Utils: Add some backtrace dumping facility to QTC_ASSERT

Unix only for now, opt-in, by setting QTC_BACKTRACE_MAXDEPTH=<number>
in the environment.

Change-Id: Ice110dbf5d25003706a947b27c279fec464df7a1
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/qtcassert.cpp

@@ -26,9 +26,30 @@
 #include "qtcassert.h"
 
 #include <QByteArray>
+#include <QDebug>
+
+#if defined(Q_OS_UNIX)
+#include <stdio.h>
+#include <signal.h>
+#include <execinfo.h>
+#endif
 
 namespace Utils {
 
+void dumpBacktrace(int maxdepth)
+{
+    if (maxdepth == -1)
+        maxdepth = 1000;
+#if defined(Q_OS_UNIX)
+    void *bt[1000] = {nullptr};
+    int size = backtrace(bt, sizeof(bt) / sizeof(bt[0]));
+    char **lines = backtrace_symbols(bt, size);
+    for (int i = 0; i < size; ++i)
+        qDebug() << "0x" + QByteArray::number(quintptr(bt[i]), 16) << lines[i];
+    free(lines);
+#endif
+}
+
 void writeAssertLocation(const char *msg)
 {
     static bool goBoom = qEnvironmentVariableIsSet("QTC_FATAL_ASSERTS");
@@ -36,6 +57,10 @@ void writeAssertLocation(const char *msg)
         qFatal("SOFT ASSERT made fatal: %s", msg);
     else
         qDebug("SOFT ASSERT: %s", msg);
+
+    static int maxdepth = qEnvironmentVariableIntValue("QTC_BACKTRACE_MAXDEPTH");
+    if (maxdepth != 0)
+        dumpBacktrace(maxdepth);
 }
 
 } // namespace Utils

src/libs/utils/qtcassert.h

@@ -27,7 +27,10 @@
 
 #include "utils_global.h"
 
-namespace Utils { QTCREATOR_UTILS_EXPORT void writeAssertLocation(const char *msg); }
+namespace Utils {
+QTCREATOR_UTILS_EXPORT void writeAssertLocation(const char *msg);
+QTCREATOR_UTILS_EXPORT void dumpBacktrace(int maxdepth);
+} // Utils
 
 #define QTC_ASSERT_STRINGIFY_HELPER(x) #x
 #define QTC_ASSERT_STRINGIFY(x) QTC_ASSERT_STRINGIFY_HELPER(x)