Closure Compiler Generated Source Maps Don't Let Preview Values

[zavr-1]

Issue Type: Bug

The source maps works itself, but I can't hover over variables to get their names. It's not the case in Chrome.

VS Code version: Code 1.33.1 (51b0b28, 2019-04-11T08:22:55.268Z)
OS version: Darwin x64 18.0.0

map.js

This is the source code.

const get = async () => {
  const { hash, port  } = process.env
  return { hash, port }
}
(async () => {
  const res = await get()
  console.log(res)
})()

map1.js

This is the generated source code using Google Closure Compiler.

'use strict';
const c = async() => {
  const {hash:a, port:b} = process.env;
  return {hash:a, port:b};
};
(async() => {
  const a = await c();
  console.log(a);
})();


# sourceMappingURL=map1.js.map

map1.js.map

This is the map produced by the compiler.

{
"version":3,
"file":"t/map-vs/map1.js",
"lineCount":10,
"mappings":"A;AAAA,MAAMA,IAAMA,KAAM,EAANA,IAAY;AACtB,QAAM,CAAE,KAAAC,CAAF,EAAQ,KAAAC,CAAR,CAAA,GAAkBC,OAAAC,IAAxB;AACA,SAAO,CAAEH,KAAAA,CAAF,EAAQC,KAAAA,CAAR,CAAP;AAFsB,CAAxB;AAIC,MAAM,EAAN,IAAY;AACX,QAAMG,IAAM,MAAML,CAAA,EAAlB;AACAM,SAAAC,IAAA,CAAYF,CAAZ,CAAA;AAFW,CAAZ,CAAD,EAAA;;",
"sources":["t/map-vs/map.js"],
"sourcesContent":["const get = async () => {\n  const { hash, port  } = process.env\n  return { hash, port }\n}\n(async () => {\n  const res = await get()\n  console.log(res)\n})()"],
"names":["get","hash","port","process","env","res","console","log"]
}

It's great that the source map works, and I know I can't hover over { hash, port } because of return optimisations, but I should be able to preview res. And it's the simplest example, there's the same problem in more complex code.

this is the visualisation

[zavr-1]

This works in Chrome btw https://contexttesting.github.io/mask/

[isidorn]

@zavr-1 When you are stopped at that point do you see a variable res in the variables view?

[zavr-1]

nope I see a which is closure's variable. you can copy the scripts i've attached you'll be able to reproduce.

[isidorn]

Well that is the issue, our debug hover has that limitation that it only looks in the variables view to find variables.
And node debug is returning the closure variable name. Not sure if something can be done here @roblourens

[roblourens]

This looks like #12066

[zavr-1]

@roblourens @isidorn thanks for looking into it. Didn't know VSCode doesn't support this feature.