1283534 - Debugger.Environment expects all bindings to be aliased on ModuleEnvObject

Status: RESOLVED DUPLICATE of bug 1518308

(Core :: JavaScript Engine, defect)

Description

[Jon Coppeard (:jonco)]

As reported by shu on IRC.

From DebugScope::handleUnaliasedAccess:

        if (scope->is<ModuleEnvironmentObject>()) {
            /* Everything is aliased and stored in the environment object. */
            return true;
        }

This has not been true since bug 1233109.

Comment 1

[Jon Coppeard (:jonco)]

I'm trying to write a test to exercise this but I'm having trouble working out how to do it.

From the comments in ScopeObject.cpp it seems like I need to have a DebugScopeObject for a module that is no longer executing.  Is that right?  

I tried this:

    var g = newGlobal();
    var dbg = Debugger(g);
    var env;

    dbg.onDebuggerStatement = function (frame) {
        env = frame.environment;
    };

    g.eval(
    `
        let m = parseModule(
        \`
            var a = 1;
            debugger;
        \`);
        m.declarationInstantiation();
        m.evaluation();
    `);

     assertEq(env.getVariable('a'), 1);

I saw a DebugScopeObject being created, but none of the proxy handler methods for it got called and the test passes.  Any ideas how to do this?

Comment 2

[Jon Coppeard (:jonco)]

The method in the description is called DebugEnvironmentProxyHandler::handleUnaliasedAccess now.

Comment 3

[Jon Coppeard (:jonco)]

Jim, do you know how to proceed here?  I don't understand how debug scopes work enough to work out how to trigger this.

Comment 4

[Jon Coppeard (:jonco)]

bhackett pointed out that the debugger statement marks all variables in scope as aliased which explains why the test didn't work. The bug itself will be fixed by bug 1518308.