Your results are interesting; of the 18 real compiles you're seeing 17 direct hits and 1 preprocessed hit. I turned on CCACHE_LOGFILE, which I missed the first time through the docs. The 'unsupported compiler option' is due to -E (by autoconf I think). So those numbers increase, but that's not the bug. On my mac, with ccache 3.1.4, it looks for a different hash every time, with or without CCACHE_SLOPPINESS set to everything. With ccache 2.4 (which was in pkgsrc until 2011-03-02), I get the expected caching behavior (18 hits per build). Turning on CCACHE_SLOPPINESS makes the next run not hit, but then future runs hit, presmably based on the alternately-hashed objects with the __TIME__ not expanded. With a pre-loaded cache, and after ccache -z, I get (ccache 2.4): cache directory /Users/gdt/.ccache cache hit 18 cache miss 0 called for link 1 autoconf compile/link 11 no input file 3 files in cache 150 cache size 764 Kbytes max cache size 1024.0 Mbytes which seems to match your results reasonably. What OS version, cpu arch, etc. are you running? I wonder if something in the bl3 wrappers are being picked up by newer ccache as different, like the symlink times.
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