Fix SMTChecker bug when a public library function is called internally by an internal library function, which in turn is called internally by a contract.

libsolidity/formal/CHC.cpp

@@ -1172,7 +1172,14 @@ void CHC::defineInterfacesAndSummaries(SourceUnit const& _source)
 
 				m_summaries[contract].emplace(function, createSummaryBlock(*function, *contract));
 
-				if (!function->isConstructor() && function->isPublic() && resolved.count(function))
+				if (
+					!function->isConstructor() &&
+					function->isPublic() &&
+					// Public library functions should have interfaces only for the libraries
+					// they're declared in.
+					(!function->libraryFunction() || (function->scope() == contract)) &&
+					resolved.count(function)
+				)
 				{
 					m_externalSummaries[contract].emplace(function, createSummaryBlock(*function, *contract));
 

libsolidity/formal/SMTEncoder.cpp

@@ -3162,11 +3162,10 @@ void SMTEncoder::collectFreeFunctions(set<SourceUnit const*, ASTNode::CompareByI
 				auto contract = dynamic_cast<ContractDefinition const*>(node.get());
 				contract && contract->isLibrary()
 			)
-			{
 				for (auto function: contract->definedFunctions())
-					if (!function->isPublic())
-						m_freeFunctions.insert(function);
-			}
+					// We need to add public library functions too because they can be called
+					// internally by internal library functions that are considered free functions.
+					m_freeFunctions.insert(function);
 }
 
 void SMTEncoder::createFreeConstants(set<SourceUnit const*, ASTNode::CompareByID> const& _sources)