Snippet transforms don't work with choice placeholders

[a01fe]

Issue Type: Bug

Snippet placeholder transforms do not work when the placeholder has choices instead of a default value.

Reproduce with this snippet:

"test": {
	"prefix": "test",
	"body": [
		"placeholder thing ${1:this}",
		"choice thing ${2|this,that,other|}",
		"transform placeholder ${1/(this)|(that)|(other)/${1:+1}${2:+2}${3:+3}/}",
		"transform placeholder ${2/(this)|(that)|(other)/${1:+1}${2:+2}${3:+3}/}",
		"$0"
	],
	"description": "test test test"
}

Expanding the snippet with that entered for both placeholders results in:

placeholder thing that
choice thing that
transform placeholder 2
transform placeholder that

VS Code version: Code - Insiders 1.27.0-insider (e0a6826, 2018-08-22T05:12:41.569Z)
OS version: Darwin x64 16.7.0

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz (8 x 4200)
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 video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled
Load (avg)	2, 2, 1
Memory (System)	64.00GB (42.73GB free)
Process Argv	/Applications/Visual Studio Code - Insiders.app/Contents/MacOS/Electron
Screen Reader	no
VM	43%

Extensions (18)

Extension	Author (truncated)	Version
xml	Dot	2.3.2
EditorConfig	Edi	0.12.4
asciidoctor-vscode	joa	0.15.0
vscode-emacs-friendly	lfs	0.8.2
mssql	ms-	1.4.0
python	ms-	2018.7.1
azure-account	ms-	0.4.3
PowerShell	ms-	1.8.3
gradle-language	nac	0.2.3
vscode-docker	Pet	0.1.0
remote-vscode	raf	1.1.0
java	red	0.29.0
code-spell-checker	str	1.6.10
vscode-java-debug	vsc	0.11.0
vscode-java-pack	vsc	0.3.0
vscode-java-test	vsc	0.8.0
vscode-maven	vsc	0.10.0
plsql-language	xyz	1.4.2

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Test placeholder transformations (#52796)
• Add default value for placeholders or add label to Choice (#44216)
• Snippets: placeholder with both default value and transform don't work (#56703)
• Inconsistent propagation of transformed placeholder (#52968)

[jrieken]

Yeah, that's the design and I don't think that Textmate snippets support that.

[a01fe]

Ahh, ok. If there's a design reason for disallowing placeholders with choice values to be used with transforms, then perhaps the documentation should reflect that?

[jrieken]

We have this document (and a grammar definition): https://code.visualstudio.com/docs/editor/userdefinedsnippets#_grammar

[vscodebot]

This issue is being closed to keep the number of issues in our inbox on a manageable level, we are closing issues that are not going to be addressed in the foreseeable future: We look at the number of votes the issue has received and the number of duplicate issues filed. If you disagree and feel that this issue is crucial: We are happy to listen and to reconsider.

If you wonder what we are up to, please see our roadmap and issue reporting guidelines.

Thanks for your understanding and happy coding!

[ChuckJonas]

Come-on... At the very least the documentation needs to be updated to reflect this limitation. Wasted a lot of time trying to figure this out.