Normative: Arbitrary module namespace identifier names

[Jack Works (Jack-Works)]

Implementing tc39/ecma262#2154

[Jack Works (Jack-Works)]

Made a full rewrite of this PR. Just get the compiler part to work. Will handle language service days later.

[ExE Boss (ExE-Boss)]

Nit: extraneous whitespace:

Suggested change

	if(nameArg){
	if(nameArg){

[Jack Works (Jack-Works)]

Hi, Daniel Rosenwasser (@DanielRosenwasser) I have a question. With this PR, it's possible to define members with names that cannot be an identifier on a Symbol.

exportconstenumInternalSymbolName{Call="__call",// Call signaturesConstructor="__constructor",// Constructor implementationsNew="__new",// Constructor signaturesIndex="__index",// Index signaturesExportStar="__export",// Module export * declarationsGlobal="__global",// Global self-referenceMissing="__missing",// Indicates missing symbolType="__type",// Anonymous type literal symbolObject="__object",// Anonymous object literal declarationJSXAttributes="__jsxAttributes",// Anonymous JSX attributes object literal declarationClass="__class",// Unnamed class expressionFunction="__function",// Unnamed function expressionComputed="__computed",// Computed property name declaration with dynamic nameResolving="__resolving__",// Indicator symbol used to mark partially resolved type aliasesExportEquals="export=",// Export assignment symbolDefault="default",// Default export symbol (technically not wholly internal, but included here for usability)This="this",}

I wonder if this PR gonna make programmers able to write code that breaks TS by declaring a symbol member that has the same name as an internal symbol, like

export{itemas"this"}// orexport{itemas"export=",itemas__new}

[Daniel Rosenwasser (DanielRosenwasser)]

I think the comment

Default export symbol (technically not wholly internal, but included here for usability)

is the key here, and the same applies to This. those symbols are just for comparisons in various places. If anything relied on this or default being special entities within a symbol table, they'd probably already be broken.

Maybe Wesley Wigham (@weswigham) or Gabriela Araujo Britto (@gabritto) can back me up on that statement though.