" = xyes ; then
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  AC_DEFINE(Ac_define, 1, [Define to 1 if `]$1[' works and is 64 bits.])
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fi
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undefine([Ac_define])dnl
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undefine([Ac_cachevar])dnl
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])# PGAC_TYPE_64BIT_INT
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# PGAC_C_FUNCNAME_SUPPORT
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# -----------------------
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# Check if the C compiler understands __func__ (C99) or __FUNCTION__ (gcc).
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# Define HAVE_FUNCNAME__FUNC or HAVE_FUNCNAME__FUNCTION accordingly.
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AC_DEFUN([PGAC_C_FUNCNAME_SUPPORT],
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[AC_CACHE_CHECK(for __func__, pgac_cv_funcname_func_support,
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[AC_TRY_COMPILE([#include <stdio.h>],
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[printf("%s\n", __func__);],
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[pgac_cv_funcname_func_support=yes],
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[pgac_cv_funcname_func_support=no])])
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if test x"$pgac_cv_funcname_func_support" = xyes ; then
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AC_DEFINE(HAVE_FUNCNAME__FUNC, 1,
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          [Define to 1 if your compiler understands __func__.])
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else
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AC_CACHE_CHECK(for __FUNCTION__, pgac_cv_funcname_function_support,
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[AC_TRY_COMPILE([#include <stdio.h>],
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[printf("%s\n", __FUNCTION__);],
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[pgac_cv_funcname_function_support=yes],
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[pgac_cv_funcname_function_support=no])])
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if test x"$pgac_cv_funcname_function_support" = xyes ; then
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AC_DEFINE(HAVE_FUNCNAME__FUNCTION, 1,
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          [Define to 1 if your compiler understands __FUNCTION__.])
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fi
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fi])# PGAC_C_FUNCNAME_SUPPORT
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# PGAC_PROG_CC_CFLAGS_OPT
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# -----------------------
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# Given a string, check if the compiler supports the string as a
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# command-line option. If it does, add the string to CFLAGS.
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AC_DEFUN([PGAC_PROG_CC_CFLAGS_OPT],
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[AC_MSG_CHECKING([if $CC supports $1])
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pgac_save_CFLAGS=$CFLAGS
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CFLAGS="$pgac_save_CFLAGS $1"
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_AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
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                   AC_MSG_RESULT(yes),
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                   [CFLAGS="$pgac_save_CFLAGS"
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                    AC_MSG_RESULT(no)])
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])# PGAC_PROG_CC_CFLAGS_OPT
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# PGAC_PROG_CC_LDFLAGS_OPT
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# ------------------------
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# Given a string, check if the compiler supports the string as a
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# command-line option. If it does, add the string to LDFLAGS.
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# For reasons you'd really rather not know about, this checks whether
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# you can link to a particular function, not just whether you can link.
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# In fact, we must actually check that the resulting program runs :-(
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AC_DEFUN([PGAC_PROG_CC_LDFLAGS_OPT],
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[AC_MSG_CHECKING([if $CC supports $1])
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pgac_save_LDFLAGS=$LDFLAGS
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LDFLAGS="$pgac_save_LDFLAGS $1"
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AC_RUN_IFELSE([AC_LANG_PROGRAM([extern void $2 (); void (*fptr) () = $2;],[])],
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              AC_MSG_RESULT(yes),
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              [LDFLAGS="$pgac_save_LDFLAGS"
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               AC_MSG_RESULT(no)],
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              [LDFLAGS="$pgac_save_LDFLAGS"
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               AC_MSG_RESULT(assuming no)])
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])# PGAC_PROG_CC_LDFLAGS_OPT
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