libgo/go/golang.org/x/tools/go/analysis/passes/printf/types.go - gofrontend - Git at Google

 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package printf

 import (
 	"go/ast"
 	"go/types"

 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
 )

 var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)

 // matchArgType reports an error if printf verb t is not appropriate
 // for operand arg.
 //
 // typ is used only for recursive calls; external callers must supply nil.
 //
 // (Recursion arises from the compound types {map,chan,slice} which
 // may be printed with %d etc. if that is appropriate for their element
 // types.)
 func matchArgType(pass *analysis.Pass, t printfArgType, typ types.Type, arg ast.Expr) bool {
 	return matchArgTypeInternal(pass, t, typ, arg, make(map[types.Type]bool))
 }

 // matchArgTypeInternal is the internal version of matchArgType. It carries a map
 // remembering what types are in progress so we don't recur when faced with recursive
 // types or mutually recursive types.
 func matchArgTypeInternal(pass *analysis.Pass, t printfArgType, typ types.Type, arg ast.Expr, inProgress map[types.Type]bool) bool {
 	// %v, %T accept any argument type.
 	if t == anyType {
 		return true
 	}
 	if typ == nil {
 		// external call
 		typ = pass.TypesInfo.Types[arg].Type
 		if typ == nil {
 			return true // probably a type check problem
 		}
 	}

 	// %w accepts only errors.
 	if t == argError {
 		return types.ConvertibleTo(typ, errorType)
 	}

 	// If the type implements fmt.Formatter, we have nothing to check.
 	if isFormatter(typ) {
 		return true
 	}
 	// If we can use a string, might arg (dynamically) implement the Stringer or Error interface?
 	if t&argString != 0 && isConvertibleToString(pass, typ) {
 		return true
 	}

 	typ = typ.Underlying()
 	if inProgress[typ] {
 		// We're already looking at this type. The call that started it will take care of it.
 		return true
 	}
 	inProgress[typ] = true

 	switch typ := typ.(type) {
 	case *types.Signature:
 		return t == argPointer

 	case *types.Map:
 		return t == argPointer ||
 			// Recur: map[int]int matches %d.
 			(matchArgTypeInternal(pass, t, typ.Key(), arg, inProgress) && matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress))

 	case *types.Chan:
 		return t&argPointer != 0

 	case *types.Array:
 		// Same as slice.
 		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
 			return true // %s matches []byte
 		}
 		// Recur: []int matches %d.
 		return matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress)

 	case *types.Slice:
 		// Same as array.
 		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
 			return true // %s matches []byte
 		}
 		if t == argPointer {
 			return true // %p prints a slice's 0th element
 		}
 		// Recur: []int matches %d. But watch out for
 		//	type T []T
 		// If the element is a pointer type (type T[]*T), it's handled fine by the Pointer case below.
 		return matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress)

 	case *types.Pointer:
 		// Ugly, but dealing with an edge case: a known pointer to an invalid type,
 		// probably something from a failed import.
 		if typ.Elem().String() == "invalid type" {
 			if false {
 				pass.Reportf(arg.Pos(), "printf argument %v is pointer to invalid or unknown type", analysisutil.Format(pass.Fset, arg))
 			}
 			return true // special case
 		}
 		// If it's actually a pointer with %p, it prints as one.
 		if t == argPointer {
 			return true
 		}

 		under := typ.Elem().Underlying()
 		switch under.(type) {
 		case *types.Struct: // see below
 		case *types.Array: // see below
 		case *types.Slice: // see below
 		case *types.Map: // see below
 		default:
 			// Check whether the rest can print pointers.
 			return t&argPointer != 0
 		}
 		// If it's a top-level pointer to a struct, array, slice, or
 		// map, that's equivalent in our analysis to whether we can
 		// print the type being pointed to. Pointers in nested levels
 		// are not supported to minimize fmt running into loops.
 		if len(inProgress) > 1 {
 			return false
 		}
 		return matchArgTypeInternal(pass, t, under, arg, inProgress)

 	case *types.Struct:
 		return matchStructArgType(pass, t, typ, arg, inProgress)

 	case *types.Interface:
 		// There's little we can do.
 		// Whether any particular verb is valid depends on the argument.
 		// The user may have reasonable prior knowledge of the contents of the interface.
 		return true

 	case *types.Basic:
 		switch typ.Kind() {
 		case types.UntypedBool,
 			types.Bool:
 			return t&argBool != 0

 		case types.UntypedInt,
 			types.Int,
 			types.Int8,
 			types.Int16,
 			types.Int32,
 			types.Int64,
 			types.Uint,
 			types.Uint8,
 			types.Uint16,
 			types.Uint32,
 			types.Uint64,
 			types.Uintptr:
 			return t&argInt != 0

 		case types.UntypedFloat,
 			types.Float32,
 			types.Float64:
 			return t&argFloat != 0

 		case types.UntypedComplex,
 			types.Complex64,
 			types.Complex128:
 			return t&argComplex != 0

 		case types.UntypedString,
 			types.String:
 			return t&argString != 0

 		case types.UnsafePointer:
 			return t&(argPointer|argInt) != 0

 		case types.UntypedRune:
 			return t&(argInt|argRune) != 0

 		case types.UntypedNil:
 			return false

 		case types.Invalid:
 			if false {
 				pass.Reportf(arg.Pos(), "printf argument %v has invalid or unknown type", analysisutil.Format(pass.Fset, arg))
 			}
 			return true // Probably a type check problem.
 		}
 		panic("unreachable")
 	}

 	return false
 }

 func isConvertibleToString(pass *analysis.Pass, typ types.Type) bool {
 	if bt, ok := typ.(*types.Basic); ok && bt.Kind() == types.UntypedNil {
 		// We explicitly don't want untyped nil, which is
 		// convertible to both of the interfaces below, as it
 		// would just panic anyway.
 		return false
 	}
 	if types.ConvertibleTo(typ, errorType) {
 		return true // via .Error()
 	}

 	// Does it implement fmt.Stringer?
 	if obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "String"); obj != nil {
 		if fn, ok := obj.(*types.Func); ok {
 			sig := fn.Type().(*types.Signature)
 			if sig.Params().Len() == 0 &&
 				sig.Results().Len() == 1 &&
 				sig.Results().At(0).Type() == types.Typ[types.String] {
 				return true
 			}
 		}
 	}

 	return false
 }

 // hasBasicType reports whether x's type is a types.Basic with the given kind.
 func hasBasicType(pass *analysis.Pass, x ast.Expr, kind types.BasicKind) bool {
 	t := pass.TypesInfo.Types[x].Type
 	if t != nil {
 		t = t.Underlying()
 	}
 	b, ok := t.(*types.Basic)
 	return ok && b.Kind() == kind
 }

 // matchStructArgType reports whether all the elements of the struct match the expected
 // type. For instance, with "%d" all the elements must be printable with the "%d" format.
 func matchStructArgType(pass *analysis.Pass, t printfArgType, typ *types.Struct, arg ast.Expr, inProgress map[types.Type]bool) bool {
 	for i := 0; i < typ.NumFields(); i++ {
 		typf := typ.Field(i)
 		if !matchArgTypeInternal(pass, t, typf.Type(), arg, inProgress) {
 			return false
 		}
 		if t&argString != 0 && !typf.Exported() && isConvertibleToString(pass, typf.Type()) {
 			// Issue #17798: unexported Stringer or error cannot be properly formatted.
 			return false
 		}
 	}
 	return true
 }
	// Copyright 2018 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package printf

	import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/internal/analysisutil"
	)

	var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)

	// matchArgType reports an error if printf verb t is not appropriate
	// for operand arg.
	//
	// typ is used only for recursive calls; external callers must supply nil.
	//
	// (Recursion arises from the compound types {map,chan,slice} which
	// may be printed with %d etc. if that is appropriate for their element
	// types.)
	func matchArgType(pass *analysis.Pass, t printfArgType, typ types.Type, arg ast.Expr) bool {
	return matchArgTypeInternal(pass, t, typ, arg, make(map[types.Type]bool))
	}

	// matchArgTypeInternal is the internal version of matchArgType. It carries a map
	// remembering what types are in progress so we don't recur when faced with recursive
	// types or mutually recursive types.
	func matchArgTypeInternal(pass *analysis.Pass, t printfArgType, typ types.Type, arg ast.Expr, inProgress map[types.Type]bool) bool {
	// %v, %T accept any argument type.
	if t == anyType {
	return true
	}
	if typ == nil {
	// external call
	typ = pass.TypesInfo.Types[arg].Type
	if typ == nil {
	return true // probably a type check problem
	}
	}

	// %w accepts only errors.
	if t == argError {
	return types.ConvertibleTo(typ, errorType)
	}

	// If the type implements fmt.Formatter, we have nothing to check.
	if isFormatter(typ) {
	return true
	}
	// If we can use a string, might arg (dynamically) implement the Stringer or Error interface?
	if t&argString != 0 && isConvertibleToString(pass, typ) {
	return true
	}

	typ = typ.Underlying()
	if inProgress[typ] {
	// We're already looking at this type. The call that started it will take care of it.
	return true
	}
	inProgress[typ] = true

	switch typ := typ.(type) {
	case *types.Signature:
	return t == argPointer

	case *types.Map:
	return t == argPointer \|\|
	// Recur: map[int]int matches %d.
	(matchArgTypeInternal(pass, t, typ.Key(), arg, inProgress) && matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress))

	case *types.Chan:
	return t&argPointer != 0

	case *types.Array:
	// Same as slice.
	if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
	return true // %s matches []byte
	}
	// Recur: []int matches %d.
	return matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress)

	case *types.Slice:
	// Same as array.
	if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && t&argString != 0 {
	return true // %s matches []byte
	}
	if t == argPointer {
	return true // %p prints a slice's 0th element
	}
	// Recur: []int matches %d. But watch out for
	// type T []T
	// If the element is a pointer type (type T[]*T), it's handled fine by the Pointer case below.
	return matchArgTypeInternal(pass, t, typ.Elem(), arg, inProgress)

	case *types.Pointer:
	// Ugly, but dealing with an edge case: a known pointer to an invalid type,
	// probably something from a failed import.
	if typ.Elem().String() == "invalid type" {
	if false {
	pass.Reportf(arg.Pos(), "printf argument %v is pointer to invalid or unknown type", analysisutil.Format(pass.Fset, arg))
	}
	return true // special case
	}
	// If it's actually a pointer with %p, it prints as one.
	if t == argPointer {
	return true
	}

	under := typ.Elem().Underlying()
	switch under.(type) {
	case *types.Struct: // see below
	case *types.Array: // see below
	case *types.Slice: // see below
	case *types.Map: // see below
	default:
	// Check whether the rest can print pointers.
	return t&argPointer != 0
	}
	// If it's a top-level pointer to a struct, array, slice, or
	// map, that's equivalent in our analysis to whether we can
	// print the type being pointed to. Pointers in nested levels
	// are not supported to minimize fmt running into loops.
	if len(inProgress) > 1 {
	return false
	}
	return matchArgTypeInternal(pass, t, under, arg, inProgress)

	case *types.Struct:
	return matchStructArgType(pass, t, typ, arg, inProgress)

	case *types.Interface:
	// There's little we can do.
	// Whether any particular verb is valid depends on the argument.
	// The user may have reasonable prior knowledge of the contents of the interface.
	return true

	case *types.Basic:
	switch typ.Kind() {
	case types.UntypedBool,
	types.Bool:
	return t&argBool != 0

	case types.UntypedInt,
	types.Int,
	types.Int8,
	types.Int16,
	types.Int32,
	types.Int64,
	types.Uint,
	types.Uint8,
	types.Uint16,
	types.Uint32,
	types.Uint64,
	types.Uintptr:
	return t&argInt != 0

	case types.UntypedFloat,
	types.Float32,
	types.Float64:
	return t&argFloat != 0

	case types.UntypedComplex,
	types.Complex64,
	types.Complex128:
	return t&argComplex != 0

	case types.UntypedString,
	types.String:
	return t&argString != 0

	case types.UnsafePointer:
	return t&(argPointer\|argInt) != 0

	case types.UntypedRune:
	return t&(argInt\|argRune) != 0

	case types.UntypedNil:
	return false

	case types.Invalid:
	if false {
	pass.Reportf(arg.Pos(), "printf argument %v has invalid or unknown type", analysisutil.Format(pass.Fset, arg))
	}
	return true // Probably a type check problem.
	}
	panic("unreachable")
	}

	return false
	}

	func isConvertibleToString(pass *analysis.Pass, typ types.Type) bool {
	if bt, ok := typ.(*types.Basic); ok && bt.Kind() == types.UntypedNil {
	// We explicitly don't want untyped nil, which is
	// convertible to both of the interfaces below, as it
	// would just panic anyway.
	return false
	}
	if types.ConvertibleTo(typ, errorType) {
	return true // via .Error()
	}

	// Does it implement fmt.Stringer?
	if obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "String"); obj != nil {
	if fn, ok := obj.(*types.Func); ok {
	sig := fn.Type().(*types.Signature)
	if sig.Params().Len() == 0 &&
	sig.Results().Len() == 1 &&
	sig.Results().At(0).Type() == types.Typ[types.String] {
	return true
	}
	}
	}

	return false
	}

	// hasBasicType reports whether x's type is a types.Basic with the given kind.
	func hasBasicType(pass *analysis.Pass, x ast.Expr, kind types.BasicKind) bool {
	t := pass.TypesInfo.Types[x].Type
	if t != nil {
	t = t.Underlying()
	}
	b, ok := t.(*types.Basic)
	return ok && b.Kind() == kind
	}

	// matchStructArgType reports whether all the elements of the struct match the expected
	// type. For instance, with "%d" all the elements must be printable with the "%d" format.
	func matchStructArgType(pass analysis.Pass, t printfArgType, typ types.Struct, arg ast.Expr, inProgress map[types.Type]bool) bool {
	for i := 0; i < typ.NumFields(); i++ {
	typf := typ.Field(i)
	if !matchArgTypeInternal(pass, t, typf.Type(), arg, inProgress) {
	return false
	}
	if t&argString != 0 && !typf.Exported() && isConvertibleToString(pass, typf.Type()) {
	// Issue #17798: unexported Stringer or error cannot be properly formatted.
	return false
	}
	}
	return true
	}