From 3afb0b66584d9385f02fdb73719b6ac0fc99b70b Mon Sep 17 00:00:00 2001
From: Yan <62220457+likeamahoney@users.noreply.github.com>
Date: Tue, 30 Jan 2024 23:13:18 +0300
Subject: [PATCH] [slang-tidy] Fix NoOldAlwaysSyntax checker segmentation fault
 (#882)

Co-authored-by: Yan Churkin <yan@ispras.ru>
---
 tools/tidy/include/ASTHelperVisitors.h     |  3 ++-
 tools/tidy/tests/NoOldAlwaysSyntaxTest.cpp | 24 ++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/tools/tidy/include/ASTHelperVisitors.h b/tools/tidy/include/ASTHelperVisitors.h
index f0cb45aa5..b5c7cbc80 100644
--- a/tools/tidy/include/ASTHelperVisitors.h
+++ b/tools/tidy/include/ASTHelperVisitors.h
@@ -55,7 +55,8 @@ struct CollectIdentifiers : public slang::ast::ASTVisitor<CollectIdentifiers, fa
 /// ASTVisitor that will collect all LHS assignment symbols under a node
 struct CollectLHSSymbols : public slang::ast::ASTVisitor<CollectLHSSymbols, true, true> {
     void handle(const slang::ast::AssignmentExpression& expression) {
-        symbols.push_back(expression.left().getSymbolReference());
+        if (const auto symbol = expression.left().getSymbolReference(); symbol)
+            symbols.push_back(symbol);
     }
 
     std::vector<const slang::ast::Symbol*> symbols;
diff --git a/tools/tidy/tests/NoOldAlwaysSyntaxTest.cpp b/tools/tidy/tests/NoOldAlwaysSyntaxTest.cpp
index 00c7d340d..ba98eaa1c 100644
--- a/tools/tidy/tests/NoOldAlwaysSyntaxTest.cpp
+++ b/tools/tidy/tests/NoOldAlwaysSyntaxTest.cpp
@@ -199,3 +199,27 @@ endmodule
     bool result = visitor->check(root);
     CHECK(result);
 }
+
+TEST_CASE("NoOldAlwaysSyntax: composite lhs") {
+    auto tree = SyntaxTree::fromText(R"(
+module top();
+    logic n;
+
+    always @(*) begin
+        {n} = 1;
+    end
+endmodule
+)");
+
+    Compilation compilation;
+    compilation.addSyntaxTree(tree);
+    compilation.getAllDiagnostics();
+    auto& root = compilation.getRoot();
+
+    TidyConfig config;
+    Registry::setConfig(config);
+    Registry::setSourceManager(compilation.getSourceManager());
+    auto visitor = Registry::create("NoOldAlwaysSyntax");
+    bool result = visitor->check(root);
+    CHECK(result);
+}