fix: 事前にtype-switchの位置を調べてそこではエラーが出ないようにした

go.sum

@@ -1,19 +1,25 @@
 github.com/sanposhiho/tools v0.4.5 h1:pXf98dp7iQLmfXcDKDXUyAAjLYcZc9AENSGaU2OnNNI=
 github.com/sanposhiho/tools v0.4.5/go.mod h1:59aVZoWPC49+9aLqjfYxCX6iyckGwaz+LaP6nI95s+s=
+github.com/yuin/goldmark v1.2.1 h1:ruQGxdhGHe7FWOJPT0mKs5+pD2Xs1Bm/kdGlHO04FmM=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnkZWQJsqcURM6tKiBApRjXI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200822124328-c89045814202 h1:VvcQYSHwXgi7W+TpUR6A9g6Up98WAHf3f/ulnJ62IyA=
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208 h1:qwRHBd0NqMbJxfbotnDhm2ByMI1Shq4Y6oRJo21SGJA=
 golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd h1:xhmwyvizuTgC2qz7ZlMluP20uW+C3Rm0FD/WLDX8884=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200902171120-36b1a880d5d1 h1:5SfEmaQTww9A35eeANMuoDMDbba7pCPVplPWQ72i5lY=

testdata/src/a/a.go

@@ -1,9 +1,25 @@
 package a
 
+import (
+	"strings"
+)
+
 func p(x int) int {
 	return x + 1
 }
 
+func multiple(val interface{}, times uint) interface{} {
+
+	switch hogehoge := val.(type) {
+	case int:
+		return 12
+	case string:
+		return strings.Repeat(hogehoge, int(times))
+	default:
+		return nil
+	}
+}
+
 func noUseParams(params string) int {
 	a := 12
 	println(a)

wastedassign.go

@@ -1,8 +1,13 @@
 package wastedassign
 
 import (
+	"go/ast"
+	"go/token"
+
 	"github.com/sanposhiho/tools/go/analysis/passes/buildssa"
+	"github.com/sanposhiho/tools/go/analysis/passes/inspect"
 	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/ast/inspector"
 	"golang.org/x/tools/go/ssa"
 )
 
@@ -15,12 +20,30 @@ var Analyzer = &analysis.Analyzer{
 	Run:  run,
 	Requires: []*analysis.Analyzer{
 		buildssa.Analyzer,
+		inspect.Analyzer,
 	},
 }
 
+type wastedAssignStruct struct {
+	pos    token.Pos
+	reason string
+}
+
 func run(pass *analysis.Pass) (interface{}, error) {
-	s := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
 
+	// type switchのあるlineの検出
+	typeSwitchPos := map[int]bool{}
+	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+	inspect.Preorder([]ast.Node{new(ast.TypeSwitchStmt)}, func(n ast.Node) {
+		switch n := n.(type) {
+		case *ast.TypeSwitchStmt:
+			typeSwitchPos[pass.Fset.Position(n.Pos()).Line] = true
+		}
+	})
+
+	wastedAssignMap := []wastedAssignStruct{}
+
+	s := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
 	for _, sf := range s.SrcFuncs {
 		for _, bl := range sf.Blocks {
 			blCopy := *bl
@@ -32,8 +55,11 @@ func run(pass *analysis.Pass) (interface{}, error) {
 					for _, op := range ist.Operands(buf[:0]) {
 						if (*op) != nil && opInLocals(sf.Locals, op) {
 							if reason := isNextOperationToOpIsStore([]*ssa.BasicBlock{&blCopy}, op, nil); reason != notWasted {
-								if ist.Pos() != 0 {
-									pass.Reportf(ist.Pos(), reason.String())
+								if ist.Pos() != 0 && !typeSwitchPos[pass.Fset.Position(ist.Pos()).Line] {
+									wastedAssignMap = append(wastedAssignMap, wastedAssignStruct{
+										pos:    ist.Pos(),
+										reason: reason.String(),
+									})
 								}
 							}
 						}
@@ -42,9 +68,45 @@ func run(pass *analysis.Pass) (interface{}, error) {
 			}
 		}
 	}
+	for _, was := range wastedAssignMap {
+		pass.Reportf(was.pos, was.reason)
+	}
 	return nil, nil
 }
 
+func searchTypeSwitchStmt(bodyList []ast.Stmt) []token.Pos {
+	result := []token.Pos{}
+
+	for _, l := range bodyList {
+		switch a := l.(type) {
+		case *ast.IfStmt:
+			re := searchTypeSwitchStmt(a.Body.List)
+			result = append(result, re...)
+		case *ast.BlockStmt:
+			re := searchTypeSwitchStmt(a.List)
+			result = append(result, re...)
+		case *ast.SwitchStmt:
+			re := searchTypeSwitchStmt(a.Body.List)
+			result = append(result, a.Pos())
+			result = append(result, re...)
+		case *ast.TypeSwitchStmt:
+			re := searchTypeSwitchStmt(a.Body.List)
+			result = append(result, re...)
+		case *ast.SelectStmt:
+			re := searchTypeSwitchStmt(a.Body.List)
+			result = append(result, re...)
+		case *ast.ForStmt:
+			re := searchTypeSwitchStmt(a.Body.List)
+			result = append(result, re...)
+		case *ast.RangeStmt:
+			re := searchTypeSwitchStmt(a.Body.List)
+			result = append(result, re...)
+		}
+	}
+
+	return result
+}
+
 type wastedReason string
 
 const (