From a5240e3eb325574111fe954759c628848e9d46c3 Mon Sep 17 00:00:00 2001
From: MikePopoloski <mike@popoloski.com>
Date: Fri, 28 Apr 2023 21:05:29 -0400
Subject: [PATCH] Fix off-by-one in symbol lookup location for detecting
 parameters used before declared

---
 source/ast/Symbol.cpp              |  4 ++--
 tests/unittests/HierarchyTests.cpp | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/source/ast/Symbol.cpp b/source/ast/Symbol.cpp
index 351c0fcd1..8b180a1d4 100644
--- a/source/ast/Symbol.cpp
+++ b/source/ast/Symbol.cpp
@@ -205,14 +205,14 @@ std::optional<bool> Symbol::isDeclaredBefore(LookupLocation target) const {
     // If target wasn't in a direct scope of any of our own parents,
     // repeat the process walking up target's scopes.
     sym = &target.getScope()->asSymbol();
-    ll = LookupLocation::before(*sym);
+    ll = LookupLocation::after(*sym);
 
     while ((scope = ll.getScope()) != nullptr && sym->kind != SymbolKind::CompilationUnit) {
         if (auto it = locMap.find(scope); it != locMap.end())
             return it->second < ll;
 
         sym = &scope->asSymbol();
-        ll = LookupLocation::before(*sym);
+        ll = LookupLocation::after(*sym);
     }
 
     return std::nullopt;
diff --git a/tests/unittests/HierarchyTests.cpp b/tests/unittests/HierarchyTests.cpp
index 4639e8016..07b89a6d5 100644
--- a/tests/unittests/HierarchyTests.cpp
+++ b/tests/unittests/HierarchyTests.cpp
@@ -2254,3 +2254,21 @@ endmodule
     CHECK(diags[0].code == diag::InfoTask);
     CHECK(diags[1].code == diag::InfoTask);
 }
+
+TEST_CASE("Hierarchical parameter lookup location regress") {
+    auto tree = SyntaxTree::fromText(R"(
+interface I;
+    parameter int P = 6;
+    function automatic int getP; return P; endfunction
+endinterface
+
+module m;
+    I i();
+    localparam int a = i.getP();
+endmodule
+)");
+
+    Compilation compilation;
+    compilation.addSyntaxTree(tree);
+    NO_COMPILATION_ERRORS;
+}