In https://dart-review.googlesource.com/c/sdk/+/299400, the parser was
adjusted so that it no longer accepts `when` and `as` as the names for
variable patterns in cases where there is a possible ambiguity
(e.g. `int when` is not accepted as a pattern because `int` is a
legitimate pattern, therefore `when` could introduce a guard
clause). This change further prohibits `when` and `as` from being the
names of variable patterns or identifier patterns even in the case
where there is no ambiguity. This is in line with the discussion at
https://github.com/dart-lang/sdk/issues/52199#issuecomment-1526297771,
and the spec change at
https://github.com/dart-lang/language/pull/3033.
Three new error codes are introduced, to cover the three circumstances
in which `when` or `as` might be used illegally: in a declared
variable pattern, in an assigned variable pattern, or in an identifier
pattern. I've also added analyzer tests to ensure that the parser
recovers from these errors nicely. Unfortunately, nice error recovery
is only feasible in the non-ambiguous cases.
I've also updated the language test expectations in
`tests/language/patterns/version_2_32_changes_error_test.dart` to
reflect the new error messages, and added a few more examples of uses
of `when` and `as` that are still permitted.
Fixes#52260.
Bug: https://github.com/dart-lang/sdk/issues/52260
Change-Id: I229f627aa639659c30b83c74895759207da279f7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/301482
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
This change fixes parsing of case clauses such as:
case foo when !flag:
Constructions like this require some lookahead in order to parse
correctly, because the token `when` is valid both as an identifier and
as a part of the grammar for a case clause. Therefore, at the time
`foo` is encountered, the parser must decide whether it is looking at
a variable pattern (`foo when`, where `when` is the name of the
variable) or an identifier pattern (`foo`, where `when` begins the
case's guard clause). Previous to this fix, the algorithm for
disambiguating these two choices was as follows:
- If the token sequence starting at `foo` looked like a type, and the
token that follows was an identifier, the parser assumed it was
looking at a variable pattern with a type; otherwise it assumed it
was looking at an identifier pattern.
- EXCEPT that if the token that followed the supposed type was `when`
or `as` (both of which are valid identifiers), then it probed
further:
- If the token that followed `when` or `as` was a token that could
legitimately follow a pattern, then it assumed that it was looking
at a variable pattern with a type. (The tokens that could
legitimately follow a pattern are `,`, `:`, `||`, `&&`, `)`, `}`,
`]`, `as`, `when`, `?`, `!`).
- Otherwise it assumed that it was looking at an identifier pattern.
This didn't fully disambiguate, because the third bullet didn't
account for the fact that the tokens `as`, `when`, and `!` could
_either_ legitimately follow a pattern _or_ legitimately begin an
expression (or, in the case of `when`, a type), therefore constructs
like the following were incorrectly parsed:
- `case foo when as:` (where `as` is a local boolean variable)
- `case foo when when:` (where `when` is a local boolean variable)
- `case foo when !flag:` (where `flag` is a local boolean variable)
- `case foo as when:` (where `when` is the name of a type)
The solution is to simplify the disambiguation logic so that if if the
token that follows the supposed type is `when` or `as`, then the
parser assumes that it's looking at an identifier pattern, _not_ a
typed variable pattern.
The consequence of this is that the above four constructions are
parsed correctly; however it is no longer possible for a typed
variable pattern to name a variable `when` or `as`.
For consistency we would like to prohibit _any_ variable pattern from
naming a variable `when` or `as`, however to keep this change as small
as possible (and reduce the risk involved in a possible cherry-pick)
that will be postponed until a later CL.
Fixes#52199.
Bug: https://github.com/dart-lang/sdk/issues/52199
Change-Id: Ibab9b92f01e3e4020d7d64f1ff000a9b964a4564
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/299400
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
If the sender is not `null`, then we can send.
No need for a flag, and assert() in the sending method.
If the sender is `null`, then the sending code will not able to invoke it.
Types FTW :-)
Change-Id: I7d153ba014c578a73dce2eab28aceedbb8814711
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/298440
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
- change forEachIndexed to `.indexed`
- remove `package:collection` imports for files only using `.firstOrNull`, `.singleOrNull`, `.lastOrNull` that is now available in `dart:core`
- switch from `Pair` to records
- use switch expressions
Change-Id: Id1ae22db427b4cd955f26e0d6c852944a540a05f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/298061
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
I did not change any of the test cases. I did change the names of the
tests to be more consistent, and in the process I found a couple of
tests where the test code was identical, so I deleted the duplicates.
I expect that there will be more cleanup that we'll want to do after
all of the contributor tests have been converted and merged together,
but I wanted this CL to be as straightforward as possible given its
size.
Change-Id: I2cbb6b5c0718fbbc36da521ee3c4fc7d00c36dcb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/297720
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
No functional changes here but there have been some refactors inside the meta model that required some minor tweaks (URI moved from a type alias to string to a spec-defined base type).
I also improved the handling of some type references in the comments we bring in so they're clickable in more places.
Change-Id: I7c725d01b6d7bc0925979b8118dbfd8952f78724
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/297482
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
The analyzer team has decided to adopt the convention of using `TODO`
comments to document long term issues that should persist in the
codebase, and `FIXME` comments to document short term issues that need
immediate attention. They may even consider adding a presubmit hook
to ensure that `FIXME` comments are only used during local
development.
Accordingly, it makes sense to suppress `TODO` comments from being
surfaced to the IDE "problems" view (since there are hundreds of them,
and they're not immediately actionable). This makes VSCode's
"problems" view much more usable in "tree" mode.
Change-Id: I11a0c59132fb98c1c86fb4adf22d1fdf3b547c80
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/295662
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
pq