[ccache] compile fails with ccache enabled

[Vivek Nadkarni]

Hi - 

I was hoping I could get some help in debugging what I think is a ccache
problem from this list. 

I regularly perform builds of the same codebase in several directories
using ccache and distcc. The source code is in CVS and gets updated by
several developers regularly. 

Today, I updated a build directory (directoryA) after several weeks, in
which lots of files including header files were updated, and the
definitions of a structure was changed in one header file. The build now
fails to compile, with an error message saying "error: structure has no
member named `element`", where "element" would be the name of the
element added to the structure. This implies that the C file which
accesses "element" is being compiled as if it has been updated, but the
header file which adds "element" to the structure is not being
re-compiled or re-read.  I turned off distcc, and the build still fails
to compile. 

Also, I *can* compile the same code in another directory (directoryB),
which I have been updating regularly from CVS. Both directoryA and
directoryB contain identical code. They are on the same machine, and
actually both builds are using my (common) .ccache directory as well. 

I saw the same thing happen last week. I was able to get the code to
build at that time by deleting the .ccache directory. I have left the
.ccache directory untouched at this time to aid in debugging. 

Any ideas on how to debug this problem, to see whether this strange
behavior is caused by ccache? Perhaps there are some diagnostics I can
turn on that might help? I am using ccache version 2.3 on linux. 

Thanks,
Vivek