selection: prevent use after free crash

This is hiding a bigger issue in the way changes are propagated through
the code, but it should stop an annoying crash in 5.0 from happening.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

CMakeLists.txt

@@ -29,6 +29,9 @@ MACRO_ENSURE_OUT_OF_SOURCE_BUILD(
     "We don't support building in source, please create a build folder elsewhere and remember to run git clean -xdf to remove temporary files created by CMake."
 )
 
+#Option for memory debugging
+option(SUBSURFACE_ASAN_BUILD "enable memory debugging of Subsurface binary" OFF)
+
 #Option for profiling
 option(SUBSURFACE_PROFILING_BUILD "enable profiling of Subsurface binary" OFF)
 
@@ -110,6 +113,11 @@ if (SUBSURFACE_PROFILING_BUILD)
 	SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -pg")
 	SET(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -pg")
 endif()
+# set up ASan
+if (SUBSURFACE_ASAN_BUILD)
+	SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")
+	SET(CMAKE_C_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")
+endif()
 
 # every compiler understands -Wall
 set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")

stats/statsview.cpp

@@ -377,6 +377,9 @@ void StatsView::replotIfVisible()
 
 void StatsView::divesSelected(const QVector<dive *> &dives)
 {
+	if (dive_table.nr <= 0)
+		// there are no dives, don't bother (this can happen during reset, for example)
+		return;
 	if (isVisible()) {
 		for (auto &series: series)
 			series->divesSelected(dives);