cmd/compile: generic error does not identify relevant type

[rsc]

% cat /tmp/x.go
package p

type T[X, Y any] struct {
	x X
	y Y
}

var _ T[int]

func t(x, y int) int

var _ = t(1)
% go build /tmp/x.go
# command-line-arguments
/tmp/x.go:8:7: got 1 arguments but 2 type parameters
/tmp/x.go:12:11: not enough arguments in call to t
	have (number)
	want (int, int)
% 

Note the difference in errors.

The ordinary parameter error says "not enough arguments in call to t" and then gives the argument types.

The generic error says "got 1 arguments but 2 type parameters" which does not identify the relevant type (T in this case) and is also easily misread to mean "got 1 arguments and got 2 type parameters but these numbers don't match". It would be better for this error to be worded more like the non-generic error. Perhaps:

/tmp/x.go:8:7: not enough type arguments for type T: have 1, want 2

or even

/tmp/x.go:8:7: not enough type arguments for type T
	have (int)
	want (any, any)

/cc @griesemer

[raghvenders]

@gopherbot - Assign this me.

[gopherbot]

Change https://go.dev/cl/544018 mentions this issue: cmd/compile: Fix generics error message for mismatch of number of type params and arguments