fix Issue 22023 - adding to escaped argument of a variadic defeats @…

[WalterBright]

…safe

[dlang-bot]

Thanks for your pull request, @WalterBright!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	22023	major	adding `return` to escaped argument of a variadic defeats @safe

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#13710"

[WalterBright]

Fixing this uncovered a related issue:

https://issues.dlang.org/show_bug.cgi?id=22818

[dkorpel]

Shouldn't this start as a deprecation?

[Geod24]

Aren't typesafe variadic inherently scope then ? They don't seem to be marked as such.

[WalterBright]

Aren't typesafe variadic inherently scope then ?

Only arrays and classes. See https://issues.dlang.org/show_bug.cgi?id=22818

[WalterBright]

Shouldn't this start as a deprecation?

Why would fixing a sure-fire crash require a deprecation?

[dkorpel]

Why would fixing a sure-fire crash require a deprecation?

It's not a sure-fire crash, someone might add return to a variadic array mistakenly thinking it would apply to the array elements. Or they did return a pointer to the array, but it was not stomped by new stack allocations before use.

Personally I don't mind making this an error directly, I only ask because you recently mentioned that people expect no breakage when not using preview switches.

[WalterBright]

@dkorpel you could apply that reasoning to every bug fix. This is why we leaven our rules with good judgement, and do not apply them absolutely.

[RazvanN7]

This PR has introduced a regression: https://issues.dlang.org/show_bug.cgi?id=23244 .