From fa30b68767fd3ad67517bc6601ae79f9d89e1b51 Mon Sep 17 00:00:00 2001
From: Alan Donovan <adonovan@google.com>
Date: Fri, 21 Nov 2025 11:05:05 -0500
Subject: [PATCH] go/{ast,doc}: update BasicLit.ValueEnd as well as ValuePos

For #76395

Change-Id: Ie2ad715a05cb298b08667cfe8a8394f1dfa3936c
Reviewed-on: https://go-review.googlesource.com/c/go/+/722880
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
---
 src/go/ast/import.go  | 13 ++++++++++++-
 src/go/doc/example.go | 13 ++++++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/go/ast/import.go b/src/go/ast/import.go
index 3e53f10677c..84d00fef995 100644
--- a/src/go/ast/import.go
+++ b/src/go/ast/import.go
@@ -222,7 +222,7 @@ func sortSpecs(fset *token.FileSet, f *File, d *GenDecl, specs []Spec) []Spec {
 		if s.Name != nil {
 			s.Name.NamePos = pos[i].Start
 		}
-		s.Path.ValuePos = pos[i].Start
+		updateBasicLitPos(s.Path, pos[i].Start)
 		s.EndPos = pos[i].End
 		for _, g := range importComments[s] {
 			for _, c := range g.cg.List {
@@ -245,3 +245,14 @@ func sortSpecs(fset *token.FileSet, f *File, d *GenDecl, specs []Spec) []Spec {
 
 	return specs
 }
+
+// updateBasicLitPos updates lit.Pos,
+// ensuring that lit.End is displaced by the same amount.
+// (See https://go.dev/issue/76395.)
+func updateBasicLitPos(lit *BasicLit, pos token.Pos) {
+	len := lit.End() - lit.Pos()
+	lit.ValuePos = pos
+	if lit.ValueEnd.IsValid() {
+		lit.ValueEnd = pos + len
+	}
+}
diff --git a/src/go/doc/example.go b/src/go/doc/example.go
index 5c03c6612f9..228bdf58f81 100644
--- a/src/go/doc/example.go
+++ b/src/go/doc/example.go
@@ -238,7 +238,7 @@ func playExample(file *ast.File, f *ast.FuncDecl) *ast.File {
 			spec := *s
 			path := *s.Path
 			spec.Path = &path
-			spec.Path.ValuePos = groupStart(&spec)
+			updateBasicLitPos(spec.Path, groupStart(&spec))
 			namedImports = append(namedImports, &spec)
 			delete(unresolved, n)
 		}
@@ -720,3 +720,14 @@ func isExampleSuffix(s string) bool {
 	r, size := utf8.DecodeRuneInString(s)
 	return size > 0 && unicode.IsLower(r)
 }
+
+// updateBasicLitPos updates lit.Pos,
+// ensuring that lit.End is displaced by the same amount.
+// (See https://go.dev/issue/76395.)
+func updateBasicLitPos(lit *ast.BasicLit, pos token.Pos) {
+	len := lit.End() - lit.Pos()
+	lit.ValuePos = pos
+	if lit.ValueEnd.IsValid() {
+		lit.ValueEnd = pos + len
+	}
+}