[clang] [Clang][CWG1815] Support lifetime extension of temporary created by aggregate initialization using a default member initializer (PR #87933)

[James Y Knight via cfe-commits]

jyknight wrote:

We _don't_ diagnose it at the end of the definition of M -- it looks like we explicitly intentionally stopped doing so in the commit I referenced.  That's why I'm a little confused here.

With this patch, we start to diagnose only in the final line of code, `void test(M m = {}) {}` (that line doesn't appear in the error message, but it's the trigger).


https://github.com/llvm/llvm-project/pull/87933