fix false positive case when error is not handling in condition

noinlineerr.go

@@ -57,9 +57,9 @@ func inlineErrorInspector(pass *analysis.Pass) func(n ast.Node) {
 				continue
 			}
 
-			// confirm type is error
+			// confirm type is error and it is used in condition
 			obj := pass.TypesInfo.ObjectOf(ident)
-			if !isError(obj) || ident.Name == "_" {
+			if !isError(obj) || ident.Name == "_" || !errorUsedInCondition(ifStmt.Cond, ident.Name) {
 				continue
 			}
 
@@ -132,3 +132,23 @@ func shadowVarsExists(name string, scope *types.Scope) bool {
 
 	return parentScope.Lookup(name) != nil
 }
+
+func errorUsedInCondition(cond ast.Expr, errIdentName string) bool {
+	used := false
+
+	ast.Inspect(cond, func(n ast.Node) bool {
+		ident, ok := n.(*ast.Ident)
+		if !ok {
+			return true
+		}
+
+		if ident.Name == errIdentName {
+			used = true
+			return false
+		}
+
+		return true
+	})
+
+	return used
+}

testdata/src/a/main.go

@@ -52,6 +52,11 @@ func valid() error {
 	if ok, _ := strconv.ParseBool("1"); ok {
 		fmt.Println("ok")
 	}
+
+	var myErr MyAliasErr
+	if err, ok := myErr.(error); ok {
+		fmt.Println("ok", err)
+	}
 
 	return nil
 }

testdata/src/a/main.go.golden

@@ -54,6 +54,11 @@ func valid() error {
 		fmt.Println("ok")
 	}
 
+    var myErr MyAliasErr
+	if err, ok := myErr.(error); ok {
+		fmt.Println("ok", err)
+	}
+
 	return nil
 }