Revert "[libc++] Remove trailing newline from _LIBCPP_ASSERTION_HANDLER calls"

[mysterymath]

Reverts #143573

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Daniel Thornburgh (mysterymath)

Changes

Reverts llvm/llvm-project#143573

---

Full diff: https://github.com/llvm/llvm-project/pull/144615.diff

3 Files Affected:

• (modified) libcxx/include/__assert (+2-2)
• (modified) libcxx/src/verbose_abort.cpp (-3)
• (modified) libcxx/test/support/check_assertion.h (+1-1)

diff --git a/libcxx/include/__assert b/libcxx/include/__assert
index 1bfed2890b79f..90eaa6023587b 100644
--- a/libcxx/include/__assert
+++ b/libcxx/include/__assert
@@ -20,8 +20,8 @@
 #define _LIBCPP_ASSERT(expression, message)                                                                            \
   (__builtin_expect(static_cast<bool>(expression), 1)                                                                  \
        ? (void)0                                                                                                       \
-       : _LIBCPP_ASSERTION_HANDLER(                                                                                    \
-             __FILE__ ":" _LIBCPP_TOSTRING(__LINE__) ": assertion " _LIBCPP_TOSTRING(expression) " failed: " message))
+       : _LIBCPP_ASSERTION_HANDLER(__FILE__ ":" _LIBCPP_TOSTRING(__LINE__) ": assertion " _LIBCPP_TOSTRING(            \
+             expression) " failed: " message "\n"))
 
 // WARNING: __builtin_assume can currently inhibit optimizations. Only add assumptions with a clear
 // optimization intent. See https://discourse.llvm.org/t/llvm-assume-blocks-optimization/71609 for a
diff --git a/libcxx/src/verbose_abort.cpp b/libcxx/src/verbose_abort.cpp
index efb7b9be6f61c..94bdb451dee7a 100644
--- a/libcxx/src/verbose_abort.cpp
+++ b/libcxx/src/verbose_abort.cpp
@@ -30,9 +30,6 @@ _LIBCPP_WEAK void __libcpp_verbose_abort(char const* format, ...) noexcept {
     va_list list;
     va_start(list, format);
     std::vfprintf(stderr, format, list);
-    // Callers of `__libcpp_verbose_abort` do not include a newline but when
-    // writing the message to stderr we need to include one.
-    std::fputc('\n', stderr);
     va_end(list);
   }
 
diff --git a/libcxx/test/support/check_assertion.h b/libcxx/test/support/check_assertion.h
index ea04944ea9326..a279400d651b4 100644
--- a/libcxx/test/support/check_assertion.h
+++ b/libcxx/test/support/check_assertion.h
@@ -340,7 +340,7 @@ void std::__libcpp_verbose_abort(char const* format, ...) noexcept {
 
   std::fprintf(stderr, "%s\n", Marker);
   std::vfprintf(stderr, format, args);
-  std::fprintf(stderr, "\n%s", Marker);
+  std::fprintf(stderr, "%s", Marker);
 
   va_end(args);