Typescript autocompletion not appearing for function type parameters

[adamvictorclever]

Issue Type: Bug

I'm not 100% sure this is a bug, but it isn't what I expect to happen so I wanted to clarify.

If I have a type type test<T extends "x" |"y"> = T then when I type let val: test<" the autocompletion correctly appears and suggests either "x" or "y" as options.

However, if I have a function function test<T extends "x" | "y">() {} then when I try to call test and type test<" it doesn't suggest anything. I would have expected it to again suggest "x" or "y" as options. Fully typing test<"">() and hitting command + space still doesn't suggest anything. The type error Type '""' does not satisfy the constraint '"x" | "y"' does appear so Typescript seems to know what acceptable values are, just it doesn't suggest them.

Is this a bug or working as expected?

VS Code version: Code 1.35.1 (c7d83e5, 2019-06-12T14:29:22.216Z)
OS version: Darwin x64 18.7.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz (12 x 2200)
GPU Status	2d_canvas: enabled checker_imaging: disabled_off flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: enabled rasterization: enabled surface_synchronization: enabled_on video_decode: enabled webgl: enabled webgl2: enabled
Load (avg)	2, 2, 2
Memory (System)	16.00GB (1.91GB free)
Process Argv
Screen Reader	no
VM	0%

Extensions (4)

Extension	Author (truncated)	Version
vscode-eslint	dba	1.9.0
prettier-vscode	esb	2.3.0
Go	ms-	0.11.7
vscode-typescript-tslint-plugin	ms-	1.2.2

[mjbvz]

Thanks. Opened microsoft/TypeScript#34771 to track upstream