[Issue 13196] New: Infer struct/class template args from constructor args

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13196

          Issue ID: 13196
           Summary: Infer struct/class template args from constructor args
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: DMD
          Assignee: nobody at puremagic.com
          Reporter: turkeyman at gmail.com

It would be really nice if struct/class template args could be inferred from
their constructors, just the same as function template args are inferred from
the runtime args.

struct S(T)
{
  this(T t)
  {
    m = t;
  }

  T m;
}

int myThing;
auto s = S!(typeof(myThing))(myThing); // horrible!
auto s = S(myThing); // this is much nicer, but not supported


The error is:
Error: struct db.tools.delegatethunk.S cannot deduce function from argument
types !()(int), candidates are:
        db.tools.delegatethunk.S(T)

It seems the compiler is already well aware there is only one possibly match.


These sorts of issues pay off in meta-heavy code when used alongside
non-template types.
I find my meta often gets overwhelmed by additional meta to check for and
handle edge cases like this.

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