https://issues.dlang.org/show_bug.cgi?id=21103

          Issue ID: 21103
           Summary: isDynamicArray instantiates unecessary templates
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: moonlightsentinel@disroot.org

See https://github.com/dlang/dmd/pull/9014#issuecomment-667704187 for an extensive overview.

TL:DR.
isDynamicArray should use an is-Expression instead of additional templates.

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