parseArgs duplicates collected + aliased arguments

[j0sh]

Version: Deno 1.41.2

The parseArgs function from https://deno.land/std/cli/parse_args.ts seems to duplicate collect arguments when an alias is part of the definition.

This affects the file_server with the --header option; this results in HTTP headers being written twice.

Minimal test case to repro:

import { parseArgs } from "https://deno.land/std/cli/parse_args.ts";
import { assertEquals } from "https://deno.land/std/assert/mod.ts";

Deno.test("collect with alias", () => {
  const args = ["--header", "abc", "--header", "def"];
  const parsed = parseArgs(args, {
    collect: ["header"],
    alias: {
      H: "header",
    },
  });
  assertEquals(parsed.header, ["abc", "def"])
})

Output:

$ deno test
running 1 test from ./duplicatedArgs.test.ts
collect with alias ... FAILED (4ms)

 ERRORS 

collect with alias => ./duplicatedArgs.test.ts:4:6
error: AssertionError: Values are not equal.


    [Diff] Actual / Expected


    [
      "abc",
-     "abc",
-     "def",
      "def",
    ]

Removing the alias makes things work as expected.

[iuioiua]

This issue belongs in https://github.com/denoland/deno_std

[kt3k]

This seems to have started from #4189

The example test case passes with [email protected] (and fails with [email protected]):

import { parseArgs } from "https://deno.land/[email protected]/cli/parse_args.ts";
import { assertEquals } from "https://deno.land/[email protected]/assert/mod.ts";

Deno.test("collect with alias", () => {
  const args = ["--header", "abc", "--header", "def"];
  const parsed = parseArgs(args, {
    collect: ["header"],
    alias: {
      H: "header",
    },
  });
  assertEquals(parsed.header, ["abc", "def"])
})

I'd suggest we should revert #4189

[timreichen]

I think I found the bug. The aliasMap Set for key contains key itself. On that example header contains header as an alias.

Map(2) {
  "H" => Set(1) { "header" },
  "header" => Set(2) { "H", "header" }
}

This is fixed by filtering out the key.

before:

const set = new Set([key, ...aliases]);
aliases.forEach((alias) => aliasMap.set(alias, set));

after:

aliases.forEach((alias) => aliasMap.set(alias, new Set([key, ...aliases.filter((it) => it !== alias)])));