dpkg-buildpackage: Set a set of compiler flags for a build

* scripts/dpkg-buildpackage.pl: Set a set of environment variables
for setting compiler and linker options, unless already set in the
environment. See https://wiki.ubuntu.com/DistCompilerFlags for
background information.
* man/dpkg-buildpackage.pl: Document the new behaviour.

Based on a patch by Matthias Klose <doko@cs.tu-berlin.de>

ChangeLog

@@ -1,3 +1,11 @@
+2008-02-17  Frank Lichtenheld  <djpig@debian.org>
+	    Matthias Klose  <doko@cs.tu-berlin.de>
+
+	* scripts/dpkg-buildpackage.pl: Set a set of environment variables
+	for setting compiler and linker options, unless already set in the
+	environment. See https://wiki.ubuntu.com/DistCompilerFlags for
+	background information.
+
 2008-02-13  Raphael Hertzog  <hertzog@debian.org>
 
 	* scripts/Dpkg/Version.pm: Import Dpkg::Gettext since we use _g().

debian/changelog

@@ -41,6 +41,10 @@ dpkg (1.14.17) UNRELEASED; urgency=low
     satisfied during -S. Closes: #445552
   * Add a missing space in the German scripts translation. Closes: #463398
   * Add improved deb-shlibs.5 manual page by Zack Weinberg. Closes: #466135
+  * dpkg-buildpackage exports some build related environment variables
+    now. Based on a patch by Matthias Klose. Closes: #465282
+    (See dpkg-buildpackage(1) and https://wiki.ubuntu.com/DistCompilerFlags
+     for details)
 
   [ Updated dpkg translations ]
   * Korean (Changwoo Ryu).

man/ChangeLog

@@ -3,6 +3,12 @@
 	* po/dpkg-man.pot: Regenerated.
 	* po/*.po: Merged with dpkg-man.pot.
 
+2008-02-17  Frank Lichtenheld  <djpig@debian.org>
+	    Matthias Klose  <doko@cs.tu-berlin.de>
+
+	* man/dpkg-buildpackage.1: Document the new
+	behaviour for build related environment variables.
+
 2008-02-17  Zack Weinberg  <zackw@panix.com>
 
 	* deb-shlibs.5: Make this manual page a bit

man/dpkg-buildpackage.1

@@ -204,6 +204,77 @@ Show the usage message and exit.
 .BR \-\-version
 Show the version and exit.
 .
+.SH ENVIRONMENT
+A set of environment variables for setting compiler and linker options are
+set to default values unless already set in the environment. Note that
+this mechanism was only introduced in dpkg-dev, version 1.14.17 and
+not all \fIrules\fP files and build tools will honour these variables,
+yet.
+.TP
+.B CFLAGS
+Optimization options which are passed to the debian build system and
+can/should be overriden by the package build if needed (default value:
+.BR \-g\ \-O2
+, or
+.BR \-g\ \-O0
+if
+.BR noopt
+is specified in DEB_BUILD_OPTIONS). Overriding options can be
+used to explicitely set a
+higher optimization level, or work around compiler bugs, which only
+can be seen with some optimization levels (the last opt level "wins").
+.TP
+.B CFLAGS_APPEND
+Optimization options appended to the compiler flags, which must not be
+overwritten by the package (mostly used to for test builds). Default
+value: empty.
+.TP
+.B CXXFLAGS
+Same as
+.B CFLAGS
+for C++ sources.
+.TP
+.B CXXFLAGS_APPEND
+Same as
+.B CFLAGS_APPEND
+for C++ sources.
+.TP
+.B FFLAGS
+Same as
+.B FFLAGS
+for Fortran sources.
+.TP
+.B FFLAGS_APPEND
+Same as
+.B CFLAGS_APPEND
+for Fortran sources.
+.TP
+.B CPPFLAGS
+Preprocessor flags which are passed to the debian build system and
+can/should be overriden by the package build if needed (default:
+empty). This macro is seldom used (most build systems just use
+.B CFLAGS
+instead of
+.B CPPFLAGS).
+.TP
+.B CPPFLAGS_APPEND
+Preprocessor flags appended to the preprocessor flags, which must not
+be overwritten by the package (mostly used to for test
+builds). Default value: empty.
+.TP
+.B LDFLAGS
+Options passed to the compiler when linking executables or shared
+objects (if the linker is called directly, then
+.B -Wl
+and
+.B ,
+have to be stripped from these options. Default value: empty.
+.TP
+.B LDFLAGS_APPEND
+Optimization options appended to the compiler flags when linking code,
+which must not be overwritten by the package (mostly used to for test
+builds). Default value: empty.
+.
 .SH BUGS
 It should be possible to specify spaces and shell metacharacters in
 and initial arguments for

scripts/dpkg-buildpackage.pl

@@ -242,9 +242,8 @@ if ($signcommand) {
     }
 }
 
+my $build_opts = Dpkg::BuildOptions::parse();
 if ($parallel) {
-    my $build_opts = Dpkg::BuildOptions::parse();
-
     $parallel = $build_opts->{parallel} if (defined $build_opts->{parallel});
     $ENV{MAKEFLAGS} ||= '';
     if ($parallel eq '-1') {
@@ -256,6 +255,28 @@ if ($parallel) {
     Dpkg::BuildOptions::set($build_opts);
 }
 
+my $default_flags = defined $build_opts->{noopt} ? "-g -O0" : "-g -O2";
+my %flags = ( CPPFLAGS => '',
+	      CFLAGS   => $default_flags,
+	      CXXFLAGS => $default_flags,
+	      FFLAGS   => $default_flags,
+	      LDFLAGS  => "-Wl,-Bsymbolic-functions",
+    );
+
+foreach my $flag (keys %flags) {
+    if ($ENV{$flag}) {
+	printf(_g("%s: use %s from environment: %s\n"), $progname,
+		  $flag, $ENV{$flag});
+    } else {
+	$ENV{$flag} = $flags{$flag};
+	printf(_g("%s: set %s to default value: %s\n"), $progname,
+		  $flag, $ENV{$flag});
+    }
+    if ($ENV{"${flag}_APPEND"}) {
+	$ENV{$flag} .= " ".$ENV{"${flag}_APPEND"};
+    }
+}
+
 my $cwd = cwd();
 my $dir = basename($cwd);