No spelling suggestion/quick fix for types

[DanielRosenwasser]

Follow-up from #40169.

declare let a: numbers;
declare let b: Numbers;
declare let c: objects;
declare let d: Objects;
declare let e: RegEx;

namespace yadda {
  export type Thing = string;
}
let f: yaddas: Thing;

Each of the above examples should presumably get a spelling suggestion and quick fix.

[sarathps93]

Is it ok if I take this up as my first issue? @DanielRosenwasser

[DanielRosenwasser]

Go for it!

[DanielRosenwasser]

Though, actually I'd first check if @a-tarasyuk is already working on this.

[DanielRosenwasser]

And additionally, I've marked this issue as "moderate" in difficulty. If this is your first issue, you might want to go through a couple of issues tagged with good first issue. I'm not saying you can't do this issue, but I wouldn't suggest starting out with this one.

[a-tarasyuk]

I'm fine if @sarathps93 will work on this issue. I'll take another. :). I experimented a bit with the problem, however, I didn't make a PR.

[a-tarasyuk]

My thoughts about this issue. The following cases can be handled by getSuggestedSymbolForNonexistentSymbol helper

declare let d: Objects; // Object declaration can be found in lib
declare let e: RegEx;   // RegExp declaration can be found in lib

namespace yadda {
  export type Thing = string;
}
let f: yaddas.Thing; // yadda has namespace declaration

There is an issue with the reserved type names, like number, boolean, string, etc. getSuggestedSymbolForNonexistentSymbol for the following example will suggest Number instead of number because number doesn't have a symbol in globals

declare let a: numbers; // Number ?

There is option to use getSpellingSuggestion with the list of reserved type names ["number", "string", "never"...] (maybe there is helper that returns all reserved type names). However, getSpellingSuggestion converts candidateName to lowercase, and will suggest number for Numbers. Also, ["number", "string", "never"...] is array of strings - not symbols, so in QF need to handle that, or convert string to symbols.

cc @DanielRosenwasser

[DanielRosenwasser]

@a-tarasyuk I'd say that #39060 should fix that case-sensitivity issue.

[chenjigeng]

@DanielRosenwasser Do you think the code below should be Number or number

declare let a: numbers; // Number or number

As @a-tarasyuk says, the lastest version will change it to Number