[PATCH 1/2] xfsprogs: enable sparse checking with make C=1

[Eric Sandeen <sandeen@redhat.com>]

Enable "make C=1" sparse checking when files get rebuilt.  To check
all files, run "make clean" first.

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 d031a60..05fe609 100644
--- a/Makefile
+++ b/Makefile
@@ -16,6 +16,20 @@ else
   Q = @
 endif
 
+CHECK=sparse
+CHECK_OPTS=-Wsparse-all -Wbitwise -Wno-transparent-union -Wno-return-void -Wno-undef \
+	-Wno-non-pointer-null -D__CHECK_ENDIAN__ -D__linux__
+
+ifeq ("$(origin C)", "command line")
+  ifeq ("$(C)", "1")
+    CHECK_CMD=$(CHECK) $(CHECK_OPTS)
+  else
+    CHECK_CMD=@true
+  endif
+endif
+
+export CHECK_CMD
+
 MAKEOPTS = --no-print-directory Q=$(Q)
 
 TOPDIR = .
diff --git a/doc/sparse.txt b/doc/sparse.txt
index 36a34a0..c6d1fe7 100644
--- a/doc/sparse.txt
+++ b/doc/sparse.txt
@@ -5,9 +5,18 @@ 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/.
 
-To simply build the xfsprogs source code while checking the source using
-sparse just set the compiler to cgcc, which is a wrapper that calls both
-sparse and gcc using:
+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:
+
+	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")
+
+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:
 
 	CC=cgcc ./configure
 
diff --git a/include/buildrules b/include/buildrules
index c57fdfc..297e598 100644
--- a/include/buildrules
+++ b/include/buildrules
@@ -54,10 +54,13 @@ $(LTLIBRARY) : $(SUBDIRS) $(LTOBJECTS)
 %.lo: %.c
 	@echo "    [CC]     $@"
 	$(Q)$(LTCOMPILE) -c $<
+	$(Q)$(CHECK_CMD) $(CFLAGS) $<
 else
+
 %.o: %.c
 	@echo "    [CC]     $@"
 	$(Q)$(CC) $(CFLAGS) -c $<
+	$(Q)$(CHECK_CMD) $(CFLAGS) $<
 
 endif