[clang] [Clang] Avoid crash when expression requirements are substitution failures (PR #176896)

[Thibault Monnier via cfe-commits]

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@@ -123,6 +123,7 @@ Bug Fixes to Attribute Support
 
 Bug Fixes to C++ Support
 ^^^^^^^^^^^^^^^^^^^^^^^^
+- Fixed a crash when instantiating ``requires`` expressions involving substitution failures in C++ concepts. (#GH176402)
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Thibault-Monnier wrote:

I don’t think you should be modifying this file. 

https://github.com/llvm/llvm-project/pull/176896