Add sub issue list support (#32940)

Just like GitHub, show issue icon/title when the issue number is in a list

services/markup/renderhelper_issueicontitle.go

@@ -0,0 +1,66 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package markup
+
+import (
+	"context"
+	"fmt"
+	"html/template"
+
+	"code.gitea.io/gitea/models/issues"
+	"code.gitea.io/gitea/models/perm/access"
+	"code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/htmlutil"
+	"code.gitea.io/gitea/modules/markup"
+	"code.gitea.io/gitea/modules/util"
+	gitea_context "code.gitea.io/gitea/services/context"
+)
+
+func renderRepoIssueIconTitle(ctx context.Context, opts markup.RenderIssueIconTitleOptions) (_ template.HTML, err error) {
+	webCtx, ok := ctx.Value(gitea_context.WebContextKey).(*gitea_context.Context)
+	if !ok {
+		return "", fmt.Errorf("context is not a web context")
+	}
+
+	textIssueIndex := fmt.Sprintf("(#%d)", opts.IssueIndex)
+	dbRepo := webCtx.Repo.Repository
+	if opts.OwnerName != "" {
+		dbRepo, err = repo.GetRepositoryByOwnerAndName(ctx, opts.OwnerName, opts.RepoName)
+		if err != nil {
+			return "", err
+		}
+		textIssueIndex = fmt.Sprintf("(%s/%s#%d)", dbRepo.OwnerName, dbRepo.Name, opts.IssueIndex)
+	}
+	if dbRepo == nil {
+		return "", nil
+	}
+
+	issue, err := issues.GetIssueByIndex(ctx, dbRepo.ID, opts.IssueIndex)
+	if err != nil {
+		return "", err
+	}
+
+	if webCtx.Repo.Repository == nil || dbRepo.ID != webCtx.Repo.Repository.ID {
+		perms, err := access.GetUserRepoPermission(ctx, dbRepo, webCtx.Doer)
+		if err != nil {
+			return "", err
+		}
+		if !perms.CanReadIssuesOrPulls(issue.IsPull) {
+			return "", util.ErrPermissionDenied
+		}
+	}
+
+	if issue.IsPull {
+		if err = issue.LoadPullRequest(ctx); err != nil {
+			return "", err
+		}
+	}
+
+	htmlIcon, err := webCtx.RenderToHTML("shared/issueicon", issue)
+	if err != nil {
+		return "", err
+	}
+
+	return htmlutil.HTMLFormat(`<a href="%s">%s %s %s</a>`, opts.LinkHref, htmlIcon, issue.Title, textIssueIndex), nil
+}