Migrating from getExpressionInfo to expression wrappers

[GulgDev]

Replace the obsolete getExpressionInfo with expression wrapper functions.

[GulgDev]

Related discussion: #7515

[kripken]

Nice!

[GulgDev]

Maybe we can make Expression constructor return the specific instance? Can we just make the instruction-building functions return expression wrappers? That shouldn't be a breaking change, as expression wrappers can be implicitly converted to Wasm pointers via valueOf (e.g. +expr or expr | 0).

[kripken]

Maybe we can make Expression constructor return the specific instance?

Sorry, what do you mean here? What type of code can construct something with only Expression?

[GulgDev]

I mean that the Expression constructor could possibly act as wrapExpression.

binaryen/src/js/binaryen.js-post.js

Lines 4052 to 4057 in 90ad796

	// Base class of all expression wrappers
	/** @constructor */
	function Expression(expr) {
	if (!expr) throw Error("expression reference must not be null");
	this[thisPtr] = expr;
	}

[kripken]

I see, thanks. Yes, I guess it could. Initially it felt slightly odd to me, maybe because in C++ Expression(..) returns an Expression, not the more specific subclass... but in JS it seems ok, and I can't think of anything simpler. Let's go with that.