[Issue 20328] [REG 2.089 beta] deprecation message about Nullable.get in isInputRange

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20328

FeepingCreature <default_357-line at yahoo.de> changed:

           What    |Removed                     |Added
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                 CC|                            |default_357-line at yahoo.de

--- Comment #5 from FeepingCreature <default_357-line at yahoo.de> ---
Shorter repro:

enum e = isInputRange!(Nullable!string);

I think we need to think about how to handle the case where `alias this`
triggers but doesn't change the outcome of the test. The problem is that
`foo.front` doesn't exist, so dmd looks inside the deprecated alias get this
... where it also doesn't exist. This does become relevant for things like
sticking `Nullable!(<range>)` into format(), which would previously have
identified as an input range.

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