Compiler Error on Empty file: Cannot find name 'Promise'.

[aozgaa]

TypeScript Version: master, commit 8ad68ad

Reproduced on Win10 and Ubuntu 16.04.

Code

Note: this initially appeared with nonempty files, but I tried to minimize the repro.

1. Create an empty file called "empty.ts" in a folder without tsconfig.json or anything else

2. rm -rf node_modules in the typescript repo

3. npm install and (in case you didn't have it before) npm install -g jake

4. build typescript with 'jake local'

5. Run node /path/to/built/local/tsc.js /path/to/anything.ts from the TypeScript repo folder.

Expected behavior:

Compiles successfully.

Actual behavior:

Fails with the following errors:

node_modules/@types/del/index.d.ts(10,40): error TS2304: Cannot find name 'Promise'.
node_modules/@types/del/index.d.ts(11,62): error TS2304: Cannot find name 'Promise'.
node_modules/@types/del/index.d.ts(13,43): error TS2304: Cannot find name 'Promise'.
node_modules/@types/del/index.d.ts(14,65): error TS2304: Cannot find name 'Promise'.

[aozgaa]

The problem was caused by some contents of the node_modules folder in the TypeScript repo folder.

If we don't build by specifying a tsconfig.json file at the command-line, it appears node modules are automatically loaded by walking up from the working directory, following the rules on the module resolution page.
It's unclear to me why, philosophically, any modules are searched for at all.

Building from a path that doesn't include the TypeScript repo prevents us from loading the problematic node module.

Workarounds:

1. call tsc.js from a working directory that doesn't include the offending node_modules along the path. Ie: don't issue the build command while in the TypeScript repo.

2. Add a tsconfig.json file which includes the single file, and build by pointing towards that.

3. Add the compiler flag --lib es6 to the commandline operation so promises are available.

This may be related to #11803.

[aozgaa]

Any thoughts on proper behavior here / why we do what we do in the status quo, @mhegazy, @billti, @vladima ?

[mhegazy]

the node_modules@types are automatically included. some of them depend on ES6 objects. so you get this error. I plan to discuss this in the next design meeting under #11396