Fixes internal compiler error with an unused reference to module member.

Changelog.md

@@ -8,6 +8,7 @@ Compiler Features:
 
 
 Bugfixes:
+ * Code generator: Fix internal compiler error when referencing members via module name but not using the reference.
  * Type Checker: Fix internal compiler error caused by storage parameters with nested mappings in libraries.
  * Name Resolver: Fix shadowing/same-name warnings for later declarations.
 

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1772,6 +1772,11 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 			solAssert(*_memberAccess.annotation().requiredLookup == VirtualLookup::Static, "");
 			utils().pushCombinedFunctionEntryLabel(*function);
 		}
+		else if (auto const* contract = dynamic_cast<ContractDefinition const*>(_memberAccess.annotation().referencedDeclaration))
+		{
+			if (contract->isLibrary())
+				m_context.appendLibraryAddress(contract->fullyQualifiedName());
+		}
 		break;
 	}
 	default:

test/libsolidity/syntaxTests/memberLookup/unused_module_member_reference.sol

@@ -0,0 +1,15 @@
+==== Source: s1.sol ====
+import "s1.sol" as A;
+
+library L {
+    function f() internal pure {}
+}
+
+contract C
+{
+    function test() public pure {
+        A.L;
+    }
+}
+// ----
+// Warning 6133: (s1.sol:127-130): Statement has no effect.