Missing implicit any error in destructuring with computed property

[ajafff]

TypeScript Version: 2.9.0-dev.20180411

Search Terms:

Code

// --noImplicitAny
let named = 'foo';
let {[named]: prop} = {prop: 'foo'};

Expected behavior:
Element implicitly has an 'any' type because type '{ prop: string; }' has no index signature.

Actual behavior:
prop is any, but there is no implicit any error

Playground Link: https://agentcooper.github.io/typescript-play/#code/DYUwLgBAdghgtiAJhAvBA5AMwPbfQbgChRIBvAbVgUQF0AuCABwCdtGBfVCUlthrXOnb4gA

Related Issues:
#23297 (comment)

[weswigham]

If named is const, we report the error as anticipated; so the issue here is simply that a computed property name of type string used to destructure something without an index signature to any should be an implicitAnyIndexError.

[mattmccutchen]

Duplicate of #20725 (or vice versa).

[mhegazy]

@mattmccutchen i think #20725 is a different issue, and should be fixed in 2.9.