Suggestion Backlog Slog, 3/6/2017

Question

Suggestion Backlog Slog, 3/6/2017

RyanCavanaugh opened this issue 9 years ago · 1 comments

RyanCavanaugh commented 9 years ago

#4639 int types
#13455 Allow attaching a comment before all non-user injected code.
#12936 Exact Types
#11774 Distinguish declaration file and js file when the option “Keep comments in TypeScript compiler output" is turned on
#13231 [Proposal] External Module Type
#2607 Generic decorators - could they receive some default type arguments?
#13020 tsc -w should clear screen before each run
#14301 Allow extends from any (Salsa)
#14249 Constraint Partial<T>/Readonly<T> to T extends object
#14150 strictVarianceChecks flag
#13890 JSX.ElementType to define the type of <Tag /> expressions
#13847 Enforce generator functions to contain at least one yield
#12825 Generalize handling of never for returns
#12600 Discriminated unions of non-unit-type-discriminated unions
#12410 Allow operator + on string|number-constrained T ?

Answer 1 · 2017-03-07T02:07:22.000Z

#4639 int types
- Just not all that useful
- ES is looking at adding int64
- Revisit but 👎 unless we do Web Assembly
#13455 Allow attaching a comment before all non-user injected code.
- When exactly would we emit this line?
  - Always? Only when we emit a new branch ?
  - Do our helpers suffer from this?
- Where does this happen?
  - Can you just regex the output?
- We could use a helper instead (makeSuper(_super, this))
- AMF
#13721 Pure annotation for class emit
- Needed for accurate tree shaking
- Somewhat odd Uglify doesn't identify this by itself?
- Would be emitted for classes without static initializers
- Could be implemented by an emit transform pipeline
  - But doesn't solve tsc scenarios
  - Probably OK
  - Actually this doesn't work bescause the injection has to happen between the class emit and the IIFE emit
- Punt to uglififer to detect this pattern instead?
- Make loaders handle this instead?
- Daniel will try to do this for WebPack
#12936 Exact Types
- Excess property checks are already pretty good
- Which types are exact and which aren't?
  - People may disagree
- Some APIs really are closed
- Sidebar on all-optional interfaces
  - Ryan should implement this and stop complaining
- What is the behavior of this for unions / intersections?
  - Intersection... makes no sense?
    - Violates basic assumptions of assignability (T & U assignable to T)
- What does it mean to be constrained by an exact type?
- What about instantations of exact types?
- Danger of bug farm
- What is the value add here?
- What about creating automatically-disjointing unions?
- Outcomes
  - Need specific scenarios - is this an XY problem solution?
  - We need to fix excess property checking when the target is a union type
#13020 tsc -w should clear screen before each run
- Universal acclaim in the room for this behavior
- 👍
- Sidenote: Accept PR to get rid of WScript host
#14301 Allow extends from any (Salsa)
- 👍
- When this happens, add a [s: string]: any signature to the type
#14249 Constrain Partial<T>/Readonly<T> to T extends object
- For shallow variants only
- Breaking change...
- 👎 Annoying as hell and delivers no value
#14150 strictVarianceChecks flag
- Highly infectious
  - Could anyone actually get this to work?
  - You actually can't do this without the entire set of C++-like const constructs
- Keep tabs on this
#12825 Generalize handling of never for returns
- The control flow graph is formed during binding, but we don't have type data yet
- We could store all calls at each flow control point and then check them for never returns and check this info for computing types
  - Expensive!
- Correct analysis would require multiple iterations
- Possible solutions?
  - At bind-time
    - Detect explicit : never functions
      - Or do this at parse time?
    - Store potential calls to these
  - Use this to set up a "better" flow control graph
  - Above doesn't really work due to imported identifiers...
- No clear answers in sight

Cut for time

#13890 JSX.ElementType to define the type of <Tag /> expressions
#13847 Enforce generator functions to contain at least one yield
#12600 Discriminated unions of non-unit-type-discriminated unions
#12410 Allow operator + on string|number-constrained T ?
#13231 [Proposal] External Module Type
#2607 Generic decorators - could they receive some default type arguments?
#11774 Distinguish declaration file and js file when the option “Keep comments in TypeScript compiler output" is turned on