Template strings are cached incorrectly

[wlinna]

TypeScript Version: 3.2.0-dev.20180929

Search Terms:

• template literal

Code

var invokes = [];
function test(template, _) {
  invokes.push(template); 
}

function update(value) {
  test`some ${value}!`;
}

update(1);
update(2);

document.body.textContent = '' + (invokes[0] === invokes[1]); 

Expected behavior:
After compiling and running the code in a browser console, the body's content should be "true".

The code works as expected when compiled with Babel, or run verbatim in a browser console.

Actual behavior:
The body's content becomes "false". This breaks libraries such as hyperHTML (note: now it contains a workaround that works for me at least WebReflection/hyperHTML@6d3d879)

WebReflection/hyperHTML#270

Playground Link: https://www.typescriptlang.org/play/#src=var%20invokes%20%3D%20%5B%5D%3B%0D%0Afunction%20test(template%2C%20_)%20%7B%0D%0A%20%20invokes.push(template)%3B%20%0D%0A%7D%0D%0A%0D%0Afunction%20update(value)%20%7B%0D%0A%20%20test%60some%20%24%7Bvalue%7D!%60%3B%0D%0A%7D%0D%0A%0D%0Aupdate(1)%3B%0D%0Aupdate(2)%3B%0D%0A%0D%0Adocument.body.textContent%20%3D%20''%20%2B%20(invokes%5B0%5D%20%3D%3D%3D%20invokes%5B1%5D)%3B%20%0D%0A

Related Issues:

• Tagged template literals compiled incorrectly, TemplateStringsArray not cached #17956

[DanielRosenwasser]

The problem here is that we do the right thing in modules, but not in the global scope because we don't want to have potentially conflicting variables. So we could just come up with absurdly long variable names that describe the string contents and work with that.