Fix Issue 23480 - non-empty ForStatement Increment clause should requ…

[ntrel]

…ire a side effect

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	23480	enhancement	non-empty ForStatement Increment clause should require a side effect

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#14638"

[ntrel]

OK so this triggers an error for dagon on buildkite for this line:

        for (auto i = ai_res.ai_addrlen; i > 0; --i, *dp++, *sp++)

The dereferences are useless, but I suppose that means the error needs to change to a deprecation.

[RazvanN7]

The dereferences are useless, but I suppose that means the error needs to change to a deprecation.

Why do you say that *dp++ is useless? It certainly does have a side effect, it increments the value pointed at by dp. Why do you think that this should be disallowed?

Yeah, I thought that * had priority over ++. Looking at [1] I thought that priority 0 meant that it has the biggest precedence.

[1] https://wiki.dlang.org/Operator_precedence