Repository: TypeScript
Issue: "File name X differs from Y only in casing." problem when using webpack style path alias
Labels: Bug,Help Wanted

Type: <b>Bug</b>

I am using webpack-style path aliases for Javascript imports. For example:
```
import { Pricing } from 'SRC/pricing.mjs';
```
with a `jsconfig.json` that looks like this:
```
{
    "compilerOptions": {
      "module": "es6",
      "target": "es6",
    },
    "baseUrl": ".",
    "paths": {
      "SRC/*": ["./src/*"]
    }
}
```
With the result that `SRC/pricing.mjs` is replaced with `{baseurl}/src/pricing.mjs` no matter what directory the importing code lives in.

This works fine, however I get warnings like the following in the 'Problems' view:
```
File name '<path to project>/SRC/pricing.mjs' differs from already included file name '<path to project>/src/pricing.mjs' only in casing.
  The file is in the program because:
    Matched by default include pattern '**/*'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/index-client.js'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/index-html.js'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/pricing-calculator-client.js'
    Imported via 'SRC/pricing.mjs' from file '<path to project>/src/page/pricing-calculator-html.js'
```
I think the code that checks for case insensitivity issues might not be fully / correctly aware of how `jsconfig.son` path aliases work.

I can workaround the issue by adding `"forceConsistentCasingInFileNames": false` to `compilerOptions` however then I don't get the general benefit of this problem detection.

If I use `SRC2` or `$SRC` instead of `SRC` everything is fine.

VS Code version: Code 1.77.3 (Universal) (704ed70d4fd1c6bd6342c436f1ede30d1cff4710, 2023-04-12T09:19:37.325Z)
OS version: Darwin arm64 22.4.0
Modes:
Sandboxed: Yes

<details>
<summary>System Info</summary>

|Item|Value|
|---|---|
|CPUs|Apple M1 Pro (10 x 24)|
|GPU Status|2d_canvas: enabled<br>canvas_oop_rasterization: disabled_off<br>direct_rendering_display_compositor: disabled_off_ok<br>gpu_compositing: enabled<br>metal: disabled_off<br>multiple_raster_threads: enabled_on<br>opengl: enabled_on<br>rasterization: enabled<br>raw_draw: disabled_off_ok<br>skia_renderer: enabled_on<br>video_decode: enabled<br>video_encode: enabled<br>vulkan: disabled_off<br>webgl: enabled<br>webgl2: enabled<br>webgpu: disabled_off|
|Load (avg)|2, 2, 2|
|Memory (System)|16.00GB (0.23GB free)|
|Process Argv|--disable-extensions . --crash-reporter-id eef3215b-4736-49de-82a2-9fef6d51c723|
|Screen Reader|no|
|VM|0%|
</details>Extensions disabled<details>
<summary>A/B Experiments</summary>

```
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pythonclientmv:30708685

```

</details>

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