Fix aggregate member bits lookup

src/V3LinkDot.cpp

@@ -1993,6 +1993,17 @@ class LinkDotFindVisitor final : public VNVisitor {
         // No need to insert, only the real typedef matters, but need to track for errors
         nodep->user1p(m_curSymp);
     }
+    void visit(AstNodeUOrStructDType* nodep) override {  // FindVisitor::
+        UASSERT_OBJ(m_curSymp, nodep, "Struct/union dtype not under module/package/$unit");
+        VL_RESTORER(m_curSymp);
+        m_curSymp = m_statep->insertBlock(
+            m_curSymp, "__Vdtype" + cvtToStr(nodep->uniqueNum()), nodep, m_classOrPackagep);
+        iterateChildren(nodep);
+    }
+    void visit(AstMemberDType* nodep) override {  // FindVisitor::
+        iterateChildren(nodep);
+        m_statep->insertSym(m_curSymp, nodep->name(), nodep, m_classOrPackagep);
+    }
     void visit(AstParamTypeDType* nodep) override {  // FindVisitor::
         UASSERT_OBJ(m_curSymp, nodep, "Parameter type not under module/package/$unit");
 
@@ -3511,6 +3522,21 @@ class LinkDotResolveVisitor final : public VNVisitor {
                            << declp->warnContextSecondary());
         }
     }
+    void checkMemberDeclOrder(AstNode* nodep, AstMemberDType* declp) {
+        const uint32_t declTokenNum = declp->fileline()->tokenNum();
+        if (nodep->fileline()->tokenNum() < declTokenNum) {
+            UINFO(1, "Related node " << nodep->fileline()->tokenNum() << " " << nodep);
+            UINFO(1, "Related decl " << declTokenNum << " " << declp);
+            nodep->v3error("Reference to "
+                           << nodep->prettyNameQ()
+                           << " before declaration (IEEE 1800-2023 6.18)\n"
+                           << nodep->warnMore()
+                           << "... Suggest move the declaration before the reference\n"
+                           << nodep->warnContextPrimary() << '\n'
+                           << declp->warnOther() << "... Location of original declaration\n"
+                           << declp->warnContextSecondary());
+        }
+    }
 
     void replaceWithCheckBreak(AstNode* oldp, AstNodeDType* newp) {
         // Flag now to avoid V3Broken throwing an internal error
@@ -3536,6 +3562,15 @@ class LinkDotResolveVisitor final : public VNVisitor {
         if (nodep && nodep->isParam()) nodep->usedParam(true);
     }
 
+    static VSymEnt* findIdFallbackSkipMemberDType(VSymEnt* lookp, const string& name) {
+        while (lookp) {
+            VSymEnt* const foundp = lookp->findIdFlat(name);
+            if (foundp && !VN_IS(foundp->nodep(), MemberDType)) return foundp;
+            lookp = lookp->fallbackp();
+        }
+        return nullptr;
+    }
+
     void symIterateChildren(AstNode* nodep, VSymEnt* symp) {
         // Iterate children, changing to given context, with restore to old context
         VL_RESTORER(m_ds);
@@ -4532,6 +4567,16 @@ class LinkDotResolveVisitor final : public VNVisitor {
                 } else {
                     (void)defp;  // Prevent unused variable warning
                 }
+            } else if (AstMemberDType* const defp = VN_CAST(foundp->nodep(), MemberDType)) {
+                if (allowVar) {
+                    checkMemberDeclOrder(nodep, defp);
+                    AstRefDType* const refp = new AstRefDType{nodep->fileline(), nodep->name()};
+                    refp->refDTypep(defp);
+                    replaceWithCheckBreak(nodep, refp);
+                    VL_DO_DANGLING(pushDeletep(nodep), nodep);
+                    ok = true;
+                    m_ds.m_dotText = "";
+                }
             } else if (AstEnumItem* const valuep = VN_CAST(foundp->nodep(), EnumItem)) {
                 if (allowVar) {
                     AstNode* const newp
@@ -4967,6 +5012,10 @@ class LinkDotResolveVisitor final : public VNVisitor {
             refdtypep->v3error("Self-referential enumerated type definition");
         }
     }
+    void visit(AstNodeUOrStructDType* nodep) override {
+        LINKDOT_VISIT_START();
+        symIterateChildren(nodep, m_statep->getNodeSym(nodep));
+    }
     void visit(AstEnumItemRef* nodep) override {
         // Resolve its reference
         // EnumItemRefs are created by the first pass, but V3Param may regenerate due to
@@ -5984,7 +6033,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
             if (nodep->classOrPackagep()) {
                 foundp = m_statep->getNodeSym(nodep->classOrPackagep())->findIdFlat(nodep->name());
             } else if (m_ds.m_dotPos == DP_FIRST || m_ds.m_dotPos == DP_NONE) {
-                foundp = m_curSymp->findIdFallback(nodep->name());
+                foundp = findIdFallbackSkipMemberDType(m_curSymp, nodep->name());
             } else {
                 // Defensive: dotPos should be DP_FIRST/DP_NONE or classOrPackagep set.
                 v3fatalSrc("Unexpected dotPos="

test_regress/t/t_stream_unpacked_struct.v

@@ -83,6 +83,17 @@ module t;
     byte tail;
   } packed_union_struct_t;
 
+  localparam int WORD_WIDTH = 16;
+
+  typedef union packed {
+    struct packed {
+      logic [15:0] temp_1;
+      logic [15:0] temp_2;
+      logic [15:0] temp_3;
+    } regs;
+    logic [($bits(regs) / WORD_WIDTH)-1:0][WORD_WIDTH-1:0] words;
+  } issue_4521_union_t;
+
   simple_t simple;
   simple_t simple_out;
   simple_t simple_cont_out;
@@ -106,6 +117,7 @@ module t;
   real_struct_t real_struct_out;
   packed_union_struct_t packed_union_struct;
   packed_union_struct_t packed_union_struct_out;
+  issue_4521_union_t issue_4521_union;
 
   logic [19:0] simple_bits;
   logic [31:0] wide_simple_bits;
@@ -349,6 +361,16 @@ module t;
     `checkh(packed_union_struct_out.u.byte_data, 8'hca);
     `checkh(packed_union_struct_out.tail, 8'hfe);
 
+    `checkh($bits(issue_4521_union_t), 48);
+    `checkh($bits(issue_4521_union.regs), 48);
+    `checkh($bits(issue_4521_union.words), 48);
+    issue_4521_union.regs.temp_1 = 16'h1234;
+    issue_4521_union.regs.temp_2 = 16'h5678;
+    issue_4521_union.regs.temp_3 = 16'h9abc;
+    `checkh(issue_4521_union.words[2], 16'h1234);
+    `checkh(issue_4521_union.words[1], 16'h5678);
+    `checkh(issue_4521_union.words[0], 16'h9abc);
+
     $write("*-* All Finished *-*\n");
     $finish;
   end

test_regress/t/t_struct_type_bad.out

@@ -2,4 +2,11 @@
    13 |     i badi;   
       |     ^
         ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
+%Error: t/t_struct_type_bad.v:18:19: Reference to 'later' before declaration (IEEE 1800-2023 6.18)
+                                   : ... Suggest move the declaration before the reference
+   18 |     logic [($bits(later) / 8)-1:0][7:0] bad_forward;
+      |                   ^~~~~
+        t/t_struct_type_bad.v:19:18: ... Location of original declaration
+   19 |     logic [15:0] later;
+      |                  ^~~~~
 %Error: Exiting due to

test_regress/t/t_struct_type_bad.v

@@ -13,4 +13,10 @@ module t;
     i badi;  // Bad
   } struct_t;
 
+  typedef union packed {
+    // Bad
+    logic [($bits(later) / 8)-1:0][7:0] bad_forward;
+    logic [15:0] later;
+  } forward_member_t;
+
 endmodule