skipDefaultLibCheck doesn't work with noLib #5510
Description
We rely on the performance improvement of skipping type-checking of lib.d.ts.
But, as I described in #5504 our setup is to emit ES6 while using the types from lib.d.ts. (es5).
It seems that if I pass the lib.d.ts on the command line, rather than rely on the auto-loading behavior, then the isDefaultLib argument is always false, here:
https://github.com/Microsoft/TypeScript/blob/v1.6.2/src/compiler/program.ts#L371
So that means it's slow again:
alexeagle-macbookpro2:test123 alexeagle$ time ./node_modules/.bin/tsc -p targetES6
real 0m0.696s
user 0m0.835s
sys 0m0.050s
alexeagle-macbookpro2:test123 alexeagle$ time ./node_modules/.bin/tsc -p targetES6
real 0m0.703s
user 0m0.846s
sys 0m0.049s
alexeagle-macbookpro2:test123 alexeagle$ time ./node_modules/.bin/tsc -p targetES5
real 0m0.375s
user 0m0.443s
sys 0m0.033s
alexeagle-macbookpro2:test123 alexeagle$ time ./node_modules/.bin/tsc -p targetES5
real 0m0.379s
user 0m0.441s
sys 0m0.035s
Could that hardcoded false be changed to a predicate of whether the file passed is known to be a standard lib (either with the /// <reference no-default-lib="true"/> pragma or because the path matches compilerHost#getDefaultLibFileName)?
Here's the repro directory:
alexeagle-macbookpro2:test123 alexeagle$ find target* -type f -print -exec cat {} \;
targetES5/app.ts
let a: string = "hello";
targetES5/built/app.js
var a = "hello";
targetES5/tsconfig.json
{
"compilerOptions": {
"module": "commonjs",
"target": "es5",
"skipDefaultLibCheck": true,
"noImplicitAny": false,
"outDir": "built",
"rootDir": ".",
"sourceMap": false
},
"exclude": [
"node_modules"
]
}
targetES6/app.ts
let a: string = "hello";
targetES6/built/app.js
let a = "hello";
targetES6/lib.es6-emit.d.ts
/**
* @fileoverview a subset of typings from lib.core.es6.d.ts which are required
* for the compiler to emit ES6 code, even though we only allow ES5 API usage.
* This custom typing is a suggested workaround for
* https://github.com/Microsoft/TypeScript/issues/5504
*/
interface IteratorResult<T> {
done: boolean;
value?: T;
}
interface Iterator<T> {
next(value?: any): IteratorResult<T>;
return?(value?: any): IteratorResult<T>;
throw?(e?: any): IteratorResult<T>;
}
interface Iterable<T> {
[Symbol.iterator](): Iterator<T>;
}
interface IterableIterator<T> extends Iterator<T> {
[Symbol.iterator](): IterableIterator<T>;
}
interface Symbol {
/** Returns a string representation of an object. */
toString(): string;
/** Returns the primitive value of the specified object. */
valueOf(): Object;
[Symbol.toStringTag]: string;
}
interface SymbolConstructor {
/**
* A reference to the prototype.
*/
prototype: Symbol;
/**
* Returns a new unique Symbol value.
* @param description Description of the new Symbol object.
*/
(description?: string|number): symbol;
/**
* Returns a Symbol object from the global symbol registry matching the given key if found.
* Otherwise, returns a new symbol with this key.
* @param key key to search for.
*/
for(key: string): symbol;
/**
* Returns a key from the global symbol registry matching the given Symbol if found.
* Otherwise, returns a undefined.
* @param sym Symbol to find the key for.
*/
keyFor(sym: symbol): string;
// Well-known Symbols
/**
* A method that determines if a constructor object recognizes an object as one of the
* constructor’s instances. Called by the semantics of the instanceof operator.
*/
hasInstance: symbol;
/**
* A Boolean value that if true indicates that an object should flatten to its array elements
* by Array.prototype.concat.
*/
isConcatSpreadable: symbol;
/**
* A method that returns the default iterator for an object. Called by the semantics of the
* for-of statement.
*/
iterator: symbol;
/**
* A regular expression method that matches the regular expression against a string. Called
* by the String.prototype.match method.
*/
match: symbol;
/**
* A regular expression method that replaces matched substrings of a string. Called by the
* String.prototype.replace method.
*/
replace: symbol;
/**
* A regular expression method that returns the index within a string that matches the
* regular expression. Called by the String.prototype.search method.
*/
search: symbol;
/**
* A function valued property that is the constructor function that is used to create
* derived objects.
*/
species: symbol;
/**
* A regular expression method that splits a string at the indices that match the regular
* expression. Called by the String.prototype.split method.
*/
split: symbol;
/**
* A method that converts an object to a corresponding primitive value.
* Called by the ToPrimitive abstract operation.
*/
toPrimitive: symbol;
/**
* A String value that is used in the creation of the default string description of an object.
* Called by the built-in method Object.prototype.toString.
*/
toStringTag: symbol;
/**
* An Object whose own property names are property names that are excluded from the 'with'
* environment bindings of the associated objects.
*/
unscopables: symbol;
}
declare var Symbol: SymbolConstructor;
targetES6/tsconfig.json
{
"compilerOptions": {
"target": "es6",
"skipDefaultLibCheck": true,
"noLib": true,
"noImplicitAny": false,
"outDir": "built",
"rootDir": ".",
"sourceMap": false
},
"files": [
"app.ts",
"lib.es6-emit.d.ts",
"../node_modules/typescript/lib/lib.d.ts"
]
}
cc @mprobst