SumType stopped working on LDC 1.37 with unmatched DeducedParameterType template

[dlangBugzillaToGithub]

contact reported this on 2024-07-26T19:15:46Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=24686

Description

Compiling an argument parser (cant really deduce the code snippet)  63874b2ce32b165436d3007515377ef5d5dce22d version of https://github.com/andrey-zherikov/argparse yields the following error on LDC 1.37 and beyond.

```
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(SubCommand))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(SubCommand))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(SubCommand))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(SubCommand))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(SubCommand))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(SubCommand))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Unknown))` does not match template declaration `DeducedParameterType(T)`
/home/luis/.local/bin/../import/std/sumtype.d(418): Error: template instance `DeducedParameterType!(inout(Argument))` does not match template declaration `DeducedParameterType(T)`
```

Turns out `DeducedParameterType` doesn't accept aliased types. Ultimately this should be a compiler issue, in my understanding of the language spec, as T and alias T shouldn't differ for types, but somehow it does.

Making `DeducedParameterType` accepting aliased types, works.