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1?RCS: $Id: Csym.U,v 1995/07/25 13:36:29 ram Exp $
3?RCS: Copyright (c) 1991-1993, Raphael Manfredi
5?RCS: You may redistribute only under the terms of the Artistic Licence,
6?RCS: as specified in the README file that comes with the distribution.
7?RCS: You may reuse parts of this distribution only within the terms of
8?RCS: that same Artistic Licence; a copy of which may be found at the root
9?RCS: of the source tree for dist 3.0.
11?RCS: $Log: Csym.U,v $
12?RCS: Revision 1995/07/25 13:36:29 ram
13?RCS: patch56: re-arranged compile line to include ldflags before objects
14?RCS: patch56: added quotes for OS/2 support
16?RCS: Revision 1995/05/12 12:00:33 ram
17?RCS: patch54: fixed C test program to bypasss gcc builtin type checks (ADO)
19?RCS: Revision 1994/10/31 09:34:13 ram
20?RCS: patch44: added Options to the MAKE line since it's no longer in Init.U
22?RCS: Revision 1993/08/25 14:00:05 ram
23?RCS: patch6: added ldflags as a conditional dependency and to compile line
24?RCS: patch6: a final double quote was missing in csym variable after eval
26?RCS: Revision 3.0 1993/08/18 12:04:50 ram
27?RCS: Baseline for dist 3.0 netwide release.
29?MAKE:Csym: Options contains libc libs runnm +cc +optimize +ccflags +ldflags rm
30?MAKE: -pick add $@ %<
31?LINT:define csym
32?LINT:use libc
34?S: This shell variable is used internally by Configure to check
35?S: wether a given C symbol is defined or not. A typical use is:
36?S: set symbol result [-fva] [previous]
37?S: eval $csym
38?S: That will set result to 'true' if the function [-f], variable [-v]
39?S: or array [-a] is defined, 'false' otherwise. If a previous value is
40?S: given and the -r flag was provided on the command line, that value
41?S: is reused without questioning.
44?T:tval tx tlook tf tdc tc
45: is a C symbol defined?
47case "$3" in
48-v) tf=libc.tmp; tc=""; tdc="";;
49-a) tf=libc.tmp; tc="[0]"; tdc="[]";;
50*) tlook="^$1\$"; tf=libc.list; tc="()"; tdc="()";;
53case "$reuseval-$4" in
54true-) ;;
55true-*) tx=no; eval "tval=\$$4"; case "$tval" in "") tx=yes;; esac;;
57case "$tx" in
59 case "$runnm" in
60 true)
61 if $contains $tlook $tf >/dev/null 2>&1;
62 then tval=true;
63 else tval=false;
64 fi;;
65 *)
67?X: Put symbol inside a printf to fool optimizing compilers...
69?X: We use 'short' instead of 'int' to try to circumvent overzealous
70?X: optimizing compilers using built-in prototypes for commonly used
71?X: routines to complain when seeing a different external declaration. For
72?X: instance, gcc 2.6.3 fails if we use 'int' and we attempt a test against
73?X: memcpy() on machines where sizeof(int) == sizeof(char *) (the usual return
74?X: type), the compiler assuming it's a built-in declaration given that the
75?X: returned size matches. At least with 'short' we are safe! -- RAM, for ADO
77?X: Let's thank GNU cc for making our lifes so easy! :-)
78?X: (An alternative for the future would be to use our knowledge about gcc
79?X: to force a -fno-builtin option in the compile test, in case the 'short'
80?X: trick is obsoleted by future gcc releases). -- RAM
82 echo "int main() { extern short $1$tdc; printf(\"%hd\", $1$tc); }" > t.c;
83 if $cc $optimize $ccflags $ldflags -o t t.c $libs >/dev/null 2>&1;
84 then tval=true;
85 else tval=false;
86 fi;
87 $rm -f t t.c;;
88 esac;;
90 case "$tval" in
91 $define) tval=true;;
92 *) tval=false;;
93 esac;;
95eval "$2=$tval"'