zsh-users/zsh-syntax-highlighting

$READNULLCMD / $NULLCMD are red

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#716 opened on Mar 23, 2020

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BugTaskgood first issuesyntax:command-word

Description

% tests/generate.zsh '$NULLCMD | $READNULLCMD' main nullcmd 'local NULLCMD=cat READNULLCMD=f; f(){};' 
Set copyright year to 2020? y
local NULLCMD=cat READNULLCMD=f; f(){};

BUFFER=$'$NULLCMD | $READNULLCMD'

expected_region_highlight=(
  '1 8 unknown-token' # $NULLCMD
  '10 10 commandseparator' # |
  '12 23 unknown-token' # $READNULLCMD
)

That's likely because they're special, and as such don't get expanded (which makes this another case of #695):

% p ${(t)READNULLCMD} ${(t)NULLCMD}
scalar-special scalar-special

Contributor guide

Tech stack
shell
Domain
developer experiencecli
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
basic zsh knowledgegitshell scripting
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate how $NULLCMD and $READNULLCMD are handled in the highlighting code (likely in 'highlighters/main/main highlight.zsh'). The issue notes they have the 'special' attribute, which prevents expansion. See reference to issue #695 for similar cases. The fix likely involves adding them to a list of variables that should be expanded despite being special. Look for where other special variables are expanded and replicate for these two.