Bug 22901 – Can't construct inout SumType

As of DMD 2.099.0, the following program fails to compile: --- import std.sumtype; inout(SumType!(int[])) example(inout int[] arr) { return inout(SumType!(int[]))(arr); } --- The error message is: --- onlineapp.d(5): Error: none of the overloads of `__ctor` are callable using a `inout` object /dlang/dmd/linux/bin64/../../src/phobos/std/sumtype.d(366): Candidates are: `std.sumtype.SumType!(int[]).SumType.this(int[] value)` /dlang/dmd/linux/bin64/../../src/phobos/std/sumtype.d(388): `std.sumtype.SumType!(int[]).SumType.this(const(int[]) value)` /dlang/dmd/linux/bin64/../../src/phobos/std/sumtype.d(405): `std.sumtype.SumType!(int[]).SumType.this(immutable(int[]) value)` ---

@pbackus created dlang/phobos pull request #8413 "Fix issue 22901 - Can't construct inout SumType" fixing this issue: - Fix issue 22901 - Can't construct inout SumType The template constraint is needed to ensure that the inout constructor overload is only considered when it is an exact match, without qualifier conversions. Without the constraint, a constructor call such as const(SumType!(int[]))([1, 2, 3]) ...would be ambiguous, since it would match both the const constructor overload and the inout constructor overload at the "match with qualifier conversion" level. https://github.com/dlang/phobos/pull/8413

dlang/phobos pull request #8413 "Fix issue 22901 - Can't construct inout SumType" was merged into master: - d9d104c9bc64540c3ab87cc15665aeb9d0d11e4e by Paul Backus: Fix issue 22901 - Can't construct inout SumType The template constraint is needed to ensure that the inout constructor overload is only considered when it is an exact match, without qualifier conversions. Without the constraint, a constructor call such as const(SumType!(int[]))([1, 2, 3]) ...would be ambiguous, since it would match both the const constructor overload and the inout constructor overload at the "match with qualifier conversion" level. https://github.com/dlang/phobos/pull/8413