February 23, 2019
https://issues.dlang.org/show_bug.cgi?id=19697

          Issue ID: 19697
           Summary: ReplaceType fails to compile for self-referential
                    inheritance chains
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: sludwig@outerproduct.org

Test case:

---
import std.typecons : ReplaceType;
class C : D!C {}
class D(T) {}
static assert(is(ReplaceType!(float, float, C)));
---

Generated error if instantiated outside of "is":
> /dlang/dmd/linux/bin64/../../src/phobos/std/typecons.d(8658): Error: template instance `U!(__T11ReplaceTypeTfTfTC9onlineapp1CZ)` does not match template declaration D(T)
> onlineapp.d(4): Error: template instance `std.typecons.ReplaceType!(float, float, C)` error instantiating

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