[clang] [clang] Enable Wenum-constexpr-conversion also in system headers and … (PR #67528)

[Carlos Galvez via cfe-commits]

https://github.com/carlosgalvezp created https://github.com/llvm/llvm-project/pull/67528

…macros

As per review comments on https://reviews.llvm.org/D150226, we should allow for one more release before turning this warning into a hard error, by making it visible in system headers and macros, so that people are aware of it and can work on it.

>From f9c4fb4e0a5a9017da6214fb0d98f45f89ee16be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20G=C3=A1lvez?= <carlos.galvez at zenseact.com>
Date: Wed, 27 Sep 2023 08:07:01 +0000
Subject: [PATCH] [clang] Enable Wenum-constexpr-conversion also in system
 headers and macros

As per review comments on https://reviews.llvm.org/D150226, we should
allow for one more release before turning this warning into a hard
error, by making it visible in system headers and macros, so that
people are aware of it and can work on it.
---
 clang/docs/ReleaseNotes.rst                     | 3 +++
 clang/include/clang/Basic/DiagnosticASTKinds.td | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 477a40630f11097..3b6cfa776c85e46 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -67,6 +67,9 @@ C++ Specific Potentially Breaking Changes
   (`#49884 <https://github.com/llvm/llvm-project/issues/49884>`_), and
   (`#61273 <https://github.com/llvm/llvm-project/issues/61273>`_)
 
+- The warning `-Wenum-constexpr-conversion` is now also enabled by default on system headers and
+  macros. It will be turned into a hard (non-downgradable) error in the next Clang release.
+
 ABI Changes in This Version
 ---------------------------
 - Following the SystemV ABI for x86-64, ``__int128`` arguments will no longer
diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td b/clang/include/clang/Basic/DiagnosticASTKinds.td
index d2656310e79c9b8..0019553233fdef6 100644
--- a/clang/include/clang/Basic/DiagnosticASTKinds.td
+++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -405,7 +405,8 @@ def warn_fixedpoint_constant_overflow : Warning<
   InGroup<DiagGroup<"fixed-point-overflow">>;
 def warn_constexpr_unscoped_enum_out_of_range : Warning<
   "integer value %0 is outside the valid range of values [%1, %2] for the "
-  "enumeration type %3">, DefaultError, InGroup<DiagGroup<"enum-constexpr-conversion">>;
+  "enumeration type %3">, DefaultError, ShowInSystemHeader, ShowInSystemMacro,
+  InGroup<DiagGroup<"enum-constexpr-conversion">>;
 
 // This is a temporary diagnostic, and shall be removed once our
 // implementation is complete, and like the preceding constexpr notes belongs