[dev.typeparams] cmd/compile/internal/types2: report correct line number for missing key

Use the Key position of a syntax.KeyValueExpr (not the position of the
":") when reporting an error for a missing key.

(In go/types, the KeyValueExpr position is the start of the expression
not the ":", so there this works as expected.)

Change-Id: I74147d245927847274cf4e53b4f03dbb5110c324
Reviewed-on: https://go-review.googlesource.com/c/go/+/276813
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/cmd/compile/internal/types2/expr.go

@@ -1277,9 +1277,9 @@ func (check *Checker) exprInternal(x *operand, e syntax.Expr, hint Type) exprKin
 					i := fieldIndex(utyp.fields, check.pkg, key.Value)
 					if i < 0 {
 						if check.conf.CompilerErrorMessages {
-							check.errorf(kv, "unknown field '%s' in struct literal of type %s", key.Value, base)
+							check.errorf(kv.Key, "unknown field '%s' in struct literal of type %s", key.Value, base)
 						} else {
-							check.errorf(kv, "unknown field %s in struct literal", key.Value)
+							check.errorf(kv.Key, "unknown field %s in struct literal", key.Value)
 						}
 						continue
 					}

test/run.go

@@ -2004,7 +2004,6 @@ var excluded = map[string]bool{
 	"fixedbugs/issue22200.go":  true, // types2 doesn't produce "stack frame too large" error
 	"fixedbugs/issue22200b.go": true, // types2 doesn't produce "stack frame too large" error
 	"fixedbugs/issue23732.go":  true, // types2 reports different (but ok) line numbers
-	"fixedbugs/issue24339.go":  true, // types2 reports wrong line number
 	"fixedbugs/issue25507.go":  true, // types2 doesn't produce "stack frame too large" error
 	"fixedbugs/issue25958.go":  true, // types2 doesn't report a follow-on error (pref: types2)
 	"fixedbugs/issue28079b.go": true, // types2 reports follow-on errors