Issue with Edge not respecting TerserOptions

[LuisAverhoff]

I have a piece of code that relies on function.prototype.name like so

public typeIs<TNewType>(newTypeAssertion: new (...args: any[]) => TNewType) {
    this.stringValue = `TypeIs:${newTypeAssertion.name}`
    this.segmentType = 'typeIs'
    return this.finialize<TNewType>()
  }

Initially my terser options didn't set keep_fnames to true and that caused my web application in both chrome and edge to not function properly. Now it looks like this.

minimizer: [
        new TerserPlugin({
          cache: true,
          parallel: true,
          terserOptions: {
            keep_fnames: true // This is so that the typeIs function works in production.
          }
        })
      ],

And now the function name does not get mangle in chrome but still somehow gets mangled in edge even with keep_fnames set to true. I did find a solution by doing this

minimizer: [
        new TerserPlugin({
          cache: true,
          parallel: true,
          terserOptions: {
            keep_fnames: true // This is so that the typeIs function works in production.
            compress: false // Now newTypeAssertion.name does not get mangled in edge as well.
          }
        })
      ],

But I don't want to do that because my bundle would increase quite a bit. Any clue as to why edge still mangles the function name and why setting compress to false works?

[alexander-akait]

@LuisAverhoff please use issue template