No error for C0-control characters

[RedCMD]

Describe the bug
no error is given for C0-control characters within a string
only printable characters are allowed
https://yaml.org/spec/1.2.2/#rule-c-printable

To ensure readability, YAML streams use only the printable subset of the Unicode character set. The allowed character range explicitly excludes the C0 control block15 x00-x1F (except for TAB x09, LF x0A and CR x0D which are allowed), DEL x7F, the C1 control block x80-x9F (except for NEL x85 which is allowed), the surrogate block16 xD800-xDFFF, xFFFE and xFFFF.

To Reproduce
create a string containing any number of these characters
(I can't paste them here in GitHub)

\x00\x01\x02\x03\x04\x05\x06\x07\x08\x0b\x0c\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\e\x1c\x1d\x1e\x1f

Expected behaviour
A warning to be provided saying the non-printable c0-control characters are not allowed

Versions:

• Environment: VSCode 1.121.0
• yaml: 2.9.0

Additional context

[eemeli]

Yup, confirming this is a valid bug. The lexer is not verifying that the characters excluded from c-printable are actually excluded.

This should probably be an error, though, and not just a warning? And as it's effectively a recoverable error, we should probably only catch it during composition, i.e. in resolveFlowScalar() and resolveBlockScalar().