check.later(func() {
					if pos.IsKnown() && !check.allowVersion(atPos(pos), go1_14) || !Identical(m.typ, other.Type()) {
						err := check.newError(DuplicateDecl)
						err.addf(atPos(pos), "duplicate method %s", m.name)
						err.addf(atPos(mpos[other.(*Func)]), "other declaration of method %s", m.name)
						err.report()
					}
				}).describef(atPos(pos), "duplicate method check for %s", m.name)
			}
		}
	}

	msg := check.sprintf(format, args...)
	err := check.newError(UnsupportedFeature)
	err.addf(at, "%s requires %s or later", msg, v)
	err.report()
}

// atPos reports the left (= start) position of at.
func atPos(at poser) syntax.Pos {
	switch x := at.(type) {
	case *operand:
		if x.expr != nil {
			return syntax.StartPos(x.expr)
		}
	case syntax.Node:
		return syntax.StartPos(x)
	}

				check.later(func() {
					if pos.IsValid() && !check.allowVersion(atPos(pos), go1_14) || !Identical(m.typ, other.Type()) {
						err := check.newError(DuplicateDecl)
						err.addf(atPos(pos), "duplicate method %s", m.name)
						err.addf(atPos(mpos[other.(*Func)]), "other declaration of method %s", m.name)
						err.report()
					}
				}).describef(atPos(pos), "duplicate method check for %s", m.name)
			}
		}
	}

						n.Args[0] = arg
						return false
					}
				}
			}
		}
		return true
	})
}

// fixAtPosCall updates calls of the form atPos(x) to x.Pos() in argument lists of (check).dump calls.
// TODO(gri) can we avoid this and just use atPos consistently in go/types and types2?
func fixAtPosCall(f *ast.File) {
	ast.Inspect(f, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.CallExpr:

	msg := check.sprintf(format, args...)
	err := check.newError(UnsupportedFeature)
	err.addf(at, "%s requires %s or later", msg, v)
	err.report()
}

// atPos wraps a token.Pos to implement the positioner interface.
type atPos token.Pos

func (s atPos) Pos() token.Pos {
	return token.Pos(s)
}

// posSpan holds a position range along with a highlighted position within that

		if constraint && comparable(V, true /* spec comparability */, nil, nil) {
			// V is comparable if we are at Go 1.20 or higher.
			if check == nil || check.allowVersion(atPos(pos), go1_20) { // atPos needed so that go/types generate passes
				return true
			}
			if cause != nil {
				*cause = check.sprintf("%s to %s comparable requires go1.20 or later", V, verb)
			}
			return false
		}

		// TODO(gri) We should report exactly what went wrong. At the
		//           moment we don't have the (go/constant) API for that.
		//           See also TODO in go/constant/value.go.
		check.error(atPos(opPos), InvalidConstVal, "constant result is not representable")
		return
	}

	// Typed constants must be representable in
	// their type after each constant operation.
	// x.typ cannot be a type parameter (type

		// TODO(gri) We should report exactly what went wrong. At the
		//           moment we don't have the (go/constant) API for that.
		//           See also TODO in go/constant/value.go.
		check.error(atPos(opPos), InvalidConstVal, "constant result is not representable")
		return
	}

	// Typed constants must be representable in
	// their type after each constant operation.
	// x.typ cannot be a type parameter (type

func hasDots(call *ast.CallExpr) bool { return call.Ellipsis.IsValid() }

// dddErrPos returns the positioner for reporting an invalid ... use in a call.
func dddErrPos(call *ast.CallExpr) positioner { return atPos(call.Ellipsis) }

// argErrPos returns positioner for reporting an invalid argument count.
func argErrPos(call *ast.CallExpr) positioner { return inNode(call, call.Rparen) }

// startPos returns the start position of node n.

		if constraint && comparable(V, true /* spec comparability */, nil, nil) {
			// V is comparable if we are at Go 1.20 or higher.
			if check == nil || check.allowVersion(atPos(pos), go1_20) { // atPos needed so that go/types generate passes
				return true
			}
			if cause != nil {
				*cause = check.sprintf("%s to %s comparable requires go1.20 or later", V, verb)
			}
			return false
		}