go/analysis/passes/stdmethods: split check out of vet
Also, rename to stdmethods and add more tests.
Change-Id: I09b65899dc02a8062f3ec1d909c2eae45472e236
Reviewed-on: https://go-review.googlesource.com/c/140761
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
diff --git a/go/analysis/passes/vet/method.go b/go/analysis/passes/stdmethods/stdmethods.go
similarity index 62%
rename from go/analysis/passes/vet/method.go
rename to go/analysis/passes/stdmethods/stdmethods.go
index 38efd9b..840a1b9 100644
--- a/go/analysis/passes/vet/method.go
+++ b/go/analysis/passes/stdmethods/stdmethods.go
@@ -1,30 +1,47 @@
-// +build ignore
-
// Copyright 2010 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.
-// This file contains the code to check canonical methods.
-
-package main
+package stdmethods
import (
+ "bytes"
"fmt"
"go/ast"
"go/printer"
+ "go/token"
+ "go/types"
"strings"
+
+ "golang.org/x/tools/go/analysis"
+ "golang.org/x/tools/go/analysis/passes/inspect"
+ "golang.org/x/tools/go/ast/inspector"
)
-func init() {
- register("methods",
- "check that canonically named methods are canonically defined",
- checkCanonicalMethod,
- funcDecl, interfaceType)
-}
+var Analyzer = &analysis.Analyzer{
+ Name: "stdmethods",
+ Doc: `check signature of methods of well-known interfaces
-type MethodSig struct {
- args []string
- results []string
+Sometimes a type may be intended to satisfy an interface but may fail to
+do so because of a mistake in its method signature.
+For example, the result of this WriteTo method should be (int64, error),
+not error, to satisfy io.WriterTo:
+
+ type myWriterTo struct{...}
+ func (myWriterTo) WriteTo(w io.Writer) error { ... }
+
+This check ensures that each method whose name matches one of several
+well-known interface methods from the standard library has the correct
+signature for that interface.
+
+Checked method names include:
+ Format GobEncode GobDecode MarshalJSON MarshalXML
+ Peek ReadByte ReadFrom ReadRune Scan Seek
+ UnmarshalJSON UnreadByte UnreadRune WriteByte
+ WriteTo
+`,
+ Requires: []*analysis.Analyzer{inspect.Analyzer},
+ Run: run,
}
// canonicalMethods lists the input and output types for Go methods
@@ -43,7 +60,7 @@
// method doesn't have a fmt.ScanState as its first argument,
// we let it go. But if it does have a fmt.ScanState, then the
// rest has to match.
-var canonicalMethods = map[string]MethodSig{
+var canonicalMethods = map[string]struct{ args, results []string }{
// "Flush": {{}, {"error"}}, // http.Flusher and jpeg.writer conflict
"Format": {[]string{"=fmt.State", "rune"}, []string{}}, // fmt.Formatter
"GobDecode": {[]string{"[]byte"}, []string{"error"}}, // gob.GobDecoder
@@ -63,22 +80,31 @@
"WriteTo": {[]string{"=io.Writer"}, []string{"int64", "error"}}, // io.WriterTo
}
-func checkCanonicalMethod(f *File, node ast.Node) {
- switch n := node.(type) {
- case *ast.FuncDecl:
- if n.Recv != nil {
- canonicalMethod(f, n.Name, n.Type)
- }
- case *ast.InterfaceType:
- for _, field := range n.Methods.List {
- for _, id := range field.Names {
- canonicalMethod(f, id, field.Type.(*ast.FuncType))
+func run(pass *analysis.Pass) (interface{}, error) {
+ inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+ nodeFilter := []ast.Node{
+ (*ast.FuncDecl)(nil),
+ (*ast.InterfaceType)(nil),
+ }
+ inspect.Preorder(nodeFilter, func(n ast.Node) {
+ switch n := n.(type) {
+ case *ast.FuncDecl:
+ if n.Recv != nil {
+ canonicalMethod(pass, n.Name, n.Type)
+ }
+ case *ast.InterfaceType:
+ for _, field := range n.Methods.List {
+ for _, id := range field.Names {
+ canonicalMethod(pass, id, field.Type.(*ast.FuncType))
+ }
}
}
- }
+ })
+ return nil, nil
}
-func canonicalMethod(f *File, id *ast.Ident, t *ast.FuncType) {
+func canonicalMethod(pass *analysis.Pass, id *ast.Ident, t *ast.FuncType) {
// Expected input/output.
expect, ok := canonicalMethods[id.Name]
if !ok {
@@ -93,12 +119,12 @@
}
// Do the =s (if any) all match?
- if !f.matchParams(expect.args, args, "=") || !f.matchParams(expect.results, results, "=") {
+ if !matchParams(pass, expect.args, args, "=") || !matchParams(pass, expect.results, results, "=") {
return
}
// Everything must match.
- if !f.matchParams(expect.args, args, "") || !f.matchParams(expect.results, results, "") {
+ if !matchParams(pass, expect.args, args, "") || !matchParams(pass, expect.results, results, "") {
expectFmt := id.Name + "(" + argjoin(expect.args) + ")"
if len(expect.results) == 1 {
expectFmt += " " + argjoin(expect.results)
@@ -106,15 +132,15 @@
expectFmt += " (" + argjoin(expect.results) + ")"
}
- f.b.Reset()
- if err := printer.Fprint(&f.b, f.fset, t); err != nil {
- fmt.Fprintf(&f.b, "<%s>", err)
+ var buf bytes.Buffer
+ if err := printer.Fprint(&buf, pass.Fset, t); err != nil {
+ fmt.Fprintf(&buf, "<%s>", err)
}
- actual := f.b.String()
+ actual := buf.String()
actual = strings.TrimPrefix(actual, "func")
actual = id.Name + actual
- f.Badf(id.Pos(), "method %s should have signature %s", actual, expectFmt)
+ pass.Reportf(id.Pos(), "method %s should have signature %s", actual, expectFmt)
}
}
@@ -148,7 +174,7 @@
}
// Does each type in expect with the given prefix match the corresponding type in actual?
-func (f *File) matchParams(expect []string, actual []ast.Expr, prefix string) bool {
+func matchParams(pass *analysis.Pass, expect []string, actual []ast.Expr, prefix string) bool {
for i, x := range expect {
if !strings.HasPrefix(x, prefix) {
continue
@@ -156,7 +182,7 @@
if i >= len(actual) {
return false
}
- if !f.matchParamType(x, actual[i]) {
+ if !matchParamType(pass.Fset, pass.Pkg, x, actual[i]) {
return false
}
}
@@ -167,15 +193,15 @@
}
// Does this one type match?
-func (f *File) matchParamType(expect string, actual ast.Expr) bool {
+func matchParamType(fset *token.FileSet, pkg *types.Package, expect string, actual ast.Expr) bool {
expect = strings.TrimPrefix(expect, "=")
// Strip package name if we're in that package.
- if n := len(f.file.Name.Name); len(expect) > n && expect[:n] == f.file.Name.Name && expect[n] == '.' {
+ if n := len(pkg.Name()); len(expect) > n && expect[:n] == pkg.Name() && expect[n] == '.' {
expect = expect[n+1:]
}
// Overkill but easy.
- f.b.Reset()
- printer.Fprint(&f.b, f.fset, actual)
- return f.b.String() == expect
+ var buf bytes.Buffer
+ printer.Fprint(&buf, fset, actual)
+ return buf.String() == expect
}
diff --git a/go/analysis/passes/stdmethods/stdmethods_test.go b/go/analysis/passes/stdmethods/stdmethods_test.go
new file mode 100644
index 0000000..33a0f9a
--- /dev/null
+++ b/go/analysis/passes/stdmethods/stdmethods_test.go
@@ -0,0 +1,13 @@
+package stdmethods_test
+
+import (
+ "testing"
+
+ "golang.org/x/tools/go/analysis/analysistest"
+ "golang.org/x/tools/go/analysis/passes/stdmethods"
+)
+
+func Test(t *testing.T) {
+ testdata := analysistest.TestData()
+ analysistest.Run(t, testdata, stdmethods.Analyzer, "a")
+}
diff --git a/go/analysis/passes/stdmethods/testdata/src/a/a.go b/go/analysis/passes/stdmethods/testdata/src/a/a.go
new file mode 100644
index 0000000..a007bbf
--- /dev/null
+++ b/go/analysis/passes/stdmethods/testdata/src/a/a.go
@@ -0,0 +1,23 @@
+// Copyright 2010 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 a
+
+import "fmt"
+
+type T int
+
+func (T) Scan(x fmt.ScanState, c byte) {} // want "should have signature Scan"
+
+func (T) Format(fmt.State, byte) {} // want `should have signature Format\(fmt.State, rune\)`
+
+type U int
+
+func (U) Format(byte) {} // no error: first parameter must be fmt.State to trigger check
+
+func (U) GobDecode() {} // want `should have signature GobDecode\(\[\]byte\) error`
+
+type I interface {
+ ReadByte() byte // want "should have signature ReadByte"
+}
diff --git a/go/analysis/passes/vet/testdata/method.go b/go/analysis/passes/vet/testdata/method.go
deleted file mode 100644
index 52b500d..0000000
--- a/go/analysis/passes/vet/testdata/method.go
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright 2010 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.
-
-// This file contains tests for the canonical method checker.
-
-// This file contains the code to check canonical methods.
-
-package testdata
-
-import (
- "fmt"
-)
-
-type MethodTest int
-
-func (t *MethodTest) Scan(x fmt.ScanState, c byte) { // ERROR "should have signature Scan"
-}
-
-type MethodTestInterface interface {
- ReadByte() byte // ERROR "should have signature ReadByte"
-}
