gofix: add a fix for hash.Sum.

This fix adds an output argument to hash.Sum.

Tree changes in https://golang.org/cl/5448065

R=rsc
CC=golang-dev
https://golang.org/cl/5450051

diff --git a/src/cmd/gofix/Makefile b/src/cmd/gofix/Makefile
index 6ff489dcb1451cfea8ec565aa0f41d0146af5a6b..dc42b3055d2d54bd37cf13d5c1fd6a0ee3702860 100644 (file)
--- a/src/cmd/gofix/Makefile
+++ b/src/cmd/gofix/Makefile
@@ -10,6 +10,7 @@ GOFILES=\
        filepath.go\
        fix.go\
        go1pkgrename.go\
+       hashsum.go\
        htmlerr.go\
        httpfinalurl.go\
        httpfs.go\

diff --git a/src/cmd/gofix/hashsum.go b/src/cmd/gofix/hashsum.go
new file mode 100644 (file)
index 0000000..3e36cd6
--- /dev/null
+++ b/src/cmd/gofix/hashsum.go
@@ -0,0 +1,94 @@
+// Copyright 2011 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 main
+
+import (
+       "go/ast"
+)
+
+func init() {
+       register(hashSumFix)
+}
+
+var hashSumFix = fix{
+       "hashsum",
+       "2011-11-30",
+       hashSumFn,
+       `Pass a nil argument to calls to hash.Sum
+
+This fix rewrites code so that it passes a nil argument to hash.Sum.
+The additional argument will allow callers to avoid an
+allocation in the future.
+
+http://codereview.appspot.com/5448065
+`,
+}
+
+// Type-checking configuration: tell the type-checker this basic
+// information about types, functions, and variables in external packages.
+var hashSumTypeConfig = &TypeConfig{
+       Var: map[string]string{
+               "crypto.MD4":       "crypto.Hash",
+               "crypto.MD5":       "crypto.Hash",
+               "crypto.SHA1":      "crypto.Hash",
+               "crypto.SHA224":    "crypto.Hash",
+               "crypto.SHA256":    "crypto.Hash",
+               "crypto.SHA384":    "crypto.Hash",
+               "crypto.SHA512":    "crypto.Hash",
+               "crypto.MD5SHA1":   "crypto.Hash",
+               "crypto.RIPEMD160": "crypto.Hash",
+       },
+
+       Func: map[string]string{
+               "adler32.New":    "hash.Hash",
+               "crc32.New":      "hash.Hash",
+               "crc32.NewIEEE":  "hash.Hash",
+               "crc64.New":      "hash.Hash",
+               "fnv.New32a":     "hash.Hash",
+               "fnv.New32":      "hash.Hash",
+               "fnv.New64a":     "hash.Hash",
+               "fnv.New64":      "hash.Hash",
+               "hmac.New":       "hash.Hash",
+               "hmac.NewMD5":    "hash.Hash",
+               "hmac.NewSHA1":   "hash.Hash",
+               "hmac.NewSHA256": "hash.Hash",
+               "md4.New":        "hash.Hash",
+               "md5.New":        "hash.Hash",
+               "ripemd160.New":  "hash.Hash",
+               "sha1.New224":    "hash.Hash",
+               "sha1.New":       "hash.Hash",
+               "sha256.New224":  "hash.Hash",
+               "sha256.New":     "hash.Hash",
+               "sha512.New384":  "hash.Hash",
+               "sha512.New":     "hash.Hash",
+       },
+
+       Type: map[string]*Type{
+               "crypto.Hash": &Type{
+                       Method: map[string]string{
+                               "New": "func() hash.Hash",
+                       },
+               },
+       },
+}
+
+func hashSumFn(f *ast.File) bool {
+       typeof, _ := typecheck(hashSumTypeConfig, f)
+
+       fixed := false
+
+       walk(f, func(n interface{}) {
+               call, ok := n.(*ast.CallExpr)
+               if ok && len(call.Args) == 0 {
+                       sel, ok := call.Fun.(*ast.SelectorExpr)
+                       if ok && sel.Sel.Name == "Sum" && typeof[sel.X] == "hash.Hash" {
+                               call.Args = append(call.Args, ast.NewIdent("nil"))
+                               fixed = true
+                       }
+               }
+       })
+
+       return fixed
+}

diff --git a/src/cmd/gofix/hashsum_test.go b/src/cmd/gofix/hashsum_test.go
new file mode 100644 (file)
index 0000000..241af20
--- /dev/null
+++ b/src/cmd/gofix/hashsum_test.go
@@ -0,0 +1,99 @@
+// Copyright 2011 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 main
+
+func init() {
+       addTestCases(hashSumTests, hashSumFn)
+}
+
+var hashSumTests = []testCase{
+       {
+               Name: "hashsum.0",
+               In: `package main
+
+import "crypto/sha256"
+
+func f() []byte {
+       h := sha256.New()
+       return h.Sum()
+}
+`,
+               Out: `package main
+
+import "crypto/sha256"
+
+func f() []byte {
+       h := sha256.New()
+       return h.Sum(nil)
+}
+`,
+       },
+
+       {
+               Name: "hashsum.1",
+               In: `package main
+
+func f(h hash.Hash) []byte {
+       return h.Sum()
+}
+`,
+               Out: `package main
+
+func f(h hash.Hash) []byte {
+       return h.Sum(nil)
+}
+`,
+       },
+
+       {
+               Name: "hashsum.0",
+               In: `package main
+
+import "crypto/sha256"
+
+func f() []byte {
+       h := sha256.New()
+       h.Write([]byte("foo"))
+       digest := h.Sum()
+}
+`,
+               Out: `package main
+
+import "crypto/sha256"
+
+func f() []byte {
+       h := sha256.New()
+       h.Write([]byte("foo"))
+       digest := h.Sum(nil)
+}
+`,
+       },
+
+       {
+               Name: "hashsum.0",
+               In: `package main
+
+import _ "crypto/sha256"
+import "crypto"
+
+func f() []byte {
+       hashType := crypto.SHA256
+       h := hashType.New()
+       digest := h.Sum()
+}
+`,
+               Out: `package main
+
+import _ "crypto/sha256"
+import "crypto"
+
+func f() []byte {
+       hashType := crypto.SHA256
+       h := hashType.New()
+       digest := h.Sum(nil)
+}
+`,
+       },
+}