Add error on `virtual new` (#6486).

Changes

@@ -22,6 +22,7 @@ Verilator 5.041 devel
 * Add $(LDFLAGS) and $(LIBS) to when building shared libraries (#6425) (#6426). [Ahmed El-Mahmoudy]
 * Add IMPLICITSTATIC also on procedure variables.
 * Add FUNCTIMCTL error on function invoking task or time-controlling statements (#6385).
+* Add error on `virtual new` (#6486). [Alex Solomatnikov]
 * Deprecate sensitivity list on public_flat_rw attributes (#6443). [Geza Lore]
 * Deprecate clocker attribute and --clk option (#6463). [Geza Lore]
 * Support modports referencing clocking blocks (#4555) (#6436). [Ryszard Rozak, Antmicro Ltd.]

src/V3Width.cpp

@@ -6254,6 +6254,12 @@ class WidthVisitor final : public VNVisitor {
             nodep->v3error("The 'constraint_mode' method is built-in and cannot be overridden"
                            " (IEEE 1800-2023 18.9)");
         }
+        if (nodep->classMethod() && nodep->name() == "new") {
+            if (nodep->isVirtual())
+                nodep->v3error("class 'new()' cannot be virual (IEEE 1800-2023 18.3)");
+            if (nodep->isStatic())
+                nodep->v3error("class 'new()' cannot be static (IEEE 1800-2023 18.3)");
+        }
         // Function hasn't been widthed, so make it so.
         // Would use user1 etc, but V3Width called from too many places to spend a user
         nodep->doingWidth(true);

test_regress/t/t_class_new_bad.out

@@ -1,22 +1,34 @@
-%Error: t/t_class_new_bad.v:31:16: Too many arguments in function call to FUNC 'new'
+%Error: t/t_class_new_bad.v:27:19: class 'new()' cannot be static (IEEE 1800-2023 18.3)
                                  : ... note: In instance 't'
-   31 |       c1 = new(3);   
-      |                ^
+   27 |   static function new();   
+      |                   ^~~
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
-%Error: t/t_class_new_bad.v:32:16: Too many arguments in function call to FUNC 'new'
+%Error: t/t_class_new_bad.v:32:20: class 'new()' cannot be virual (IEEE 1800-2023 18.3)
                                  : ... note: In instance 't'
-   32 |       c2 = new(3);   
+   32 |   virtual function new();   
+      |                    ^~~
+%Error: t/t_class_new_bad.v:39:19: class 'new()' cannot be virual (IEEE 1800-2023 18.3)
+                                 : ... note: In instance 't'
+   39 | function ClsNew3::new();
+      |                   ^~~
+%Error: t/t_class_new_bad.v:47:16: Too many arguments in function call to FUNC 'new'
+                                 : ... note: In instance 't'
+   47 |       c1 = new(3);   
       |                ^
-%Error: t/t_class_new_bad.v:33:12: Missing argument on non-defaulted argument 'i' in function call to FUNC 'new'
+%Error: t/t_class_new_bad.v:48:16: Too many arguments in function call to FUNC 'new'
                                  : ... note: In instance 't'
-   33 |       c3 = new();   
-      |            ^~~
-%Error: t/t_class_new_bad.v:34:12: dynamic new() not expected in this context (data type must be dynamic array)
+   48 |       c2 = new(3);   
+      |                ^
+%Error: t/t_class_new_bad.v:49:12: Missing argument on non-defaulted argument 'i' in function call to FUNC 'new'
                                  : ... note: In instance 't'
-   34 |       c1 = new[2];
+   49 |       c3 = new();   
       |            ^~~
-%Error: Internal Error: t/t_class_new_bad.v:34:12: ../V3Width.cpp:#: Node has no type
+%Error: t/t_class_new_bad.v:50:12: dynamic new() not expected in this context (data type must be dynamic array)
+                                 : ... note: In instance 't'
+   50 |       c1 = new[2];
+      |            ^~~
+%Error: Internal Error: t/t_class_new_bad.v:50:12: ../V3Width.cpp:#: Node has no type
                                                  : ... note: In instance 't'
-   34 |       c1 = new[2];
+   50 |       c1 = new[2];
       |            ^~~
                         ... This fatal error may be caused by the earlier error(s); resolve those first.

test_regress/t/t_class_new_bad.v

@@ -23,6 +23,22 @@ class ClsArg;
    endfunction
 endclass
 
+class ClsNew1;
+  static function new();  // <--- Error: new can't be static
+  endfunction
+endclass
+
+class ClsNew2;
+  virtual function new();  // <--- Error: new can't be virtual
+  endfunction
+endclass
+
+class ClsNew3;
+  extern virtual function new();  // <--- Error: new can't be virtual
+endclass
+function ClsNew3::new();
+endfunction
+
 module t;
    initial begin
       ClsNoArg c1;