Fix UsedWays bounds check

Makefile

@@ -149,6 +149,7 @@ test: \
 	test_significant_tags \
 	test_sorted_node_store \
 	test_sorted_way_store \
+	test_osm_store \
 	test_tile_coordinates_set
 
 test_append_vector: \
@@ -188,6 +189,10 @@ test_options_parser: \
 	test/options_parser.test.o
 	$(CXX) $(CXXFLAGS) -o test.options_parser $^ $(INC) $(LIB) $(LDFLAGS) && ./test.options_parser
 
+test_osm_store: \
+	test/osm_store.test.o
+	$(CXX) $(CXXFLAGS) -o test.osm_store $^ $(INC) $(LIB) $(LDFLAGS) && ./test.osm_store
+
 test_pooled_string: \
 	src/mmap_allocator.o \
 	src/pooled_string.o \

include/osm_store.h

@@ -78,13 +78,13 @@ class UsedWays {
 	// Mark a way as used
 	void insert(WayID wayid) {
 		std::lock_guard<std::mutex> lock(mutex);
-		if (wayid>usedList.size()) usedList.resize(wayid+256);
+		if (wayid>=usedList.size()) usedList.resize(wayid+256);
 		usedList[wayid] = true;
 	}
 
 	// See if a way is used
 	bool at(WayID wayid) const {
-		return (wayid>usedList.size()) ? false : usedList[wayid];
+		return (wayid>=usedList.size()) ? false : usedList[wayid];
 	}
 
 	void clear() {

test/osm_store.test.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+#include "external/minunit.h"
+#include "osm_store.h"
+
+MU_TEST(test_usedways_grows_for_first_index) {
+	UsedWays usedWays;
+	usedWays.insert(0);
+	mu_check(usedWays.at(0));
+}
+
+MU_TEST(test_usedways_grows_at_current_size) {
+	UsedWays usedWays;
+	usedWays.insert(0);
+	usedWays.insert(256);
+	mu_check(usedWays.at(256));
+}
+
+MU_TEST_SUITE(test_suite_osm_store) {
+	MU_RUN_TEST(test_usedways_grows_for_first_index);
+	MU_RUN_TEST(test_usedways_grows_at_current_size);
+}
+
+int main() {
+	MU_RUN_SUITE(test_suite_osm_store);
+	MU_REPORT();
+	return MU_EXIT_CODE;
+}