Extend comment treepath length (#35389)

Extend the maximum length of comment.treepath from 255 to 4000
characters.

All databases supported by Gitea allow VARCHAR fields of 4000, so
compatibility is ensured. Git itself does not impose a strict limit on
path length. On Windows, the `core.longpaths` setting has already been
enabled to handle long file paths.

Fix #33716

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

models/issues/comment.go

@@ -279,8 +279,8 @@ type Comment struct {
 	DependentIssue   *Issue `xorm:"-"`
 
 	CommitID        int64
-	Line            int64 // - previous line / + proposed line
+	Line            int64         // - previous line / + proposed line
-	TreePath        string
+	TreePath        string        `xorm:"VARCHAR(4000)"` // SQLServer only supports up to 4000
 	Content         string        `xorm:"LONGTEXT"`
 	ContentVersion  int           `xorm:"NOT NULL DEFAULT 0"`
 	RenderedContent template.HTML `xorm:"-"`

models/migrations/migrations.go

@@ -393,6 +393,7 @@ func prepareMigrationTasks() []*migration {
 
 		// Gitea 1.24.0 ends at database version 321
 		newMigration(321, "Use LONGTEXT for some columns and fix review_state.updated_files column", v1_25.UseLongTextInSomeColumnsAndFixBugs),
+		newMigration(322, "Extend comment tree_path length limit", v1_25.ExtendCommentTreePathLength),
 	}
 	return preparedMigrations
 }

models/migrations/v1_25/v322.go

@@ -0,0 +1,28 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_25
+
+import (
+	"code.gitea.io/gitea/models/migrations/base"
+
+	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
+)
+
+func ExtendCommentTreePathLength(x *xorm.Engine) error {
+	dbType := x.Dialect().URI().DBType
+	if dbType == schemas.SQLITE { // For SQLITE, varchar or char will always be represented as TEXT
+		return nil
+	}
+
+	return base.ModifyColumn(x, "comment", &schemas.Column{
+		Name: "tree_path",
+		SQLType: schemas.SQLType{
+			Name: "VARCHAR",
+		},
+		Length:         4000,
+		Nullable:       true, // To keep compatible as nullable
+		DefaultIsEmpty: true,
+	})
+}