Fix packed array deduction (#6046)

src/V3LinkDot.cpp

@@ -2353,9 +2353,8 @@ class LinkDotResolveVisitor final : public VNVisitor {
     std::map<AstNode*, AstPin*> m_usedPins;  // Pin used in this cell, map to duplicate
     std::map<std::string, AstNodeModule*> m_modulesToRevisit;  // Modules to revisit a second time
     AstNode* m_lastDeferredp = nullptr;  // Last node which requested a revisit of its module
-    bool m_maybePackedArray
-        = false;  // Array select parse trees may actually be packed array datatypes
     AstNodeDType* m_packedArrayDtp = nullptr;  // Datatype reference for packed array
+    bool m_inPackedArray = false;  // Currently traversing a packed array tree
 
     struct DotStates final {
         DotPosition m_dotPos;  // Scope part of dotted resolution
@@ -2811,7 +2810,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
         // Early return() above when deleted
     }
     void visit(AstDot* nodep) override {
-        // Legal under a DOT: AstDot, AstParseRef, AstPackageRef, AstNodeSel
+        // Legal under a DOT: AstDot, AstParseRef, AstPackageRef, AstNodeSel, AstPackArrayDType
         //    also a DOT can be part of an expression, but only above plus
         //    AstFTaskRef are legal children
         // Dot(PackageRef, ParseRef(text))
@@ -3404,7 +3403,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
                 if (ok) {
                     AstRefDType* const refp = new AstRefDType{nodep->fileline(), nodep->name()};
                     refp->typedefp(defp);
-                    if (m_maybePackedArray) {
+                    if (VN_IS(nodep->backp(), SelExtract)) {
                         m_packedArrayDtp = refp;
                     } else {
                         replaceWithCheckBreak(nodep, refp);
@@ -4058,11 +4057,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
         AstNodeDType* packedArrayDtp = nullptr;  // Datatype reference for packed array
         {
             VL_RESTORER(m_packedArrayDtp);
-            {
-                VL_RESTORER(m_maybePackedArray);
-                m_maybePackedArray = true;
-                iterateAndNextNull(nodep->fromp());
-            }
+            iterateAndNextNull(nodep->fromp());
             symIterateNull(nodep->rhsp(), m_curSymp);
             symIterateNull(nodep->thsp(), m_curSymp);
 
@@ -4074,7 +4069,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
                     = new AstPackArrayDType(nodep->fileline(), m_packedArrayDtp, newRangep);
                 newArrayTypep->childDTypep(m_packedArrayDtp);
                 newArrayTypep->refDTypep(nullptr);
-                if (m_maybePackedArray) {
+                if (VN_IS(nodep->backp(), SelExtract)) {
                     packedArrayDtp = newArrayTypep;
                 } else {
                     replaceWithCheckBreak(nodep, newArrayTypep);
@@ -4576,8 +4571,13 @@ class LinkDotResolveVisitor final : public VNVisitor {
     void visit(AstAttrOf* nodep) override { iterateChildren(nodep); }
 
     void visit(AstNode* nodep) override {
-        LINKDOT_VISIT_START();
-        checkNoDot(nodep);
+        VL_RESTORER(m_inPackedArray);
+        if (VN_IS(nodep, PackArrayDType)) {
+            m_inPackedArray = true;
+        } else if (!m_inPackedArray) {
+            LINKDOT_VISIT_START();
+            checkNoDot(nodep);
+        }
         iterateChildren(nodep);
     }
 

test_regress/t/t_bitsel_2d_slice.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios("simulator")
+
+test.compile()
+
+test.execute()
+
+test.passes()

test_regress/t/t_bitsel_2d_slice.v

@@ -0,0 +1,29 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t (/*AUTOARG*/
+    // Inputs
+    clk
+    );
+    input clk;
+
+    localparam int width = 8;
+    typedef logic [width-1:0] [15:0] two_dee_t;
+    typedef logic[$clog2(width)-1:0] index_t;
+
+    two_dee_t the_two_dee;
+
+    initial begin
+        the_two_dee[index_t'(5)][7:0] = 8'hab;
+        the_two_dee[index_t'(5)][15:8] = 8'h12;
+    end
+
+    always @ (posedge clk) begin
+        if (the_two_dee[5] != 16'h12ab) $stop();
+        $write("*-* All Finished *-*\n");
+        $finish;
+    end
+endmodule

test_regress/t/t_type_param.v

@@ -4,6 +4,10 @@
 // without warranty, 2019 by Todd Strader.
 // SPDX-License-Identifier: CC0-1.0
 
+package some_package;
+    typedef logic [15:0] two_bytes_t;
+endpackage
+
 module foo
   #(parameter type bar = logic)
    (output int bar_size);
@@ -54,6 +58,11 @@ module t();
    foo #(.bar (some_struct_t [2:0] [5:0]))
    foo_inst5 (.bar_size (bar_size5));
 
+   int bar_size6;
+
+   foo #(.bar (some_package::two_bytes_t [4-1:0]))
+   foo_inst6 (.bar_size (bar_size6));
+
    localparam bar_bits = 13;
    int bar_size_wrapper;
 
@@ -106,6 +115,11 @@ module t();
                  bar_size5, $bits(some_struct_t) * 3 * 6);
          $stop();
       end
+      if (bar_size6 != $bits(some_package::two_bytes_t)*4) begin
+         $display("%m: bar_size6 != bits of some_package::two_bytes_t * 4 (%0d, %0d)",
+                 bar_size6, $bits(some_package::two_bytes_t) * 4);
+         $stop();
+      end
       if (bar_size_wrapper != bar_bits) begin
          $display("%m: bar_size_wrapper != bar_bits (%0d, %0d)",
                  bar_size_wrapper, bar_bits);