Typescript workspace problems not being detected

[rbingham]

VsCode will only report typescript problems when files with the problems are open even though there is a tsconfig.json file.

• VSCode Version: 1.18.1
• OS Version: Arch Linux 4.13.12-1 (Kernel version)

Steps to Reproduce:

1. Create typescript project with two typescript files: index.ts and test.ts
2. export class from test.ts
3. import class from test into index.ts and call non-existant method on the imported class. Error appears
4. close index.ts error disappears

tsconfig.json contents

{
	"compilerOptions": {
			"target": "es6",
			"module": "commonjs",
			"sourceMap": true,
			"rootDir": "./"
	},
	"include": [
		"**/*.ts"
	]
}

test1.ts contents

export class test {
    public static test123(): number {
        console.log('Hello World');
        return 0;
    }
}

index.ts contents

import { test } from "./test";

test.main();

Reproduces without extensions: Yes

In the gif, the tsconfig.json has the 'files' option, but I can confirm that it is still happening when using the 'include' option

[mjbvz]

duplicate of #13953