Suggestion Backlog Slog, 1/23/2017

[RyanCavanaugh]

• Type hole with compatibility between optional parameters/extra parameters #13043 Fix type hole around optional / ignored parameters
• Enums can not be used for index signature types #13042 Allow enums as index signature key types again
• (0,eval) produces TS2695 #12978 Allow the expression (0, eval)
• Type Inference in for... in combined with typeof #12944 Narrow x to ... & Function in typeof x === 'function'-guarded blocks
• Narrow "string" to "keyof T" with "in" guard? #12892 Narrow k to keyof typeof obj in k in obj-guarded blocks
• Reverse Enum Member Initialization Order for Constants #12693 Invert enum emit to improve minification when value is constant
• should warn/error on forward references during field initialization #12673 Disallow forward references in class member initialization
• [Suggestion] should Overloads not differ only by return type? #11281 Disallow trivially unreachable overloads
• Type annotations for default export #13626 Type annotations for default export
• Consider making implicit any the default for all generic type parameters #13609 Consider making implicit any the default for all generic type parameters
• unknown: less-permissive alternative to any #10715 unknown: less-permissive alternative to any
• Explore supporting ES import() proposal  #12364 Explore supporting ES import() proposal
• Allow interfaces to declare protected members and allow implementors to implement protected and private members. #3854 Allow interfaces to declare protected members and allow implementors to implement protected and private members
• error TS5042: Option 'project' cannot be mixed with source files on a command line. #13575 error TS5042: Option 'project' cannot be mixed with source files on a command line.
• async/await: nowait keyword? #13376 Detect failing to await a Promise in an async function
• Proposal: int types #4639 int types
• Allow attaching a comment before all non-user injected code. #13455 Allow attaching a comment before all non-user injected code.
• Exact Types #12936 Exact Types
• Distinguish declaration file and js file when the option “Keep comments in TypeScript compiler output" is turned on #11774 Distinguish declaration file and js file when the option “Keep comments in TypeScript compiler output" is turned on
• [Proposal] External Module Type #13231 [Proposal] External Module Type
• Type hole with compatibility between optional parameters/extra parameters #13043 Type hole with compatibility between optional parameters/extra parameters
• Allow type casts around shorthand property names #13035 Allow type casts around shorthand property names
• Generalize never type handling for control flow analysis based type guard #12825 Generalize never type handling for control flow analysis based type guard
• Generic decorators - could they receive some default type arguments? #2607 Generic decorators - could they receive some default type arguments?
• tsc -w should clear screen before each run #13020 tsc -w should clear screen before each run

[RyanCavanaugh]

• Type hole with compatibility between optional parameters/extra parameters #13043 Fix type hole around optional / ignored parameters
  • Widening of "remainder" type similar to how object literal freshness works
  • Key difference: functions which we know are not aliased and therefore have the correct arity
  • Would be interested to see what this breaks
• Enums can not be used for index signature types #13042 Allow enums as index signature key types again
  • Note that this does not cause enum indexing to be nominal
    • Ryan doesn't want to triage this bug every day...
  • e.g. here resolve the index type to "0" | "1"
  • But only for enums with computable values
  • 👍 special case for enums
• (0,eval) produces TS2695 #12978 Allow the expression (0, eval)
  • Use void 0 instead?
  • Just the bare identifier eval on the right is special-cased
  • 👍
• Type Inference in for... in combined with typeof #12944 Narrow x to ... & Function in typeof x === 'function'-guarded blocks
  • 👍
• Narrow "string" to "keyof T" with "in" guard? #12892 Narrow k to keyof typeof obj in k in obj-guarded blocks
  • Not a technically sound reduction
  • Shouldn't this example just use a normal index signature?
    • getDescription doesn't need T
    • But getDefault would
  • Write an indexed-type return type instead?
  • This can be rewritten to do the correct thing
    • @mhegazy will demonstrate
• Reverse Enum Member Initialization Order for Constants #12693 Invert enum emit to improve minification when value is constant
  • Would be a breaking change for the reverse map when duplicate names exist
    • Could cause runtime failures
  • Use const enum if you care about enum emit size
  • 👎
• should warn/error on forward references during field initialization #12673 Disallow forward references in class member initialization
  • 👍
• [Suggestion] should Overloads not differ only by return type? #11281 Disallow trivially unreachable overloads
  • Slippery slope of only finding some of these bad cases and not others
  • Just best to consistently leave you out in the cold
  • 👎
• Type annotations for default export #13626 Type annotations for default export
  • Grammatical ambiguity / weird synax
  • 👎
• Consider making implicit any the default for all generic type parameters #13609 Consider making implicit any the default for all generic type parameters
  • 👍
• Allow type casts around shorthand property names #13035 Allow type casts around shorthand property names
  • Any possible grammatical ambiguity?
    • No?
  • AMF
• unknown: less-permissive alternative to any #10715 unknown: less-permissive alternative to any
  • Similar to mixed ?
  • Revisit
• async/await: nowait keyword? #13376 Detect failing to await a Promise in an async function
  • Rule: Expression statements where the expression is a function/method call which is a Promise = error
  • 👍 and it's the default. Use void f(); or <any>f(); to discard result
• Bug with type discrimination and string literal types. #13628 Union types and literal inference
  • Annoying / weird behavior
  • Is subtype reduction the problem?
    • Better not be
  • What if contextually typing by a string or stringlike caused literal inference?
    • Any primitive-like contextual type
  • 👍

---

Out of time

• Proposal: int types #4639 int types
• Allow attaching a comment before all non-user injected code. #13455 Allow attaching a comment before all non-user injected code.
• Exact Types #12936 Exact Types
• Distinguish declaration file and js file when the option “Keep comments in TypeScript compiler output" is turned on #11774 Distinguish declaration file and js file when the option “Keep comments in TypeScript compiler output" is turned on
• [Proposal] External Module Type #13231 [Proposal] External Module Type
• Generalize never type handling for control flow analysis based type guard #12825 Generalize never type handling for control flow analysis based type guard
• Generic decorators - could they receive some default type arguments? #2607 Generic decorators - could they receive some default type arguments?
• tsc -w should clear screen before each run #13020 tsc -w should clear screen before each run

[jwbay]

Many thanks for continuing to post these breakdowns + notes from team design meetings. It's greatly appreciated!

[ghost]

I see #12364 in the agenda, but not in the minutes.

[mhegazy]

I see #12364 in the agenda, but not in the minutes.

We ran out of time before talking about this one. I would expect us to talk about in the next week.