Re: Need to get Lisp backtrace when error is in C code

[Robert Weiner]

On Tue, Oct 3, 2017 at 1:50 PM, Stefan Monnier <address@hidden> wrote:

> Personally, for errors like this, I would typically include the function
> name reference so that the location is obvious and users without debug
> symbols in their Emacs could still report a more useful error.
> Is this doable?  A good idea?

I think it's desirable, yes.  The problem is how to do it.

Even just showing the Lisp backtrace by itself with some note that

the error was raised in C code would narrow down the location tremendously

I think.

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I guess we could try to replace `Ferror` with a C macro that pushes some

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caller-info onto the Lisp backtrace before signaling the error (a bit

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like we currently push some pseudo-function onto that stack trace

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during garbage collection and redisplay).  It won't handle the cases

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where we call `Fsignal` instead, nor the cases where we call some

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generic C function which then calls Ferror, so to make it really work

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well, it'll require more manual work to place the caller-info at the

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"right" spot.

​A full solution would be a big win.

Bob