The listener API for variable patterns is split into three separate
functions, to handle the three separate behaviors:
- `handleAssignedVariablePattern` for variable names appearing in an
assignment context (these assign to an existing variable upon a
successful match).
- `handleDeclaredVariablePattern` for variable declarations appearing
in a declaration or matching context (these cause a new variable
name to come into scope).
- `handleWildcardPattern` for wildcards in any context (these don't
capture the matched value).
Also, responsibility is shifted to the parser for reporting the
following error conditions:
- VariablePatternKeywordInDeclarationContext (e.g.
`var (var x) = ...;`)
- PatternAssignmentDeclaresVariable (e.g. `[x, var y] = ...;`)
Previously these errors were detected by the implementations, and
weren't fully covering all possible error scenarios.
In the case of VariablePatternKeywordInDeclarationContext, the
listener method `handleDeclaredVariablePattern` is called instead of
`handleAssignedVariablePattern`. This ensures that no tokens are
dropped from the analyzer AST. The CFE uses the `inAssignmentPattern`
argument of `handleDeclaredVariablePattern` to distinguish this error
recovery case from a legitimate declared variable pattern.
Fixes#51868.
Bug: https://github.com/dart-lang/sdk/issues/51868
Change-Id: I28ec679b73d64033166721c6460be35f15e23171
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/291583
Reviewed-by: Jens Johansen <jensj@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Variable patterns behave so differently inside a patternAssignment
that we may want to represent them using different AST nodes inside
the analyzer/CFE. This change adds a boolean flag allowing the
implementation to know what kind of variable pattern it's looking at
when parsing occurs.
Bug: https://github.com/dart-lang/sdk/issues/50035
Change-Id: I60adf2865bbe24f85b72a79b1360833bf823bd67
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/273829
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Expressions can also occur in patterns, either after an equality or
relational operator (e.g. `== e`), or after `const` (though what's
allowed after `const` is heavily restricted). We need to make sure
that the expression parser doesn't greedily treat `=>` as introducing
a function expression when parsing these constructs inside a switch
expression.
But it's ok to allow function expressions inside list patterns, map
patterns, parenthesized patterns, and in the argument part of object
patterns. (These will be rejected by a later stage of analysis
because expressions inside of patterns must be const, and a function
expression can't be const. But the parser should still accept them so
that we can give useful error messages).
Fixes#50591.
Bug: https://github.com/dart-lang/sdk/issues/50591
Change-Id: I828555782f5bc8cb8aae8a3948849b7a75bdec57
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/273286
Reviewed-by: Jens Johansen <jensj@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Chloe Stefantsova