Re: broken doc build (orchestra.ly)

[David Kastrup]

Knut Petersen <address@hidden> writes:

> Am 20.05.2016 um 14:20 schrieb David Kastrup:
>> Knut Petersen <address@hidden> writes:
>>
>>> Hi everybody!
>>>
>>> Building the current git lilypond binary succeeds, but building the
>>> documentation is broken even if I try a single core build.
>>>
> [...]
>>> So there really is a lot of "Huh?" involved here.  Can you reproduce
>>> this by running LilyPond _only_ on the given file?
>>>
>
> As nobody had a quick idea I bisected the problem. make doc / orchestra.ly is 
> first broken by
>
> Commit c1d7bc2217462a63bf5c5c6d6f6df5cb00099180
> Author: David Kastrup <address@hidden>
> Date:   Tue May 3 19:11:15 2016 +0200
>
>     Issue 4842/6: Don't special-case Scheme_engraver's acknowledgers
>
>
> /build/Documentation/ly-examples/orchestra.preview.log
> ===============================================
> Changing working directory to: `./out-www'
> Processing `/home/knut/sources/lily/Documentation/ly-examples/orchestra.ly'
> Parsing...
> Interpreting music...ERROR: Wrong type (expecting exact integer): (x y)

Oh wow.  The expression with the wrong type is something completely
different here.  That makes it likely that we are dealing with an
expression that has been garbage-collected prematurely and is
overwritten with something else randomly before use.

But "expecting exact integer": exact integers of the size LilyPond is
usually dealing with are _immediate_ values that are not prone to
garbage-collection at all.  So maybe it's a callback?

I'll take a look at the commit (and it's vicinity) to see whether there
is an obvious oversight with garbage-protecting some structure.  Other
than that, I'm afraid that I'll want the extended traceback from

lilypond -ddebug

in order to figure out the Scheme stack: the error message, as far as I
can tell, is not from LilyPond but rather from within the Guile
interpreter, so there might be some call context giving us more of a
clue.

-- 
David Kastrup