Re: Small warning, automake 1.10 incompatible change in DEFAULT_INCLUDES

[Ralf Wildenhues]

Hello Kent,

Thank you for the report.

* Kent Boortz wrote on Fri, Nov 09, 2007 at 04:27:38PM CET:
> 
> In case you have several headers with the same name in your source
> tree you might get problems from that in automake 1.10 the default
> header search order will differ a bit if doing a build inside the
> source tree, or from a separate directory. I.e. if you do a builds
> where $(srcdir) is the same as $(builddir)
[...]
> The problem is the automatically generated variable DEFAULT_INCLUDES,
> that is filled in by automake with the path to the directory where it
> will put the generated "config.h", and the paths to the "current
> source directory". Earlier it was set like
> 
>   DEFAULT_INCLUDES = -I. -I$(srcdir) -I$(top_builddir)/include
> 
> ensuring that your "current source directory", independent on if one
> or the other of the build methods above, would come first. Now in
> automake 1.10 it is like
> 
>   DEFAULT_INCLUDES = -I. -I$(top_builddir)/include -I$(srcdir)
> 
> that in the case that you build outside the source directory, will
> search for include files first in the current build directory, then
> another location, and last the current source directory.
> 
> I'm sure the risk of having problems caused by this is small, why name
> headers the same to begin with?!

But you just seemed to have hit it, with:

> Ref: http://bugs.mysql.com/bug.php?id=24809

This was introduced by 
<http://git.savannah.gnu.org/gitweb/?p=automake.git;a=commitdiff;h=8ae25d96fddea93d469d9b86c78519245dc911d8;hp=f83d84f889456cdce7e9741d5e87d8f305b631d1>

IIRC, back then, Alexandre introduced this upon request by Paul to
shorten compile command lines: omit `-I$(srcdir)' if srcdir is `.'.  The
changed ordering happened as a side effect, unintended, I presume.

The question is which order makes more sense.  Since `$(srcdir)' may be
`.', thus we cannot guarantee that the location of the config header
appears before the source tree (-I. must always come first), I'm
inclined to treat this as a regression and restore the previous order.

I'll apply this patch to master and branch-1-10, and putting you, Kent,
in THANKS.  Testsuite is still running.

Cheers, and thanks,
Ralf

    Fix default includes ordering to be `-I. -I$(srcdir) ...' again.
    
    * automake.in (handle_compile): Put -I$(srcdir) before include
    paths for config headers, as was done before Automake 1.10, but
    keep uniquified list without multiple adjacent spaces.
    * doc/automake.texi (Program variables): List include paths
    in order.
    * NEWS: Mention 1.10 regression.
    * tests/stdinc.test: New test.
    * tests/Makefile.am: Adjust.
    * THANKS: Update.
    Report by Kent Boortz.

diff --git a/NEWS b/NEWS
index 79a3dea..d4f81b1 100644
--- a/NEWS
+++ b/NEWS
@@ -64,6 +64,9 @@ Bugs fixed in 1.10a:
   - $(EXEEXT) is automatically appended to filenames of XFAIL_TESTS
     that have been declared as programs in the same Makefile.
     This is for consistency with the analogous change to TESTS in 1.10.
+
+  - Fix order of standard includes to again be `-I. -I$(srcdir)',
+    followed by directories containing config headers.
 
 New in 1.10:
 
diff --git a/automake.in b/automake.in
index 127a607..ee1391f 100755
--- a/automake.in
+++ b/automake.in
@@ -2312,7 +2312,7 @@ sub handle_compile ()
     my $default_includes = '';
     if (! option 'nostdinc')
       {
-       my @incs = ('-I.');
+       my @incs = ('-I.', subst ('am__isrc'));
 
        my $var = var 'CONFIG_HEADER';
        if ($var)
@@ -2326,8 +2326,9 @@ sub handle_compile ()
        # and unaesthetic in non-VPATH builds.  We use address@hidden@`
        # instead.  It will be replaced by '-I.' or '-I. -I$(srcdir)'.
        # Items in CONFIG_HEADER are never in $(srcdir) so it is safe
-       # to just append @address@hidden
-       $default_includes = ' ' . uniq (@incs) . subst ('am__isrc');
+       # to just put @am__isrc@ right after `-I.', without a space.
+       ($default_includes = ' ' . uniq (@incs)) =~ s/ @/@/;
+       print "D: $default_includes";
       }
 
     my (@mostly_rms, @dist_rms);
diff --git a/doc/automake.texi b/doc/automake.texi
index 2a39ec1..3b70557 100644
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -5748,8 +5748,8 @@ instance, @option{-I} and @option{-D} options should be 
listed here.
 
 Automake already provides some @option{-I} options automatically, in a
 separate variable that is also passed to every compilation that invokes
-the C preprocessor.  In particular it generates @samp{-I$(srcdir)},
address@hidden, and a @option{-I} pointing to the directory holding
+the C preprocessor.  In particular it generates @samp{-I.},
address@hidden(srcdir)}, and a @option{-I} pointing to the directory holding
 @file{config.h} (if you've used @code{AC_CONFIG_HEADERS} or
 @code{AM_CONFIG_HEADER}).  You can disable the default @option{-I}
 options using the @option{nostdinc} option.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 79a89d0..81a0382 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -501,6 +501,7 @@ spell2.test \
 spell3.test \
 spelling.test \
 spy.test \
+stdinc.test \
 stamph2.test \
 stdlib.test \
 stdlib2.test \
diff --git a/tests/Makefile.in b/tests/Makefile.in
index e0e30ca..999ed24 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -649,6 +649,7 @@ spell2.test \
 spell3.test \
 spelling.test \
 spy.test \
+stdinc.test \
 stamph2.test \
 stdlib.test \
 stdlib2.test \
diff --git a/tests/stdinc.test b/tests/stdinc.test
new file mode 100755
index 0000000..04301be
--- /dev/null
+++ b/tests/stdinc.test
@@ -0,0 +1,67 @@
+#! /bin/sh
+# Copyright (C) 2007  Free Software Foundation, Inc.
+#
+# This file is part of GNU Automake.
+#
+# GNU Automake is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3, or (at your option)
+# any later version.
+#
+# GNU Automake is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Automake; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+
+# Test to make sure the standard include order is stable.
+# Report by Kent Boortz.
+
+. ./defs || exit 1
+
+set -e
+
+cat >> configure.in << 'END'
+AC_PROG_CC
+AC_CONFIG_HEADERS([sub/config.h])
+AC_CONFIG_FILES([sub/bar.h])
+AC_OUTPUT
+END
+
+cat > Makefile.am << 'END'
+bin_PROGRAMS = foo
+foo_SOURCES = foo.c
+BUILT_SOURCES = bar.h
+END
+
+mkdir sub
+
+cat >foo.c <<'END'
+#include <config.h>
+#include <bar.h>
+int main() { return bar (); }
+END
+cat >bar.h <<'END'
+int bar () { return 0; }
+END
+cat >sub/bar.h.in <<'END'
+choke me
+END
+
+$ACLOCAL
+$AUTOCONF
+$AUTOHEADER
+$AUTOMAKE
+
+mkdir build
+cd build
+../configure -C
+$MAKE
+
+cd ..
+./configure -C
+$MAKE