Regression 3.7.2 : Build with Project References ignore prepend: false when compileonsave is true and outfile

[Outlivier]

Search Terms: Project references prepend composite

Description

In Visual Studio 2019, with nuget package Microsoft.TypeScript.MSBuild.3.7.2, and <TypeScriptBuildMode>true</TypeScriptBuildMode> in .csproj file, with the following structure :

FolderA
    A.ts
    tsconfig.json
FolderB
    B.ts
    tsconfig.json

• A.ts

let a: number = 15;

• FolderA\tsconfig.json

{
	"compileOnSave": true,
	"compilerOptions": {
		"noImplicitAny": false,
		"noEmitOnError": true,
		"removeComments": false,
		"sourceMap": true,
		"target": "es5",
		"composite": true,
		"declarationMap": true,
		"declaration": true,
		"outFile": "../file-a.js"
	},
	"exclude": [
		"node_modules",
		"wwwroot"
	]
}

• B.ts

let b: number = a + 15;

• FolderB\tsconfig.json

{
	"compileOnSave": true,
	"compilerOptions": {
		"noImplicitAny": false,
		"noEmitOnError": true,
		"removeComments": false,
		"sourceMap": true,
		"target": "es5",
		"composite": true,
		"declarationMap": true,
		"declaration": true,
		"outFile": "../file-b.js"
	},
	"exclude": [
		"node_modules",
		"wwwroot"
	],
	"references": [
		{ "path": "../FolderA/tsconfig.json", "prepend":  false }
	]
}

Expected behavior:

When Modifing File B.ts, after saving, the output of file-b.js should be

var b = a + 15;

Actual behavior:

The output of FolderA is prepend in file-b.js :

var a = 15;
var b = a + 15;

This behavior doesn't happen if

• TypeScript version is 3.6.4 instead of 3.7.2.
• CompileOnSave is false, and we build the project after modifing files.

[sheetalkamat]

This is fixed by #35335 and duplicate of #35226