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Compilation of function indirection leads to runtime error #10267
Description
TypeScript Version: 2.1.0-dev.20160810
Code
Tried with --target es5 and --target es6
'use strict';
class O {
constructor(private n: string) { }
public getA = () => this.n;
public getZ() { return this.n; }
}
let o = new O('5');
let getB = () => '5';
let getC = () => o.getZ();
let getD = function() { return o.getZ() };
console.log(o.getA());
console.log(getB());
console.log(getC());
console.log(getD());
console.log(o.getZ());
console.log();
function indirect(f: () => string) {
return f();
}
console.log(indirect(o.getA));
console.log(indirect(getB));
console.log(indirect(getC));
console.log(indirect(getD));
console.log(indirect(o.getZ.bind(o)));
console.log(indirect(o.getZ));Expected behavior:
A warning or error on transpilation because this will be undefined.
OR
A warning or error on transpilation because we're passing a class instance method as a function parameter.
Actual behavior:
Transpiles and then on run:
5
5
5
5
5
5
5
5
5
5
/home/seth/Desktop/test.js:8
O.prototype.getZ = function () { return this.n; };
^
TypeError: Cannot read property 'n' of undefined
at O.getZ (/home/seth/Desktop/test.js:8:49)
at indirect (/home/seth/Desktop/test.js:21:12)
at Object.<anonymous> (/home/seth/Desktop/test.js:28:13)
at Module._compile (module.js:413:34)
at Object.Module._extensions..js (module.js:422:10)
at Module.load (module.js:357:32)
at Function.Module._load (module.js:314:12)
at Function.Module.runMain (module.js:447:10)
at startup (node.js:148:18)
at node.js:405:3
Activity
gcnew commentedon Aug 11, 2016
If you add
thisannotations, it will be an error:Sadly automatic inferring of
thisdidn't make it, because of negative performance implications :(. For further information see #6739