Fix generating compare link (#21519)

Fix #6318

Co-authored-by: zeripath <art27@cantab.net>

modules/templates/helper.go

@@ -459,6 +459,19 @@ func NewFuncMap() []template.FuncMap {
 			return items
 		},
 		"HasPrefix": strings.HasPrefix,
+		"CompareLink": func(baseRepo, repo *repo_model.Repository, branchName string) string {
+			var curBranch string
+			if repo.ID != baseRepo.ID {
+				curBranch += fmt.Sprintf("%s/%s:", url.PathEscape(repo.OwnerName), url.PathEscape(repo.Name))
+			}
+			curBranch += util.PathEscapeSegments(branchName)
+
+			return fmt.Sprintf("%s/compare/%s...%s",
+				baseRepo.Link(),
+				util.PathEscapeSegments(baseRepo.DefaultBranch),
+				curBranch,
+			)
+		},
 	}}
 }
 

templates/repo/home.tmpl

@@ -70,7 +70,7 @@
 				<!-- If home page, show new PR. If not, show breadcrumb -->
 				{{if eq $n 0}}
 					{{if and .CanCompareOrPull .IsViewBranch (not .Repository.IsArchived)}}
-						<a href="{{.BaseRepo.Link}}/compare/{{PathEscapeSegments .BaseRepo.DefaultBranch}}...{{if ne .Repository.Owner.Name .BaseRepo.Owner.Name}}{{PathEscape .Repository.Owner.Name}}{{if .BaseRepo.IsFork}}/{{PathEscape .Repository.Name}}{{end}}:{{end}}{{PathEscapeSegments .BranchName}}">
+						<a href="{{CompareLink .BaseRepo .Repository .BranchName}}">
 							<button id="new-pull-request" class="ui compact basic button tooltip" data-content="{{if .PullRequestCtx.Allowed}}{{.locale.Tr "repo.pulls.compare_changes"}}{{else}}{{.locale.Tr "action.compare_branch"}}{{end}}"><span class="text">{{svg "octicon-git-pull-request"}}</span></button>
 						</a>
 					{{end}}