https://issues.dlang.org/show_bug.cgi?id=21780

moonlightsentinel@disroot.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |moonlightsentinel@disroot.o
                   |                            |rg
           Hardware|x86_64                      |All
            Summary|alias this preferred over   |deprecation warning for
                   |immutable conversion even   |considered but unused alias
                   |if alias this is deprecated |this
                   |and de is on                |
                 OS|Linux                       |All
           Severity|trivial                     |regression

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https://issues.dlang.org/show_bug.cgi?id=21780

moonlightsentinel@disroot.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|deprecation warning for     |alias this preferred over
                   |considered but unused alias |immutable conversion even
                   |this                        |if alias this is deprecated
                   |                            |and de is on

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https://issues.dlang.org/show_bug.cgi?id=21780

--- Comment #1 from moonlightsentinel@disroot.org ---
This is actually a regression. Extending your example with appropriate
puts("Nullable") / puts("S") yields:

Up to      2.060  : Success with output: Nullable

2.061   to 2.075.1: <Doesn't compile due to overload resolution error>

2.076.1 to 2.087.1: Success with output: S
Since      2.088.1: Success with output:
-----
onlineapp.d(14): Deprecation: `alias get_ this` is deprecated
S
-----

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https://issues.dlang.org/show_bug.cgi?id=21780

--- Comment #2 from FeepingCreature <default_357-line@yahoo.de> ---
That's not really a "regression" - well, it is a regression, but it's an expected regression, because Nullable's alias get this is in the process of being deprecated and has been removed in master. A deprecation is functionally equivalent to a regression, that's why there was a year of warning messages.

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https://issues.dlang.org/show_bug.cgi?id=21780

--- Comment #3 from FeepingCreature <default_357-line@yahoo.de> ---
Oh wait you're right! I thought you were talking about std.typecons.Nullable for a second.

It's still not a regression - it's a bugfix: https://issues.dlang.org/show_bug.cgi?id=20033 , I believe.

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https://issues.dlang.org/show_bug.cgi?id=21780

--- Comment #4 from moonlightsentinel@disroot.org ---
(In reply to FeepingCreature from comment #2)
> That's not really a "regression" - well, it is a regression, but it's an

This is still a regression. DMD should prefer const-conversions over implicit conversions (e.g. alias this).

This extends example exhibits wrong behaviour since 2.061 : (Unless i misunderstood the rules for overload matching)

extern(C) void puts(const scope char*);

immutable struct S { }

struct Nullable {
    S get_() { return S.init; }
    deprecated alias get_ this;
}

void foo(immutable Nullable) { puts("Nullable"); }
void foo(immutable S) { puts("S"); }

void main() {
    foo(Nullable()); // prints "S"
}

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https://issues.dlang.org/show_bug.cgi?id=21780

--- Comment #5 from moonlightsentinel@disroot.org ---
The regression refers to the change which overload is called, not the deprecation message.

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https://issues.dlang.org/show_bug.cgi?id=21780

--- Comment #6 from moonlightsentinel@disroot.org ---
Even worse when removing the immutable from S and using const parameters:

extern(C) void puts(const scope char*);

struct S { }

struct Nullable {
    S get_() { return S.init; }
    deprecated alias get_ this;
}

void foo(const Nullable) { puts("Nullable"); }
void foo(const S) { puts("S"); }

void main() {
    foo(Nullable()); // fails due to ambiguity
}

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