https://codereview.chromium.org/1306583002/diff/60001/src/preparser.h
File src/preparser.h (right):
https://codereview.chromium.org/1306583002/diff/60001/src/preparser.h#newcode3604
src/preparser.h:3604: ArrowFormalParametersUnexpectedToken(classifier);
On 2015/08/20 15:22:57, caitp wrote:
probably want to make sure destructuring still works properly, `({ x:
x =
foo.bar }) => {}` for example. I don't expect `({ x = foo.bar }) =>
{}` to work
properly because CoverInitializedName parsing is pretty messed up in
maybe-expressions, might be worth marking that as a TODO though in the
test case
This also applies to other tokens which can legally occur in binding
patterns
within arrow formals, I guess.
If this is covered by other tests, then that's ok
Thanks for having a look!
I'm pretty sure that destructuring should still work properly, and the
reasoning is a bit convoluted: an assignmentexpression is a valid arrow
formal parameter list if it is a bare identifier, or if it starts with a
parenthesis, only contains binding patterns separated by commas,
possibly ending in a rest pattern (which, oddly, can't contain
patterns). OK. That is what was already the case before and is covered
by DestructuringPositiveTests and DestructuringNegativeTests in
test-parser.cc.
The way the above classifier works is that when parsing a parenthesized
list in ParsePrimaryExpression, the expression as a whole remains a
valid ArrowFormalParameterList iff the inner productions are valid
BindingPatterns. Specifically the invalid-ArrowFormalParameterList
*does not* accumulate out from the individual arguments -- instead it's
the BindingPattern flag that propagates out. See the gnarly special
case in ExpressionClassifier::Accumulate. So I don't think additional
tests are necessary for existing destructuring foo.
What we missed is that the classifier would accept things as valid
ArrowFormalParameterLists that weren't valid. That's what this patch
fixes. These additional flags won't cause problems for arrow function
formals because they are explicitly ignored there.
https://codereview.chromium.org/1306583002/
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