[clang] [OpenMP] Support capturing structured bindings in OpenMP regions. (PR #190832)

[Alexey Bataev via cfe-commits]

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@@ -772,6 +772,10 @@ OpenMP Support
 - Added support for ``transparent`` clause in task and taskloop directives.
 - Added support for ``use_device_ptr`` clause to accept an optional
   ``fallback`` modifier (``fb_nullify`` or ``fb_preserve``) with OpenMP >= 61.
+- Added support for C++17 structured bindings in OpenMP regions. Structured
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alexey-bataev wrote:

'C++17 structured bindings in OpenMP regions' is misleading: structured bindings have always worked in OpenMP regions, and the diagnostic this PR replaces (`ext_capture_binding`) calls capturing them 'a C++20 extension'. Reword to: 'Added support for capturing structured bindings in OpenMP regions (C++20; warned as an extension in C++17).' Also, the 'will produce a compilation error' claim is wrong as currently implemented - tuple-like bindings hit `llvm_unreachable` in CodeGen and crash the compiler instead of producing a diagnostic.

https://github.com/llvm/llvm-project/pull/190832