With the goal of reusing that handler to do other things besides
handling assertions (such as terminating when an exception is thrown
under -fno-exceptions), the name `__libcpp_assertion_handler` doesn't
really make sense anymore.
Furthermore, I didn't want to use the name `__libcpp_abort_handler`,
since that would give the impression that the handler is called
whenever `std::abort()` is called, which is not the case at all.
Differential Revision: https://reviews.llvm.org/D130562
Instead of taking a fixed set of arguments, use variadics so that
we can pass arbitrary arguments to the handler. This is the first
step towards using the handler to handle other non-assertion-related
failures, like std::unreachable and an exception being thrown in
-fno-exceptions mode, which would improve user experience by including
additional information in crashes (right now, we call abort() without
additional information).
Differential Revision: https://reviews.llvm.org/D130507
This patch adds a lightweight assertion handler mechanism that can be
overriden at link-time in a fashion similar to `operator new`.
This is a third take on https://llvm.org/D121123 (which allowed customizing
the assertion handler at compile-time), and https://llvm.org/D119969
(which allowed customizing the assertion handler at runtime only).
This approach is, I think, the best of all three explored approaches.
Indeed, replacing the assertion handler in user code is ergonomic,
yet we retain the ability to provide a custom assertion handler when
deploying to older platforms that don't have a default handler in
the dylib.
As-is, this patch provides a pretty good amount of backwards compatibility
with the previous debug mode:
- Code that used to set _LIBCPP_DEBUG=0 in order to get basic assertions
in their code will still get basic assertions out of the box, but
those assertions will be using the new assertion handler support.
- Code that was previously compiled with references to __libcpp_debug_function
and friends will work out-of-the-box, no changes required. This is
because we provide the same symbols in the dylib as we used to.
- Code that used to set a custom __libcpp_debug_function will stop
compiling, because we don't provide that declaration anymore. Users
will have to migrate to the new way of setting a custom assertion
handler, which is extremely easy. I suspect that pool of users is
very limited, so breaking them at compile-time is probably acceptable.
The main downside of this approach is that code being compiled with
assertions enabled but deploying to an older platform where the assertion
handler didn't exist yet will fail to compile. However users can easily
fix the problem by providing a custom assertion handler and defining
the _LIBCPP_AVAILABILITY_CUSTOM_ASSERTION_HANDLER_PROVIDED macro to
let the library know about the custom handler. In a way, this is
actually a feature because it avoids a load-time error that one would
otherwise get when trying to run the code on the older target.
Differential Revision: https://reviews.llvm.org/D121478
Prior to this patch, there was no distinction between tests that check
basic assertions and tests that check full-fledged iterator debugging
assertions. Both were disabled when support for the debug mode is not
provided in the dylib, which is stronger than it needs to be.
Furthermore, all of the tests using "debug_macros.h" that contain more
than one assertion in them were broken -- any code after the first
assertion would never be executed.
This patch refactors all of our assertion-related tests to:
1. Be enabled whenever they can, i.e. basic assertions tests are run
even when the debug mode is disabled.
2. Use the superior `check_assertion.h` (previously `debug_mode_helper.h`)
instead of `debug_macros.h`, which allows multiple assertions in the
same program.
3. Coalesce some tests into the same file to make them more readable.
4. Use consistent naming for test files -- no more db{1,2,3,...,10} tests.
This is a large but mostly mechanical patch.
Differential Revision: https://reviews.llvm.org/D121462
Louis Dionne