makepkg: add option to include debugging compiler flags

Add a "debug" option that appends the compiler flags specified in the
variables DEBUG_CFLAGS and DEBUG_CXXFLAGS in makepkg.conf to their
counterpart buildflags.

Signed-off-by: Allan McRae <allan@archlinux.org>

doc/PKGBUILD.5.txt

@@ -274,6 +274,9 @@ A normal sync or upgrade will not use its value.
 		`!makeflags` with select packages that have problems building with
 		custom makeflags such as `-j2` (or higher).
 
+	*debug*;;
+		Add the user-specified debug flags (DEBUG_CFLAGS, DEBUG_CXXFLAGS) to
+		their counterpart buildflags as specified in linkman:makepkg.conf[5].
 
 build() Function
 ----------------

doc/makepkg.conf.5.txt

@@ -77,6 +77,14 @@ Options
 	This is often used to set the number of jobs used, for example, `-j2`.
 	Other flags that make accepts can also be passed.
 
+**DEBUG_CFLAGS=**"debug_cflags"::
+	Additional compiler flags appended to CFLAGS for use in debugging. Usually
+	this would include: ``-g''. Read gcc(1) for more details on the wide
+	variety of compiler flags available.
+
+**DEBUG_CXXFLAGS=**"debug_cxxflags"::
+	Debug flags used for the C++ compiler; see DEBUG_CFLAGS for more info.
+
 **BUILDENV=(**fakeroot !distcc color !ccache check !sign**)**::
 	This array contains options that affect the build environment, the defaults
 	are shown here. All options should always be left in the array; to enable
@@ -167,6 +175,10 @@ Options
 		Compress binary executable files using UPX.  Additional options
 		can be passed to UPX by specifying the `UPXFLAGS` variable.
 
+	*debug*;;
+		Add the user-specified debug flags as specified in DEBUG_CFLAGS and
+		DEBUG_CXXFLAGS to their counterpart buildflags.
+
 **INTEGRITY_CHECK=(**check1 ...**)**::
 	File integrity checks to use. Multiple checks may be specified; this
 	affects both generation and checking. The current valid options are:

etc/makepkg.conf.in

@@ -33,6 +33,9 @@ CHOST="@CHOST@"
 #LDFLAGS=""
 #-- Make Flags: change this for DistCC/SMP systems
 #MAKEFLAGS="-j2"
+#-- Debugging flags
+#DEBUG_CFLAGS="-g"
+#DEBUG_CXXFLAGS="-g"
 
 #########################################################################
 # BUILD ENVIRONMENT
@@ -62,7 +65,7 @@ BUILDENV=(fakeroot !distcc color !ccache check !sign)
 #   These are default values for the options=() settings
 #########################################################################
 #
-# Default: OPTIONS=(strip docs libtool emptydirs zipman purge !upx)
+# Default: OPTIONS=(strip docs libtool emptydirs zipman purge !upx !debug)
 #  A negated option will do the opposite of the comments below.
 #
 #-- strip:     Strip symbols from binaries/libraries
@@ -72,8 +75,9 @@ BUILDENV=(fakeroot !distcc color !ccache check !sign)
 #-- zipman:    Compress manual (man and info) pages in MAN_DIRS with gzip
 #-- purge:     Remove files specified by PURGE_TARGETS
 #-- upx:       Compress binary executable files using UPX
+#-- debug:     Add debugging flags as specified in DEBUG_* variables
 #
-OPTIONS=(strip docs libtool emptydirs zipman purge !upx)
+OPTIONS=(strip docs libtool emptydirs zipman purge !upx !debug)
 
 #-- File integrity checks to use. Valid: md5, sha1, sha256, sha384, sha512
 INTEGRITY_CHECK=(md5)

scripts/makepkg.sh.in

@@ -44,7 +44,8 @@ declare -r confdir='@sysconfdir@'
 declare -r BUILDSCRIPT='@BUILDSCRIPT@'
 declare -r startdir="$PWD"
 
-packaging_options=('strip' 'docs' 'libtool' 'emptydirs' 'zipman' 'purge' 'upx')
+packaging_options=('strip' 'docs' 'libtool' 'emptydirs' 'zipman' 'purge' 'upx' \
+                   'debug')
 other_options=('ccache' 'distcc' 'buildflags' 'makeflags')
 splitpkg_overrides=('pkgver' 'pkgrel' 'epoch' 'pkgdesc' 'arch' 'url' 'license' \
                     'groups' 'depends' 'optdepends' 'provides' 'conflicts' \
@@ -1340,6 +1341,11 @@ run_function() {
 		unset CPPFLAGS CFLAGS CXXFLAGS LDFLAGS
 	fi
 
+	if check_option "debug" "y"; then
+		CFLAGS+=" $DEBUG_CFLAGS"
+		CXXFLAGS+=" $DEBUG_CXXFLAGS"
+	fi
+
 	# clear user-specified makeflags if requested
 	if check_option "makeflags" "n"; then
 		unset MAKEFLAGS