[notmuch] [PATCH] Makefile: Magic silent rules.

[Chris Wilson]

Use the facilities of GNU make to create a magic function that will
on the first invocation print a description of how to enable verbose
compile lines and then print the quiet rule.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Carl Worth <cworth at cworth.org>
Cc: Mikhail Gusarov <dottedmag at dottedmag.net>

[ickle: Rebased, and duplicate command string eliminated.]
[ickle: Fixed verbose bug pointed out by Mikhail]
---
 Makefile           |   23 ++++++++++++++++++++---
 Makefile.local     |    4 ++--
 lib/Makefile.local |    2 +-
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/Makefile b/Makefile
index 3fedcf1..5d8f321 100644
--- a/Makefile
+++ b/Makefile
@@ -2,6 +2,10 @@
 WARN_FLAGS=-Wall -Wextra -Wmissing-declarations -Wwrite-strings -Wswitch-enum
 CFLAGS=-O2
 
+# Additional programs that are used during the compilation process.
+EMACS ?= emacs
+GZIP ?= gzip
+
 # Additional flags that we will append to whatever the user set.
 # These aren't intended for the user to manipulate.
 extra_cflags := $(shell pkg-config --cflags glib-2.0 gmime-2.4 talloc)
@@ -31,14 +35,27 @@ include lib/Makefile.local
 # And get user settings from the output of configure
 include Makefile.config
 
+# The user has not set any verbosity, default to quiet mode and inform the
+# user how to enable verbose compiles.
+ifeq ($(V),)
+quiet_DOC := "Use \"$(MAKE) V=1\" to see the verbose compile lines.\n"
+quiet = @echo $(quiet_DOC)$(eval quiet_DOC:=)"  $1	$@"; $($1)
+endif
+# The user has explicitly enabled quiet compilation.
+ifeq ($(V),0)
+quiet = @echo "  $1	$@"; $($1)
+endif
+# Otherwise, print the full command line.
+quiet ?= $($1)
+
 %.o: %.cc $(all_deps)
-	$(CXX) -c $(CXXFLAGS) $< -o $@
+	$(call quiet,CXX) -c $(CXXFLAGS) $< -o $@
 
 %.o: %.c $(all_deps)
-	$(CC) -c $(CFLAGS) $< -o $@
+	$(call quiet,CC) -c $(CFLAGS) $< -o $@
 
 %.elc: %.el
-	emacs -batch -f batch-byte-compile $<
+	$(call quiet,EMACS) -batch -f batch-byte-compile $<
 
 .deps/%.d: %.c $(all_deps)
 	@set -e; rm -f $@; mkdir -p $$(dirname $@) ; \
diff --git a/Makefile.local b/Makefile.local
index 3c99624..5fd5d4f 100644
--- a/Makefile.local
+++ b/Makefile.local
@@ -20,10 +20,10 @@ notmuch_client_srcs =		\
 
 notmuch_client_modules = $(notmuch_client_srcs:.c=.o)
 notmuch: $(notmuch_client_modules) lib/notmuch.a
-	$(CXX) $^ $(LDFLAGS) -o $@
+	$(call quiet,CXX) $^ $(LDFLAGS) -o $@
 
 notmuch.1.gz: notmuch.1
-	gzip --stdout notmuch.1 > notmuch.1.gz
+	$(call quiet,GZIP) --stdout $^ > $@
 
 install: all notmuch.1.gz
 	for d in $(DESTDIR)$(prefix)/bin/ $(DESTDIR)$(prefix)/share/man/man1 \
diff --git a/lib/Makefile.local b/lib/Makefile.local
index 79f7b0b..a7562c9 100644
--- a/lib/Makefile.local
+++ b/lib/Makefile.local
@@ -18,7 +18,7 @@ libnotmuch_cxx_srcs =		\
 
 libnotmuch_modules = $(libnotmuch_c_srcs:.c=.o) $(libnotmuch_cxx_srcs:.cc=.o)
 $(dir)/notmuch.a: $(libnotmuch_modules)
-	$(AR) rcs $@ $^
+	$(call quiet,AR) rcs $@ $^
 
 SRCS  := $(SRCS) $(libnotmuch_c_srcs) $(libnotmuch_cxx_srcs)
 CLEAN := $(CLEAN) $(libnotmuch_modules) $(dir)/notmuch.a
-- 
1.6.5.3