[RFC PATCH v2 1/2] Makefile: add check-headers target

[David Aguilar <davvid@gmail.com>]

This allows us to ensure that each header can be included
individually without needing to include other headers first.

Signed-off-by: David Aguilar <davvid@gmail.com>
---
Changes since v1:
We now include xdiff, ewah, and vcs-svn headers.

 Makefile         |  6 ++++++
 check-headers.sh | 29 +++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100755 check-headers.sh

diff --git a/Makefile b/Makefile
index 30cc622..39ecc70 100644
--- a/Makefile
+++ b/Makefile
@@ -2591,6 +2591,12 @@ check-docs::
 check-builtins::
 	./check-builtins.sh
 
+### Make sure headers include their dependencies
+#
+check-headers::
+	./check-headers.sh $(CC) $(ALL_CFLAGS) $(EXTRA_CPPFLAGS)
+
+
 ### Test suite coverage testing
 #
 .PHONY: coverage coverage-clean coverage-compile coverage-test coverage-report
diff --git a/check-headers.sh b/check-headers.sh
new file mode 100755
index 0000000..2722dd2
--- /dev/null
+++ b/check-headers.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+exit_code=0
+
+maybe_exit () {
+	status="$1"
+	if test "$status" != 0
+	then
+		exit_code="$status"
+		if test -n "$CHECK_HEADERS_STOP"
+		then
+			exit "$status"
+		fi
+	fi
+}
+
+IFS='
+'
+git ls-files *.h ewah/*.h vcs-svn/*.h xdiff/*.h |
+while read header
+do
+	subdir=$(dirname "$header") &&
+	echo "HEADER $header" &&
+	"$@" -Wno-unused -I"$subdir" -c -o "$header".check -x c - <"$header" &&
+	rm "$header".check ||
+	maybe_exit $?
+done
+
+exit $exit_code
-- 
2.1.0.62.g3e88d26