with some simple code, seems that ccache ends up searching -I paths *before* $PWD when looking for files included as "file.h".  seems the datestamps cause misbehavior in some way ?

simple test code below.  to reproduce, i checked out latest ccache code (5cdd7980895683613026967ac190c4a5bea196f3), then made a subdir in there called "foo" and added the code below to a shell script called "doit.sh".  upon running `./doit.sh`, it caught the misbehavior -- the 2nd compile picked up y.h from the subdir "dir/" instead of the one in $PWD, so "STR" was defined to "B" instead of "C".

if i remove the "touch" from the script, then things work as expected ...

tested ccache-2.4 works, but ccache-3.0 and ccache-3.1.7 fail.  a git bisect shows commit 702db98740f0a76998a03f6d7c043e7d5f94c8ae as the first bad one.

#!/bin/bash
rm -rf .ccache
export CCACHE_DIR=$PWD/.ccache

PATH=/usr/bin:$PATH
c=$PWD/../ccache

rm -rf t && mkdir t && cd t

cat <<\EOF > y.c
#include "y.h"
main(){puts(STR);}
EOF

mkdir dir
echo '#define STR "B"' > dir/y.h
touch -d '2008-12-03 15:37' dir/y.h

$c gcc -Idir -c y.c -o y.o
$c gcc y.o -o y
[[ $(./y) == "B" ]]

echo '#define STR "C"' > y.h
$c gcc -Idir -c y.c -o y.o
$c gcc y.o -o y
if [[ $(./y) != "C" ]] ; then
    echo "FAIL"
    exit 1
else
    echo "PASS"
    exit 0
fi