[BUG] Compiler fails to find correct overload with inferred parameter on a generic struct

[soraros]

Bug description

As title. Related to #4199. CC @dgurchenkov.

Steps to reproduce

Code:

@value
struct Ptr[dtype: DType = DType.int32]:
  fn store(self, offset: Int, val: Int):
    pass

  fn store[width: Int, //](self, offset: Int):
    pass

fn main():
  p = Ptr()
  i = 1
  p.store[width=4](i)  # error

Error:

/workspaces/ubuntu/max/playground/main.mojo:31:19: error: no matching method in call to 'store'
  p.store[width=4](i)
  ~~~~~~~~~~~~~~~~^~~
/workspaces/ubuntu/max/playground/main.mojo:22:6: note: candidate not viable: missing 1 required positional argument: 'val'
  fn store(self, offset: Int, val: Int):
     ^
/workspaces/ubuntu/max/playground/main.mojo:25:6: note: candidate not viable: inferred parameter passed out of order: 'width'
  fn store[width: Int, //](self, offset: Int):

System information

mojo 25.4.0.dev2025050905 (e3051145)

[VerdagonModular]

Repro'd, thanks for the snippet! This might get fixed soon in some coming refactors in the parameter inference system, fingers crossed. Moving to the backlog to be considered for next cycle, just in case.

[soraros]

Another interesting case. Maybe this widening should be encoded as a __merge_with__ instead of implicit conversion.

struct V[dtype: DType, size: Int]:
  fn __init__(out self):
    pass

  @implicit
  fn __init__(out self, data: V[dtype, 1]):
    pass

fn fma[
  dtype: DType, width: Int, //
](a: V[dtype, width], b: V[dtype, width], c: V[dtype, width]):
  pass

fn f[dtype: DType, width: Int]():
  var s = V[dtype, 1]()
  var v = V[dtype, width]()

  fma[width=width](s, v, v)  # error: invalid call to 'fma': failed to infer parameter 'dtype'
  fma[dtype=dtype, width=width](s, v, v)

Error:

/workspaces/ubuntu/max/playground/bug.mojo:39:19: error: invalid call to 'fma': failed to infer parameter 'dtype'
  fma[width=width](s, v, v)
  ~~~~~~~~~~~~~~~~^~~~~~~~~
/workspaces/ubuntu/max/playground/bug.mojo:39:23: note: failed to infer parameter 'width', parameter inferred to two different values: '1' and 'width'
  fma[width=width](s, v, v)
                      ^
/workspaces/ubuntu/max/playground/bug.mojo:30:4: note: function declared here
fn fma[
   ^