Re: A flaw in dep generation with gcc -MMD?

On Fri, Nov 18, 2011 at 6:34 PM, Nguyen Thai Ngoc Duy [off-list ref] wrote:

OK it's not gcc problem. I upgraded to 4.5.3 and still had the same
problem. I used ccache though. Without ccache, gcc produced correct
.o.d files.

"gcc -MF depfile -MMD -MP -c -o path/to/file.o" will produce "depfile"
with target given by "-o". When ccache runs, it executes "gcc -MF
depfile -MMD -MP -E" instead to get the final content for hashing.
Notice that "-c -o" combination is replaced by "-E". The latter
produces target without leading path.

Not sure if I should report this to ccache or gcc. In the meantime,
may be we should recognize the situation and switch off
COMPUTE_HEADER_DEPENDENCIES when ccache is used (maybe hard).
-- 
Duy