| // Copyright 2019 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 deepequalerrors defines an Analyzer that checks for the use |
| // of reflect.DeepEqual with error values. |
| package deepequalerrors |
| |
| import ( |
| "go/ast" |
| "go/types" |
| |
| "golang.org/x/tools/go/analysis" |
| "golang.org/x/tools/go/analysis/passes/inspect" |
| "golang.org/x/tools/go/analysis/passes/internal/analysisutil" |
| "golang.org/x/tools/go/ast/inspector" |
| "golang.org/x/tools/go/types/typeutil" |
| ) |
| |
| const Doc = `check for calls of reflect.DeepEqual on error values |
| |
| The deepequalerrors checker looks for calls of the form: |
| |
| reflect.DeepEqual(err1, err2) |
| |
| where err1 and err2 are errors. Using reflect.DeepEqual to compare |
| errors is discouraged.` |
| |
| var Analyzer = &analysis.Analyzer{ |
| Name: "deepequalerrors", |
| Doc: Doc, |
| URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/deepequalerrors", |
| Requires: []*analysis.Analyzer{inspect.Analyzer}, |
| Run: run, |
| } |
| |
| func run(pass *analysis.Pass) (interface{}, error) { |
| if !analysisutil.Imports(pass.Pkg, "reflect") { |
| return nil, nil // doesn't directly import reflect |
| } |
| |
| inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector) |
| |
| nodeFilter := []ast.Node{ |
| (*ast.CallExpr)(nil), |
| } |
| inspect.Preorder(nodeFilter, func(n ast.Node) { |
| call := n.(*ast.CallExpr) |
| fn, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Func) |
| if !ok { |
| return |
| } |
| if fn.FullName() == "reflect.DeepEqual" && hasError(pass, call.Args[0]) && hasError(pass, call.Args[1]) { |
| pass.ReportRangef(call, "avoid using reflect.DeepEqual with errors") |
| } |
| }) |
| return nil, nil |
| } |
| |
| var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface) |
| |
| // hasError reports whether the type of e contains the type error. |
| // See containsError, below, for the meaning of "contains". |
| func hasError(pass *analysis.Pass, e ast.Expr) bool { |
| tv, ok := pass.TypesInfo.Types[e] |
| if !ok { // no type info, assume good |
| return false |
| } |
| return containsError(tv.Type) |
| } |
| |
| // Report whether any type that typ could store and that could be compared is the |
| // error type. This includes typ itself, as well as the types of struct field, slice |
| // and array elements, map keys and elements, and pointers. It does not include |
| // channel types (incomparable), arg and result types of a Signature (not stored), or |
| // methods of a named or interface type (not stored). |
| func containsError(typ types.Type) bool { |
| // Track types being processed, to avoid infinite recursion. |
| // Using types as keys here is OK because we are checking for the identical pointer, not |
| // type identity. See analysis/passes/printf/types.go. |
| inProgress := make(map[types.Type]bool) |
| |
| var check func(t types.Type) bool |
| check = func(t types.Type) bool { |
| if t == errorType { |
| return true |
| } |
| if inProgress[t] { |
| return false |
| } |
| inProgress[t] = true |
| switch t := t.(type) { |
| case *types.Pointer: |
| return check(t.Elem()) |
| case *types.Slice: |
| return check(t.Elem()) |
| case *types.Array: |
| return check(t.Elem()) |
| case *types.Map: |
| return check(t.Key()) || check(t.Elem()) |
| case *types.Struct: |
| for i := 0; i < t.NumFields(); i++ { |
| if check(t.Field(i).Type()) { |
| return true |
| } |
| } |
| case *types.Named: |
| return check(t.Underlying()) |
| |
| // We list the remaining valid type kinds for completeness. |
| case *types.Basic: |
| case *types.Chan: // channels store values, but they are not comparable |
| case *types.Signature: |
| case *types.Tuple: // tuples are only part of signatures |
| case *types.Interface: |
| } |
| return false |
| } |
| |
| return check(typ) |
| } |