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Subject: Re: AC_CHECK_LIB issues under maintainer mode (Was: Re: Tagging
 2.4.29 / 2.5.0-{alpha/beta?} today)
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From: Rainer Jung <rainer.jung@kippdata.de>
Message-ID: <66ffac39-6c6b-eb40-c0ed-0a6eda3c6e21@kippdata.de>
Date: Mon, 16 Oct 2017 15:25:06 +0200
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archived-at: Mon, 16 Oct 2017 13:25:16 -0000

Am 16.10.2017 um 12:31 schrieb Joe Orton:
> On Fri, Oct 13, 2017 at 11:51:54AM -0400, Jim Jagielski wrote:
>> The long and short is that under maintainer mode, we cannot
>> expect AC_CHECK_LIB to being correct any longer, because
>> the combination of -Werror and -Wstrict-prototypes means
>> that any and all functions looked for/checked for using
>> AC_CHECK_LIB will NOT be found, due to warnings which are
>> now fatal errors during configure time, even if those
>> functions DO exist.
> 
> IMO the correct fix is to add all -W... flags to NOTEST_CFLAGS not
> CFLAGS so they don't take effect during the configure run at all.  At
> least I can't think of a good motivation for having compiler warnings
> enabled when running autoconf tests in general.

Good hint, never used that variable. So what about the following patch 
instead: just tried it on trunk and seemed to work fine there. Ut 
changes APACHE_ADD_GCC_CFLAG to operate on NOTEST_CFLAGS instead of 
CFLAGS (the macro currently is only used in places where we IMHO 
actually want that change) and introduces NOTEST_CFLAGS use to configure 
where we handle maintainer mode and debugger mode.

Index: acinclude.m4
===================================================================
--- acinclude.m4        (revision 1812263)
+++ acinclude.m4        (working copy)
@@ -960,7 +960,7 @@
  dnl
  dnl APACHE_ADD_GCC_CFLAGS
  dnl
-dnl Check if compiler is gcc and supports flag. If yes, add to CFLAGS.
+dnl Check if compiler is gcc and supports flag. If yes, add to 
NOTEST_CFLAGS.
  dnl
  AC_DEFUN([APACHE_ADD_GCC_CFLAG], [
    define([ap_gcc_ckvar], [ac_cv_gcc_]translit($1, [-:.=], [____]))
@@ -973,7 +973,7 @@
        CFLAGS="$save_CFLAGS"
      ])
      if test "$]ap_gcc_ckvar[" = "yes" ; then
-       APR_ADDTO(CFLAGS,[$1])
+       APR_ADDTO(NOTEST_CFLAGS,[$1])
      fi
    fi
    undefine([ap_gcc_ckvar])
Index: configure.in
===================================================================
--- configure.in        (revision 1812263)
+++ configure.in        (working copy)
@@ -627,14 +627,10 @@
 
AC_ARG_ENABLE(maintainer-mode,APACHE_HELP_STRING(--enable-maintainer-mode,Turn 
on debugging and compile time warnings and load all compiled modules),
  [
    if test "$enableval" = "yes"; then
-    APR_ADDTO(CPPFLAGS, -DAP_DEBUG)
+    APR_ADDTO(NOTEST_CPPFLAGS, -DAP_DEBUG)
      if test "$GCC" = "yes"; then
-      APR_ADDTO(CFLAGS,[-Wall -Wmissing-prototypes -Wstrict-prototypes 
-Wmissing-declarations -Wpointer-arith])
-      # Next flag needed, because -Wstrict-prototypes in combination with
-      # -Werror leads to compiler errors during configure checks (autoconf
-      # generates incomplete prototypes).
-      APACHE_ADD_GCC_CFLAG([-Wno-error=strict-prototypes])
-      APACHE_ADD_GCC_CFLAG([-std=c89])
+      APR_ADDTO(NOTEST_CFLAGS,[-Wall -Wmissing-prototypes 
-Wstrict-prototypes -Wmissing-declarations -Wpointer-arith])
+      #APACHE_ADD_GCC_CFLAG([-std=c89])
        APACHE_ADD_GCC_CFLAG([-Werror])
        APACHE_ADD_GCC_CFLAG([-Wdeclaration-after-statement])
        APACHE_ADD_GCC_CFLAG([-Wformat])
@@ -641,7 +637,7 @@
        APACHE_ADD_GCC_CFLAG([-Wformat-security])
        APACHE_ADD_GCC_CFLAG([-Wunused])
      elif test "$AIX_XLC" = "yes"; then
-      APR_ADDTO(CFLAGS,-qfullpath -qinitauto=FE -qcheck=all -qinfo=pro)
+      APR_ADDTO(NOTEST_CFLAGS,-qfullpath -qinitauto=FE -qcheck=all 
-qinfo=pro)
      fi
      if test "x$enable_load_all_modules" = "x"; then
        LOAD_ALL_MODULES=yes
@@ -657,9 +653,9 @@
 
AC_ARG_ENABLE(debugger-mode,APACHE_HELP_STRING(--enable-debugger-mode,Turn 
on debugging and compile time warnings and turn off optimization),
  [
    if test "$enableval" = "yes"; then
-    APR_ADDTO(CPPFLAGS, -DAP_DEBUG)
+    APR_ADDTO(NOTEST_CPPFLAGS, -DAP_DEBUG)
      if test "$GCC" = "yes"; then
-      APR_ADDTO(CFLAGS,[-Wall -Wmissing-prototypes -Wstrict-prototypes 
-Wmissing-declarations -Wpointer-arith -O0])
+      APR_ADDTO(NOTEST_CFLAGS,[-Wall -Wmissing-prototypes 
-Wstrict-prototypes -Wmissing-declarations -Wpointer-arith -O0])
        APACHE_ADD_GCC_CFLAG([-Wdeclaration-after-statement])
        APACHE_ADD_GCC_CFLAG([-Werror=declaration-after-statement])
        APACHE_ADD_GCC_CFLAG([-Wformat])
@@ -666,7 +662,7 @@
        APACHE_ADD_GCC_CFLAG([-Wformat-security])
        APACHE_ADD_GCC_CFLAG([-Werror=format-security])
      elif test "$AIX_XLC" = "yes"; then
-      APR_ADDTO(CFLAGS,-qfullpath -qinitauto=FE -qcheck=all -qinfo=pro)
+      APR_ADDTO(NOTEST_CFLAGS,-qfullpath -qinitauto=FE -qcheck=all 
-qinfo=pro)
      fi
    fi
  ])dnl


Regards,

Rainer