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 reverts commit 4919729f00.
This CL also adds back in logic to handle older package:js versions to avoid
failures in our static checking. It also supports dart:js_interop's @JS
annotation since it can now be used for @staticInterop classes.
CoreLibraryReviewExempt: Reland of backend-specific library changes.
Change-Id: I104653a9a6b2593f6bab658808287e2074c18550
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/294130
Reviewed-by: Joshua Litt <joshualitt@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Samuel Rawlins <srawlins@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>
There is a quite complicated logic in resolving directives and walking
augmentations and parts. And we don't expect users write a lot of code
in directives, so there is less need for optimizations than when typing
in method bodies.
Change-Id: Id38e90f09eb5c1e84be8fc28ed4211d03762d2e0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/298220
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@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>
In order for an analyzer quick fix to aid the user in correcting
exhaustiveness errors, it needs to know not just the text of the
witness pattern that needs to be inserted, but also which elements are
referenced by the identifiers in that pattern. This will allow it to
add in imports if the user's code doesn't yet import the necessary
library, or insert import prefixes in the case where the user is
already importing the necessary library in a prefixed fashion.
To reduce the effect on the exhaustiveness logic (which was designed
with the intention of building up the witness pattern into a
StringBuffer), we introduce a new type, `DartTemplateBuffer`, which
behaves similarly to StringBuffer but also captures the necessary
semantic information so that the analyzer will be able to fix up
imports in an appropriate way.
This change is mostly isolated to the _fe_analyzer_shared package; it
doesn't add the necessary logic to the analyzer to capture the
elements; it simply plumbs them up to the API boundary between the
packages. Future CLs will add the necessary analyzer logic to make
use of the information.
Change-Id: I7c030fc49a2510acbefd6aeb567e0e7b7102855a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/296385
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
Chloe Stefantsova