A line that begins with a document marker ('---' or '...') followed by a
boundary is forbidden inside a multi-line scalar, since it is ambiguous
with a document boundary. A multi-line quoted scalar folded such a line
into its value instead of rejecting it.
scanQuotedScalar now checks, on crossing each line break, whether the next
line begins a document marker, and rejects the scalar if so. The check
requires the marker at the line start with a following boundary, so inline
dashes ('a --- b'), '---' with no boundary ('---b'), an indented '---',
and dots not at a line start stay ordinary content.
Measured against the official YAML test-suite, parse-level conformance
rises from 268/333 (80.5%) to 270/333 (81.1%) with no regression.
Mihaela M
c1dda8bbab