[libc++] Bypass calling exception-throwing functions in the dylib with -fno-exceptions

basic_string and vector currently have a hard dependency on the compiled
library because they need to call __vector_base_common::__throw_xxx(),
which are externally instantiated in the compiled library. That makes
sense when exceptions are enabled (because we're trying to localize the
exception-throwing code to the compiled library), but it doesn't really
make sense when exceptions are disabled, and the __throw_xxx functions
are just calling abort() anyways.

This patch simply overrides the __throw_xxx() functions so that they
don't rely on the compiled library when exceptions are disabled.

Differential Revision: https://reviews.llvm.org/D108389

libcxx/include/string

@@ -522,6 +522,7 @@ basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++1
 #include <algorithm>
 #include <compare>
 #include <cstdio>  // EOF
+#include <cstdlib>
 #include <cstring>
 #include <cwchar>
 #include <initializer_list>
@@ -1714,6 +1715,24 @@ private:
         return data() <= __p && __p <= data() + size();
     }
 
+    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
+    void __throw_length_error() const {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        __basic_string_common<true>::__throw_length_error();
+#else
+        _VSTD::abort();
+#endif
+    }
+
+    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
+    void __throw_out_of_range() const {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        __basic_string_common<true>::__throw_out_of_range();
+#else
+        _VSTD::abort();
+#endif
+    }
+
     friend basic_string operator+<>(const basic_string&, const basic_string&);
     friend basic_string operator+<>(const value_type*, const basic_string&);
     friend basic_string operator+<>(value_type, const basic_string&);

libcxx/include/vector

@@ -281,6 +281,7 @@ erase_if(vector<T, Allocator>& c, Predicate pred);    // C++20
 #include <algorithm>
 #include <climits>
 #include <compare>
+#include <cstdlib>
 #include <cstring>
 #include <initializer_list>
 #include <iosfwd> // for forward declaration of vector
@@ -390,6 +391,25 @@ protected:
             is_nothrow_move_assignable<allocator_type>::value)
         {__move_assign_alloc(__c, integral_constant<bool,
                       __alloc_traits::propagate_on_container_move_assignment::value>());}
+
+    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
+    void __throw_length_error() const {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        __vector_base_common<true>::__throw_length_error();
+#else
+        _VSTD::abort();
+#endif
+    }
+
+    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
+    void __throw_out_of_range() const {
+#ifndef _LIBCPP_NO_EXCEPTIONS
+        __vector_base_common<true>::__throw_out_of_range();
+#else
+        _VSTD::abort();
+#endif
+    }
+
 private:
     _LIBCPP_INLINE_VISIBILITY
     void __copy_assign_alloc(const __vector_base& __c, true_type)