From 5748b37b1c914a25087b2087d8f66733ba6d78be Mon Sep 17 00:00:00 2001
From: Krystine Sherwin <93062060+KrystalDelusion@users.noreply.github.com>
Date: Fri, 7 Mar 2025 10:10:05 +1300
Subject: [PATCH 1/2] tests: Add test for reassigning localparam

i.e. Wrong error message mentioning defparam when overriding localparam #4927
---
 tests/various/hierarchy_reassign_localparam.ys | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 tests/various/hierarchy_reassign_localparam.ys

diff --git a/tests/various/hierarchy_reassign_localparam.ys b/tests/various/hierarchy_reassign_localparam.ys
new file mode 100644
index 000000000..e39203465
--- /dev/null
+++ b/tests/various/hierarchy_reassign_localparam.ys
@@ -0,0 +1,18 @@
+read_verilog -defer <<EOT
+
+module bb (...);
+localparam A = "abc";
+input a;
+output b;
+endmodule
+
+module top (...);
+input a;
+output b;
+bb #(.A("def")) my_bb (a, b);
+endmodule
+
+EOT
+
+logger -expect error "does not have a parameter named 'A'" 1
+hierarchy -check -top top

From 913ac04764dfdeebc9f965e4cae889098062faf6 Mon Sep 17 00:00:00 2001
From: Krystine Sherwin <93062060+KrystalDelusion@users.noreply.github.com>
Date: Fri, 7 Mar 2025 10:12:29 +1300
Subject: [PATCH 2/2] hierarchy: Derive abstract cells in top mod

Previously abstract cells would only be derived if there was no top module declared, this means that `-check` would miss certain kinds of errors that it would normally detect.  This fixes #4927.
---
 passes/hierarchy/hierarchy.cc | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc
index 8372c0339..c1edf90fc 100644
--- a/passes/hierarchy/hierarchy.cc
+++ b/passes/hierarchy/hierarchy.cc
@@ -1066,6 +1066,17 @@ struct HierarchyPass : public Pass {
 					mod->attributes[ID::initial_top] = RTLIL::Const(1);
 				else
 					mod->attributes.erase(ID::initial_top);
+
+			std::vector<IdString> abstract_ids;
+			for (auto cell : top_mod->cells()) {
+				IdString abstract_id = "$abstract" + cell->type.str();
+				if (design->module(cell->type) == nullptr && design->module(abstract_id))
+					abstract_ids.push_back(abstract_id);
+			}
+			for (auto abstract_id : abstract_ids)
+				design->module(abstract_id)->derive(design, {});
+			for (auto abstract_id : abstract_ids)
+				design->remove(design->module(abstract_id));
 		}
 
 		bool did_something = true;