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