[clang] [Clang] Tolerate constant evaluation failure when transforming SubstNonTypeTemplateParmExpr in unevaluated contexts (PR #196791)

[via cfe-commits]

wx257osn2 wrote:

Above issue appears to be resolved by not storing the result of `SemaRef.CheckTemplateArgument()` in `Replacement` for an evaluated context regardless of the result of `isInvalid()`.
I also added a test to verify that that, when constraint satisfaction fails, the diagnostic is emitted correctly.

https://github.com/llvm/llvm-project/pull/196791