gopls/internal/analysis/simplifyrange: suppress on range-over-func

go1.23's range-over-func currently requires all the vars be
declared, blank if necessary. That may change, but for now,
suppress the checker.

Fixes golang/go#67239
Updates golang/go#65236

Change-Id: I3e783fcfcb6a6f01f3acf62428cd9accbeb160c1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/588056
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
Commit-Queue: Alan Donovan <adonovan@google.com>

gopls/internal/analysis/simplifyrange/simplifyrange.go

@@ -10,6 +10,7 @@ import (
 	"go/ast"
 	"go/printer"
 	"go/token"
+	"go/types"
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/inspect"
@@ -34,15 +35,16 @@ func run(pass *analysis.Pass) (interface{}, error) {
 		(*ast.RangeStmt)(nil),
 	}
 	inspect.Preorder(nodeFilter, func(n ast.Node) {
-		var copy *ast.RangeStmt
-		if stmt, ok := n.(*ast.RangeStmt); ok {
-			x := *stmt
-			copy = &x
-		}
-		if copy == nil {
+		stmt := n.(*ast.RangeStmt)
+
+		// go1.23's range-over-func requires all vars, blank if necessary.
+		// TODO(adonovan): this may change in go1.24; see #65236.
+		if _, ok := pass.TypesInfo.TypeOf(stmt.X).Underlying().(*types.Signature); ok {
 			return
 		}
-		end := newlineIndex(pass.Fset, copy)
+
+		copy := *stmt
+		end := newlineIndex(pass.Fset, &copy)
 
 		// Range statements of the form: for i, _ := range x {}
 		var old ast.Expr
@@ -63,7 +65,7 @@ func run(pass *analysis.Pass) (interface{}, error) {
 			Pos:            old.Pos(),
 			End:            old.End(),
 			Message:        "simplify range expression",
-			SuggestedFixes: suggestedFixes(pass.Fset, copy, end),
+			SuggestedFixes: suggestedFixes(pass.Fset, &copy, end),
 		})
 	})
 	return nil, nil

gopls/internal/analysis/simplifyrange/simplifyrange_test.go

@@ -5,13 +5,18 @@
 package simplifyrange_test
 
 import (
+	"go/build"
 	"testing"
 
 	"golang.org/x/tools/go/analysis/analysistest"
 	"golang.org/x/tools/gopls/internal/analysis/simplifyrange"
+	"golang.org/x/tools/gopls/internal/util/slices"
 )
 
 func Test(t *testing.T) {
 	testdata := analysistest.TestData()
 	analysistest.RunWithSuggestedFixes(t, testdata, simplifyrange.Analyzer, "a")
+	if slices.Contains(build.Default.ReleaseTags, "go1.23") {
+		analysistest.RunWithSuggestedFixes(t, testdata, simplifyrange.Analyzer, "rangeoverfunc")
+	}
 }

gopls/internal/analysis/simplifyrange/testdata/src/rangeoverfunc/rangeoverfunc.go

@@ -0,0 +1,21 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testdata
+
+import "iter"
+
+func _(seq1 iter.Seq[int], seq2 iter.Seq2[int, int]) {
+	for _ = range "" { // want "simplify range expression"
+	}
+
+	// silence
+	for _ = range seq1 {
+	}
+	for _, v := range seq2 {
+		_ = v
+	}
+	for _, _ = range seq2 {
+	}
+}

gopls/internal/analysis/simplifyrange/testdata/src/rangeoverfunc/rangeoverfunc.go.golden

@@ -0,0 +1,21 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testdata
+
+import "iter"
+
+func _(seq1 iter.Seq[int], seq2 iter.Seq2[int, int]) {
+	for range "" { // want "simplify range expression"
+	}
+
+	// silence
+	for _ = range seq1 {
+	}
+	for _, v := range seq2 {
+		_ = v
+	}
+	for _, _ = range seq2 {
+	}
+}