Merge pull request #6 from muhammadjawadkhan/feat/param-classes

SV: ANSI class parameter port lists (defaults)

docs/STATUS.md

@@ -12,8 +12,8 @@ Last updated: 2026-07-21
 |------|--------|
 | Icarus Verilog tree | Fork of `steveicarus/iverilog` (`master` @ merge of SV array ordering work) |
 | [`uvm/`](../uvm/) | Seeded from IVL_UVM (VerifWorks) — messaging, CLP, stub phases, poor-man’s mailbox/semaphore; **not** Accellera-compatible |
-| [`examples/hello_uvm`](../examples/hello_uvm) | Smoke TB for the seeded library |
-| Parameterized classes | **In progress** on `feat/param-classes` |
+| [`examples/hello_uvm`](../examples/hello_uvm) | Smoke TB for the seeded library (`Makefile` included) |
+| Parameterized classes | **Partial** on `feat/param-classes`: ANSI `class C #(type T = int, parameter int W = 8);` parses into the class scope and elaborates with **defaults**. Explicit specializations `C#(byte)` / overrides not done yet. See [`examples/param_classes`](../examples/param_classes). |
 | Associative arrays | Missing |
 | Virtual interfaces | Missing |
 | Constraints / randomize | Missing |

docs/param-classes.md

@@ -0,0 +1,52 @@
+# Tier A #1 — Parameterized classes
+
+Track: **muhammadjawadkhan/iverilog-uvm** only (`feat/param-classes`). Do not open PRs to `steveicarus/iverilog` for this work.
+
+## Goal
+
+Support SystemVerilog parameterized classes needed for Accellera-shaped UVM (`uvm_*#(T)`, `config_db`, etc.):
+
+```systemverilog
+class C #(type T = int, parameter int W = 8);
+  // ...
+endclass
+
+C#(byte) c;   // explicit specialization — not done yet
+```
+
+## What landed (ANSI parameter ports + defaults)
+
+### Grammar (`parse.y`)
+
+`class_declaration` now pushes the class scope **before** the optional `#(...)` parameter port list (same idea as modules), then applies `extends`:
+
+1. `K_virtual_opt K_class lifetime_opt identifier_name` → start class / typedef (`pform_start_class_declaration` with base type deferred).
+2. `module_parameter_port_list_opt` — reuse the existing module ANSI parameter-port grammar so `type T = int`, `parameter int W = 8`, etc. land in the class `LexicalScope`.
+3. `class_declaration_extends_opt ';'` → `pform_set_class_extends(...)`.
+4. class items / `endclass` as before.
+
+### Pform (`pform_pclass.cc` / `pform.h`)
+
+- **`pform_set_class_extends`** — fills `base_type` / `base_args` on the current class after the parameter port list (replacing the old path that passed extends into `pform_start_class_declaration` before `#(...)` could exist).
+- Related: `pform_start_class_declaration`, `pform_end_class_declaration`, property helpers unchanged in role.
+
+With defaults present, a bare instance like `box b;` elaborates using those defaults.
+
+### Smoke example
+
+[`examples/param_classes/box_default.sv`](../examples/param_classes/box_default.sv) — `class box #(type T = int, parameter int W = 8);` constructed and used without an explicit `#()` override. Companion regression: `plain_class.sv`.
+
+```bash
+iverilog -g2012 -o box_default.vvp examples/param_classes/box_default.sv && vvp box_default.vvp
+# expect: PASS box_default ...
+```
+
+## TODO
+
+- [ ] Explicit specialization / overrides: `C#(byte)`, `C#(byte, 16)`, named overrides — parse, elaborate a specialized class type, and wire instances to it.
+- [ ] Inheritance + parameters interactions as needed by UVM base classes.
+- [ ] Broader ivtest coverage beyond the local smoke examples.
+
+## Status pointer
+
+See [STATUS.md](STATUS.md) (Parameterized classes row) and [ROADMAP.md](ROADMAP.md) Tier A item 1.

examples/param_classes/box_default.sv

@@ -0,0 +1,29 @@
+// Smoke: ANSI class parameter port list with defaults (no explicit #() override).
+class box #(type T = int, parameter int W = 8);
+  T val;
+  bit [W-1:0] data;
+  function new(T v);
+    val = v;
+    data = v;
+  endfunction
+  function T get();
+    return val;
+  endfunction
+endclass
+
+module top;
+  box b;
+  initial begin
+    b = new(42);
+    if (b.get() !== 42) begin
+      $display("FAIL: get=%0d", b.get());
+      $finish(1);
+    end
+    if (b.data !== 8'h2a) begin
+      $display("FAIL: data=%0h", b.data);
+      $finish(1);
+    end
+    $display("PASS box_default val=%0d data=%0h", b.val, b.data);
+    $finish;
+  end
+endmodule

examples/param_classes/plain_class.sv

@@ -0,0 +1,21 @@
+// Regression: plain (non-parameterized) class still works.
+class counter;
+  int n;
+  function new(); n = 0; endfunction
+  function void inc(); n++; endfunction
+endclass
+
+module top;
+  counter c;
+  initial begin
+    c = new;
+    c.inc();
+    c.inc();
+    if (c.n !== 2) begin
+      $display("FAIL n=%0d", c.n);
+      $finish(1);
+    end
+    $display("PASS plain_class n=%0d", c.n);
+    $finish;
+  end
+endmodule

parse.y

@@ -1237,7 +1237,9 @@ assertion_item_label_opt
   ;
 
 class_declaration /* IEEE1800-2005: A.1.2 */
-  : K_virtual_opt K_class lifetime_opt identifier_name class_declaration_extends_opt ';'
+  /* Push the class scope before the optional #(...) parameter port list so
+     parameters land in the class LexicalScope (same idea as modules). */
+  : K_virtual_opt K_class lifetime_opt identifier_name
       { /* Up to 1800-2017 the grammar in the LRM allowed an optional lifetime
 	 * qualifier for class declarations. But the LRM never specified what
 	 * this qualifier should do. Starting with 1800-2023 the qualifier has
@@ -1253,15 +1255,20 @@ class_declaration /* IEEE1800-2005: A.1.2 */
 	class_type_t *class_type= new class_type_t(name);
 	FILE_NAME(class_type, @4);
 	pform_set_typedef(@4, name, class_type, nullptr);
-	pform_start_class_declaration(@2, class_type, $5.type, $5.args, $1);
+	/* Base class is filled in after parameter_port_list / extends. */
+	pform_start_class_declaration(@2, class_type, 0, 0, $1);
+      }
+    module_parameter_port_list_opt
+    class_declaration_extends_opt ';'
+      { pform_set_class_extends(@7, $7.type, $7.args);
       }
     class_items_opt K_endclass
       { // Process a class.
-	pform_end_class_declaration(@9);
+	pform_end_class_declaration(@11);
       }
     label_opt
       { // Wrap up the class.
-	check_end_label(@11, "class", $4, $11);
+	check_end_label(@13, "class", $4, $13);
 	delete[] $4;
       }
   ;

pform.h

@@ -191,6 +191,9 @@ extern void pform_class_property(const struct vlltype&loc,
 extern void pform_set_this_class(const struct vlltype&loc, PTaskFunc*net);
 extern void pform_set_constructor_return(PFunction*net);
 
+extern void pform_set_class_extends(const struct vlltype&loc,
+				    data_type_t*base_type,
+				    std::list<named_pexpr_t> *base_args);
 extern void pform_end_class_declaration(const struct vlltype&loc);
 extern bool pform_in_class();
 

pform_pclass.cc

@@ -64,6 +64,31 @@ void pform_start_class_declaration(const struct vlltype&loc,
       }
 }
 
+void pform_set_class_extends(const struct vlltype&loc,
+			     data_type_t*base_type,
+			     list<named_pexpr_t> *base_args)
+{
+      ivl_assert(loc, pform_cur_class);
+      class_type_t*type = pform_cur_class->type;
+      ivl_assert(loc, type);
+
+      if (base_type == 0 && (base_args == 0 || base_args->empty())) {
+	    if (base_args)
+		  delete base_args;
+	    return;
+      }
+
+      ivl_assert(loc, type->base_type == 0);
+      type->base_type.reset(base_type);
+
+      ivl_assert(loc, type->base_args.empty());
+      if (base_args) {
+	    type->base_args.insert(type->base_args.begin(), base_args->begin(),
+			           base_args->end());
+	    delete base_args;
+      }
+}
+
 void pform_class_property(const struct vlltype&loc,
 			  property_qualifier_t property_qual,
 			  data_type_t*data_type,