Bug 13283 – dmd fails to generate ambiguous overload error

I have a generic Vector struct that is constructed by helper functions that deduce the length and element type and forward the arguments to the appropriate constructor. Almost all of them had a constraint on them that required the length of the vector the be at least 2, but the Vector struct itself had no such constraint, and one of the helper functions was missing it as well. When I added the constraint to either the Vector struct or the helper function (I've since added them to both) then everything links fine. It looks like what was happening was that a "fill constructor helper function" (intended use: vector!4 (x) => vector (x, x, x, x)) was routing to a "variadic constructor helper function" (vector (args) => vector!(args.length)(args)) that attempted to generate a 1-element vector and somewhere along the way - linker error. There are the mangled names that the linker could not resolve references to: `_D3evx7vectors16__T6VectorVm1TdZ6Vector6__initZ` `_D3evx7vectors16__T6VectorVm1TdZ6Vector6__ctorMFNaNbNcNfdZS3evx7vectors16__T6VectorVm1TdZ6Vector` the second of which demangles to this: pure nothrow ref @safe evx.vectors.Vector!(1uL, double).Vector evx.vectors.Vector!(1uL, double).Vector.__ctor(double) So, there's my one-element vector constructor, which is likely having a hard time with the following overloads: this (Elements...)(Elements elements) if (Elements.length == length) { foreach (i, element; elements) components[i] = element; } this (Element element) { components[] = element; } So, while the mistake was mine, this should be an ambiguous overload error at compile-time, instead of a linker error.

It's not clear what the original code and the problem with the linker was. Just to check, without the constraint, this code is fine: struct S{ this (Elements...)(Elements elements){...} this (Element element){...} } S s = S(Element.init); The above call matches this(Element), the constructor template is less specialized.

This bug report contains insufficient information to see what the issue is. As such I will close this as MOVED, but if new information arises, feel free to reopen.