From 194c2379b4bd93f687a0f49cf7551af8724ac699 Mon Sep 17 00:00:00 2001
From: Leandro Lucarella <llucarella@integratech.com.ar>
Date: Thu, 17 Sep 2009 14:09:29 -0300
Subject: [PATCH] Rearrange detection of changes in build flags

Move the code to detect flags changes to trigger a rebuild together,
allowing more accurate messages and adding new variables to the list of
variables to monitor for changes to trigger a rebuild.
---
 Lib.mak | 57 ++++++++++++++++++++++++++++++---------------------------
 1 file changed, 30 insertions(+), 27 deletions(-)

diff --git a/Lib.mak b/Lib.mak
index 106c208..db9b6a8 100644
--- a/Lib.mak
+++ b/Lib.mak
@@ -166,19 +166,6 @@ override LDFLAGS += -pg --coverage
 endif
 
 
-# Automatic rebuilding when flags or commands changes
-######################################################
-
-# Re-compile C files if one of this variables changes
-COMPILE.c.FLAGS := $(CC) ~ $(CPPFLAGS) ~ $(CFLAGS) ~ $(TARGET_ARCH)
-
-# Re-compile C++ files if one of this variables changes
-COMPILE.cpp.FLAGS := $(CXX) ~ $(CPPFLAGS) ~ $(CXXFLAGS) ~ $(TARGET_ARCH)
-
-# Re-link binaries and libraries if one of this variables changes
-LINK.o.FLAGS := $(LD) ~ $(LDFLAGS) ~ $(TARGET_ARCH)
-
-
 # Automatic dependency handling
 ################################
 
@@ -221,19 +208,10 @@ all: $$(all)
 # Create build directory structure
 ###################################
 
-# Create a file with flags used to trigger rebuilding when they change. The
-# first argument is the name of the file where to store the flags, the second
-# are the flags and the third argument is a text to be displayed if the flags
-# have changed.  This should be used as a rule action or something where
-# a shell script is expected.
-gen_rebuild_flags = if test x"$2" != x"`cat $1 2>/dev/null`"; then \
-		test -f $1 && echo "$3"; \
-		echo "$2" > $1 ; fi
 
 # Create $O, $B, $L and $(INCLUDE_DIR) directories and replicate the directory
 # structure of the project into $O. Create one symlink "last" to the current
-# build directory.  It update the flags files to detect flag and/or compiler
-# changes to force a rebuild.
+# build directory.
 #
 # NOTE: the second mkdir can yield no arguments if the project don't have any
 #       subdirectories, that's why the current directory "." is included, so it
@@ -242,17 +220,42 @@ setup_build_dir__ := $(shell \
 	mkdir -p $O $B $L $(INCLUDE_DIR); \
 	mkdir -p . $(addprefix $O,$(patsubst $T%,%,\
 			$(shell find $T -type d -not -path '$D*'))); \
+	test -L $D/last || ln -s $F $D/last )
+
+
+# Automatic rebuilding when flags or commands changes
+######################################################
+
+# Re-compile C files if one of this variables changes
+COMPILE.c.FLAGS += $(CC) ~ $(CPPFLAGS) ~ $(CFLAGS) ~ $(TARGET_ARCH)
+
+# Re-compile C++ files if one of this variables changes
+COMPILE.cpp.FLAGS += $(CXX) ~ $(CPPFLAGS) ~ $(CXXFLAGS) ~ $(TARGET_ARCH)
+
+# Re-link binaries and libraries if one of this variables changes
+LINK.o.FLAGS += $(LD) ~ $(LDFLAGS) ~ $(TARGET_ARCH)
+
+# Create a file with flags used to trigger rebuilding when they change. The
+# first argument is the name of the file where to store the flags, the second
+# are the flags and the third argument is a text to be displayed if the flags
+# have changed.  This should be used as a rule action or something where
+# a shell script is expected.
+gen_rebuild_flags = if test x"$2" != x"`cat $1 2>/dev/null`"; then \
+		test -f $1 && echo "$3"; \
+		echo "$2" > $1 ; fi
+
+# Create files containing the current flags to trigger a rebuild if they change
+setup_flag_files__ := $(shell \
 	$(call gen_rebuild_flags,$G/compile-c-flags, \
 			$(COMPILE.c.FLAGS),C compiler or flags;); \
 	$(call gen_rebuild_flags,$G/compile-cpp-flags, \
 			$(COMPILE.cpp.FLAGS),C++ compiler or flags;); \
 	$(call gen_rebuild_flags,$G/link-o-flags, \
-			$(LINK.o.FLAGS),linker or link flags;); \
-	test -L $D/last || ln -s $F $D/last )
+			$(LINK.o.FLAGS),linker or link flags;) )
 
 # Print any generated message (if verbose)
-$(if $V,$(if $(setup_build_dir__), \
-	$(info !! Something changed: $(setup_build_dir__) \
+$(if $V,$(if $(setup_flag_files__), \
+	$(info !! Something changed: $(setup_flag_files__) \
 			re-building affected files...)))
 
 endif
-- 
2.43.0