x.vweb: fix $vweb.html() integration in cgen for the newer x.vweb module (fix #20204)

examples/xvweb/todo/main.v

@@ -39,9 +39,7 @@ pub fn (app &App) index(mut ctx Context) vweb.Result {
 	todos := sql app.db {
 		select from Todo
 	} or { return ctx.server_error('could not fetch todos from database!') }
-
+	return $vweb.html()
-	// TODO: use $vweb.html()
-	return ctx.html($tmpl('templates/index.html'))
 }
 
 // This method will only handle POST requests to the index page

vlib/v/gen/c/cgen.v

@@ -246,6 +246,7 @@ mut:
 	has_reflection       bool
 	reflection_strings   &map[string]int
 	defer_return_tmp_var string
+	vweb_filter_fn_name  string // vweb__filter or x__vweb__filter, used by $vweb.html() for escaping strings in the templates, depending on which `vweb` import is used
 }
 
 // global or const variable definition string

vlib/v/gen/c/comptime.v

@@ -59,25 +59,43 @@ fn (mut g Gen) comptime_call(mut node ast.ComptimeCall) {
 			cur_line = g.go_before_last_stmt()
 		}
 
+		ret_sym := g.table.sym(g.fn_decl.return_type)
+		fn_name := g.fn_decl.name.replace('.', '__') + node.pos.pos.str()
+		is_x_vweb := ret_sym.cname == 'x__vweb__Result'
+
 		for stmt in node.vweb_tmpl.stmts {
 			if stmt is ast.FnDecl {
-				// insert stmts from vweb_tmpl fn
 				if stmt.name.starts_with('main.vweb_tmpl') {
 					if is_html {
 						g.inside_vweb_tmpl = true
+						if is_x_vweb {
+							g.vweb_filter_fn_name = 'x__vweb__filter'
+						} else {
+							g.vweb_filter_fn_name = 'vweb__filter'
 						}
+					}
+					// insert stmts from vweb_tmpl fn
 					g.stmts(stmt.stmts.filter(it !is ast.Return))
+					//
 					g.inside_vweb_tmpl = false
+					g.vweb_filter_fn_name = ''
 					break
 				}
 			}
 		}
 
-		fn_name := g.fn_decl.name.replace('.', '__') + node.pos.pos.str()
 		if is_html {
-			// return vweb html template
+			// return a vweb or x.vweb html template
+			if is_x_vweb {
+				ctx_name := g.fn_decl.params[1].name
+				g.writeln('x__vweb__Context_html(${ctx_name}, _tmpl_res_${fn_name});')
+			} else {
+				// old vweb:
 				app_name := g.fn_decl.params[0].name
-			g.writeln('vweb__Context_html(&${app_name}->Context, _tmpl_res_${fn_name}); strings__Builder_free(&sb_${fn_name}); string_free(&_tmpl_res_${fn_name});')
+				g.writeln('vweb__Context_html(&${app_name}->Context, _tmpl_res_${fn_name});')
+			}
+			g.writeln('strings__Builder_free(&sb_${fn_name});')
+			g.writeln('string_free(&_tmpl_res_${fn_name});')
 		} else {
 			// return $tmpl string
 			g.write(cur_line)

vlib/v/gen/c/str_intp.v

@@ -168,7 +168,7 @@ fn (mut g Gen) str_val(node ast.StringInterLiteral, i int, fmts []u8) {
 	typ_sym := g.table.sym(typ)
 	if typ == ast.string_type && g.comptime.comptime_for_method.len == 0 {
 		if g.inside_vweb_tmpl {
-			g.write('vweb__filter(')
+			g.write('${g.vweb_filter_fn_name}(')
 			if expr.is_auto_deref_var() && fmt != `p` {
 				g.write('*')
 			}

vlib/x/vweb/escape_html_strings_in_templates.v

@@ -0,0 +1,11 @@
+module vweb
+
+import encoding.html
+
+// Do not delete.
+// Calls to this function are generated by `fn (mut g Gen) str_val(node ast.StringInterLiteral, i int, fmts []u8) {` in vlib/v/gen/c/str_intp.v,
+// for string interpolation inside vweb templates.
+// TODO: move it to template render
+fn filter(s string) string {
+	return html.escape(s)
+}