Re: Diagnostic advice for "Internal compiler error in ?" ?

On Sat, 13 Jun 2026, Ross Patterson via Gcc-help wrote:

> I've got a thorny problem, and I could use some advice about how to
> diagnose it.  I've got an ancient version of GCC (3.2.3), built for a
> platform GCC hasn't supported in years (IBM System/370), and using a
> back-end that was removed from GCC 20 years ago (i370).  Upgrading isn't an
> option - this is the newest there is.  Switching to another compiler isn't
> either - this is all there is.
>
> The error message is literally:
>
> rxvmvars.h: In function `extract_double_decimal':
> rxvmvars.h:1547: Internal compiler error in ?, at <stdin>:902
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <URL:http://gcc.gnu.org/bugs.html> for instructions.

Since it is compiling stdin, I guess that this is a second (or later)
pass on output from a previous pass.
I would want to discover which passes and what stdin contains
at this  point. In particular I would want to know whether the 
intermediate result is garbage and thus whether the bug is
in the first or second pass.

> I'm not asking anyone to chase this bug, but other that just randomly
> cutting code out of my program over and over until it goes away, are there
> hints I can follow for this?  I'm a very experienced OS-level programmer,
> so I've got the background to dig into this.  But "Internal compiler error
> in ?" isn't much of a pointer to follow :-)
>
> Thanks,
> Ross Patterson

-- 
Andrew C. Aitchison                      Kendal, UK
                    [email protected]