refine error message

src/V3AssertPre.cpp

@@ -93,8 +93,10 @@ private:
             fromAlways = true;
         }
         if (!senip) {
-            nodep->v3error("Concurrent assertion has no clock; provide a clocking event, a default"
-                           " clocking, or a clocked procedural context (IEEE 1800-2023 16.16)");
+            nodep->v3error("Concurrent assertion has no clock (IEEE 1800-2023 16.16)\n"
+                           << nodep->warnMore()
+                           << "... Suggest provide a clocking event, a default"
+                              " clocking, or a clocked procedural context");
             newp = new AstSenTree{nodep->fileline(), nullptr};
         } else {
             if (cassertp && fromAlways) cassertp->senFromAlways(true);

test_regress/t/t_assert_seq_clocking_unsup.out

@@ -15,17 +15,20 @@
                                                         : ... note: In instance 't'
    27 |     @clk a
       |     ^
-%Error: t/t_assert_seq_clocking_unsup.v:32:3: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_seq_clocking_unsup.v:32:3: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                             : ... note: In instance 't'
+                                            : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
    32 |   assert property (s_nest ##1 a);
       |   ^~~~~~
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
-%Error: t/t_assert_seq_clocking_unsup.v:33:3: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_seq_clocking_unsup.v:33:3: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                             : ... note: In instance 't'
+                                            : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
    33 |   assert property (s_level);
       |   ^~~~~~
-%Error: t/t_assert_seq_clocking_unsup.v:34:3: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_seq_clocking_unsup.v:34:3: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                             : ... note: In instance 't'
+                                            : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
    34 |   assert property (s_level2);
       |   ^~~~~~
 %Error: Exiting due to

test_regress/t/t_assert_unclocked_bad.out

@@ -1,18 +1,22 @@
-%Error: t/t_assert_unclocked_bad.v:9:3: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_unclocked_bad.v:9:3: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                       : ... note: In instance 't'
+                                      : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
     9 |   assert property (a);
       |   ^~~~~~
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
-%Error: t/t_assert_unclocked_bad.v:10:22: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_unclocked_bad.v:10:22: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                         : ... note: In instance 't'
+                                        : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
    10 |   assert property (a |=> b);
       |                      ^~~
-%Error: t/t_assert_unclocked_bad.v:10:3: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_unclocked_bad.v:10:3: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                        : ... note: In instance 't'
+                                       : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
    10 |   assert property (a |=> b);
       |   ^~~~~~
-%Error: t/t_assert_unclocked_bad.v:11:3: Concurrent assertion has no clock; provide a clocking event, a default clocking, or a clocked procedural context (IEEE 1800-2023 16.16)
+%Error: t/t_assert_unclocked_bad.v:11:3: Concurrent assertion has no clock (IEEE 1800-2023 16.16)
                                        : ... note: In instance 't'
+                                       : ... Suggest provide a clocking event, a default clocking, or a clocked procedural context
    11 |   cover property (a);
       |   ^~~~~
 %Error: Exiting due to