_Assert: {"assert", 1, false, statement},
	_Trace:  {"trace", 0, true, statement},
}

func defPredeclaredFuncs() {
	for i := range predeclaredFuncs {
		id := builtinId(i)
		if id == _Assert || id == _Trace {
			continue // only define these in testing environment
		}
		def(newBuiltin(id))
	}
}

// DefPredeclaredTestFuncs defines the assert and trace built-ins.

	_Assert: {"assert", 1, false, statement},
	_Trace:  {"trace", 0, true, statement},
}

func defPredeclaredFuncs() {
	for i := range predeclaredFuncs {
		id := builtinId(i)
		if id == _Assert || id == _Trace {
			continue // only define these in testing environment
		}
		def(newBuiltin(id))
	}
}

// DefPredeclaredTestFuncs defines the assert and trace built-ins.

	"slice.go":         nil,
	"subst.go":         func(f *ast.File) { fixTokenPos(f); renameSelectors(f, "Trace->_Trace") },
	"termlist.go":      nil,
	"termlist_test.go": nil,
	"tuple.go":         nil,
	"typelists.go":     nil,
	"typeset.go":       func(f *ast.File) { fixTokenPos(f); renameSelectors(f, "Trace->_Trace") },
	"typeparam.go":     nil,
	"typeterm_test.go": nil,
	"typeterm.go":      nil,
	"typestring.go":    nil,

	for i := top; i < len(check.delayed); i++ {
		a := &check.delayed[i]
		if check.conf._Trace {
			if a.desc != nil {
				check.trace(a.desc.pos.Pos(), "-- "+a.desc.format, a.desc.args...)
			} else {
				check.trace(nopos, "-- delayed %p", a.f)
			}
		}
		a.f() // may append to check.delayed
		if check.conf._Trace {
			fmt.Println()
		}
	}
	assert(top <= len(check.delayed)) // stack must not have shrunk

	// declarations within _cgo_gotypes.go.
	//
	// It is an error to set both FakeImportC and go115UsesCgo.
	go115UsesCgo bool

	// If _Trace is set, a debug trace is printed to stdout.
	_Trace bool

	// If Error != nil, it is called with each error found
	// during type checking; err has dynamic type Error.
	// Secondary errors (for instance, to enumerate all types

		}
		// result is constant - no need to record signature

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		// (no argument evaluated yet)
		if nargs == 0 {
			check.dump("%v: trace() without arguments", call.Pos())
			x.mode = novalue
			break
		}

	if check.conf._Trace {
		check.trace(e0.Pos(), "-- type %s", e0)
		check.indent++
		defer func() {
			check.indent--
			var under Type
			if T != nil {
				// Calling under() here may lead to endless instantiations.
				// Test case: type T[P any] *T[P]
				under = safeUnderlying(T)
			}
			if T == under {
				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
			} else {

		msg := err.desc[0].msg
		if strings.Index(msg, "invalid operand") > 0 || strings.Index(msg, "invalid type") > 0 {
			return
		}
	}

	if check.conf._Trace {
		check.trace(err.posn().Pos(), "ERROR: %s (code = %d)", err.desc[0].msg, err.code)
	}

	// In go/types, if there is a sub-error with a valid position,
	// call the typechecker error handler for each sub-error.

		}
		// result is constant - no need to record signature

	case _Trace:
		// trace(x, y, z, ...) dumps the positions, expressions, and
		// values of its arguments. The result of trace is the value
		// of the first argument.
		// Note: trace is only available in self-test mode.
		// (no argument evaluated yet)
		if nargs == 0 {
			check.dump("%v: trace() without arguments", atPos(call))
			x.mode = novalue
			break
		}

			// ignored for now
		default:
			panic("unreachable")
		}
	}

	if check.conf._Trace {
		check.trace(obj.Pos(), "## cycle detected: objPath = %s->%s (len = %d)", pathString(cycle), obj.Name(), len(cycle))
		if tparCycle {
			check.trace(obj.Pos(), "## cycle contains: generic type in a type parameter list")
		} else {
			check.trace(obj.Pos(), "## cycle contains: %d values, %d type definitions", nval, ndef)
		}
		defer func() {