Merge pull request #10265 from ethereum/fixMappingInit

Fix initializing mapping return variables.

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -208,7 +208,9 @@ void IRGeneratorForStatements::initializeLocalVar(VariableDeclaration const& _va
 		solAssert(m_context.isLocalVariable(_varDecl), "Must be a local variable.");
 
 		auto const* type = _varDecl.type();
-		if (auto const* refType = dynamic_cast<ReferenceType const*>(type))
+		if (dynamic_cast<MappingType const*>(type))
+			return;
+		else if (auto const* refType = dynamic_cast<ReferenceType const*>(type))
 			if (refType->dataStoredIn(DataLocation::Storage) && refType->isPointer())
 				return;
 

test/libsolidity/semanticTests/functionCall/mapping_internal_return.sol

@@ -17,6 +17,8 @@ contract test {
         return (a[0], a[1], a[2], b[0], b[1], b[2]);
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // g() -> 0, 42, 0, 0, 84, 21
 // h() -> 0, 42, 0, 0, 84, 17