Recognize parametric types

[projekter]

I just ran into a similar issue based on this signature recognition bug: if you have a method with (::Any) signature and another one with type parameters, you cannot selectively print the one with type parameters only in the documentation, as the generic one will always be found.
Regarding your analysis, I would propose a change that still allows to differentiate parametric constructors. For this, I add the parameters of the constructor as a unique type to the front of the method signature.
Here, I also preserve the behavior that you need not specify the where part for constructors, but I completely agree with your analysis that in this way, it is impossible to make the distinction between existing types and parametric types (which cannot be done well during macro deconstruction). This is also an issue in the code currently in Base; any type parameter will always be seen as parametric. For this reason, I'd rather see this whole behavior disappear; in the end, you cannot write Julia code like this. Removing the if isempty would prevent this. A kind of middle ground would be to allow the current behavior, but only if the type is constrained (because this would not be possible for existing types).

[projekter]

I now moved this to the main Julia repo as #54324.

[matthias314]

Sorry, I didn't see your PR before. In any case, it's probably better to discuss it within the Julia repo. I hope that one of the maintainers gives it a look!