fix issue 17290 - DMD crash due to circular reference in function return type

[ghost]

The fix is actually a generalization of what's been done in #9365.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	17290	normal	DMD crash due to circular reference in function return type

Testing this PR locally

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

dub fetch digger
dub run digger -- build "master + dmd#9403"

[thewilsonator]

Otherwise looks good.

[thewilsonator]

Test runnable/gdb15729.sh failed. The logged output:
warning: Error disabling address space randomization: Operation not permitted
test_results/runnable/gdb15729.gdb:2: Error in sourced command file:
During startup program exited normally.
==============================

Huh?

[ghost]

Unfortunately I don't have the privileges to relaunch the CircleCI tests myself, can you @thewilsonator ?

[thewilsonator]

Magic! it appears to have fixed itself.

[ghost]

No magic here, the problem in #9404