[PATCH] D63960: [C++20] Add consteval-specific semantic for functions

[Tyker via Phabricator via cfe-commits]

Tyker added inline comments.


================
Comment at: clang/lib/AST/ExprConstant.cpp:13618
+  if (InPlace) {
+    LValue LVal;
+    if (!::EvaluateInPlace(Result.Val, Info, LVal, this) ||
----------------
rsmith wrote:
> This isn't sufficient: the evaluation process can refer back to the object under construction (eg, via `this`), and we need an lvalue that actually names the result in order for this to work.
> 
> I think you'll need to do something like creating a suitable object (perhaps a `LifetimeExtendedTemporaryDecl`) in the caller to represent the result of the immediate invocation, and passing that into here.
i believe this solution should work. without LifetimeExtendedTemporaryDecl because reference/pointer on temporaries are not valid results of constant evaluation. so the AST should never store an APValue whose LValue is a ConstantExpr.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D63960/new/

https://reviews.llvm.org/D63960