"delete all unused declarations" really only deletes declarations

[mjbvz]

From alexfung888 on June 8, 2018 4:34

Issue Type: Bug

let useless = true;
useless = false;

VSCode notices that the variable is never read. It will offer to delete the declaration (the first line), but it won't delete the second line. Then user will need to hunt down all the updates, which are now flagged in red as cannot fine name 'useless'

VS Code version: Code 1.24.0 (6a6e02cef0f2122ee1469765b704faf5d0e0d859, 2018-06-06T17:35:40.560Z)
OS version: Windows_NT x64 10.0.17134

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz (8 x 3392)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software rasterization: disabled_software video_decode: enabled video_encode: enabled vpx_decode: unavailable_software webgl: enabled webgl2: enabled
Memory (System)	7.88GB (1.01GB free)
Process Argv	C:\Program Files\Microsoft VS Code\Code.exe
Screen Reader	no
VM	0%

Extensions (13)

Extension	Author (truncated)	Version
path-intellisense	chr	1.4.2
githistory	don	0.4.1
EditorConfig	Edi	0.12.4
tslint	eg2	1.0.30
Angular2	joh	6.1.1
azure-account	ms-	0.4.0
PowerShell	ms-	1.7.0
debugger-for-chrome	msj	4.5.0
angular2-inline	nat	0.0.17
vscode-docker	Pet	0.0.27
ejs-language-support	Qas	0.0.1
vscode-bolt-language	smk	0.0.4
autoimport	ste	1.5.3

Copied from original issue: microsoft/vscode#51416

[mjbvz]

From alexfung888 on June 8, 2018 5:8

Actually the same happens to function parameters. When VSCode deletes the unused parameters for you, you will need hunt down all the callers to fix their parameter list, hoping that it will no longer match the signature.

In this pathetic case, the behaviour will change after b is removed, and the author may not even notice!

private f (a: number, b: number, c?: number) {
 return c ? 42 : a;
}
f(3, 5);

Reopening for the parameter part.