Fix #15180: [REG2.069.0-b1] Segfault with empty struct used as UDA

Thanks to Kenji Hara for the fix.

src/objc.d

@@ -154,22 +154,24 @@ extern (C++) void objc_InterfaceDeclaration_semantic_objcExtern(InterfaceDeclara
 // MARK: semantic
 extern (C++) void objc_FuncDeclaration_semantic_setSelector(FuncDeclaration fd, Scope* sc)
 {
+    import ddmd.tokens;
+
     if (!fd.userAttribDecl)
         return;
     Expressions* udas = fd.userAttribDecl.getAttributes();
     arrayExpressionSemantic(udas, sc, true);
     for (size_t i = 0; i < udas.dim; i++)
     {
         Expression uda = (*udas)[i];
-        assert(uda.type);
-        if (uda.type.ty != Ttuple)
+        assert(uda);
+        if (uda.op != TOKtuple)
             continue;
         Expressions* exps = (cast(TupleExp)uda).exps;
         for (size_t j = 0; j < exps.dim; j++)
         {
             Expression e = (*exps)[j];
-            assert(e.type);
-            if (e.type.ty != Tstruct)
+            assert(e);
+            if (e.op != TOKstructliteral)
                 continue;
             StructLiteralExp literal = cast(StructLiteralExp)e;
             assert(literal.sd);

test/compilable/uda.d

@@ -0,0 +1,7 @@
+/************************************************/
+// 15180: [REG2.069.0-b1] Segfault with empty struct used as UDA
+
+struct foo { }
+@foo bar () { }
+
+/************************************************/