DRTVWR-476: Enrich LLExceptions thrown by LLTHROW() with stack trace.

The LLTHROW() abstraction allows us to enrich the subject exception with a
boost::stacktrace -- without having to propagate the boost/stacktrace.hpp
header throughout the code base.

To my delight, our existing use of
boost::current_exception_diagnostic_information() already reports the newly
added boost::stacktrace information -- we don't have to query it specifically!

1 files changed, 27 insertions, 0 deletions

diff --git a/indra/llcommon/llexception.cpp b/indra/llcommon/llexception.cpp
index b32ec2c9c9..c0483e8927 100644
--- a/indra/llcommon/llexception.cpp
+++ b/indra/llcommon/llexception.cpp
@@ -18,10 +18,23 @@
 #include <typeinfo>
 // external library headers
 #include <boost/exception/diagnostic_information.hpp>
+#include <boost/exception/error_info.hpp>
+// On Mac, got:
+// #error "Boost.Stacktrace requires `_Unwind_Backtrace` function. Define
+// `_GNU_SOURCE` macro or `BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED` if
+// _Unwind_Backtrace is available without `_GNU_SOURCE`."
+#define BOOST_STACKTRACE_GNU_SOURCE_NOT_REQUIRED
+#include <boost/stacktrace.hpp>
 // other Linden headers
 #include "llerror.h"
 #include "llerrorcontrol.h"
 
+// used to attach and extract stacktrace information to/from boost::exception,
+// see https://www.boost.org/doc/libs/release/doc/html/stacktrace/getting_started.html#stacktrace.getting_started.exceptions_with_stacktrace
+// apparently the struct passed as the first template param needs no definition?
+typedef boost::error_info<struct errinfo_stacktrace_, boost::stacktrace::stacktrace>
+        errinfo_stacktrace;
+
 namespace {
 // used by crash_on_unhandled_exception_() and log_unhandled_exception_()
 void log_unhandled_exception_(LLError::ELevel level,
@@ -53,3 +66,17 @@ void log_unhandled_exception_(const char* file, int line, const char* pretty_fun
     // routinely, but we DO expect to return from this function.
     log_unhandled_exception_(LLError::LEVEL_WARN, file, line, pretty_function, context);
 }
+
+void annotate_exception_(boost::exception& exc)
+{
+    // https://www.boost.org/doc/libs/release/libs/exception/doc/tutorial_transporting_data.html
+    // "Adding of Arbitrary Data to Active Exception Objects"
+    // Given a boost::exception&, we can add boost::error_info items to it
+    // without knowing its leaf type.
+    // The stacktrace constructor that lets us skip a level -- and why would
+    // we always include annotate_exception_()? -- also requires a max depth.
+    // For the nullary constructor, the stacktrace class declaration itself
+    // passes static_cast<std::size_t>(-1), but that's kind of dubious.
+    // Anyway, which of us is really going to examine more than 100 frames?
+    exc << errinfo_stacktrace(boost::stacktrace::stacktrace(1, 100));
+}