TypeScript: Warning for upper case lib value in tsconfig.json

[sangaman]

• VSCode Version: 1.22.2
• OS Version: Windows 10 Home - 10.0.16299 Build 16299

Steps to Reproduce:

1. In a TypeScript project, go to tsconfig.json and set a value for lib using upper case letters such as ES2015 or ES2016
2. Observe a warning message Value is not accepted. Valid values: "es5", "es6", "es2015", "es7", "es2016", "es2017", "es2018", "esnext", "dom", "dom.iterable", "webworker", "scripthost", "es2015.core", "es2015.collection", "es2015.generator", "es2015.iterable", "es2015.promise", "es2015.proxy", "es2015.reflect", "es2015.symbol", "es2015.symbol.wellknown", "es2016.array.include", "es2017.object", "es2017.sharedmemory", "es2017.string", "es2017.typedarrays", "es2018.promise", "es2018.regexp", "esnext.array", "esnext.asynciterable".

I'm not sure if this is a problem with vscode specifically but I haven't been able to connect it to anything else. The possibly values on the official website do have upper case letters (https://www.typescriptlang.org/docs/handbook/compiler-options.html) and there's no warning message if the target value uses upper case letters.

It would be desirable if the lib option behaves like target and accepts either upper or lower case letters without warnings, either way works as far as compiling code goes.

Does this issue occur when all extensions are disabled?: Yes

[mjbvz]

Opened SchemaStore/schemastore#449 to track this upstream