allow "export as namespace" in non-declaration files

[nippur72]

According to #7125, the new export as namespace

[...] is only legal as a top-level declaration a .d.ts file containing other top-level export declarations

Now this is a nuisance for library authors that are generating declarations via the --declaration flag, because everytime there's a recompile, .d.ts are rewritten and the export as namespace typed previously is gone.

What about if export as namespace could be written in the actual code and exported in the generated .d.ts file? E.g.:

myreact.ts:

export function createElement() { /* ... */ };
export as namespace React;

(generated) myreact.d.ts:

export declare function createElement() {};
export as namespace React;

[mhegazy]

so what would the emitted code be?

[nippur72]

the emitted code would be none: export as namespace would be ignored in .ts but written into .d.ts.

[mhegazy]

mmm.. that is not what i would expect from a declaration like that in a .ts file. for instance export = does emit code, and do not expect you to assign the output to module.exports yourself. so why would this be any different.

[nippur72]

what about if the emitted code is a publishing into globals as per your suggestion in #8436 ?

[mhegazy]

yup. that is what i had in mind, though i forgot about that other comment :)

[mhegazy]

#8436 seems to have more details. would you mind moving this suggestion to #8436.

[nippur72]

closing as discussion merges with #8436