Track: mvdan.cc/sh array slicing bug workaround

[kolkov]

Summary

We have a workaround in internal/metadata/evaluator.go for a bug in mvdan.cc/sh where array slicing inside double quotes returns the full array instead of the slice.

The Bug

# Bash (correct)
$ bash -c 'a=(1 2 3 4 5); echo "${a[@]:2:2}"'
3 4

# mvdan.cc/sh (wrong)
$ gosh -c 'a=(1 2 3 4 5); echo "${a[@]:2:2}"'
1 2 3 4 5

Without quotes it works correctly:

$ gosh -c 'a=(1 2 3 4 5); echo ${a[@]:2:2}'
3 4

Upstream

• Bug Report: interp: array slicing inside double quotes doesn't work correctly mvdan/sh#1239
• Status: Accepted by maintainer, awaiting fix

Workaround

internal/metadata/evaluator.go — The ver_cut function uses indexed variables (comp_0, comp_1, ...) instead of array slicing to avoid the bug.

Action Items

• Monitor upstream issue status
• When mvdan.cc/sh releases fix, update dependency
• Remove workaround and use standard array slicing
• Close this issue

Related

• continue on #45 same error for emerge #50 — Original issue about gcc SRC_URI evaluation