Passing the result of typeof into a generic fucntion causes an AssertionError in the compiler?

[Heath123]

Save this to test.ts

function test<T>(value: T): void {}
test(typeof 1)

$ asc test.ts --binaryFile test.wasm

▌ Whoops, the AssemblyScript compiler has crashed during compile :-(
▌ 
▌ Here is the stack trace hinting at the problem, perhaps it's useful?
▌ 
▌ AssertionError: assertion failed
▌     at assert (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/std/portable/index.js:200:11)
▌     at h.resolveUnaryPrefixExpression (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/resolver.ts:1781:16)
▌     at h.resolveExpression (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/resolver.ts:1108:21)
▌     at h.maybeInferCall (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/resolver.ts:746:27)
▌     at f.compileCallExpression (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/compiler.ts:6330:46)
▌     at f.compileExpression (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/compiler.ts:3490:21)
▌     at f.compileExpressionStatement (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/compiler.ts:2521:17)
▌     at f.compileStatement (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/compiler.ts:2213:21)
▌     at f.compileTopLevelStatement (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/compiler.ts:2175:25)
▌     at f.compileFile (/usr/lib/node_modules/assemblyscript/dist/webpack:/assemblyscript/src/compiler.ts:1111:12)
▌ 
▌ If it refers to the dist files, try to 'npm install source-map-support' and
▌ run again, which should then show the actual code location in the sources.
▌ 
▌ If you see where the error is, feel free to send us a pull request. If not,
▌ please let us know: https://github.com/AssemblyScript/assemblyscript/issues
▌ 
▌ Thank you!

[romdotdog]

This is a bug, for sure

for the record, the correct code is

function test<T>(value: T): void {}
test<typeof 1>(1)

[Heath123]

This is a bug, for sure

for the record, the correct code is

function test<T>(value: T): void {}
test<typeof 1>(1)

Well, not in this case, it was a log function and I wanted to see what the type was as a string

Original code:

let a: i32 = 1
let b: u32 = 2
let c = a + b
log(typeof c)

[romdotdog]

I don't believe we should allow such JS-like behavior as it might lead to "abuse" (comparing types by checking for string equality) which could lead to a performance penalty. For type checking, it's better to use

function idof<T>(): u32

otherwise, if you're logging for debugging purposes, we have

function nameof<T>(value?: T): string

e.g.

let a: i32 = 1
let b: u32 = 2
let c = a + b
log(nameof(c))

from: https://www.assemblyscript.org/stdlib/globals.html#utilities

[dcodeIO]

There is an implementation of the typeof unary operator that is supposed to always return a string. It's relatively limited, in that the string adheres to what JS would return, but it should work.

assemblyscript/src/compiler.ts

Lines 9821 to 9823 in e89cec2

	case Token.TYPEOF: {
	return this.compileTypeof(expression, contextualType, constraints);
	}

The assertion indicates that it is only implemented in compile* functions and that the resolver is missing it around here. That would in fact be a bug.