From cc11ff8c5368ecca9a6f7cc87b63b5b3b47e06be Mon Sep 17 00:00:00 2001
From: Ryszard Rozak <rrozak@antmicro.com>
Date: Thu, 1 Jan 2026 16:21:09 +0100
Subject: [PATCH] Fix dynamic array elements passed to ref argument (#6877)

---
 src/V3Task.cpp                  |  7 ++-
 test_regress/t/t_func_ref_arg.v | 82 ++++++++++++++++++---------------
 2 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/src/V3Task.cpp b/src/V3Task.cpp
index 75544d232..b527ff445 100644
--- a/src/V3Task.cpp
+++ b/src/V3Task.cpp
@@ -534,8 +534,11 @@ class TaskVisitor final : public VNVisitor {
                         refArgOk = cMethodp->method() == VCMethod::DYN_AT_WRITE_APPEND
                                    || cMethodp->method() == VCMethod::DYN_AT_WRITE_APPEND_BACK;
                     } else {
-                        refArgOk = cMethodp->method() == VCMethod::ARRAY_AT
-                                   || cMethodp->method() == VCMethod::ARRAY_AT_BACK;
+                        if (cMethodp->method() == VCMethod::ARRAY_AT) {
+                            // Change the method to writable variant
+                            cMethodp->method(VCMethod::ARRAY_AT_WRITE);
+                        }
+                        refArgOk = cMethodp->method() == VCMethod::ARRAY_AT_WRITE;
                     }
                 }
                 if (refArgOk) {
diff --git a/test_regress/t/t_func_ref_arg.v b/test_regress/t/t_func_ref_arg.v
index d2c371762..9d864d078 100644
--- a/test_regress/t/t_func_ref_arg.v
+++ b/test_regress/t/t_func_ref_arg.v
@@ -8,53 +8,63 @@
 `define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got='h%x exp='h%x\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
 
 class MyInt;
-   int x;
-   function new(int a);
-      x = a;
-   endfunction
+  int x;
+  function new(int a);
+    x = a;
+  endfunction
 endclass
 
 function int get_val_set_5(ref int x);
-   automatic int y = x;
-   x = 5;
-   return y;
+  automatic int y = x;
+  x = 5;
+  return y;
 endfunction
 
 class Cls;
-   function int get_val_set_2(ref int x);
-      automatic int y = x;
-      x = 2;
-      return y;
-   endfunction
+  function int get_val_set_2(ref int x);
+    automatic int y = x;
+    x = 2;
+    return y;
+  endfunction
 endclass
 
 module t;
-   int a, b;
-   int arr[1];
-   Cls cls;
-   MyInt mi;
-   initial begin
-      a = 10;
-      b = get_val_set_5(a);
-      `checkh(a, 5);
-      `checkh(b, 10);
+  int a, b;
+  int arr[1];
+  int dyn_arr[];
+  Cls cls;
+  MyInt mi;
+  initial begin
+    a = 10;
+    b = get_val_set_5(a);
+    `checkh(a, 5);
+    `checkh(b, 10);
 
-      cls = new;
-      b = cls.get_val_set_2(a);
-      `checkh(a, 2);
-      `checkh(b, 5);
+    cls = new;
+    b   = cls.get_val_set_2(a);
+    `checkh(a, 2);
+    `checkh(b, 5);
 
-      mi = new(1);
-      b = cls.get_val_set_2(mi.x);
-      `checkh(mi.x, 2);
-      `checkh(b, 1);
+    mi = new(1);
+    b  = cls.get_val_set_2(mi.x);
+    `checkh(mi.x, 2);
+    `checkh(b, 1);
 
-      arr[0] = 10;
-      b = cls.get_val_set_2(arr[0]);
-      `checkh(arr[0], 2);
-      `checkh(b, 10);
+    arr[0] = 10;
+    b = cls.get_val_set_2(arr[0]);
+    `checkh(arr[0], 2);
+    `checkh(b, 10);
 
-      $write("*-* All Finished *-*\n");
-      $finish;
-   end
+    dyn_arr = new[3];
+    dyn_arr[1] = 10;
+    b = get_val_set_5(dyn_arr[1]);
+    `checkh(dyn_arr[1], 5);
+    `checkh(b, 10);
+    b = cls.get_val_set_2(dyn_arr[1]);
+    `checkh(dyn_arr[1], 2);
+    `checkh(b, 5);
+
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
 endmodule