cmd: make use of maps.{Copy, Clone}

Change-Id: I8a38b4c71c34d3544ee32be9c6e767bb1099a720
GitHub-Last-Rev: ff4cb4e91b
GitHub-Pull-Request: golang/go#69424
Reviewed-on: https://go-review.googlesource.com/c/go/+/612735
Reviewed-by: Keith Randall <khr@golang.org>
Commit-Queue: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>

src/cmd/cgo/main.go

@@ -18,6 +18,7 @@ import (
 	"go/token"
 	"internal/buildcfg"
 	"io"
+	"maps"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -598,12 +599,8 @@ func (p *Package) Record(f *File) {
 	}
 
 	// merge nocallback & noescape
-	for k, v := range f.NoCallbacks {
-		p.noCallbacks[k] = v
-	}
-	for k, v := range f.NoEscapes {
-		p.noEscapes[k] = v
-	}
+	maps.Copy(p.noCallbacks, f.NoCallbacks)
+	maps.Copy(p.noEscapes, f.NoEscapes)
 
 	if f.ExpFunc != nil {
 		p.ExpFunc = append(p.ExpFunc, f.ExpFunc...)

src/cmd/compile/internal/pgoir/irgraph.go

@@ -50,6 +50,7 @@ import (
 	"cmd/compile/internal/types"
 	"cmd/internal/pgo"
 	"fmt"
+	"maps"
 	"os"
 )
 
@@ -296,10 +297,7 @@ func addIndirectEdges(g *IRGraph, namedEdgeMap pgo.NamedEdgeMap) {
 	// package build by VisitIR. We want to filter for local functions
 	// below, but we also add unknown callees to IRNodes as we go. So make
 	// an initial copy of IRNodes to recall just the local functions.
-	localNodes := make(map[string]*IRNode, len(g.IRNodes))
-	for k, v := range g.IRNodes {
-		localNodes[k] = v
-	}
+	localNodes := maps.Clone(g.IRNodes)
 
 	// N.B. We must consider edges in a stable order because export data
 	// lookup order (LookupMethodFunc, below) can impact the export data of

src/cmd/fix/typecheck.go

@@ -9,6 +9,7 @@ import (
 	"go/ast"
 	"go/parser"
 	"go/token"
+	"maps"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -272,9 +273,9 @@ func typecheck(cfg *TypeConfig, f *ast.File) (typeof map[any]string, assign map[
 					if !copied {
 						copied = true
 						// Copy map lazily: it's time.
+						cfg1.Type = maps.Clone(cfg.Type)
+						if cfg1.Type == nil {
 							cfg1.Type = make(map[string]*Type)
-						for k, v := range cfg.Type {
-							cfg1.Type[k] = v
 						}
 					}
 					t := &Type{Field: map[string]string{}}

src/cmd/go/internal/load/godebug.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"go/build"
 	"internal/godebugs"
+	"maps"
 	"sort"
 	"strconv"
 	"strings"
@@ -89,9 +90,7 @@ func defaultGODEBUG(p *Package, directives, testDirectives, xtestDirectives []bu
 	defaults := godebugForGoVersion(goVersion)
 	if defaults != nil {
 		// Apply m on top of defaults.
-		for k, v := range m {
-			defaults[k] = v
-		}
+		maps.Copy(defaults, m)
 		m = defaults
 	}
 

src/cmd/go/internal/load/test.go

@@ -15,6 +15,7 @@ import (
 	"go/parser"
 	"go/token"
 	"internal/lazytemplate"
+	"maps"
 	"path/filepath"
 	"slices"
 	"sort"
@@ -212,9 +213,7 @@ func TestPackagesAndErrors(ctx context.Context, done func(), opts PackageOpts, p
 		if testEmbed == nil && len(p.Internal.Embed) > 0 {
 			testEmbed = map[string][]string{}
 		}
-		for k, v := range p.Internal.Embed {
-			testEmbed[k] = v
-		}
+		maps.Copy(testEmbed, p.Internal.Embed)
 		ptest.Internal.Embed = testEmbed
 		ptest.EmbedFiles = str.StringList(p.EmbedFiles, p.TestEmbedFiles)
 		ptest.Internal.OrigImportPath = p.Internal.OrigImportPath