From d51fc260e46a29edbd918d678554d319dd9ccd6d Mon Sep 17 00:00:00 2001
From: aimuz <mr.imuz@gmail.com>
Date: Fri, 17 May 2024 04:15:53 +0000
Subject: [PATCH] internal/fmtsort: use cmp.Compare for value comparisons

Refactor compare function to use cmp.Compare for various types.
Remove redundant floatCompare and isNaN functions.

Change-Id: I146a7af9158538499d07daee930aad8cf89b7e8f
GitHub-Last-Rev: d98365c0444c0467d8b4213674f6cf166906e900
GitHub-Pull-Request: golang/go#67454
Reviewed-on: https://go-review.googlesource.com/c/go/+/586239
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
---
 src/internal/fmtsort/sort.go      | 76 ++++---------------------------
 src/internal/fmtsort/sort_test.go |  4 --
 2 files changed, 9 insertions(+), 71 deletions(-)

diff --git a/src/internal/fmtsort/sort.go b/src/internal/fmtsort/sort.go
index ea042e1811..f51cdc7083 100644
--- a/src/internal/fmtsort/sort.go
+++ b/src/internal/fmtsort/sort.go
@@ -9,6 +9,7 @@
 package fmtsort
 
 import (
+	"cmp"
 	"reflect"
 	"slices"
 )
@@ -75,43 +76,19 @@ func compare(aVal, bVal reflect.Value) int {
 	}
 	switch aVal.Kind() {
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		a, b := aVal.Int(), bVal.Int()
-		switch {
-		case a < b:
-			return -1
-		case a > b:
-			return 1
-		default:
-			return 0
-		}
+		return cmp.Compare(aVal.Int(), bVal.Int())
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		a, b := aVal.Uint(), bVal.Uint()
-		switch {
-		case a < b:
-			return -1
-		case a > b:
-			return 1
-		default:
-			return 0
-		}
+		return cmp.Compare(aVal.Uint(), bVal.Uint())
 	case reflect.String:
-		a, b := aVal.String(), bVal.String()
-		switch {
-		case a < b:
-			return -1
-		case a > b:
-			return 1
-		default:
-			return 0
-		}
+		return cmp.Compare(aVal.String(), bVal.String())
 	case reflect.Float32, reflect.Float64:
-		return floatCompare(aVal.Float(), bVal.Float())
+		return cmp.Compare(aVal.Float(), bVal.Float())
 	case reflect.Complex64, reflect.Complex128:
 		a, b := aVal.Complex(), bVal.Complex()
-		if c := floatCompare(real(a), real(b)); c != 0 {
+		if c := cmp.Compare(real(a), real(b)); c != 0 {
 			return c
 		}
-		return floatCompare(imag(a), imag(b))
+		return cmp.Compare(imag(a), imag(b))
 	case reflect.Bool:
 		a, b := aVal.Bool(), bVal.Bool()
 		switch {
@@ -123,28 +100,12 @@ func compare(aVal, bVal reflect.Value) int {
 			return -1
 		}
 	case reflect.Pointer, reflect.UnsafePointer:
-		a, b := aVal.Pointer(), bVal.Pointer()
-		switch {
-		case a < b:
-			return -1
-		case a > b:
-			return 1
-		default:
-			return 0
-		}
+		return cmp.Compare(aVal.Pointer(), bVal.Pointer())
 	case reflect.Chan:
 		if c, ok := nilCompare(aVal, bVal); ok {
 			return c
 		}
-		ap, bp := aVal.Pointer(), bVal.Pointer()
-		switch {
-		case ap < bp:
-			return -1
-		case ap > bp:
-			return 1
-		default:
-			return 0
-		}
+		return cmp.Compare(aVal.Pointer(), bVal.Pointer())
 	case reflect.Struct:
 		for i := 0; i < aVal.NumField(); i++ {
 			if c := compare(aVal.Field(i), bVal.Field(i)); c != 0 {
@@ -191,22 +152,3 @@ func nilCompare(aVal, bVal reflect.Value) (int, bool) {
 	}
 	return 0, false
 }
-
-// floatCompare compares two floating-point values. NaNs compare low.
-func floatCompare(a, b float64) int {
-	switch {
-	case isNaN(a):
-		return -1 // No good answer if b is a NaN so don't bother checking.
-	case isNaN(b):
-		return 1
-	case a < b:
-		return -1
-	case a > b:
-		return 1
-	}
-	return 0
-}
-
-func isNaN(a float64) bool {
-	return a != a
-}
diff --git a/src/internal/fmtsort/sort_test.go b/src/internal/fmtsort/sort_test.go
index 29a9c2c43f..d33bb6f7fd 100644
--- a/src/internal/fmtsort/sort_test.go
+++ b/src/internal/fmtsort/sort_test.go
@@ -67,10 +67,6 @@ func TestCompare(t *testing.T) {
 				switch {
 				case i == j:
 					expect = 0
-					// NaNs are tricky.
-					if typ := v0.Type(); (typ.Kind() == reflect.Float32 || typ.Kind() == reflect.Float64) && math.IsNaN(v0.Float()) {
-						expect = -1
-					}
 				case i < j:
 					expect = -1
 				case i > j:
-- 
2.48.1