[clang] [Clang] Implement consteval blocks for C++26 (PR #188665)

[Corentin Jabot via cfe-commits]

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@@ -1434,6 +1445,9 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
       TrailingReturnTypeLoc = Range.getBegin();
       if (Range.getEnd().isValid())
         DeclEndLoc = Range.getEnd();
+    } else if (ConstevalBlockStart.isValid()) {
+      TrailingReturnType = ParsedType::make(Actions.Context.VoidTy);
+      TrailingReturnTypeLoc = ConstevalBlockStart;
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cor3ntin wrote:

this implies you can write `consteval noexcept {}` - I don;t think you can actually get there but it's unnecessary work / dead code

https://github.com/llvm/llvm-project/pull/188665