all: make more use of slices.Compare and slices.CompareFunc

Sometimes their use isn't particularly obvious, particularly for code
written for previous versions of Go without generics.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: I9a0a4b12f45741c704ea87e1d8cf78ca78a5db65
Dispatch-Trailer: {"type":"trybot","CL":1206379,"patchset":3,"ref":"refs/changes/79/1206379/3","targetBranch":"master"}

cue/errors/errors.go

@@ -362,18 +362,6 @@ func (p *list) Add(err Error) {
 // Reset resets an List to no errors.
 func (p *list) Reset() { *p = (*p)[:0] }
 
-func comparePath(a, b []string) int {
-	for i, x := range a {
-		if i >= len(b) {
-			break
-		}
-		if c := cmp.Compare(x, b[i]); c != 0 {
-			return c
-		}
-	}
-	return cmp.Compare(len(a), len(b))
-}
-
 // Sanitize sorts multiple errors and removes duplicates on a best effort basis.
 // If err represents a single or no error, it returns the error as is.
 func Sanitize(err Error) Error {
@@ -407,7 +395,7 @@ func (p list) Sort() {
 		if c := a.Position().Compare(b.Position()); c != 0 {
 			return c
 		}
-		if c := comparePath(a.Path(), b.Path()); c != 0 {
+		if c := slices.Compare(a.Path(), b.Path()); c != 0 {
 			return c
 		}
 		return cmp.Compare(a.Error(), b.Error())
@@ -436,7 +424,7 @@ func approximateEqual(a, b Error) bool {
 	if aPos == token.NoPos || bPos == token.NoPos {
 		return a.Error() == b.Error()
 	}
-	return aPos.Compare(bPos) == 0 && comparePath(a.Path(), b.Path()) == 0
+	return aPos.Compare(bPos) == 0 && slices.Compare(a.Path(), b.Path()) == 0
 }
 
 // An List implements the error interface.

internal/core/toposort/cycles_test.go

@@ -99,7 +99,7 @@ func TestElementaryCycles(t *testing.T) {
 					for _, cycle := range cyclesNames {
 						rotateToStartAt(cycle, slices.Min(cycle))
 					}
-					slices.SortFunc(cyclesNames, compareStringses)
+					slices.SortFunc(cyclesNames, slices.Compare)
 
 					if !slices.EqualFunc(cyclesNames, tc.expected, slices.Equal) {
 						t.Fatalf(`

internal/core/toposort/graph.go

@@ -139,22 +139,12 @@ func (index *indexComparison) compareNodeByName(a, b *Node) int {
 	return cmp.Compare(a.Name(index), b.Name(index))
 }
 
-func (index *indexComparison) compareNodesByNames(a, b Nodes) int {
-	lim := min(len(a), len(b))
-	for i := 0; i < lim; i++ {
-		if comparison := index.compareNodeByName(a[i], b[i]); comparison != 0 {
-			return comparison
-		}
-	}
-	return cmp.Compare(len(a), len(b))
-}
-
 func (index *indexComparison) compareCyclesByNames(a, b *Cycle) int {
-	return index.compareNodesByNames(a.Nodes, b.Nodes)
+	return slices.CompareFunc(a.Nodes, b.Nodes, index.compareNodeByName)
 }
 
 func (index *indexComparison) compareComponentsByNodes(a, b *StronglyConnectedComponent) int {
-	return index.compareNodesByNames(a.Nodes, b.Nodes)
+	return slices.CompareFunc(a.Nodes, b.Nodes, index.compareNodeByName)
 }
 
 func chooseCycleEntryNode(cycle *Cycle) (entryNode *Node, enabledSince, brokenEdgeCount int) {

internal/core/toposort/graph_test.go

@@ -15,7 +15,6 @@
 package toposort_test
 
 import (
-	"cmp"
 	"fmt"
 	"math/rand"
 	"os"
@@ -174,16 +173,6 @@ func makeFeatures(index adt.StringIndexer, inputs [][]string) [][]adt.Feature {
 	return result
 }
 
-func compareStringses(a, b []string) int {
-	lim := min(len(a), len(b))
-	for i := 0; i < lim; i++ {
-		if comparison := cmp.Compare(a[i], b[i]); comparison != 0 {
-			return comparison
-		}
-	}
-	return cmp.Compare(len(a), len(b))
-}
-
 // Consider that names are nodes in a cycle, we want to rotate the
 // slice so that it starts at the given node name. This modifies the
 // names slice in-place.

internal/core/toposort/scc_test.go

@@ -118,7 +118,7 @@ func TestStronglyConnectedComponents(t *testing.T) {
 						slices.Sort(names)
 						componentsNames[i] = names
 					}
-					slices.SortFunc(componentsNames, compareStringses)
+					slices.SortFunc(componentsNames, slices.Compare)
 
 					if !slices.EqualFunc(componentsNames, tc.expected, slices.Equal) {
 						t.Fatalf(`