In a flow collection a '-' that begins a plain scalar must be followed by
a non-indicator character. Immediately before a flow indicator ('[-]',
'[-, -]', '{a: -}') the dash is not a valid scalar, but the scanner
accepted it as the scalar '-'.
scanToken now rejects a '-' in flow context when the next character is a
flow indicator, before falling through to plain-scalar scanning. A dash
followed by ordinary content stays valid: negative numbers, a dash inside
a scalar, a dash starting a word, and a quoted dash are unaffected.
Measured against the official YAML test-suite, parse-level conformance
rises from 273/333 (82.0%) to 275/333 (82.6%) with no regression.
Mihaela M
30dbd9316b