From 97d5844f2ea62bead1b2b7bc0db157e0919d1e86 Mon Sep 17 00:00:00 2001
From: Ryszard Rozak <rrozak@antmicro.com>
Date: Thu, 8 Jan 2026 15:02:28 +0100
Subject: [PATCH] Support dynamic array elements in std::randomize (#6896)

---
 src/V3Randomize.cpp                             |  5 +++++
 src/V3Width.cpp                                 | 12 +++++++++---
 test_regress/t/t_randomize_arraysel_membersel.v |  9 +++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/V3Randomize.cpp b/src/V3Randomize.cpp
index bc6e8d20a..313fba115 100644
--- a/src/V3Randomize.cpp
+++ b/src/V3Randomize.cpp
@@ -184,6 +184,8 @@ class RandomizeMarkVisitor final : public VNVisitor {
                     exprp = arrselp->fromp();
                 } else if (const AstStructSel* const strselp = VN_CAST(exprp, StructSel)) {
                     exprp = strselp->fromp();
+                } else if (const AstCMethodHard* const methodp = VN_CAST(exprp, CMethodHard)) {
+                    exprp = methodp->fromp();
                 } else {
                     break;
                 }
@@ -359,6 +361,9 @@ class RandomizeMarkVisitor final : public VNVisitor {
             } else if (AstStructSel* const structSelp = VN_CAST(exprp, StructSel)) {
                 exprp = structSelp->fromp();
                 continue;  // Skip StructSel, continue traversing
+            } else if (AstCMethodHard* const methodp = VN_CAST(exprp, CMethodHard)) {
+                exprp = methodp->fromp();
+                continue;
             } else if (AstVarRef* const varrefp = VN_CAST(exprp, VarRef)) {
                 randVarp = varrefp->varp();
                 varrefp->user1(true);
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 888c4bea7..24d6a3bda 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -6781,12 +6781,18 @@ class WidthVisitor final : public VNVisitor {
                 // IEEE 1800-2023 (18.12) limits args to current scope variables.
                 // Verilator accepts this for compatibility with other simulators.
                 continue;
-            } else if (VN_IS(exprp, VarRef) || VN_IS(exprp, ArraySel) || VN_IS(exprp, StructSel)) {
+            }
+            if (VN_IS(exprp, VarRef) || VN_IS(exprp, ArraySel) || VN_IS(exprp, StructSel)) {
                 // Valid usage
                 continue;
-            } else {
-                argp->v3error("Non-variable arguments for 'std::randomize()'.");
             }
+            if (const AstCMethodHard* const methodp = VN_CAST(exprp, CMethodHard)) {
+                if (methodp->method() == VCMethod::ARRAY_AT
+                    || methodp->method() == VCMethod::ARRAY_AT_WRITE) {
+                    continue;
+                }
+            }
+            argp->v3error("Non-variable arguments for 'std::randomize()'.");
         }
         if (nullp) nullp->v3error("'std::randomize()' does not accept 'null' as arguments.");
     }
diff --git a/test_regress/t/t_randomize_arraysel_membersel.v b/test_regress/t/t_randomize_arraysel_membersel.v
index 9ad7fa351..a7c1dd65a 100644
--- a/test_regress/t/t_randomize_arraysel_membersel.v
+++ b/test_regress/t/t_randomize_arraysel_membersel.v
@@ -9,6 +9,7 @@ typedef struct {int x;} struct_t;
 class inner_class;
   logic [3:0] c;
   logic [3:0] d[2];
+  logic [3:0] dyn[];
   struct_t s;
 endclass
 
@@ -20,9 +21,11 @@ endclass
 
 module t;
   initial begin
+    int x = 2;
     test_class example;
     example = new;
     example.b = new;
+    example.b.dyn = new[3];
 
     // Simple array element access
     repeat (5) begin
@@ -83,6 +86,12 @@ module t;
       if (example.b.d[1] < 2 || example.b.d[1] > 6) $stop;
     end
 
+    // Nested object with dynamic array: obj.b.dyn[x]
+    repeat (5) begin
+      if (std::randomize(example.b.dyn[x]) with {example.b.dyn[x] inside {[1 : 3]};} == 0) $stop;
+      if (example.b.dyn[x] < 1 || example.b.dyn[x] > 3) $stop;
+    end
+
     // Nested object with struct: obj.b.s.x
     repeat (5) begin
       if (std::randomize(example.b.s.x) with {example.b.s.x inside {[7 : 9]};} == 0) $stop;