Unreachable switch cases are not removed when switch value is known

[TheHolyWaffle]

When the value of a switch case is hardcoded, either literally in code or through define option, esbuild does not treeshake the unreachable switch cases.

Reproduction 0.24.2: https://esbuild.github.io/try/#dAAwLjI0LjIALS1taW5pZnkgAHN3aXRjaCAoImEiKSB7CiAgICBjYXNlICJhIjogewogICAgICBjb25zb2xlLmxvZygiYSIpOwogICAgfQogICAgY2FzZSAiYiI6IHsKICAgICAgY29uc29sZS5sb2coImIiKTsKICAgIH0KICB9

Expected output after minification:

console.log("a")

[evanw]

Thanks for the suggestion. I agree that this is something esbuild should be doing, as it's an easy win that could potentially lead to large size savings. This should also be added to esbuild's dead code analysis, which happens even without minification enabled (and which prunes edges in the module graph so they aren't even traversed in the first place during bundling).

[niedzielski]

as near as I can tell, this issue is still present in v0.25.0 both in the original report and in build mode.

[evanw]

Your code example is missing a break. The new minification logic doesn’t handle complex fall-through cases.