[libcxx-commits] [libcxx] [libc++] Encode additional ODR-affecting properties in the ABI tag (PR #69669)

[Louis Dionne via libcxx-commits]

================
@@ -734,22 +730,54 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_EXCLUDE_FROM_EXPLICIT_INSTANTIATION _LIBCPP_ALWAYS_INLINE
 #  endif
 
+#  if _LIBCPP_ENABLE_HARDENED_MODE
+#    define _LIBCPP_HARDENING_SIG h
+#  elif _LIBCPP_ENABLE_SAFE_MODE
+#    define _LIBCPP_HARDENING_SIG s
+#  elif _LIBCPP_ENABLE_DEBUG_MODE
+#    define _LIBCPP_HARDENING_SIG d
+#  else
+#    define _LIBCPP_HARDENING_SIG u // for unchecked
+#  endif
+
+#  ifdef _LIBCPP_HAS_NO_EXCEPTIONS
+#    define _LIBCPP_EXCEPTIONS_SIG n
+#  else
+#    define _LIBCPP_EXCEPTIONS_SIG e
+#  endif
+
+#  define _LIBCPP_ODR_SIGNATURE                                                                                        \
+    _LIBCPP_CONCAT(_LIBCPP_CONCAT(_LIBCPP_CONCAT(v, _LIBCPP_VERSION), _LIBCPP_HARDENING_SIG), _LIBCPP_EXCEPTIONS_SIG)
----------------
ldionne wrote:

With the latest comments applied, it looks like
```
_LIBCPP_CONCAT(_LIBCPP_CONCAT(_LIBCPP_HARDENING_SIG, _LIBCPP_EXCEPTIONS_SIG), _LIBCPP_VERSION)
```
without any custom formatting. I think the shorter line is pretty readable now and we don't need to add `clang-format off` -- please LMK if you disagree.

https://github.com/llvm/llvm-project/pull/69669