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

[Zahira Ammarguellat via cfe-commits]

================
@@ -3589,6 +3589,51 @@ static bool canEmitSpuriousReferenceToVariable(CodeGenFunction &CGF,
   }
 }
 
+/// Emit an LValue for a structured binding captured in an OpenMP region.
+/// Handles extracting individual bindings from the captured decomposed
+/// declaration (struct fields, array elements, etc.).
+LValue CodeGenFunction::EmitOMPCapturedBindingLValue(const BindingDecl *BD) {
+  assert(CapturedStmtInfo &&
+         CapturedStmtInfo->getKind() == CapturedRegionKind::CR_OpenMP &&
+         CGM.getLangOpts().OpenMP);
+  auto *DD = cast<VarDecl>(BD->getDecomposedDecl());
+  QualType AggregType = DD->getType();
+  if (AggregType->isReferenceType())
+    AggregType = AggregType->getPointeeType();
+  DeclarationNameInfo NameInfo(DD->getDeclName(), SourceLocation());
+  DeclRefExpr *DRE = DeclRefExpr::Create(
+      getContext(), NestedNameSpecifierLoc(), SourceLocation(), DD,
+      /*RefersToEnclosingVariableOrCapture=*/false, NameInfo, AggregType,
+      VK_LValue);
+  LValue CapLVal = EmitLValue(DRE);
+
+  // Extract the specific binding from the decomposed object.
+  Expr *BindingExpr = BD->getBinding()->IgnoreImplicit();
+  if (auto *ME = dyn_cast<MemberExpr>(BindingExpr)) {
+    // Struct/union: access field.
+    FieldDecl *Field = cast<FieldDecl>(ME->getMemberDecl());
+    return EmitLValueForField(CapLVal, Field);
+  } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(BindingExpr)) {
----------------
zahiraam wrote:

`EmitLValue(BD->getBinding())` crashes because the `DeclRefExpr` inside the binding expression resolves to a pointer with the wrong element type (element type is` i32` not `[N x i32]`), causing `EmitArraySubscriptExpr` to emit an invalid multi-index GEP. Computing this manually correctly uses the already-fixed-up `CapLVal` address as the base.

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