// contexts to canonicalize instances, and it would probably be possible to
// achieve such a guarantee.

// A Context is an opaque type checking context. It may be used to share
// identical type instances across type-checked packages or calls to
// Instantiate. Contexts are safe for concurrent use.
//
// The use of a shared context does not guarantee that identical instances are
// deduplicated in all cases.

Laura Kassovic <******@****.***> 1701107622 -0800

// contexts to canonicalize instances, and it would probably be possible to
// achieve such a guarantee.

// A Context is an opaque type checking context. It may be used to share
// identical type instances across type-checked packages or calls to
// Instantiate. Contexts are safe for concurrent use.
//
// The use of a shared context does not guarantee that identical instances are
// deduplicated in all cases.

Laura Kassovic <******@****.***> 1701107622 -0800

        run("generate")

        then:
        result.assertTaskNotSkipped(":generate")
        output.count("checking") == 22 // checked twice, once to snapshot and once when the task action runs. Should be memoized when snapshotting
        outputContains("checking a/a.txt")
        outputContains("checking d/d.txt")
        file("out.txt").text == "a.txt,c.txt,d.txt"
    }

// Blank methods need to be type-checked.
// Verify by checking that errors are reported.
func (T /* ERROR "undefined" */ ) _() {}
func (T1) _(undefined /* ERROR "undefined" */ ) {}
func (T1) _() int { return "foo" /* ERRORx "cannot use .* in return statement" */ }

// Methods with undefined receiver type can still be checked.
// Verify by checking that errors are reported.
func (Foo /* ERROR "undefined" */ ) m() {}

	_, err = conf.Check("runtime", fset, files, &info)
	if err != nil {
		t.Fatalf("typechecking runtime failed: %v", err)
	}

	// Analyze all atomic.*64 callsites.
	v := Visitor{t: t, fset: fset, types: info.Types, checked: checked}
	ast.Walk(&v, pkg)
}

type Visitor struct {
	fset    *token.FileSet
	types   map[ast.Expr]types.TypeAndValue
	checked map[string]bool
	t       *testing.T
}

// rhs must not be nil.
func (check *Checker) newAlias(obj *TypeName, rhs Type) *Alias {
	assert(rhs != nil)
	a := new(Alias)
	a.obj = obj
	a.orig = a
	a.fromRHS = rhs
	if obj.typ == nil {
		obj.typ = a
	}

	// Ensure that a.actual is set at the end of type checking.
	if check != nil {
		check.needsCleanup(a)
	}

	return a
}

// The positioner interface is used to extract the position of type-checker errors.
type positioner interface {
	Pos() token.Pos
}

func (check *Checker) error(at positioner, code Code, msg string) {
	err := check.newError(code)
	err.addf(at, "%s", msg)
	err.report()
}

func (check *Checker) errorf(at positioner, code Code, format string, args ...any) {
	err := check.newError(code)
	err.addf(at, format, args...)

// rhs must not be nil.
func (check *Checker) newAlias(obj *TypeName, rhs Type) *Alias {
	assert(rhs != nil)
	a := new(Alias)
	a.obj = obj
	a.orig = a
	a.fromRHS = rhs
	if obj.typ == nil {
		obj.typ = a
	}

	// Ensure that a.actual is set at the end of type checking.
	if check != nil {
		check.needsCleanup(a)
	}

	return a
}