On 10/7/22 08:27, Nathan Sidwell wrote:
VAR and FIELD decls can become part of a lambda context, when the
lambda is 'attached' to that entity (It's a C++20 ODR thing that was
discovered with modules, but is actually separate.) We were not
marking those decls as substitution candidates, leading to demangling
failures and compiler variance.
The alternative I chose is to bump the ABI, and add them to the
substitution table. I think this is the intent of the ABI.
Agreed: <closure-prefix> is a <prefix>, and <prefix>es are substitution
candidates.
The other alternative would be for the demangler to pop off the most
recent substitution when it saw the 'M'. But we'd have to change [at
least] the libiberty demangler[*] and the clang demangler and the clang
mangler, which seems a bigger challenge.
I'll commit this next week, unless y'all have comments.
We have other divergence from clang, with templated lambdas. Clang
added new manglings [Ty, Tn, Tt] for the lambda's template head (Richard
has a pull request, but it's not merged
https://github.com/itanium-cxx-abi/cxx-abi/issues/31). Without that, we
consider all the template args to be auto when demangling (which is
going to look odd for non-type template args). This divergence in
signature also affects the lambda numbering, as gcc & clang differ in
their opinions about 'same lamda signature'. thoughts on addressing
that to in this cycle?
That sounds good: From looking over the issue and pull request, it seems
pretty well baked.
I have some demangler fixes coming up.
nathan
[*] the demangler already seems to have a bug with 'M' handling.
