bug#67483: Wrong warning position given by the byte compiler for a malformed function

[Alan Mackenzie]

Hello, Mattias.

Ping?

On Fri, Dec 22, 2023 at 20:09:19 +0000, Alan Mackenzie wrote:
> Hello, Mattias.

> On Fri, Dec 22, 2023 at 14:12:46 +0100, Mattias Engdegård wrote:
> > 22 dec. 2023 kl. 12.24 skrev Alan Mackenzie <acm@muc.de>:

> > > What's the process of converting to a closure got to do with
> > > maintaining the stack of forms for error processing?

> > Not much, but cconv has evolved to one major part of the compiler
> > front-end (the other being macroexp-all) and isn't restricted to just
> > closure conversion.

> No, it hasn't "evolved", somebody has changed it.  Why?  A file, just
> like a function, should have a particular purpose, and degrading a
> specific purpose file to being a general place to put random things is a
> BAD THING.  What's going on, here?

> > In fact, it's now used for dynbound code as well.

> Does this file, in fact, still have a purpose?

> > In particular it's a natural place for various front-end checks and
> > transforms, so don't let the place and name distract you. There are
> > plans to refactor it later on for other reasons.

> > > Whoops!  There was no patch.

> > Attached it now, sorry.

> > > You've put the new macro into macroexp.el.  This file is purely about
> > > macro handling.

> > Actually macroexp.el does more than that, and in any case the file
> > isn't very important; the macro ended up there to be next to
> > byte-compile-form-stack. Nor is the name; it can be changed at any
> > time.

> > However, it probably needs to be in that file for bootstrap reasons.

> byte-compile-form-stack is in there for bootstrap reasons.  But it's
> logically part of bytecomp.el, hence the name.

> > > And is the "--" in the name appropriate, given that the macro is used
> > > by several files?  I'm not sure about that rule.

> > The double-dash just means that users shouldn't get any funny ideas.
> > (The converse isn't true: a name without double-dash isn't
> > automatically fair game.)

> > > Also, byte-compile-form-stack gets bound in cconv-closure-convert.
> > > Why?

> > It's just a backstop. Not strictly needed. It's probably fine to remove
> > it if you are worried, but then again there shouldn't be any (non-bug)
> > error signalling here. I'll have a look.

> How can you be so casual about this?  It's critically important to
> byte-compile-form-stack's correct working that it does NOT get bound.
> Surely you understand this?

> Also, you ignored and snipped the most important point in my last post,
> namely this:

> > > But cconv-closure-convert doesn't get called recursively.  So it
> > > would seem the wrong place to be maintaining byte-compile-form-stack.
> > > What's needed is a place where that stack grows steadily as the
> > > source code is recursed into, to ensure there will be a correct
> > > position on it in the event of an warning/error.

> Please attend to this point now.  Does byte-compile-form-stack get pushed
> onto at each recursive descent into the source code?  This is important.

-- 
Alan Mackenzie (Nuremberg, Germany).