feature: fmt.Sprintf with one argument optimization

Author: catenacyber

README.md

@@ -20,6 +20,22 @@ perfsprint --fix ./...
 To disable int/uint cast, you can use the flag `-int-conversion=false`
 
 To disable `fmt.Errorf` optimization, you can use the flag `-errorf=false`
+This optimization is not always equivalent.
+The code
+```
+msg := "format string attack %s"
+fmt.Errorf(msg)
+```
+will panic when its optimized version will not (so it should be safer).
+
+To disable `fmt.Sprintf("toto")` optimization, you can use the flag `-sprintf1=false`
+This optimization is not always equivalent.
+The code
+```
+msg := "format string attack %s"
+fmt.Sprintf(msg)
+```
+will panic when its optimized version will not (so it should be safer).
 
 To enable `err.Error()` optimization, you can use the flag `-err-error=true`
 This optimization only works when the error is not nil, otherwise the resulting code will panic.

analyzer/analyzer.go

@@ -19,10 +19,16 @@ type perfSprint struct {
 	intConv  bool
 	errError bool
 	errorf   bool
+	sprintf1 bool
 }
 
 func newPerfSprint() *perfSprint {
-	return &perfSprint{intConv: true, errError: false, errorf: true}
+	return &perfSprint{
+		intConv:  true,
+		errError: false,
+		errorf:   true,
+		sprintf1: true,
+	}
 }
 
 func New() *analysis.Analyzer {
@@ -36,6 +42,7 @@ func New() *analysis.Analyzer {
 	r.Flags.BoolVar(&n.intConv, "int-conversion", true, "optimizes even if it requires an int or uint type cast")
 	r.Flags.BoolVar(&n.errError, "err-error", false, "optimizes into err.Error() even if it is only equivalent for non-nil errors")
 	r.Flags.BoolVar(&n.errorf, "errorf", true, "optimizes fmt.Errorf")
+	r.Flags.BoolVar(&n.sprintf1, "sprintf1", true, "optimizes fmt.Sprintf with only one argument")
 	return r
 }
 
@@ -81,6 +88,13 @@ func (n *perfSprint) run(pass *analysis.Pass) (interface{}, error) {
 			verb = "%v"
 			value = call.Args[0]
 
+		case calledObj == fmtSprintfObj && len(call.Args) == 1:
+			if n.sprintf1 {
+				fn = "fmt.Sprintf"
+				verb = "%s"
+				value = call.Args[0]
+			}
+
 		case calledObj == fmtSprintfObj && len(call.Args) == 2:
 			verbLit, ok := call.Args[0].(*ast.BasicLit)
 			if !ok {

analyzer/testdata/src/noconv/p.go

@@ -104,9 +104,6 @@ func negative() {
 
 	fmt.Sprint("test", 42)
 	fmt.Sprint(42, 42)
-	fmt.Sprintf("test")
-	fmt.Sprintf("%v")
-	fmt.Sprintf("%d")
 	fmt.Sprintf("%d", 42, 42)
 	fmt.Sprintf("%#d", 42)
 	fmt.Sprintf("value %d", 42)

analyzer/testdata/src/noconv/p.go.golden

@@ -104,9 +104,6 @@ func negative() {
 
 	fmt.Sprint("test", 42)
 	fmt.Sprint(42, 42)
-	fmt.Sprintf("test")
-	fmt.Sprintf("%v")
-	fmt.Sprintf("%d")
 	fmt.Sprintf("%d", 42, 42)
 	fmt.Sprintf("%#d", 42)
 	fmt.Sprintf("value %d", 42)

analyzer/testdata/src/p/p.go

@@ -16,6 +16,7 @@ func positive() {
 	var s string
 	fmt.Sprintf("%s", "hello") // want "fmt.Sprintf can be replaced with just using the string"
 	fmt.Sprintf("%v", "hello") // want "fmt.Sprintf can be replaced with just using the string"
+	fmt.Sprintf("hello")       // want "fmt.Sprintf can be replaced with just using the string"
 	fmt.Sprint("hello")        // want "fmt.Sprint can be replaced with just using the string"
 	fmt.Sprintf("%s", s)       // want "fmt.Sprintf can be replaced with just using the string"
 	fmt.Sprintf("%v", s)       // want "fmt.Sprintf can be replaced with just using the string"
@@ -197,9 +198,6 @@ func negative() {
 
 	fmt.Sprint("test", 42)
 	fmt.Sprint(42, 42)
-	fmt.Sprintf("test")
-	fmt.Sprintf("%v")
-	fmt.Sprintf("%d")
 	fmt.Sprintf("%d", 42, 42)
 	fmt.Sprintf("%#d", 42)
 	fmt.Sprintf("value %d", 42)

analyzer/testdata/src/p/p.go.golden

@@ -16,6 +16,7 @@ func positive() {
 	var s string
 	"hello"             // want "fmt.Sprintf can be replaced with just using the string"
 	"hello"             // want "fmt.Sprintf can be replaced with just using the string"
+	"hello"             // want "fmt.Sprintf can be replaced with just using the string"
 	"hello"             // want "fmt.Sprint can be replaced with just using the string"
 	s                   // want "fmt.Sprintf can be replaced with just using the string"
 	s                   // want "fmt.Sprintf can be replaced with just using the string"
@@ -197,9 +198,6 @@ func negative() {
 
 	fmt.Sprint("test", 42)
 	fmt.Sprint(42, 42)
-	fmt.Sprintf("test")
-	fmt.Sprintf("%v")
-	fmt.Sprintf("%d")
 	fmt.Sprintf("%d", 42, 42)
 	fmt.Sprintf("%#d", 42)
 	fmt.Sprintf("value %d", 42)