[Breaking Change] Typescript 3.7 converts reference paths to tsconfig specified paths breaking multi-project compiles.

[Griffork]

Typescript is replacing part of a relative path with one of the paths specified in tsconfig's path section. This is breaking the projects that rely on this file as they cannot resolve the path.

TypeScript Version: 3.7
Visual Studio Version: Community 2017

Search Terms:
Typescirpt paths tsconfig reference paths alias.

Code

In the client project at folder\folder\file.ts

/// <reference path="../../External/Knockout/index.d.ts" />

Becomes (in ClientDeclarations) folder\folder\file.d.ts:

/// <reference types="@Client/external/knockout/index" />

My tsconfig file (folder names with sensitive information are replaced with ***)

{
  "compileOnSave": true,
  "compilerOptions": {
    "module": "amd",
    "target": "es6",
    "lib": [ "es6", "dom" ],
    "sourceMap": true,
    "strict": true,
    "build": true,
    "declaration": true,
    "declarationDir": "../ClientDeclarations",
    "baseUrl": "./",
    "paths": {
      "@Common/*": [ "../Common/*" ],
      "@Server/*": [ "../ServerDeclarations/*" ],
      "@Client/*": [ "./*"]
    }
  },
  "include": [
    "./*",
    "./External/***/koco.ts",
    "./External/***/kocss.ts",
    "./External/***/kopath.ts"
  ],
  "exclude": [
    "node_modules"
  ],
  "references": [
    { "path": "../Common" }
  ]
}

Expected behavior:
The path should not be transformed during output.

Actual behavior:
The path is transformed to include an @Client reference, which my dependant projects can't resolve. This did not happen in tsc 3.4.

Additionally all of the casing is altered - meaning that this path would not resolve on linux machines.

Related Issues:
I haven't been able to find any - probably because what I'm trying to look for is called a "path" (in tsconfig) which is a highly overloaded term, making searching for anything related to it almost impossible. It would be nice to call it something like a "path alias" so that searching for related issues was easier.

[Griffork]

I think I found the root of the issue (from issue 5112):

The .d.ts files are considered "references" the compiler will not touch them, not move them, or recreate them. the only thing it will do, if you have a /// to an input.d.ts, the generated output will have the reference rewritten to point to the source location.

Typescript is now rewriting the paths to use the custom paths specified in tsconfig rather than a relative path breaking the project that includes the client. The project that includes client specifies @Client as relative the the declaration output directory (which doesn't have Knockout/index.d.ts because declaration files don't get copied to the output directory) whereas client specifies @Client as relative to it's own directory.

[DanielRosenwasser]

@weswigham wasn't there another similar issue you'd been involved in?

[sheetalkamat]

Does https://github.com/microsoft/TypeScript/compare/experimentRelativePaths help this.. I had prototyped this for internal team who was running into similar issue but later they said they will work around it.

[Griffork]

@sheetalkamat I don't know enough about tsc's code to know what that commit is doing.

[sheetalkamat]

@Griffork You can build from that branch and see if that fixes your issue.

[Griffork]

@sheetalkamat sorry I don't really have time to do that at the moment due to various work deadlines and home circumstances 😟. I just made a temporary fix so I could keep working (a post-build script that fixes all the paths) while waiting for replies.

I will still need this fixed eventually or I'll have to revert but I'd rather not because the ?. operator is the best thing since the ! operator.

[huntjosh]

Running into the same issue on another multi-project, only occurs when adding the baseUrl property. Will try the custom branch.

[Griffork]

@huntjosh did the custom branch work for you?

[jacobbubu]

Running into the same issue on another multi-project, only occurs when adding the baseUrl property. Will try the custom branch.

I've got the same issue as yours.

[Griffork]

I just updated to 4.0 and this issue is present again (but in reverse?). I now have a file in my server which has decided to export a particular type using an inline import rather than a top-level import. The inline import is being resolved to a relative path through import/exports even though the original import statement uses a path alias:

Server's Actor.ts

import { Actor as ActorBase } from "@Common/GameMechanics/Actors/Actor";
import { Actor as ClientActor } from "@Client/GameMechanics/Actors/Actor/Actor"; //used for something else.
export module Actor {
	export type Definition = ActorBase.Definition;
}

Server's World.ts

import { World as ClientWorld } from "@Client/GameMechanics/Environment/World";
import { Actor } from "../Actors/Actor";
import { Structure } from "@Common/GameMechanics/Environment/Structure";

export module World {

	//---------- Definitions.
	var EntityDefinitions = new Map<string, Actor.Definition | Structure.Definition>();

	export function GetDefinition(name: string) {
		return EntityDefinitions.get(name);
	}
}

Server's World.ts output:

import { Structure } from "@Common/GameMechanics/Environment/Structure";
export declare module World {
    function GetDefinition(name: string): Structure.Definition | import("../../../Common/GameMechanics/Actors/Actor").Actor.Definition | undefined;
}

Is there a way for me to force these imports to always be top-level and not get erased? It's particularly weird to me that the import is being inlined ignoring a middle file.