Some scripts I used in my header-cleanups branch

Usage:
   ./search-headers.sh | tee RESULTS
   ./search-warnings-headers.sh
   ./search-files.sh | tee RESULTS
   ./search-warnings-files.sh

and then, uh, figure it out.  :-)

search-files.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+warn() {
+    echo "$@" >&2
+    git checkout -q HEAD $2
+}
+
+FLAGS="-DUSE_THE_INDEX_COMPATIBILITY_MACROS -DHAVE_FSMONITOR_DAEMON_BACKEND -Wmissing-prototypes"
+for f in `git grep -l 'include.*"cache.h"' -- '*.c'`; do
+	sed -i 's/#include "cache.h"/#include "git-compat-util.h"/' $f
+
+	if gcc $FLAGS -E -I. $f 2>/dev/null | grep -e '"cache.h"' -e '/cache.h"' >/dev/null; then
+	    warn FAILURE-PREPROCESS $f
+	    continue
+	fi
+
+	OBJ_FILE=$(echo $f | sed -e s/\\.c$/\\.o/)
+	if ! make DEVELOPER=1 $OBJ_FILE >/dev/null 2>&1; then
+
+	    if gcc -c $FLAGS -I. $f >/dev/null 2>&1; then
+		echo SUCCESS-WITH-WARNINGS $f
+		git checkout -q HEAD $f
+		continue
+	    fi
+
+	    warn FAILURE-COMPILE $f
+	    continue
+	fi
+
+	echo SUCCESS $f
+done

search-headers.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+
+warn() {
+    echo "$@" >&2
+    git checkout -q HEAD $2
+}
+
+FLAGS="-DUSE_THE_INDEX_COMPATIBILITY_MACROS -DHAVE_FSMONITOR_DAEMON_BACKEND -Wmissing-prototypes"
+for f in `git grep -l 'include.*"cache.h"' -- '*.h'`; do
+	sed -i '/#include "cache.h"/d' $f
+
+	if gcc $FLAGS -E -I. $f | grep '"cache.h"' >/dev/null; then
+	    warn FAILURE-PREPROCESS $f
+	    continue
+	fi
+
+	cat >temp.c <<-EOF &&
+	#include "git-compat-util.h"
+	#include "$f"
+	int main() {}
+	EOF
+
+	if ! gcc -c $FLAGS -I. temp.c >output 2>&1; then
+	    warn FAILURE-COMPILE $f
+	    rm output
+	    continue
+	fi
+
+	if [[ -s output ]]; then
+	    echo SUCCESS-WITH-WARNINGS $f
+	    git checkout -q HEAD $f
+	    rm output
+	    continue
+	fi
+
+	rm output
+	echo SUCCESS $f
+done

search-warnings-files.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+FLAGS="-DUSE_THE_INDEX_COMPATIBILITY_MACROS -DHAVE_FSMONITOR_DAEMON_BACKEND -Wmissing-prototypes"
+for f in $(grep WARNINGS RESULTS | awk {print\$2}); do
+    echo "======================================================================"
+    echo "=== $f ==="
+    echo "======================================================================"
+    sed -i 's/#include "cache.h"/#include "git-compat-util.h"/' $f
+    OBJ_FILE=$(echo $f | sed -e s/\\.c$/\\.o/)
+    make DEVELOPER=1 $OBJ_FILE
+    git checkout -q HEAD $f
+done

search-warnings-headers.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+FLAGS="-DUSE_THE_INDEX_COMPATIBILITY_MACROS -DHAVE_FSMONITOR_DAEMON_BACKEND -Wmissing-prototypes"
+for f in $(grep WARNINGS RESULTS | awk {print\$2}); do
+    echo "======================================================================"
+    echo "=== $f ==="
+    echo "======================================================================"
+    sed -i '/#include "cache.h"/d' $f
+	cat >temp.c <<-EOF &&
+	#include "git-compat-util.h"
+	#include "$f"
+	int main() {}
+	EOF
+
+    gcc -c $FLAGS -I. temp.c
+    git checkout -q HEAD $f
+done