To use the simple `filename="..."` form, the value must conform to the
official grammar from RFC6266[^1]:
filename-parm = "filename" "=" value
value = <value, defined in [RFC2616], Section 3.6>
; token | quoted-string
The `quoted-string` definition comes from RFC 9110[^2]:
```
quoted-string = DQUOTE *( qdtext / quoted-pair ) DQUOTE
qdtext = HTAB / SP / %x21 / %x23-5B / %x5D-7E / obs-text
The backslash octet ("\") can be used as a single-octet quoting
mechanism within quoted-string and comment constructs. Recipients that
process the value of a quoted-string MUST handle a quoted-pair as if
it were replaced by the octet following the backslash.
quoted-pair = "\" ( HTAB / SP / VCHAR / obs-text )
A sender SHOULD NOT generate a quoted-pair in a quoted-string except
where necessary to quote DQUOTE and backslash octets occurring within
that string.
```
That is, quoted strings are able to express horizontal tabs, space
characters, and everything in the range from 0x21 to 0x7e, expect for
0x22 (`"`) and 0x5C (`\`), which can still be expressed but must be
escaped with their own `\`.
We ignore the case of `obs-text`, which is defined as the range
0x80-0xFF, since its presence is there for permissive parsing of
accidental high-bit characters, and it should not be generated by
conforming implementations.
Transform this character range into a regex and apply it in addition
to the "is ASCII" check. This ensures that all simple filenames are
expressed in the simple format, and that all filenames with newlines
and other control characters are properly expressed with the
percent-encoded `filename*=...`form.
[^1]: https://datatracker.ietf.org/doc/html/rfc6266#section-4.1
[^2]: https://datatracker.ietf.org/doc/html/rfc9110#name-quoted-strings
BigAutoField is the default type for primary keys. In models.txt, the linked
anchor shows that the default primary key is a BigAutoField, so it now defers
to that section instead of duplicating an (incorrect) type.
This feature flag useful with MongoDB: "Rounding to the nearest even
value supports more even distribution of rounded data than always
rounding up or down."
Urlizer was not properly encoding email addresses containing punctuation
in generated mailto links. Per RFC 6068, fixed by percent encoding
(urllib.parse.quote) the local and domain address parts.
While AlterUniqueTogether has been documented to be still allowed in historical
migrations for the foreseeable future it has been crashing since 2abf417c81
was merged because the latter removed support for Meta.index_together which the
migration framework uses to render models to perform schema changes.
CreateModel(options["unique_together"]) was also affected.
Refs #27236.
Co-authored-by: Simon Charette <charette.s@gmail.com>
