any name for error, not just 'err'

README.md

@@ -1,6 +1,6 @@
 # deferror
 
-Deferror is a Go linter that suggests a customly made `defer` function call when the function has a return error named `err` and the function does not already start with a `defer` call.
+Deferror is a Go linter that suggests a customly made `defer` function call when the function has a return named error and the function does not already start with a `defer` call.
 
 ## Install
 
@@ -51,6 +51,7 @@ type F struct {
 	RecvType    string
 	RecvPointer bool
 	Params      []P
+	ErrName     string
 }
 
 type P struct {
@@ -82,7 +83,7 @@ func (r *R) MyExample(now time.Duration, i *int) (a int, err error) {
 The input data map for the template is:
 
 ```go
-&{PkgName:example PkgPath:github.com/Jiang-Gianni/deferror/example FnName:MyExample RecvName:r RecvType:*R RecvPointer:true Params:[{Name:now Type:time.Duration Pointer:false} {Name:i Type:*int Pointer:true}]}
+&{PkgName:example PkgPath:github.com/Jiang-Gianni/deferror/example FnName:MyExample RecvName:r RecvType:*R RecvPointer:true Params:[{Name:now Type:time.Duration Pointer:false} {Name:i Type:*int Pointer:true}] ErrName: err}
 ```
 
 The following defer call is suggested with the default template:

check.go

@@ -4,23 +4,21 @@ import (
 	"go/ast"
 )
 
-func (a *A) namedReturnErr(fd *ast.FuncDecl) bool {
+// Return true/false and the name of the error
+func (a *A) namedReturnErr(fd *ast.FuncDecl) (bool, string) {
 	if fd.Type == nil || fd.Type.Results == nil || fd.Type.Results.List == nil {
-		return false
+		return false, ""
 	}
 	for _, field := range fd.Type.Results.List {
 		ident, ok := field.Type.(*ast.Ident)
-		if ok && ident.Name == "error" {
-			for _, name := range field.Names {
-				if name.Name == "err" {
-					return true
-				}
-			}
+		if ok && ident.Name == "error" && field.Names != nil && len(field.Names) > 0 && field.Names[0].Name != "" {
+			return true, field.Names[0].Name
 		}
 	}
-	return false
+	return false, ""
 }
 
+// Function body start with a defer call
 func (a *A) deferStart(fd *ast.FuncDecl) bool {
 	if len(fd.Body.List) == 0 {
 		return false

cmd/init.go

@@ -42,8 +42,8 @@ var initCmd = &cobra.Command{
 }
 
 var tmplContents = []byte(`{{define "main"}}   defer func({{template "input" .}}) {
-    if err != nil {
-        err = fmt.Errorf("{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}}): %w", {{template "plist" .}}{{if .Params}} ,{{end}}err)
+    if {{.ErrName}} != nil {
+        {{.ErrName}} = fmt.Errorf("{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}}): %w", {{template "plist" .}}{{if .Params}} ,{{end}}{{.ErrName}})
     }
 }({{template "plist" .}})
 {{end}}

deferror.go

@@ -28,8 +28,8 @@ func run(pass *analysis.Pass) (any, error) {
 	a.inspect.Preorder(nodeFilter, func(n ast.Node) {
 		switch n := n.(type) {
 		case *ast.FuncDecl:
-			if a.namedReturnErr(n) && !a.deferStart(n) {
-				a.report(n)
+			if ok, name := a.namedReturnErr(n); ok && !a.deferStart(n) {
+				a.report(n, name)
 			}
 		}
 	})

deferror.tmpl

@@ -1,6 +1,6 @@
 {{define "main"}}   defer func({{template "input" .}}) {
-    if err != nil {
-        err = fmt.Errorf("{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}}): %w", {{template "plist" .}}{{if .Params}} ,{{end}}err)
+    if {{.ErrName}} != nil {
+        {{.ErrName}} = fmt.Errorf("{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}}): %w", {{template "plist" .}}{{if .Params}} ,{{end}}{{.ErrName}})
     }
 }({{template "plist" .}})
 {{end}}

example/readme.go

@@ -11,16 +11,17 @@ func (r *R) MyExample(now time.Duration, i *int) (a int, err error) {
 	return 0, fmt.Errorf("new err is right here")
 }
 
-/*
-	Default
+/* Default:
+
+defer func(now time.Duration, i *int) {
+    if err != nil {
+        err = fmt.Errorf("r.MyExample(%v, %v): %w", now, i ,err)
+    }
+}(now, i)
+
 */
-// defer func(now time.Duration, i *int) {
-//     if err != nil {
-//         err = fmt.Errorf("r.MyExample(%v, %v): %w", now, i ,err)
-//     }
-// }(now, i)
-
-/*
-	Wrap
+
+/* Wrap:
+
+defer dfrr.Wrap(&err, "r.MyExample(%v, %v)",now, i)
 */
-// defer dfrr.Wrap(&err, "r.MyExample(%v, %v)",now, i)

global.go

@@ -25,6 +25,7 @@ type F struct {
 	RecvType    string
 	RecvPointer bool
 	Params      []P
+	ErrName     string
 }
 
 type P struct {

report.go

@@ -8,13 +8,14 @@ import (
 	"golang.org/x/tools/go/analysis"
 )
 
-func (a *A) report(fd *ast.FuncDecl) {
+func (a *A) report(fd *ast.FuncDecl, errName string) {
 
 	f := &F{
 		PkgName: a.pass.Pkg.Name(),
 		PkgPath: a.pass.Pkg.Path(),
 		FnName:  fd.Name.String(),
 		Params:  params(fd),
+		ErrName: errName,
 	}
 	f.RecvName, f.RecvType, f.RecvPointer = receiver(fd)
 	// fmt.Printf("\n%+v\n", f)

templates/default.tmpl

@@ -1,6 +1,6 @@
 {{define "main"}}   defer func({{template "input" .}}) {
-    if err != nil {
-        err = fmt.Errorf("{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}}): %w", {{template "plist" .}}{{if .Params}} ,{{end}}err)
+    if {{.ErrName}} != nil {
+        {{.ErrName}} = fmt.Errorf("{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}}): %w", {{template "plist" .}}{{if .Params}} ,{{end}}err)
     }
 }({{template "plist" .}})
 {{end}}

templates/wrap.tmpl

@@ -1,4 +1,4 @@
-{{define "main"}}   defer dfrr.Wrap(&err, "{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}})"{{if .Params}},{{end}}{{template "plist" .}})
+{{define "main"}}   defer dfrr.Wrap(&{{.ErrName}}, "{{if .RecvName}}{{.RecvName}}.{{end}}{{.FnName}}({{template "percV" .}})"{{if .Params}},{{end}}{{template "plist" .}})
 {{end}}
 
 {{define "plist"}}{{range $index, $item := .Params}}{{if $index}}, {{end}}{{$item.Name}}{{end}}{{end}}