feature: optimize fmt.Sprintf("%x" to strconv.FormatUint

using base 16

Author: catenacyber

analyzer/analyzer.go

@@ -283,7 +283,11 @@ func (n *perfSprint) run(pass *analysis.Pass) (interface{}, error) {
 				},
 			}
 
-		case isBasicType(valueType, types.Uint8, types.Uint16, types.Uint32, types.Uint) && oneOf(verb, "%v", "%d") && n.intConv:
+		case isBasicType(valueType, types.Uint8, types.Uint16, types.Uint32, types.Uint) && oneOf(verb, "%v", "%d", "%x") && n.intConv:
+			base := []byte("), 10")
+			if verb == "%x" {
+				base = []byte("), 16")
+			}
 			d = &analysis.Diagnostic{
 				Pos:     call.Pos(),
 				End:     call.End(),
@@ -300,13 +304,17 @@ func (n *perfSprint) run(pass *analysis.Pass) (interface{}, error) {
 							{
 								Pos:     value.End(),
 								End:     value.End(),
-								NewText: []byte("), 10"),
+								NewText: base,
 							},
 						},
 					},
 				},
 			}
-		case isBasicType(valueType, types.Uint64) && oneOf(verb, "%v", "%d"):
+		case isBasicType(valueType, types.Uint64) && oneOf(verb, "%v", "%d", "%x"):
+			base := []byte(", 10")
+			if verb == "%x" {
+				base = []byte(", 16")
+			}
 			d = &analysis.Diagnostic{
 				Pos:     call.Pos(),
 				End:     call.End(),
@@ -323,7 +331,7 @@ func (n *perfSprint) run(pass *analysis.Pass) (interface{}, error) {
 							{
 								Pos:     value.End(),
 								End:     value.End(),
-								NewText: []byte(", 10"),
+								NewText: base,
 							},
 						},
 					},

analyzer/replacements_bench_test.go

@@ -182,3 +182,19 @@ func BenchmarkUintFormatting(b *testing.B) {
 		b.ReportAllocs()
 	})
 }
+
+func BenchmarkUintHexFormatting(b *testing.B) {
+	b.Run("fmt.Sprintf", func(b *testing.B) {
+		for n := 0; n < b.N; n++ {
+			_ = fmt.Sprintf("%x", uint64(math.MaxUint))
+		}
+		b.ReportAllocs()
+	})
+
+	b.Run("strconv.FormatUint", func(b *testing.B) {
+		for n := 0; n < b.N; n++ {
+			_ = strconv.FormatUint(math.MaxUint, 16)
+		}
+		b.ReportAllocs()
+	})
+}

analyzer/testdata/src/p/p.go

@@ -118,6 +118,8 @@ func positive() {
 	fmt.Sprint(uint32(42))        // want "fmt.Sprint can be replaced with faster strconv.FormatUint"
 	fmt.Sprintf("%d", ui64)       // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
 	fmt.Sprintf("%v", ui64)       // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
+	fmt.Sprintf("%x", ui64)       // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
+	fmt.Sprintf("%x", uint(42))       // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
 	fmt.Sprint(ui64)              // want "fmt.Sprint can be replaced with faster strconv.FormatUint"
 	fmt.Sprintf("%d", uint64(42)) // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
 	fmt.Sprintf("%v", uint64(42)) // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
@@ -386,7 +388,6 @@ func malformed() {
 	fmt.Sprintf("%F", uint(42))
 	fmt.Sprintf("%g", uint(42))
 	fmt.Sprintf("%G", uint(42))
-	fmt.Sprintf("%x", uint(42))
 	fmt.Sprintf("%X", uint(42))
 
 	fmt.Sprintf("%d", 42.42)

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

@@ -118,6 +118,8 @@ func positive() {
 	strconv.FormatUint(uint64(uint32(42)), 10) // want "fmt.Sprint can be replaced with faster strconv.FormatUint"
 	strconv.FormatUint(ui64, 10)               // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
 	strconv.FormatUint(ui64, 10)               // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
+	strconv.FormatUint(ui64, 16)               // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
+	fmt.Sprintf("%x", uint(42))                // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
 	strconv.FormatUint(ui64, 10)               // want "fmt.Sprint can be replaced with faster strconv.FormatUint"
 	strconv.FormatUint(uint64(42), 10)         // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
 	strconv.FormatUint(uint64(42), 10)         // want "fmt.Sprintf can be replaced with faster strconv.FormatUint"
@@ -386,7 +388,6 @@ func malformed() {
 	fmt.Sprintf("%F", uint(42))
 	fmt.Sprintf("%g", uint(42))
 	fmt.Sprintf("%G", uint(42))
-	fmt.Sprintf("%x", uint(42))
 	fmt.Sprintf("%X", uint(42))
 
 	fmt.Sprintf("%d", 42.42)