go/analysis/passes/directive: do not report adjoining //go:debug

Fixes golang/go#66046

Change-Id: I5fc8a2370c46b5d35df9759d3632b7659685aa5c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/569360
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: timothy-king

go/analysis/passes/directive/directive.go

@@ -70,11 +70,7 @@ func checkGoFile(pass *analysis.Pass, f *ast.File) {
 	check := newChecker(pass, pass.Fset.File(f.Package).Name(), f)
 
 	for _, group := range f.Comments {
-		// A +build comment is ignored after or adjoining the package declaration.
-		if group.End()+1 >= f.Package {
-			check.inHeader = false
-		}
-		// A //go:build comment is ignored after the package declaration
+		// A //go:build or a //go:debug comment is ignored after the package declaration
 		// (but adjoining it is OK, in contrast to +build comments).
 		if group.Pos() >= f.Package {
 			check.inHeader = false
@@ -104,8 +100,7 @@ type checker struct {
 	pass     *analysis.Pass
 	filename string
 	file     *ast.File // nil for non-Go file
-	inHeader bool      // in file header (before package declaration)
-	inStar   bool      // currently in a /* */ comment
+	inHeader bool      // in file header (before or adjoining package declaration)
 }
 
 func newChecker(pass *analysis.Pass, filename string, file *ast.File) *checker {

go/analysis/passes/directive/directive_test.go

@@ -5,19 +5,16 @@
 package directive_test
 
 import (
-	"runtime"
-	"strings"
 	"testing"
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/analysistest"
 	"golang.org/x/tools/go/analysis/passes/directive"
+	"golang.org/x/tools/internal/testenv"
 )
 
 func Test(t *testing.T) {
-	if strings.HasPrefix(runtime.Version(), "go1.") && runtime.Version() < "go1.16" {
-		t.Skipf("skipping on %v", runtime.Version())
-	}
+	testenv.NeedsGo1Point(t, 16)
 	analyzer := *directive.Analyzer
 	analyzer.Run = func(pass *analysis.Pass) (interface{}, error) {
 		defer func() {

go/analysis/passes/directive/testdata/src/a/issue66046.go

@@ -0,0 +1,8 @@
+// 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.
+
+//go:build ignore
+
+//go:debug panicnil=1
+package main