go/analysis/passes/structtag: split out from vet

Change-Id: Ib3c4c783e4bca2bf2b3c76bea8f19959b7e39539
Reviewed-on: https://go-review.googlesource.com/c/142097
Reviewed-by: Michael Matloob <matloob@golang.org>

go/analysis/passes/structtag/structtag.go

@@ -1,60 +1,70 @@
-// +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 test for canonical struct tags.
+package structtag
-
-package main
 
 import (
 	"errors"
 	"go/ast"
 	"go/token"
 	"go/types"
+	"path/filepath"
 	"reflect"
 	"strconv"
 	"strings"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
 )
 
-func init() {
+var Analyzer = &analysis.Analyzer{
-	register("structtags",
+	Name: "structtag",
-		"check that struct field tags have canonical format and apply to exported fields as needed",
+	Doc: `check that struct field tags conform to reflect.StructTag.Get
-		checkStructFieldTags,
+
-		structType)
+Also report certain struct tags (json, xml) used with unexported fields.`,
+	Requires:         []*analysis.Analyzer{inspect.Analyzer},
+	RunDespiteErrors: true,
+	Run:              run,
 }
 
-// checkStructFieldTags checks all the field tags of a struct, including checking for duplicates.
+func run(pass *analysis.Pass) (interface{}, error) {
-func checkStructFieldTags(f *File, node ast.Node) {
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
-	astType := node.(*ast.StructType)
+
-	typ := f.pkg.types[astType].Type.(*types.Struct)
+	nodeFilter := []ast.Node{
-	var seen map[[2]string]token.Pos
+		(*ast.StructType)(nil),
-	for i := 0; i < typ.NumFields(); i++ {
-		field := typ.Field(i)
-		tag := typ.Tag(i)
-		checkCanonicalFieldTag(f, astType, field, tag, &seen)
 	}
+	inspect.Preorder(nodeFilter, func(n ast.Node) {
+		styp := pass.TypesInfo.Types[n.(*ast.StructType)].Type.(*types.Struct)
+		var seen map[[2]string]token.Pos
+		for i := 0; i < styp.NumFields(); i++ {
+			field := styp.Field(i)
+			tag := styp.Tag(i)
+			checkCanonicalFieldTag(pass, field, tag, &seen)
+		}
+	})
+	return nil, nil
 }
 
 var checkTagDups = []string{"json", "xml"}
 var checkTagSpaces = map[string]bool{"json": true, "xml": true, "asn1": true}
 
 // checkCanonicalFieldTag checks a single struct field tag.
-// top is the top-level struct type that is currently being checked.
+func checkCanonicalFieldTag(pass *analysis.Pass, field *types.Var, tag string, seen *map[[2]string]token.Pos) {
-func checkCanonicalFieldTag(f *File, top *ast.StructType, field *types.Var, tag string, seen *map[[2]string]token.Pos) {
 	for _, key := range checkTagDups {
-		checkTagDuplicates(f, tag, key, field, field, seen)
+		checkTagDuplicates(pass, tag, key, field, field, seen)
 	}
 
 	if err := validateStructTag(tag); err != nil {
-		f.Badf(field.Pos(), "struct field tag %#q not compatible with reflect.StructTag.Get: %s", tag, err)
+		pass.Reportf(field.Pos(), "struct field tag %#q not compatible with reflect.StructTag.Get: %s", tag, err)
 	}
 
 	// Check for use of json or xml tags with unexported fields.
 
 	// Embedded struct. Nothing to do for now, but that
 	// may change, depending on what happens with issue 7363.
+	// TODO(adonovan): investigate, now that that issue is fixed.
 	if field.Anonymous() {
 		return
 	}
@@ -65,7 +75,7 @@ func checkCanonicalFieldTag(f *File, top *ast.StructType, field *types.Var, tag
 
 	for _, enc := range [...]string{"json", "xml"} {
 		if reflect.StructTag(tag).Get(enc) != "" {
-			f.Badf(field.Pos(), "struct field %s has %s tag but is not exported", field.Name(), enc)
+			pass.Reportf(field.Pos(), "struct field %s has %s tag but is not exported", field.Name(), enc)
 			return
 		}
 	}
@@ -74,7 +84,7 @@ func checkCanonicalFieldTag(f *File, top *ast.StructType, field *types.Var, tag
 // checkTagDuplicates checks a single struct field tag to see if any tags are
 // duplicated. nearest is the field that's closest to the field being checked,
 // while still being part of the top-level struct type.
-func checkTagDuplicates(f *File, tag, key string, nearest, field *types.Var, seen *map[[2]string]token.Pos) {
+func checkTagDuplicates(pass *analysis.Pass, tag, key string, nearest, field *types.Var, seen *map[[2]string]token.Pos) {
 	val := reflect.StructTag(tag).Get(key)
 	if val == "-" {
 		// Ignored, even if the field is anonymous.
@@ -92,7 +102,7 @@ func checkTagDuplicates(f *File, tag, key string, nearest, field *types.Var, see
 					continue
 				}
 				tag := typ.Tag(i)
-				checkTagDuplicates(f, tag, key, nearest, field, seen)
+				checkTagDuplicates(pass, tag, key, nearest, field, seen)
 			}
 		}
 		// Ignored if the field isn't anonymous.
@@ -122,7 +132,10 @@ func checkTagDuplicates(f *File, tag, key string, nearest, field *types.Var, see
 		*seen = map[[2]string]token.Pos{}
 	}
 	if pos, ok := (*seen)[[2]string{key, val}]; ok {
-		f.Badf(nearest.Pos(), "struct field %s repeats %s tag %q also at %s", field.Name(), key, val, f.loc(pos))
+		posn := pass.Fset.Position(pos)
+		posn.Filename = filepath.Base(posn.Filename)
+		posn.Column = 0
+		pass.Reportf(nearest.Pos(), "struct field %s repeats %s tag %q also at %s", field.Name(), key, val, posn)
 	} else {
 		(*seen)[[2]string{key, val}] = field.Pos()
 	}

go/analysis/passes/structtag/structtag_test.go

@@ -0,0 +1,13 @@
+package structtag_test
+
+import (
+	"testing"
+
+	"golang.org/x/tools/go/analysis/analysistest"
+	"golang.org/x/tools/go/analysis/passes/structtag"
+)
+
+func TestFromFileSystem(t *testing.T) {
+	testdata := analysistest.TestData()
+	analysistest.Run(t, testdata, structtag.Analyzer, "a")
+}

go/analysis/passes/structtag/testdata/src/a/a.go

@@ -0,0 +1,113 @@
+// 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 test for canonical struct tags.
+
+package a
+
+import "encoding/xml"
+
+type StructTagTest struct {
+	A   int "hello"            // want "`hello` not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
+	B   int "\tx:\"y\""        // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
+	C   int "x:\"y\"\tx:\"y\"" // want "not compatible with reflect.StructTag.Get"
+	D   int "x:`y`"            // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
+	E   int "ct\brl:\"char\""  // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
+	F   int `:"emptykey"`      // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
+	G   int `x:"noEndQuote`    // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
+	H   int `x:"trunc\x0"`     // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
+	I   int `x:"foo",y:"bar"`  // want "not compatible with reflect.StructTag.Get: key:.value. pairs not separated by spaces"
+	J   int `x:"foo"y:"bar"`   // want "not compatible with reflect.StructTag.Get: key:.value. pairs not separated by spaces"
+	OK0 int `x:"y" u:"v" w:""`
+	OK1 int `x:"y:z" u:"v" w:""` // note multiple colons.
+	OK2 int "k0:\"values contain spaces\" k1:\"literal\ttabs\" k2:\"and\\tescaped\\tabs\""
+	OK3 int `under_scores:"and" CAPS:"ARE_OK"`
+}
+
+type UnexportedEncodingTagTest struct {
+	x int `json:"xx"` // want "struct field x has json tag but is not exported"
+	y int `xml:"yy"`  // want "struct field y has xml tag but is not exported"
+	z int
+	A int `json:"aa" xml:"bb"`
+}
+
+type unexp struct{}
+
+type JSONEmbeddedField struct {
+	UnexportedEncodingTagTest `is:"embedded"`
+	unexp                     `is:"embedded,notexported" json:"unexp"` // OK for now, see issue 7363
+}
+
+type AnonymousJSON struct{}
+type AnonymousXML struct{}
+
+type AnonymousJSONField struct {
+	DuplicateAnonJSON int `json:"a"`
+
+	A int "hello" // want "`hello` not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
+}
+
+type DuplicateJSONFields struct {
+	JSON              int `json:"a"`
+	DuplicateJSON     int `json:"a"` // want "struct field DuplicateJSON repeats json tag .a. also at a.go:52"
+	IgnoredJSON       int `json:"-"`
+	OtherIgnoredJSON  int `json:"-"`
+	OmitJSON          int `json:",omitempty"`
+	OtherOmitJSON     int `json:",omitempty"`
+	DuplicateOmitJSON int `json:"a,omitempty"` // want "struct field DuplicateOmitJSON repeats json tag .a. also at a.go:52"
+	NonJSON           int `foo:"a"`
+	DuplicateNonJSON  int `foo:"a"`
+	Embedded          struct {
+		DuplicateJSON int `json:"a"` // OK because it's not in the same struct type
+	}
+	AnonymousJSON `json:"a"` // want "struct field AnonymousJSON repeats json tag .a. also at a.go:52"
+
+	AnonymousJSONField // want "struct field DuplicateAnonJSON repeats json tag .a. also at a.go:52"
+
+	XML              int `xml:"a"`
+	DuplicateXML     int `xml:"a"` // want "struct field DuplicateXML repeats xml tag .a. also at a.go:68"
+	IgnoredXML       int `xml:"-"`
+	OtherIgnoredXML  int `xml:"-"`
+	OmitXML          int `xml:",omitempty"`
+	OtherOmitXML     int `xml:",omitempty"`
+	DuplicateOmitXML int `xml:"a,omitempty"` // want "struct field DuplicateOmitXML repeats xml tag .a. also at a.go:68"
+	NonXML           int `foo:"a"`
+	DuplicateNonXML  int `foo:"a"`
+	Embedded2        struct {
+		DuplicateXML int `xml:"a"` // OK because it's not in the same struct type
+	}
+	AnonymousXML `xml:"a"` // want "struct field AnonymousXML repeats xml tag .a. also at a.go:68"
+	Attribute    struct {
+		XMLName     xml.Name `xml:"b"`
+		NoDup       int      `xml:"b"`                // OK because XMLName above affects enclosing struct.
+		Attr        int      `xml:"b,attr"`           // OK because <b b="0"><b>0</b></b> is valid.
+		DupAttr     int      `xml:"b,attr"`           // want "struct field DupAttr repeats xml attribute tag .b. also at a.go:84"
+		DupOmitAttr int      `xml:"b,omitempty,attr"` // want "struct field DupOmitAttr repeats xml attribute tag .b. also at a.go:84"
+
+		AnonymousXML `xml:"b,attr"` // want "struct field AnonymousXML repeats xml attribute tag .b. also at a.go:84"
+	}
+
+	AnonymousJSONField `json:"not_anon"` // ok; fields aren't embedded in JSON
+	AnonymousJSONField `json:"-"`        // ok; entire field is ignored in JSON
+}
+
+type UnexpectedSpacetest struct {
+	A int `json:"a,omitempty"`
+	B int `json:"b, omitempty"` // want "suspicious space in struct tag value"
+	C int `json:"c ,omitempty"`
+	D int `json:"d,omitempty, string"` // want "suspicious space in struct tag value"
+	E int `xml:"e local"`
+	F int `xml:"f "`                 // want "suspicious space in struct tag value"
+	G int `xml:" g"`                 // want "suspicious space in struct tag value"
+	H int `xml:"h ,omitempty"`       // want "suspicious space in struct tag value"
+	I int `xml:"i, omitempty"`       // want "suspicious space in struct tag value"
+	J int `xml:"j local ,omitempty"` // want "suspicious space in struct tag value"
+	K int `xml:"k local, omitempty"` // want "suspicious space in struct tag value"
+	L int `xml:" l local,omitempty"` // want "suspicious space in struct tag value"
+	M int `xml:"m  local,omitempty"` // want "suspicious space in struct tag value"
+	N int `xml:" "`                  // want "suspicious space in struct tag value"
+	O int `xml:""`
+	P int `xml:","`
+	Q int `foo:" doesn't care "`
+}

go/analysis/passes/vet/testdata/structtag.go

@@ -1,113 +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 the test for canonical struct tags.
-
-package testdata
-
-import "encoding/xml"
-
-type StructTagTest struct {
-	A   int "hello"            // ERROR "`hello` not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
-	B   int "\tx:\"y\""        // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
-	C   int "x:\"y\"\tx:\"y\"" // ERROR "not compatible with reflect.StructTag.Get"
-	D   int "x:`y`"            // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
-	E   int "ct\brl:\"char\""  // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
-	F   int `:"emptykey"`      // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
-	G   int `x:"noEndQuote`    // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
-	H   int `x:"trunc\x0"`     // ERROR "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
-	I   int `x:"foo",y:"bar"`  // ERROR "not compatible with reflect.StructTag.Get: key:.value. pairs not separated by spaces"
-	J   int `x:"foo"y:"bar"`   // ERROR "not compatible with reflect.StructTag.Get: key:.value. pairs not separated by spaces"
-	OK0 int `x:"y" u:"v" w:""`
-	OK1 int `x:"y:z" u:"v" w:""` // note multiple colons.
-	OK2 int "k0:\"values contain spaces\" k1:\"literal\ttabs\" k2:\"and\\tescaped\\tabs\""
-	OK3 int `under_scores:"and" CAPS:"ARE_OK"`
-}
-
-type UnexportedEncodingTagTest struct {
-	x int `json:"xx"` // ERROR "struct field x has json tag but is not exported"
-	y int `xml:"yy"`  // ERROR "struct field y has xml tag but is not exported"
-	z int
-	A int `json:"aa" xml:"bb"`
-}
-
-type unexp struct{}
-
-type JSONEmbeddedField struct {
-	UnexportedEncodingTagTest `is:"embedded"`
-	unexp                     `is:"embedded,notexported" json:"unexp"` // OK for now, see issue 7363
-}
-
-type AnonymousJSON struct{}
-type AnonymousXML struct{}
-
-type AnonymousJSONField struct {
-	DuplicateAnonJSON int `json:"a"`
-
-	A int "hello" // ERROR "`hello` not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
-}
-
-type DuplicateJSONFields struct {
-	JSON              int `json:"a"`
-	DuplicateJSON     int `json:"a"` // ERROR "struct field DuplicateJSON repeats json tag .a. also at structtag.go:52"
-	IgnoredJSON       int `json:"-"`
-	OtherIgnoredJSON  int `json:"-"`
-	OmitJSON          int `json:",omitempty"`
-	OtherOmitJSON     int `json:",omitempty"`
-	DuplicateOmitJSON int `json:"a,omitempty"` // ERROR "struct field DuplicateOmitJSON repeats json tag .a. also at structtag.go:52"
-	NonJSON           int `foo:"a"`
-	DuplicateNonJSON  int `foo:"a"`
-	Embedded          struct {
-		DuplicateJSON int `json:"a"` // OK because its not in the same struct type
-	}
-	AnonymousJSON `json:"a"` // ERROR "struct field AnonymousJSON repeats json tag .a. also at structtag.go:52"
-
-	AnonymousJSONField // ERROR "struct field DuplicateAnonJSON repeats json tag .a. also at structtag.go:52"
-
-	XML              int `xml:"a"`
-	DuplicateXML     int `xml:"a"` // ERROR "struct field DuplicateXML repeats xml tag .a. also at structtag.go:68"
-	IgnoredXML       int `xml:"-"`
-	OtherIgnoredXML  int `xml:"-"`
-	OmitXML          int `xml:",omitempty"`
-	OtherOmitXML     int `xml:",omitempty"`
-	DuplicateOmitXML int `xml:"a,omitempty"` // ERROR "struct field DuplicateOmitXML repeats xml tag .a. also at structtag.go:68"
-	NonXML           int `foo:"a"`
-	DuplicateNonXML  int `foo:"a"`
-	Embedded2        struct {
-		DuplicateXML int `xml:"a"` // OK because its not in the same struct type
-	}
-	AnonymousXML `xml:"a"` // ERROR "struct field AnonymousXML repeats xml tag .a. also at structtag.go:68"
-	Attribute    struct {
-		XMLName     xml.Name `xml:"b"`
-		NoDup       int      `xml:"b"`                // OK because XMLName above affects enclosing struct.
-		Attr        int      `xml:"b,attr"`           // OK because <b b="0"><b>0</b></b> is valid.
-		DupAttr     int      `xml:"b,attr"`           // ERROR "struct field DupAttr repeats xml attribute tag .b. also at structtag.go:84"
-		DupOmitAttr int      `xml:"b,omitempty,attr"` // ERROR "struct field DupOmitAttr repeats xml attribute tag .b. also at structtag.go:84"
-
-		AnonymousXML `xml:"b,attr"` // ERROR "struct field AnonymousXML repeats xml attribute tag .b. also at structtag.go:84"
-	}
-
-	AnonymousJSONField `json:"not_anon"` // ok; fields aren't embedded in JSON
-	AnonymousJSONField `json:"-"`        // ok; entire field is ignored in JSON
-}
-
-type UnexpectedSpacetest struct {
-	A int `json:"a,omitempty"`
-	B int `json:"b, omitempty"` // ERROR "suspicious space in struct tag value"
-	C int `json:"c ,omitempty"`
-	D int `json:"d,omitempty, string"` // ERROR "suspicious space in struct tag value"
-	E int `xml:"e local"`
-	F int `xml:"f "`                 // ERROR "suspicious space in struct tag value"
-	G int `xml:" g"`                 // ERROR "suspicious space in struct tag value"
-	H int `xml:"h ,omitempty"`       // ERROR "suspicious space in struct tag value"
-	I int `xml:"i, omitempty"`       // ERROR "suspicious space in struct tag value"
-	J int `xml:"j local ,omitempty"` // ERROR "suspicious space in struct tag value"
-	K int `xml:"k local, omitempty"` // ERROR "suspicious space in struct tag value"
-	L int `xml:" l local,omitempty"` // ERROR "suspicious space in struct tag value"
-	M int `xml:"m  local,omitempty"` // ERROR "suspicious space in struct tag value"
-	N int `xml:" "`                  // ERROR "suspicious space in struct tag value"
-	O int `xml:""`
-	P int `xml:","`
-	Q int `foo:" doesn't care "`
-}