// checkUntaggedLiteral checks if a composite literal is an struct literal with
// untagged fields.
func (f *File) checkUntaggedLiteral(c *ast.CompositeLit) {
	if !vet("composites") {
		return
	}

	// Check that the CompositeLit's type is a slice or array (which need no tag), if possible.
	if f.pkg != nil {
		typ := f.pkg.types[c]
		if typ != nil {
			// If it's a named type, pull out the underlying type.
			if namedType, ok := typ.(*types.NamedType); ok {
				typ = namedType.Underlying
			}
			switch typ.(type) {
			case *types.Slice:
				return
			case *types.Array:
				return
			}
		}
	}

	// It's a struct, or we can't tell it's not a struct because we don't have types.

	// Check if the CompositeLit contains an untagged field.
	allKeyValue := true
	for _, e := range c.Elts {
		if _, ok := e.(*ast.KeyValueExpr); !ok {
			allKeyValue = false
			break
		}
	}
	if allKeyValue {
		return
	}

	// Check that the CompositeLit's type has the form pkg.Typ.
	s, ok := c.Type.(*ast.SelectorExpr)
	if !ok {
		return
	}
	pkg, ok := s.X.(*ast.Ident)
	if !ok {
		return
	}

	// Convert the package name to an import path, and compare to a whitelist.
	path := pkgPath(f, pkg.Name)
	if path == "" {
		f.Warnf(c.Pos(), "unresolvable package for %s.%s literal", pkg.Name, s.Sel.Name)
		return
	}
	typ := path + "." + s.Sel.Name
	if *compositeWhiteList && untaggedLiteralWhitelist[typ] {
		return
	}

	f.Warnf(c.Pos(), "%s composite literal uses untagged fields", typ)
}

// checkUntaggedLiteral checks if a composite literal is an struct literal with
// untagged fields.
func (f *File) checkUntaggedLiteral(c *ast.CompositeLit) {
	if !*vetUntaggedLiteral && !*vetAll {
		return
	}
	// Check if the CompositeLit contains an untagged field.
	allKeyValue := true
	for _, e := range c.Elts {
		if _, ok := e.(*ast.KeyValueExpr); !ok {
			allKeyValue = false
			break
		}
	}
	if allKeyValue {
		return
	}

	// Check that the CompositeLit's type has the form pkg.Typ.
	s, ok := c.Type.(*ast.SelectorExpr)
	if !ok {
		return
	}
	pkg, ok := s.X.(*ast.Ident)
	if !ok {
		return
	}

	// Convert the package name to an import path, and compare to a whitelist.
	path := pkgPath(f, pkg.Name)
	if path == "" {
		f.Warnf(c.Pos(), "unresolvable package for %s.%s literal", pkg.Name, s.Sel.Name)
		return
	}
	typ := path + "." + s.Sel.Name
	if untaggedLiteralWhitelist[typ] {
		return
	}

	f.Warnf(c.Pos(), "%s struct literal uses untagged fields", typ)
}

// checkUntaggedLiteral checks if a composite literal is a struct literal with
// untagged fields.
func (f *File) checkUntaggedLiteral(c *ast.CompositeLit) {
	if !vet("composites") {
		return
	}

	typ := c.Type
	for {
		if typ1, ok := c.Type.(*ast.ParenExpr); ok {
			typ = typ1
			continue
		}
		break
	}

	switch typ.(type) {
	case *ast.ArrayType:
		return
	case *ast.MapType:
		return
	case *ast.StructType:
		return // a literal struct type does not need to use tags
	case *ast.Ident:
		// A simple type name like t or T does not need tags either,
		// since it is almost certainly declared in the current package.
		// (The exception is names being used via import . "pkg", but
		// those are already breaking the Go 1 compatibility promise,
		// so not reporting potential additional breakage seems okay.)
		return
	}

	// Otherwise the type is a selector like pkg.Name.
	// We only care if pkg.Name is a struct, not if it's a map, array, or slice.
	isStruct, typeString := f.pkg.isStruct(c)
	if !isStruct {
		return
	}

	if typeString == "" { // isStruct doesn't know
		typeString = f.gofmt(typ)
	}

	// It's a struct, or we can't tell it's not a struct because we don't have types.

	// Check if the CompositeLit contains an untagged field.
	allKeyValue := true
	for _, e := range c.Elts {
		if _, ok := e.(*ast.KeyValueExpr); !ok {
			allKeyValue = false
			break
		}
	}
	if allKeyValue {
		return
	}

	// Check that the CompositeLit's type has the form pkg.Typ.
	s, ok := c.Type.(*ast.SelectorExpr)
	if !ok {
		return
	}
	pkg, ok := s.X.(*ast.Ident)
	if !ok {
		return
	}

	// Convert the package name to an import path, and compare to a whitelist.
	path := pkgPath(f, pkg.Name)
	if path == "" {
		f.Badf(c.Pos(), "unresolvable package for %s.%s literal", pkg.Name, s.Sel.Name)
		return
	}
	typeName := path + "." + s.Sel.Name
	if *compositeWhiteList && untaggedLiteralWhitelist[typeName] {
		return
	}

	f.Warn(c.Pos(), typeString+" composite literal uses untagged fields")
}