--- /dev/null
+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
+}
projects / dotfiles / .git / blobdiff