Implement https://cplusplus.github.io/CWG/issues/2631.html.
Immediate calls in default arguments and defaults members
are not evaluated.
Instead, we evaluate them when constructing a
`CXXDefaultArgExpr`/`BuildCXXDefaultInitExpr`.
The immediate calls are executed by doing a
transform on the initializing expression.
Note that lambdas are not considering subexpressions so
we do not need to transform them.
As a result of this patch, unused default member
initializers are not considered odr-used, and
errors about members binding to local variables
in an outer scope only surface at the point
where a constructor is defined.
Reviewed By: aaron.ballman, #clang-language-wg
Differential Revision: https://reviews.llvm.org/D136554
Patch VisitCXXDeleteExpr() in clang::UsedDeclVisitor to avoid it crashing
when the expression's destroyed type is null. According to the comments
in CXXDeleteExpr::getDestroyedType(), this can happen when the type to
delete is a dependent type.
Patch by Geoff Levner.
Differential Revision: https://reviews.llvm.org/D88949
