[rollup-plugin-typescript] declarationDir inside same directory as file option

[mririgoyen]

Perhaps related to #1772.

• Rollup Plugin Name: rollup-plugin-typescript
• Rollup Plugin Version: 12.1.0
• Rollup Version: 4.22.4
• Operating System (or Browser):
• Node Version: 20.17

Expected Behavior

Nested sub-directories continue to be valid.

Actual Behavior

Based on the breaking change, output must be the same as the declaration directory. However, I believe this check is being over-zealous, disallowing sub-directories within the declaration directory.

After the v12 update, the following error is presented:

@rollup/plugin-typescript: Path of Typescript compiler option 'declarationDir' must be located inside the same directory as the Rollup 'file' option.

Additional Information

The declaration directory in tsconfig.json:

"declarationDir": "lib",

The rollup config:

  {
    input: 'src/tailwind/config.ts',
    output: [{ file: 'lib/tailwind/config.js', format: 'cjs' }],
    plugins: [
      typescript({
        filterRoot: 'src/tailwind',
      }),
    ],
  },

If I simplify the output to lib/config.js, the error is gone. However, my directory structure is no longer valid.

[shellscape]

We'd be happy to take a look at a Pull Request which resolves this condition, but one which keeps current tests passing.

(Please also note that moving forward, issues without a valid reproduction will be moved to a Q & A discussion. Those aren't optional, and the issue template mentions that a bunch)