[PATCH 2/7] Fix the way FOOFLAGS is handled

[Jeremie Koenig]

* config.make.in: _set_ the initial value for $({C,CPP,LD}FLAGS).
* Makeconf: alter $(FOOFLAGS) _after_ config.make has been included.
* */Makefile: make sure $(FOOFLAGS) is modified after Makeconf has
  been included.

The current situation with {C,CPP,LD}FLAGS is this:
- foo/Makefile may in principle set an initial value corresponding to
  the extra flags it needs;
- Makeconf adds some stuff on top of this;
- config.make, included by Makeconf, appends the configured value.

The first problem with this is that the most specific options will end
up at the beginning, where they run the risk of being overridden by the
more generic ones. In practice, most Makefiles actually alter the value
after they include Makeconf, maybe to avoid this.

Furthermore, this approach is incompatible with the user overriding
FOOFLAGS when running make. If we're lucky, they will do so on the
command-line, and as a result the user-specified options will be merely
prepended to the one we set.

But a more problematic scenario can occur: the first "FOOFLAGS +=" will
reference an undefined variable, so make will try to pull its value from
the environment. If it succeeds, the variable will be marked as exported
and its altered value will be passed downstream, resulting in a new copy
of the whole thing being added when a sub-make is invoked.

This patch makes sure that this doesn't happen and that the user can
safely override the flags on the make command line.

NB: the flag duplication which still happens when building the Debian
package is the combined result of dpkg-buildpackage and cdbs and is not
related to any of this.

Signed-off-by: Jeremie Koenig <jk@jk.fr.eu.org>
---
 Makeconf                |   13 ++++++-------
 config.make.in          |   14 ++++++++------
 configure.in            |    1 +
 console-client/Makefile |    4 ++--
 defpager/Makefile       |    2 ++
 libftpconn/Makefile     |    4 ++--
 mach-defpager/Makefile  |    3 ++-
 7 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/Makeconf b/Makeconf
index 8c2bd0c..fd47ee0 100644
--- a/Makeconf
+++ b/Makeconf
@@ -55,18 +55,11 @@ top_srcdir = ..
 endif
 endif
 
-# Generic compiler options, appended to whatever the particular makefile set.
-# The config.make file will append the values chosed by configure.
 INCLUDES = -I. $(srcdirinc)
 ifneq (.,$(dir))
 INCLUDES += -I.. $(top_srcdirinc)
 endif
 INCLUDES += -I$(..)include -I$(top_srcdir)/include
-CPPFLAGS += $(INCLUDES) \
-            -D_GNU_SOURCE -D_IO_MTSAFE_IO -D_FILE_OFFSET_BITS=64 \
-           $($*-CPPFLAGS)
-CFLAGS += -std=gnu99 $(gnu89-inline-CFLAGS) -Wall -g -O3 \
-           $($*-CFLAGS)
 
 # Include the configure-generated file of parameters.
 # This sets up variables for build tools and installation directories.
@@ -76,6 +69,12 @@ include $(..)config.make
 configured = yes
 endif
 
+# Complement the configured values.
+CFLAGS := -std=gnu99 $(gnu89-inline-CFLAGS) $(CFLAGS) $($*-CFLAGS)
+CPPFLAGS += $(INCLUDES) \
+            -D_GNU_SOURCE -D_IO_MTSAFE_IO -D_FILE_OFFSET_BITS=64 \
+           $($*-CPPFLAGS)
+
 # If we're not configured, don't do deps; then `make TAGS' and such can work.
 ifndef configured
 no_deps = t
diff --git a/config.make.in b/config.make.in
index 986ea2a..7876d47 100644
--- a/config.make.in
+++ b/config.make.in
@@ -45,14 +45,16 @@ MIG = @MIG@
 MIGCOM = $(MIG) -cc cat - /dev/null
 AWK = @AWK@
 
-# Compilation flags.  Append these to the definitions already made by
-# the specific Makefile.
-CPPFLAGS += @CPPFLAGS@ @DEFS@
-CFLAGS += @CFLAGS@
-LDFLAGS += @LDFLAGS@
-
+# Compilation flags.
+CFLAGS = @CFLAGS@
+CPPFLAGS = @CPPFLAGS@
+LDFLAGS = @LDFLAGS@
 gnu89-inline-CFLAGS = @libc_cv_gnu89_inline@
 
+# Append the preprocessor definitions in a second pass; this way they will be
+# included even if the user overrides CPPFLAGS on the make command line.
+CPPFLAGS += @DEFS@
+
 # `yes' or `no' to indicate if ld --version-script is available.
 VERSIONING = @VERSIONING@
 
diff --git a/configure.in b/configure.in
index 1cf4daa..a0994cb 100644
--- a/configure.in
+++ b/configure.in
@@ -83,6 +83,7 @@ INSTALL="$SHELL $(readlink -f "$ac_install_sh")"\ -C || unset 
INSTALL]
 AC_PROG_INSTALL
 AC_PROG_AWK
 
+: ${CFLAGS="-Wall -g -O3"}
 AC_PROG_CC
 # Require GCC.
 if test x$GCC != xyes; then
diff --git a/console-client/Makefile b/console-client/Makefile
index 22a492a..64f056f 100644
--- a/console-client/Makefile
+++ b/console-client/Makefile
@@ -43,11 +43,11 @@ LDLIBS = -ldl
 module-dir = $(libdir)/hurd/console
 console-LDFLAGS = -Wl,-E
 
+include ../Makeconf
+
 # In seeking, thou shalt find it!
 CPPFLAGS += -DQUAERENDO_INVENIETIS
 
-include ../Makeconf
-
 driver-CPPFLAGS = -D'CONSOLE_DEFPATH="$(module-dir)\0"' \
        -D'CONSOLE_SONAME_SUFFIX=".so.$(hurd-version)"'
 
diff --git a/defpager/Makefile b/defpager/Makefile
index 8f92dd7..9d54905 100644
--- a/defpager/Makefile
+++ b/defpager/Makefile
@@ -18,6 +18,8 @@
 #   along with this program; if not, write to the Free Software
 #   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
+# XXX this is broken
+
 dir := defpager
 makemode := misc
 
diff --git a/libftpconn/Makefile b/libftpconn/Makefile
index 05f3ddf..4f5123e 100644
--- a/libftpconn/Makefile
+++ b/libftpconn/Makefile
@@ -29,6 +29,6 @@ LCLHDRS = ftpconn.h priv.h
 
 OBJS = $(SRCS:.c=.o)
 
-CPPFLAGS += -DHAVE_HURD_HURD_TYPES_H -DHAVE_STAT_ST_AUTHOR
-
 include ../Makeconf
+
+CPPFLAGS += -DHAVE_HURD_HURD_TYPES_H -DHAVE_STAT_ST_AUTHOR
diff --git a/mach-defpager/Makefile b/mach-defpager/Makefile
index 5ed8f11..e903954 100644
--- a/mach-defpager/Makefile
+++ b/mach-defpager/Makefile
@@ -29,10 +29,11 @@ OBJS        := $(SRCS:.c=.o) \
           default_pager_replyUser.o
 
 HURDLIBS:= threads
-LDFLAGS += -static
 
 include ../Makeconf
 
+LDFLAGS += -static
+
 vpath %.c $(srcdir)/../serverboot
 CPPFLAGS += -I$(srcdir)/../serverboot
 
-- 
1.7.1