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Update perlhacktips about default gcc warning flags
[perl5.git] / cflags.SH
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1#!/bin/sh
2
cb9238a7 3# Generate the cflags script, which is used to determine what cflags
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4# to pass to the compiler for compiling the core perl.
5#
6# This does NOT affect the XS compilation (ext, dist, cpan)
7# since that uses %Config values directly.
8#
9# For example, since -Wall adds -Wunused-*, a bare -Wall (without
10# amending that with -Wno-unused-..., or with the PERL_UNUSED_...)
11# would be too much for XS code because there are too many generated
12# but often unused things.
13#
14# We create a temporary test C program and repeatedly compile it with
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15# various candidate flags, and from the compiler output, determine what
16# flags are supported.
ea14a82d 17#
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18# From this we initialise the following variables in the cflags script:
19#
ea14a82d 20# $myccflags (possibly edited version of $Config{ccflags})
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21# $warn
22# $stdflags
23# $extra
24# $_exe
25
a02608de 26case $PERL_CONFIG_SH in
1c3d792e 27'')
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28 if test -f config.sh; then TOP=.;
29 elif test -f ../config.sh; then TOP=..;
30 elif test -f ../../config.sh; then TOP=../..;
31 elif test -f ../../../config.sh; then TOP=../../..;
32 elif test -f ../../../../config.sh; then TOP=../../../..;
33 else
34 echo "Can't find config.sh."; exit 1
35 fi
36 . $TOP/config.sh
37 ;;
1c3d792e 38esac
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39# This forces SH files to create target in same directory as SH file.
40# This is so that make depend always knows where to find SH derivatives.
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41case "$0" in
42*/*) cd `expr X$0 : 'X\(.*\)/'` ;;
43esac
bc730b18 44
37723ebb 45if test -f config_h.SH -a ! -f config.h; then
6ef8aa7c 46 . ./config_h.SH
11e2f395 47 CONFIG_H=already-done
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48fi
49
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50warn=''
51
52# Add -Wall for the core modules iff gcc and not already -Wall
53case "$gccversion" in
54'') ;;
55Intel*) ;; # The Intel C++ plays gcc on TV but is not really it.
56*) case "$ccflags" in
57 *-Wall*) ;;
58 *) warn="$warn -Wall" ;;
59 esac
60 ;;
61esac
62
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63# Create a test source file for testing what options can be fed to
64# gcc in this system; include a selection of most common and commonly
65# hairy include files.
66
67cat >_cflags.c <<__EOT__
68#include "EXTERN.h"
69#include "perl.h"
70/* The stdio.h, errno.h, and setjmp.h should be there in any ANSI C89. */
71#include <stdio.h>
72#include <errno.h>
73#include <setjmp.h>
74/* Just in case the inclusion of perl.h did not
75 * pull in enough system headers, let's try again. */
76#ifdef I_STDLIB
77#include <stdlib.h>
78#endif
79#ifdef I_STDDEF
80#include <stddef.h>
81#endif
82#ifdef I_STDARG
83#include <stdarg.h>
84#endif
85#ifdef I_LIMITS
86#include <limits.h>
87#endif
88#ifdef I_DIRENT
89#include <dirent.h>
90#endif
91#ifdef I_UNISTD
92#include <unistd.h>
93#endif
463bdbaf 94#ifdef I_SYS_TYPES
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95#include <sys/types.h>
96#endif
463bdbaf 97#ifdef I_SYS_PARAM
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98#include <sys/param.h>
99#endif
463bdbaf 100#ifdef I_SYS_RESOURCE
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101#include <sys/resource.h>
102#endif
463bdbaf 103#ifdef I_SYS_SELECT
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104#include <sys/select.h>
105#endif
106#if defined(HAS_SOCKET) && !defined(VMS) && !defined(WIN32) /* See perl.h. */
107#include <sys/socket.h>
108#endif
463bdbaf 109#ifdef I_SYS_STAT
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110#include <sys/stat.h>
111#endif
463bdbaf 112#ifdef I_SYS_TIME
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113#include <sys/time.h>
114#endif
463bdbaf 115#ifdef I_SYS_TIMES
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116#include <sys/times.h>
117#endif
463bdbaf 118#ifdef I_SYS_WAIT
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119#include <sys/wait.h>
120#endif
121/* The gcc -ansi can cause a lot of noise in Solaris because of:
122 /usr/include/sys/resource.h:148: warning: 'struct rlimit64' declared inside parameter list
123 */
124int main(int argc, char *argv[]) {
125
126/* Add here test code found to be problematic in some gcc platform. */
127
128/* Off_t/off_t is a struct in Solaris with largefiles, and with gcc -ansi
129 * that struct cannot be compared in some gcc releases with a flat
130 * integer, such as a STRLEN. */
131
215ed6ce 132 IV iv;
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133 Off_t t0a = 2;
134 STRLEN t0b = 3;
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135 int t0c = (STRLEN)t0a == t0b;
136
137 printf("%s: %d\n", argv[0], argc);
a07cd53d 138
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139/* In FreeBSD 6.2 (and probably other releases too), with -Duse64bitint,
140 perl will use atoll(3). However, that declaration is hidden in <stdlib.h>
141 if we force the compiler to use -std=c89 mode.
142*/
143 iv = Atol("42");
144
145 return (!t0c && (iv == 42)) ? 0 : -1; /* Try to avoid 'unused' warnings. */
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146}
147__EOT__
148
149stdflags=''
bc730b18 150
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151# Further gcc warning options. Build up a list of options that work.
152# Note that some problems may only show up with combinations of options,
153# e.g. a warning might show up only with -Wall -ansi, not with either
154# one individually.
813665af 155# TODO: Ponder whether to migrate this back to Configure so hints files can
215ed6ce 156# tweak it. Also, be paranoid about whether results we've deduced in Configure
813665af 157# (especially about things like long long, which are not in C89) will still be
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158# valid if we now add flags like -std=c89.
159
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160pedantic=''
161case "$gccansipedantic" in
162define) pedantic='-pedantic' ;;
163esac
164
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165case "$gccversion" in
166'') ;;
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167[12]*) ;; # gcc versions 1 (gasp!) and 2 are not good for this.
168Intel*) ;; # # Is that you, Intel C++?
f049db42 169#
fd9d4a0b 170# NOTE 1: the -std=c89 without -pedantic is a bit pointless.
abf4b099 171# Just -std=c89 means "if there is room for interpretation,
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172# interpret the C89 way." It does NOT mean "strict C89" on its own.
173# You need to add the -pedantic for that. To do this with Configure,
174# do -Dgccansipedantic (note that the -ansi is included in any case,
175# the option is a bit oddly named, for historical reasons.)
176#
177# NOTE 2: -pedantic necessitates adding a couple of flags:
178# * -PERL_GCC_PEDANTIC so that the perl code can adapt: there's nothing
179# added by gcc itself to indicate pedanticness.
180# * -Wno-overlength-strings under -DDEBUGGING because quite many of
181# the LEAVE_with_name() and assert() calls generate string literals
182# longer then the ANSI minimum of 509 bytes.
183#
184# NOTE 3: the relative order of these options matters:
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185# -Wextra before -W
186# -std=c89 before -ansi
187# -pedantic* before -Werror=d-a-s
abf4b099 188#
bf78513f 189*) for opt in -std=c89 -ansi $pedantic \
d2d49204 190 -Werror=declaration-after-statement \
f049db42 191 -Wextra -W \
fae2e960 192 -Wc++-compat -Wwrite-strings
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193 do
194 case " $ccflags " in
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195 *" $opt "*) ;; # Skip if already there.
196 *) rm -f _cflags$_exe
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197 flags="-DPERL_NO_INLINE_FUNCTIONS $ccflags $warn $stdflags $opt"
198 case "$opt" in
199 *-pedantic*) flags="$flags -DPERL_GCC_PEDANTIC" ;;
200 esac
201 # echo "opt = $opt, flags = $flags"
202 cmd="$cc $flags _cflags.c -o _cflags$_exe"
203 out="`$cmd 2>&1`"
204 # echo "$cmd --> $out"
205 case "$out" in
bc730b18 206 *"unrecognized"*) ;;
d39195d4 207 *"unknown"*) ;;
215ed6ce 208 *"implicit declaration"*) ;; # Was something useful hidden?
bc730b18 209 *"Invalid"*) ;;
9ac4c107 210 *"is valid for C"*) ;;
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211 *) if test -x _cflags$_exe
212 then
213 case "$opt" in
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214 -std*)
215 echo "cflags.SH: Adding $opt."
216 stdflags="$stdflags $opt"
217 ;;
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218 -ansi)
219 # -std=c89 is the modern form of -ansi, so add
220 # -ansi only if -std=c89 is not there already.
221 case " $stdflags " in
222 *-std=c89*) ;;
223 *)
224 echo "cflags.SH: Adding $opt."
225 stdflags="$stdflags $opt"
226 ;;
227 esac
228 ;;
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229 -W)
230 # -Wextra is the modern form of -W, so add
231 # -W only if -Wextra is not there already.
232 case " $warn " in
233 *-Wextra*) ;;
234 *)
235 echo "cflags.SH: Adding $opt."
236 warn="$warn $opt"
237 ;;
238 esac
239 ;;
240 -Werror=declaration-after-statement)
241 # -pedantic* (with -std=c89) covers -Werror=d-a-s.
242 case "$stdflags$warn" in
243 *-std=c89*-pedantic*|*-pedantic*-std=c89*) ;;
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244 *)
245 echo "cflags.SH: Adding $opt."
246 warn="$warn $opt"
247 ;;
905ccdc7 248 esac
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249 ;;
250 *)
251 echo "cflags.SH: Adding $opt."
252 warn="$warn $opt"
253 ;;
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254 esac
255 fi
256 ;;
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257 esac
258 ;;
259 esac
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260 case "$ccflags$warn" in
261 *-pedantic*)
262 overlength=''
263 case "$ccflags$optimize" in
264 *-DDEBUGGING*) overlength='-Wno-overlength-strings' ;;
265 esac
266 for opt2 in -DPERL_GCC_PEDANTIC $overlength
267 do
268 case "$ccflags$warn" in
269 *"$opt2"*) ;;
270 *) echo "cflags.SH: Adding $opt2 because of -pedantic."
271 warn="$warn $opt2" ;;
272 esac
273 done
274 ;;
275 esac
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276 done
277 ;;
278esac
a07cd53d 279rm -f _cflags.c _cflags$_exe
bc730b18 280
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281case "$gccversion" in
282'') ;;
283*)
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284 case "$warn$ccflags" in
285 *-pedantic*)
3e8416a3 286 # If we have -Duse64bitint (or equivalent) in effect and the quadtype
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287 # has become 'long long', gcc -pedantic* becomes unbearable
288 # (moreso when combined with -Wall) because long long and LL and %lld|%Ld
3e8416a3 289 # become warn-worthy. So let's drop the -pedantic in that case.
f049db42 290 #
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291 # Similarly, since 'long long' isn't part of C89, FreeBSD 6.2 headers
292 # don't declare atoll() under -std=c89, but we need it. In general,
293 # insisting on -std=c89 is inconsistent with insisting on using
813665af 294 # 'long long'. So drop -std=c89 and -ansi as well if we're using
215ed6ce 295 # 'long long' as our main integral type.
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296 #
297 # usedtrace (DTrace) uses unportable features (dollars in identifiers,
298 # and gcc statement expressions), it is just easier to turn off pedantic.
299 remove=''
300 case "$quadtype:$ivtype:$sPRId64:$usedtrace" in
301 *"long long"*|*lld*|*Ld*) remove='long long' ;;
302 *) case "$usedtrace" in
303 define) remove='usedtrace' ;;
304 esac
305 ;;
306 esac
307 case "$remove" in
308 '') ;;
309 *) echo "cflags.SH: Removing -pedantic*, -std=c89, and -ansi because of $remove."
310 ccflags=`echo $ccflags|sed -e 's/-pedantic-errors/ /' -e 's/-pedantic/ /' -e 's/-std=c89/ /' -e 's/-ansi/ /' -e 's/-DPERL_GCC_PEDANTIC/ /'`
311 warn=`echo $warn|sed -e 's/-pedantic-errors/ /' -e 's/-pedantic/ /' -e 's/-ansi/ /' -e 's/-DPERL_GCC_PEDANTIC/ /'`
312 stdflags=`echo $stdflags|sed -e 's/-std=c89/ /'`
313 ;;
215ed6ce 314 esac
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315 ;;
316 esac
317 ;;
318esac
319
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320# Older clang releases are not wise enough for -Wunused-value.
321case "$gccversion" in
322*"Apple LLVM "[34]*|*"Apple LLVM version "[34]*)
323 for f in -Wno-unused-value
324 do
325 echo "cflags.SH: Adding $f because clang version '$gccversion'"
326 warn="$warn $f"
327 done
328 ;;
329esac
330
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331# The quadmath Q format specifier will cause -Wformat to whine.
332case "$gccversion" in
333'') ;;
334*) case "$usequadmath" in
335 define)
336 for f in -Wno-format
337 do
338 echo "cflags.SH: Adding $f because of usequadmath."
339 warn="$warn $f"
340 done
341 ;;
342 esac
343 ;;
344esac
345
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346case "$cc" in
347*g++*)
348 # Extra paranoia in case people have bad canned ccflags:
349 # bad in the sense that the flags are accepted by g++,
350 # but then whined about.
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351 #
352 # -Werror=d-a-s option is valid for g++, by definition,
353 # but we remove it just for cleanliness and shorter command lines.
354 for f in -Wdeclaration-after-statement \
355 -Werror=declaration-after-statement \
49c60343 356 -Wc++-compat \
d2d49204 357 -std=c89
5bd6d383 358 do
95f0c784 359 case "$ccflags$warn" in
5bd6d383 360 *"$f"*)
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361 echo "cflags.SH: Removing $f because of g++."
362 ccflags=`echo $ccflags|sed 's/$f/ /'`
363 warn=`echo $warn|sed 's/$f/ /'`
364 ;;
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365 esac
366 done
367 ;;
368esac
369
d2d49204 370for f in -Wdeclaration-after-statement -Werror=declaration-after-statement
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371do
372 case "$cppflags" in
373 *"$f"*)
374 echo "cflags.SH: Removing $f from cppflags."
375 cppflags=`echo $cppflags|sed 's/$f/ /'` ;;
376 esac
377done
378
2eb17d1d 379# If usethreads and clang, add -Wthread-safety for clang 3.6 or later.
9ce5f19e 380# gccversion is defined also for clang, because compat, use that for matching.
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381# Apple overwrites clang version with XCode version, see hints/darwin.sh
382# for the gory details. Aggressively forward-proofing.
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383case "$usethreads" in
384define)
385case "$gccversion" in
2eb17d1d 386*" Clang 3."[56789]*|*" Clang "[456]*|*"Apple LLVM 6.1"*|*"Apple LLVM "[789]*)
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387 for f in -Wthread-safety
388 do
389 case " $warn " in
390 *" $f "*) ;; # Skip if already there.
391 *)
392 echo "cflags.SH: Adding $f because usethreads and clang and gccversion '$gccversion'"
393 warn="$warn $f"
394 ;;
395 esac
396 done
397;;
398esac
399;;
400esac
401
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402echo "cflags.SH: cc = $cc"
403echo "cflags.SH: ccflags = $ccflags"
404echo "cflags.SH: stdflags = $stdflags"
405echo "cflags.SH: optimize = $optimize"
406echo "cflags.SH: warn = $warn"
407
10edeb5d 408# Code to set any extra flags here.
a07cd53d 409extra=''
11fcce85 410
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411# Protect double or single quotes for better restoring of ccflags.
412myccflags=`echo $ccflags | sed -e 's/"/\\\"/g' -e "s/'/\\\'/g"`
413
2b317908 414echo "Extracting cflags (with variable substitutions)"
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415# This section of the file will have variable substitutions done on it.
416# Move anything that needs config subs from !NO!SUBS! section to !GROK!THIS!.
417# Protect any dollar signs and backticks that you do not want interpreted
418# by putting a backslash in front. You may delete these comments.
165b7424 419rm -f cflags
2b317908 420$spitshell >cflags <<!GROK!THIS!
ecfc5424 421$startsh
bc730b18 422
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423# !!!!!!! DO NOT EDIT THIS FILE !!!!!!!
424
425# This file is generated by cflags.SH
426
5bd6d383 427# Used to restore possible edits by cflags.SH.
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428myccflags="$myccflags"
429
11fcce85 430# Extra warnings, used e.g. for gcc.
bc730b18 431warn="$warn"
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432# Extra standardness.
433stdflags="$stdflags"
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434# Extra extra.
435extra="$extra"
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436# what do executables look like?
437_exe="$_exe"
bc730b18 438
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439!GROK!THIS!
440
44213caa 441# In the following dollars and backticks do not need the extra backslash.
2b317908 442$spitshell >>cflags <<'!NO!SUBS!'
a02608de 443case $PERL_CONFIG_SH in
2b317908 444'')
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445 if test -f config.sh; then TOP=.;
446 elif test -f ../config.sh; then TOP=..;
447 elif test -f ../../config.sh; then TOP=../..;
448 elif test -f ../../../config.sh; then TOP=../../..;
449 elif test -f ../../../../config.sh; then TOP=../../../..;
450 else
451 echo "Can't find config.sh."; exit 1
452 fi
453 . $TOP/config.sh
57d2761b 454 ccflags="$myccflags" # Restore possible edits by cflags.SH.
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455 ;;
456esac
457
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458# syntax: cflags [optimize=XXX] [file[.suffix]] ...
459# displays the proposed compiler command line for each 'file'
460#
461# with no file, dispalys it for all *.c files.
462# The optimise=XXX arg (if present) is evalled, setting the default
463# value of the $optimise variable, which is output on the command line
464# (but which may be overridden for specific files below)
75550b4e 465
1167a30e 466case "X$1" in
26102cc7 467Xoptimize=*|X"optimize=*")
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468 eval "$1"
469 shift
470 ;;
471esac
472
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473case $# in
4740) set *.c; echo "The current C flags are:" ;;
1c3d792e 475esac
2b317908 476
578789a7 477set `echo "$* " | sed -e 's/\.[oc] / /g' -e 's/\.obj / /g' -e "s/\\$obj_ext / /g"`
2b317908 478
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479for file do
480
481 case "$#" in
482 1) ;;
2b317908 483 *) echo $n " $file.c $c" ;;
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484 esac
485
44213caa 486 # allow variables like toke_cflags to be evaluated
2b317908 487
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488 case "$file" in
489 */*) ;;
490 *) eval 'eval ${'"${file}_cflags"'-""}' ;;
491 esac
2b317908 492
44213caa 493 # or customize here
2b317908 494
1c3d792e 495 case "$file" in
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496 regcomp) : work around http://bugs.debian.org/754054
497 case $archname in
498 mips-*|mipsel-*)
499 optimize="$optimize -fno-tree-vrp";;
500 esac;;
1c3d792e 501 *) ;;
5729ffdd 502
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503 # Customization examples follow.
504 #
505 # The examples are intentionally unreachable as the '*)' case above always
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506 # matches. To use them, move before the '*)' and edit as appropriate.
507 # It is not a good idea to set ccflags to an absolute value here, as it
508 # often contains general -D defines which are needed for correct
509 # compilation. It is better to edit ccflags as shown, using interpolation
510 # to add flags, or sed to remove flags.
5729ffdd 511
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512 av) ccflags=`echo $ccflags | sed -e s/-pipe//` ;;
513 deb) ccflags="$ccflags -fno-jump-tables" ;;
514 hv) warn=`echo $warn | sed -e s/-Wextra//` ;;
515 toke) optimize=-O0 ;;
7e827271 516 esac
666ea192 517
44213caa 518 # Can we perhaps use $ansi2knr here
b1e55cab 519 echo "$cc -c -DPERL_CORE $ccflags $stdflags $optimize $warn $extra"
2b317908 520
a0d0e21e 521 . $TOP/config.sh
2b317908 522
a7d59441 523 # end per file behaviour
1c3d792e 524done
2b317908 525!NO!SUBS!
a0d0e21e 526chmod 755 cflags
2b317908 527$eunicefix cflags