chore: build scripts use sed -E for cross-OS compatibility

[alex-courtis]

Many thanks to @Uanela for finding this one: #3261 (comment)

I'd be really grateful for your testing with the "standard" macos sed.

[v3ceban]

Oh, I had a lot of "fun" with this as well in the past! GNU and BSD (default macOS) sed are slightly different, particularly around the -i flag (GNU: sed -i, BSD: sed -i '') and how the r command behaves inside brace groups and with multiple -e expressions. The person here summarized the differences well. Below are a couple of workarounds that I found with a simple example from the help-defaults.sh:

---

Current usage:

sed -i -e "/${inject}/r /tmp/DEFAULT_OPTS.6.lua" -e "/${inject}/d" "${WIP}"

Workarounds:

1. Avoid using -i flag entirely and do a two-stage pipe to first filter, then delete, then replace:

# NOTE: POSIX `r` command reads the filename until end of line,
# so a newline is required after the filename to terminate it.
# GNU sed treats the end of the -e string as a line boundary, so it works, but technically it's not POSIX compliant.
sed "/${inject}/r /tmp/DEFAULT_OPTS.6.lua
" "${WIP}" | sed "/${inject}/d" > "${WIP}.tmp" && mv "${WIP}.tmp" "${WIP}"

2. Maintain two variants of the command and use the correct one for the given OS:

if [ "$(uname -s)" = "Darwin" ]; then
  sed -i '' "/${inject}/r /tmp/DEFAULT_OPTS.6.lua
  " "${WIP}"
  sed -i '' "/${inject}/d" "${WIP}"
else
  sed -i -e "/${inject}/r /tmp/DEFAULT_OPTS.6.lua" -e "/${inject}/d" "${WIP}"
fi

3. Replace sed with POSIX awk, which should behave the same on both systems:

awk "/${inject}/{while((getline line < \"/tmp/DEFAULT_OPTS.6.lua\") > 0) print line; next} {print}" "${WIP}" > "${WIP}.tmp" && mv "${WIP}.tmp" "${WIP}"

4. Require macOS users to install gsed and run the scripts with it on PATH:

PATH="$HOMEBREW_PREFIX/opt/gnu-sed/libexec/gnubin:$PATH" make help-update

or conditionally call gsed instead of sed based on user's OS (similar to the second workaround).

[Uanela]

@alex-courtis I will test this one shortly

[alex-courtis]

Below are a couple of workarounds that I found with a simple example from the help-defaults.sh:

Nice one @v3ceban , many solutions there.

1 is clear and simple. Using -i is not really necessary and is fragile and confusing.

3 is pragmatic, simple, compatible and there is precedent with doc-comments.sh

2 and 4 aren't very friendly and create friction.

Let's see how it tests.

[Uanela]

So far it LGTM. maybe if this one comes back we can try some more detailed (aka kind complex) solution. Sorry for such big delay.

[alex-courtis]

So far it LGTM. maybe if this one comes back we can try some more detailed (aka kind complex) solution. Sorry for such big delay.

Cheers for the rebase.

Merging this one, yes, we should simplify at some point. #3268 first.