Re: Nonsensical byte compiler warning.

[Markus Triska <markus.triska@gmx.at>]

Alan Mackenzie <acm@muc.de> writes:

> Would it be easy to make this change to the byte compiler?

Alas, no. The optimiser hasn't got the positioning information, and
the byte-code emitter potentially doesn't see such calls at all:
Conceptually, the optimiser is capable of totally removing unneeded
function calls (the code is there, and disabled). Conversely, the
positioning code is fragile enough already to warrant keeping it well
separated from the optimiser, and limited to the emitter. Now, since
unnecessary function calls are currently kept, detection logic from
the optimiser could be used in the emitter, but that would duplicate a
lot of code, is error-prone, and can, in my view, not yield more
useful results than byte-compiling with byte-optimize-log set to t. On
top of that, it would result in the same char-before/after confusion,
since that rewriting is performed by the optimiser, not the emitter.