PATCH 2/2] xfsprogs: enable sparse checking with "make C=2"

[Eric Sandeen <sandeen@redhat.com>]

Enable "make C=2" sparse checking of all files without rebuilding them.

This is a bit simpler than redefining CC for the whole build, which
requires extra commandline definitions and apparently is enough of a
barrier that nobody's doing sparse checking.

Note, this requires unreleased sparse after v0.5, which enables the
CHAR_BIT definition; otherwise it chokes.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
--- 

diff --git a/Makefile b/Makefile
index 05fe609..9204bed 100644
--- a/Makefile
+++ b/Makefile
@@ -21,14 +21,14 @@ CHECK_OPTS=-Wsparse-all -Wbitwise -Wno-transparent-union -Wno-return-void -Wno-u
 	-Wno-non-pointer-null -D__CHECK_ENDIAN__ -D__linux__
 
 ifeq ("$(origin C)", "command line")
-  ifeq ("$(C)", "1")
-    CHECK_CMD=$(CHECK) $(CHECK_OPTS)
-  else
-    CHECK_CMD=@true
-  endif
+  CHECK_CMD=$(CHECK) $(CHECK_OPTS)
+  CHECKSRC=$(C)
+else
+  CHECK_CMD=@true
+  CHECKSRC=0
 endif
 
-export CHECK_CMD
+export CHECK_CMD CHECKSRC
 
 MAKEOPTS = --no-print-directory Q=$(Q)
 
diff --git a/doc/sparse.txt b/doc/sparse.txt
index c6d1fe7..75b24e0 100644
--- a/doc/sparse.txt
+++ b/doc/sparse.txt
@@ -5,15 +5,12 @@ to check the source code of the open source XFS commands and utilites
 First you need to install sparse, either from your distribution or from
 source as provided at http://www.kernel.org/pub/software/devel/sparse/.
 
-The xfsprogs Makefile has a convenient shortcut to running sparse, by setting
-the C ("check") variable on the make commandline.  To perform these checks on
-files when they get rebuilt, use:
+Then, run make with "make C=1" to run sparse on all the C files that get
+recompiled, or use "make C=2" to run sparse on the files whether they need to
+be recompiled or not.  The latter is a fast way to check the whole tree if you
+have already built it.
 
-	make C=1
-
-(Note that xfsprogs does not yet support the kernel convention of checking
-all C files without compilation via "make C=2", so to run sparse on all
-C files, start with a "make clean")
+See the top-level Makefile for a list of which sparse flags are enabled.
 
 If you'd rather run sparse more manually, just set the compiler to cgcc,
 which is a wrapper that calls both sparse and gcc using:
diff --git a/include/buildrules b/include/buildrules
index 297e598..c207a16 100644
--- a/include/buildrules
+++ b/include/buildrules
@@ -40,6 +40,21 @@ endif
 # Standard targets
 #
 
+ifeq ($(CHECKSRC),2)
+
+# Check every .c file with sparse CHECK_CMD, do not call compiler
+$(LTCOMMAND) $(LTLIBRARY) : $(SUBDIRS) $(OBJECTS)
+.PHONY: $(LTCOMMAND) $(LTLIBRARY)
+
+%.lo %.o : %.c FORCE
+	@echo "    [CHECK]  $<"
+	$(Q)$(CHECK_CMD) $(CFLAGS) $<
+
+FORCE:
+
+else
+# Regular build, possibly calling sparse CHECK_CMD as well
+
 ifdef LTCOMMAND
 $(LTCOMMAND) : $(SUBDIRS) $(OBJECTS) $(LTDEPENDENCIES)
 	@echo "    [LD]     $@"
@@ -63,6 +78,7 @@ else
 	$(Q)$(CHECK_CMD) $(CFLAGS) $<
 
 endif
+endif
 
 ifdef POTHEAD
 $(POTHEAD): $(XGETTEXTFILES)