Issue 1477 in lilypond: suppress output for expected warnings

[lilypond]

Status: Accepted
Owner: ----
Labels: Type-Enhancement Priority-Medium Maintainability Frog Warning

New issue 1477 by percival.music.ca: suppress output for expected warnings
http://code.google.com/p/lilypond/issues/detail?id=1477

I'm not certain that "expected warnings" really makes sense long-term  
(particularly for the regtests), but it would definitely be in the  
medium-term (2-5 years) if we could suppress warnings that where expected  
or intended.

David Kastrup suggested:
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I'd rather we just use
#(regtest:expect_warning (_ "Some particular warning"))

before the line being the eventual cause of some expected warning, and
ly:warning get hijacked, matching the expected warnings to the given
warnings, and complaining at the end of the run in case any expected
warnings did not turn up.
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Some users might want this feature for their own scores, but I'm not  
certain what kind of performance penalty it would incur.

Frog ETA: 5 hours.