Repository navigation
Chord.Parse reads "CmMaj7"/"CMaj7" as dominant/minor sevenths and "C°7" as half-diminished #281
Description
Activity
Triage
- Category: Bug
- Priority: Medium.
CmMaj7,CMaj7andC°7parse to chords with the wrong pitches and no error. The existing round-trip test forCmMaj7passes anyway because the wrong chord round-trips consistently. - Area / suggested owner:
Semantics.Music(Chord.DetermineSeventh) - Duplicates / in progress: Not a duplicate. It belongs to the same
Chord.Parsefamily as the open Chord.Parse turns "C69", "Cadd11" and "Cadd13" into dominant-seventh chords with an extra b7 instead of rejecting them #280 (C69/Cadd11/Cadd13) and the closed Chord.Parse misreads "dimmaj7" (diminished major seventh) as a fully-diminished seventh #269 (dimmaj7) and Chord.Parse cannot parse the "6/9" chord symbol (and any bare tension after a slash) #248 (6/9). No open PR.
Next step: Match
"Maj"inhasMaj7and accept'°'in the diminished-seventh branch. Add tests that assertSeventhTypeand pitch sets, not just round-trips. It's worth fixing together with #280, since the recurring cause is chord tests that only check round-trips.
Generated by Claude Code
What's wrong
Chord.DetermineSeventh(Semantics.Music/Chord.cs~line 313) only recognizes some spellings of two seventh types that are common in chord charts.1. The capital-M
Majspelling is not recognized as a major seventh.hasMaj7checks for"maj","M7"or'Δ', using ordinal comparison."Maj7"matches none of them, so the chord falls through toSeventhType.Dominant.Chord.Parse("CmMaj7")Cm7, tones 0,3,7,10Cmmaj7, tones 0,3,7,11Chord.Parse("CMaj7")C7, tones 0,4,7,10Cmaj7, tones 0,4,7,11CmMaj7is already in theChordRoundTripTestscorpus (Semantics.Test/Music/ChordRoundTripTests.cs:13). That test still passes because the wrong chord round-trips consistently: Cm7 → "Cm7" → Cm7. It is the same trap the recentdimmaj7fix ran into.2.
°7is recognized for the triad but not for the seventh.DetermineQualityaccepts"dim"or'°'for a diminished triad. The diminished-seventh branch inDetermineSeventh, however, only checksbody.Contains("dim").Chord.Parse("C°7")Cm7b5(half-diminished), tones 0,3,6,10Cdim7, tones 0,3,6,9Key.ChordFromRomanNumeralrewrites°todimbefore it parses, which is whyvii°7works. A directChord.Parse("C°7")does not.Why it matters
Both failures produce a chord with the wrong pitches, with no exception or other signal. A lead sheet that uses
CmMaj7,CMaj7orC°7silently plays the wrong notes.Suggested fix / acceptance criteria
hasMaj7, also match"Maj", e.g.body.Contains("Maj", StringComparison.Ordinal).(body.Contains("dim", StringComparison.Ordinal) || body.Contains('°')) && hasSeven.SeventhTypeand pitch set, not only the round-trip, forCmMaj7,CMaj7andC°7.Confirmed by running the tests against
main(8c06aba) on net10.0.