Remove exception throwing debug mode handler support.

Summary:
The reason libc++ implemented a throwing debug mode handler was for ease of testing. Specifically,
I thought that if a debug violation aborted, we could only test one violation per file. This made
it impossible to test debug mode. Which throwing behavior we could test more!

However, the throwing approach didn't work either, since there are debug violations underneath noexcept
functions. This lead to the introduction of `_NOEXCEPT_DEBUG`, which was only noexcept when debug
mode was off.

Having thought more and having grown wiser, `_NOEXCEPT_DEBUG` was a horrible decision. It was
viral, it didn't cover all the cases it needed to, and it was observable to the user -- at worst
changing the behavior of their program.

  This patch removes the throwing debug handler, and rewrites the debug tests using 'fork-ing' style
  death tests.

Reviewers: mclow.lists, ldionne, thomasanderson

Reviewed By: ldionne

Subscribers: christof, arphaman, libcxx-commits, #libc

Differential Revision: https://reviews.llvm.org/D59166

llvm-svn: 356417

1 files changed, 4 insertions, 32 deletions

diff --git a/libcxx/include/__debug b/libcxx/include/__debug
index 281cf6675c9..524c5ff0284 100644
--- a/libcxx/include/__debug
+++ b/libcxx/include/__debug
@@ -11,6 +11,7 @@
 #define _LIBCPP_DEBUG_H
 
 #include <__config>
+#include <iosfwd>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -24,7 +25,6 @@
 #   include <cstdlib>
 #   include <cstdio>
 #   include <cstddef>
-#   include <exception>
 #endif
 
 #if _LIBCPP_DEBUG_LEVEL >= 1 && !defined(_LIBCPP_ASSERT)
@@ -49,10 +49,6 @@
 #define _LIBCPP_DEBUG_MODE(...) ((void)0)
 #endif
 
-#if _LIBCPP_DEBUG_LEVEL < 1
-class _LIBCPP_EXCEPTION_ABI __libcpp_debug_exception;
-#endif
-
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 struct _LIBCPP_TEMPLATE_VIS __libcpp_debug_info {
@@ -62,6 +58,9 @@ struct _LIBCPP_TEMPLATE_VIS __libcpp_debug_info {
   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
   __libcpp_debug_info(const char* __f, int __l, const char* __p, const char* __m)
     : __file_(__f), __line_(__l), __pred_(__p), __msg_(__m) {}
+
+  _LIBCPP_FUNC_VIS std::string what() const;
+
   const char* __file_;
   int __line_;
   const char* __pred_;
@@ -79,38 +78,11 @@ extern _LIBCPP_EXPORTED_FROM_ABI __libcpp_debug_function_type __libcpp_debug_fun
 _LIBCPP_NORETURN _LIBCPP_FUNC_VIS
 void __libcpp_abort_debug_function(__libcpp_debug_info const&);
 
-/// __libcpp_throw_debug_function - A debug handler that throws
-///   an instance of __libcpp_debug_exception when called.
- _LIBCPP_NORETURN _LIBCPP_FUNC_VIS
-void __libcpp_throw_debug_function(__libcpp_debug_info const&);
-
 /// __libcpp_set_debug_function - Set the debug handler to the specified
 ///    function.
 _LIBCPP_FUNC_VIS
 bool __libcpp_set_debug_function(__libcpp_debug_function_type __func);
 
-// Setup the throwing debug handler during dynamic initialization.
-#if _LIBCPP_DEBUG_LEVEL >= 1 && defined(_LIBCPP_DEBUG_USE_EXCEPTIONS)
-# if defined(_LIBCPP_NO_EXCEPTIONS)
-#   error _LIBCPP_DEBUG_USE_EXCEPTIONS cannot be used when exceptions are disabled.
-# endif
-static bool __init_dummy = __libcpp_set_debug_function(__libcpp_throw_debug_function);
-#endif
-
-#if _LIBCPP_DEBUG_LEVEL >= 1 || defined(_LIBCPP_BUILDING_LIBRARY)
-class _LIBCPP_EXCEPTION_ABI __libcpp_debug_exception : public exception {
-public:
-  __libcpp_debug_exception() _NOEXCEPT;
-  explicit __libcpp_debug_exception(__libcpp_debug_info const& __i);
-  __libcpp_debug_exception(__libcpp_debug_exception const&);
-  ~__libcpp_debug_exception() _NOEXCEPT;
-  const char* what() const _NOEXCEPT;
-private:
-  struct __libcpp_debug_exception_imp;
-  __libcpp_debug_exception_imp *__imp_;
-};
-#endif
-
 #if _LIBCPP_DEBUG_LEVEL >= 2 || defined(_LIBCPP_BUILDING_LIBRARY)
 
 struct _LIBCPP_TYPE_VIS __c_node;