local unbound variable not detected

[jaysoffian]

For bugs

• Rule Id (if any, e.g. SC1000):
• My shellcheck version (shellcheck --version or "online"): online and 0.6.0
• The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)
• I tried on shellcheck.net and verified that this is still a problem on the latest commit

For new checks and feature suggestions

• shellcheck.net (i.e. the latest commit) currently gives no useful warnings about this
• I searched through https://github.com/koalaman/shellcheck/issues and didn't find anything related

Here's a snippet or screenshot that shows the problem:

#!/bin/bash

set -u

fn1() {
        local foo=foo
        echo "$foo"
}

fn2() {
        echo "$foo"  # foo is undefined here because it is local to fn1 and not called from fn1.
}

fn1
fn2

Here's what shellcheck currently says:

Nothing. :-(

Here's what I wanted or expected to see:

foo is not defined in fn2 because it was declared local in fn1 so ShellCheck should warn about this. I realize scoping is dynamic, not lexical but I think even a lexical analysis with a warning such as:

Line 11:
        echo "$foo"
              ^-- SCXXXX: foo is referenced but may not be assigned.

Maybe related to #1497 and #1225. Possible dupe of #518.

[matthewpersico]

Huh? You just assigned the string “foo” to the variable $foo in the previous line; what am I missing?

[jaysoffian]

@matthewpersico I updated the description to be clearer. foo is local to fn1 so ShellCheck should warn about the reference to $foo in fn2.

[matthewpersico]

Duh. Seems I can’t count to 11. 🤦🏻‍♂️ Thanks.

[SebastianSimon]

This is the same issue as ShellCheck failing to warn about the unused variable foo (in function y) in this script, isn’t it?

#!/bin/bash

x(){
  local foo='foo'

  echo "${foo}"
}

y(){
  local foo='foo' # This is unused! Why doesn’t ShellCheck warn about it?

  echo "no foo"
}

x
y