`forceConsistentCasingInFileNames` does not always work with `paths` compiler option

[stephenbrady]

TypeScript Version: 2.4.2

Code

// Base tsconfig at /Users/a_user/a_repo/core.json
{
  "compilerOptions": {
    "forceConsistentCasingInFileNames": true,
    "baseUrl": "",
    "paths": {
      "*": [ "*", "src/*" ]
    }
  }
}

// tsconfig at /Users/a_user/a_repo/tsconfig.json
{
  "extends": "./core"
}

// Source file in /Users/a_user/a_repo/src/foo.ts
const v = 1;
export default v;

// Source file in /Users/a_user/a_repo/src/bar.ts
import v from "foo";

Expected behavior:
No compiler errors/warnings

Actual behavior:

error TS1149: File name '/Users/a_user/a_repo/src/foo.ts' differs from already included file name '/users/a_user/a_repo/src/foo.ts' only in casing.

---

This is running on OS X 10.9.5 (default case-insensitive HFS file system).

I am only able to reproduce the issue when using configuration inheritance. Using an absolute path with the expected casing for baseUrl resolves the issue.

This issue is filed off of these remarks: #17542 (comment)

[aluanhaddad]

Thank you for filing this. I see the exact same behavior. Interestingly, if I set baseUrl in the extending tsconfig, it also resolves the error.

[afshinm]

I have the same problem on mac OS, node 7.6.0.

[arackaf]

Reproduced on Windows 10 as well. Interestingly, we don't even have paths set. Full tsconfig:

{
    "compilerOptions": {
        "target": "esnext",
        "baseUrl": "./src",
        "jsx": "react",
        "allowSyntheticDefaultImports": true,
        "allowUnreachableCode": true,
        "allowJs": true,
        "moduleResolution": "node",
        "module": "es2015",
        "experimentalDecorators": true,
        "forceConsistentCasingInFileNames": true,
        "lib": ["es2015", "dom"],
        "typeRoots" : ["./typings/modules", "./node_modules/@types"]
    },
    "include": [
        "./src/**/*.ts",
        "./src/**/*.tsx",
        "./src/**/*.js",
        "./src/**/*.jsx",
        "./test/**/*.ts*"
    ],
    "exclude": [
        "./node_modules/**/*",
        "./dist/**/*",
        "./src/assets/**/*",
        "./src/build/**/*"
    ]
}

[aluanhaddad]

@arackaf it is --baseUrl that causes the issue. When it is inherited, it seems to get resolved in such a way that the resulting paths begin with its lowercase variant. the simplest work around currently is to specify the base URL a second time in the inheriting configuration.

[arackaf]

What do you mean "inherited" ? I only have one tsconfig file - what's being inherited where?

[aluanhaddad]

Sorry, it's not in the issue title but the op states that the issue can only be reproduced when using configuration inheritance. This has been my experience as well.

I'm also running Windows 10, professional x64