Fix bad assignment for virtual interface element select by reversing …

…the order of the selectors so that we encounter element select syntax first followed by member selectors. We can remove the reverse on the nameParts as a result (#1118)

source/ast/Lookup.cpp

@@ -1340,12 +1340,14 @@ void Lookup::selectChild(const Type& virtualInterface, SourceRange range,
     SmallVector<const ElementSelectSyntax*> elementSelects;
     auto& comp = context.getCompilation();
 
-    for (auto& selector : selectors) {
+    for (auto& selector : std::views::reverse(selectors)) {
         if (auto memberSel = std::get_if<LookupResult::MemberSelector>(&selector)) {
             NamePlusLoc npl;
             npl.dotLocation = memberSel->dotLocation;
             npl.name.text = memberSel->name;
             npl.name.range = memberSel->nameRange;
+            std::ranges::reverse(elementSelects); // reverse the element selects since we initially
+                                                  // saw them in reverse order
             npl.name.selectors = elementSelects.copy(comp);
 
             nameParts.push_back(npl);
@@ -1356,13 +1358,8 @@ void Lookup::selectChild(const Type& virtualInterface, SourceRange range,
         }
     }
 
-    // lookupDownward expects names in reverse order...
-    SmallVector<NamePlusLoc, 4> namePartsReversed(nameParts.size(), UninitializedTag());
-    for (auto& npl : std::views::reverse(nameParts))
-        namePartsReversed.push_back(npl);
-
     result.found = getVirtualInterfaceTarget(virtualInterface, context, range);
-    lookupDownward(namePartsReversed, unused, context, LookupFlags::None, result);
+    lookupDownward(nameParts, unused, context, LookupFlags::None, result);
 }
 
 const ClassType* Lookup::findClass(const NameSyntax& className, const ASTContext& context,

tests/unittests/ast/TypeTests.cpp

@@ -2214,3 +2214,33 @@ logic [-2147483648:-2147483649] a;
     CHECK(diags[1].code == diag::SignedIntegerOverflow);
     CHECK(diags[2].code == diag::SignedIntegerOverflow);
 }
+
+TEST_CASE("Virtual interface element select of member") {
+    auto tree = SyntaxTree::fromText(R"(
+    interface iface;
+        logic [255:0] data[2048];
+        logic [255:0] data_3d[2048][128][128];
+    endinterface
+
+    class cls1;
+        virtual iface vif;
+    endclass
+
+    class cls2;
+        cls1 c;
+        logic [255:0] data;
+        function set(int idx);
+            c.vif.data[idx] = data;
+            c.vif.data_3d[idx][64][8] = data;
+            c.vif.data_3d[idx][64][8][10:0] = data[10:0]; // index + range select
+        endfunction
+    endclass
+
+    module top;
+    endmodule
+)");
+
+    Compilation compilation;
+    compilation.addSyntaxTree(tree);
+    NO_COMPILATION_ERRORS;
+}