Re: compiler rebuild invalidates precompiled header

[Paul Brook <paul at codesourcery dot com>]

On Friday 14 May 2004 17:03, Jan Beulich wrote:
> Trying to run the libstdc++ testsuite after a couple of rebuilds to the
> compiler all I got was internal compiler errors for each and every
> compiled file. Investigating this, I had to learn that the precompiled
> header stores not just configuration values, but also pointers created
> during the previous build (e.g. into the compiler image itself). This
> would be fine, if the precompiled header would be considered invalid by
> a compiler build different from the one that created it. That, however,
> is not done, and what I'm trying to find out is whether this is
> intentional (in which case I'd consider precompiled headers useless for
> anyone trying to work on the compiler itself), and if so if there is any
> suggested workaround for this (other than manually deleting the
> precompiled headers each time the compiler gets rebuilt).
> Obviously, I'd consider this a bug with the suggested solution of
> adding a timestamp (or even better a random value of good quality) to
> the compiler that it then stores into the precompiled header and
> verifies when it loads it).

IMHO It would also be useful if the libstdc++ build system automatically 
rebuilt its PCH when g++ changed.
I'm not offering to produce patches to do this though, so I'm not going to 
complain too much.

Paul