Incorrect bash/zsh syntax highlighting

[VorpalBlade]

Issue Type: Bug

Vscode gets confused by the following fragment of zsh code (where the first line is taken verbatim from the _arguments completion helper code that is bundled with zsh):

"${(@)^${(@)tmp:#^*:*}//:/[}]"
# This part should not be in the string in zsh

The second line (and everything after in the file) is incorrectly considered part of the string by VSCode's shell syntax highlighting. For some to me unfathomable reason it appears VSCode does not properly detect the end quote of the string on the first line.

Here is how it looks in vscode:

Removing the last ] in the string "fixes" the highlighting (but of course breaks the code):

VS Code version: Code 1.66.2 (dfd34e8, 2022-04-11T07:49:24.808Z)
OS version: Linux x64 5.17.3-arch1-1
Restricted Mode: No

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz (8 x 2816)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: disabled_off opengl: enabled_on rasterization: disabled_software raw_draw: disabled_off_ok skia_renderer: enabled_on video_decode: disabled_software video_encode: disabled_software vulkan: disabled_off webgl: enabled webgl2: enabled
Load (avg)	1, 1, 0
Memory (System)	31.12GB (24.32GB free)
Process Argv	--disable-extensions --crash-reporter-id a77f92e1-4f12-4a9f-aad2-4dc61886222c
Screen Reader	no
VM	0%
DESKTOP_SESSION	cinnamon
XDG_CURRENT_DESKTOP	X-Cinnamon
XDG_SESSION_DESKTOP	cinnamon
XDG_SESSION_TYPE	x11

Extensions disabled

[VorpalBlade]

After debugging this I believe the issue may be that VSCode gives higher "precedence" to [] than {}. I believe that the [ and ] at the end in the code are in fact unrelated (though I admit the code is hard to read!).

"${var//:/[}]"

is a simplified example that still exhibits the issue. The correct interpretation of it is

1. $var but with all : replaced with [
2. A final ] outside the variable substitution.

Zsh processes nested substitutions from inside out, so the whole ${...} is processed before ] is considered, and a lone ] at the end of the string is a normal literal character (as is the [ in the replacement string of the //search/replace section), nothing fancy going on.

[VorpalBlade]

By the way, this is not zsh specific, I can reproduce this with the following bash code, which also syntax highlights incorrectly in vscode in the same manner:

v="a:b"
echo "${v/:/[}]"
# Prints a[b]

[alexr00]

We get our shellscript grammar from https://github.com/atom/language-shellscript, but the textmate grammar there is no longer maintained. This issue would need to be solved by adopting a new shellscript grammar: #77675