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

[Alexey Bataev via cfe-commits]

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@@ -19409,6 +19409,18 @@ static bool isVariableCapturable(CapturingScopeInfo *CSI, ValueDecl *Var,
   }
 
   if (isa<BindingDecl>(Var)) {
+    if (auto *RSI = dyn_cast<CapturedRegionScopeInfo>(CSI)) {
+      if (RSI->CapRegionKind == CR_OpenMP) {
+        if (Diagnose && S.getLangOpts().CPlusPlus) {
+          S.Diag(Loc, S.LangOpts.CPlusPlus20
+                          ? diag::warn_cxx17_compat_capture_binding
+                          : diag::ext_capture_binding)
+              << Var;
+          S.Diag(Var->getLocation(), diag::note_entity_declared_at) << Var;
+        }
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alexey-bataev wrote:

Missing early rejection of tuple-like bindings. This causes two problems: (a) the extension warning fires for tuple-like bindings that will be rejected by an error, producing confusing diagnostics (warning says "extension" implying it works, error says "not supported"); (b) the variable is processed as capturable through multiple Sema layers before rejection, which is fragile. This was requested in a prior review (May 24) and marked "Done" but the code here has no tuple-like check. Add if (cast<BindingDecl>(Var)->getHoldingVar()) guard to return false for tuple-like bindings immediately.

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