[clang] [Clang] Backport P2741R3 (static_assert with user-generated message) to C++11 (PR #102044)

[Mital Ashok via cfe-commits]

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@@ -671,10 +671,8 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
                         LangOpts.CPlusPlus23   ? "202211L"
                         : LangOpts.CPlusPlus17 ? "201603L"
                                                : "200907");
-    Builder.defineMacro("__cpp_static_assert", LangOpts.CPlusPlus26 ? "202306L"
-                                               : LangOpts.CPlusPlus17
-                                                   ? "201411L"
-                                                   : "200410");
+    // C++17 / C++26 static_assert backported
+    Builder.defineMacro("__cpp_static_assert", "202306L");
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MitalAshok wrote:

I see that other features that have been backported only define the feature test macro if it didn't exist in the older versions. This sounds reasonable, I'll revert this change.

https://github.com/llvm/llvm-project/pull/102044