From 1010137a2096e90f5706c47c566c526912554265 Mon Sep 17 00:00:00 2001
From: micron-ian <133904139+micron-ian@users.noreply.github.com>
Date: Sun, 15 Sep 2024 13:21:17 -0600
Subject: [PATCH] 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             | 11 ++++-------
 tests/unittests/ast/TypeTests.cpp | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/source/ast/Lookup.cpp b/source/ast/Lookup.cpp
index 6827ea1b0..87dc071d3 100644
--- a/source/ast/Lookup.cpp
+++ b/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,
diff --git a/tests/unittests/ast/TypeTests.cpp b/tests/unittests/ast/TypeTests.cpp
index a96b22ed8..a57e4bab6 100644
--- a/tests/unittests/ast/TypeTests.cpp
+++ b/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;
+}