update contextual discrimination to include omitted members

[Erik Brinkman (erikbrinkman)]

This diff extends the types checked by discriminateContextualTypeByObjectMembers and discriminateContextualTypeByJSXAttributes to also include any optional components in the type union.

fixes#41759 although it doesn't address the better error reporting for their last repro, which I'm not sure how to address.

[Deleted user (ghost)]

All CLA requirements met.

[Erik Brinkman (erikbrinkman)]

Wesley Wigham (@weswigham) that check makes sense. It should be resolved, although I had trouble accepting the changes through gh. Thanks for the pointers of where to start btw, probably wouldn't have thrown this together without them.

[Andrew Schmadel (schmod)]

Under the TS 4.3 beta, this change appears to have introduced a stack overflow in my codebase:

RangeError: Maximum call stack size exceeded
at checkIdentifier (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:55295:26)
at checkExpressionWorker (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:61948:28)
at checkExpression (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:61903:38)
at checkNonNullExpression (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:57527:37)
at checkPropertyAccessExpression (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:57572:85)
at checkExpressionWorker (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:61977:28)
at checkExpression (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:61903:38)
at getTypeOfExpression (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:61857:24)
at getMatchingUnionConstituentForObjectLiteral (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:53649:40)
at discriminateContextualTypeByObjectMembers (/Users/andrew/code/repo_name/node_modules/typescript/lib/tsc.js:56277:20)

[Erik Brinkman (erikbrinkman)]

Andrew Schmadel (@schmod) can you provide more context? Ideally a minimum working example, and even more ideally a bisect showing it was this commit? The call stack seems to indicate that it's causing a stack overflow at getMatchingUnionConstituentForObjectLiteral which is called before this commit's change to discriminateContextualTypeByObjectMembers .