When a specialization was ambiguous, we would mark it as invalid, even
if the specialization occured in an immediate context.
This would subsequently lead to scenarios where invalid specialization
produced no diagnostics, causing crashes during codegen.
Fixes#51866
This fixes partial ordering of pack expansions of NTTPs, by procedding
with the check using the pattern of the NTTP through the rules of the
non-pack case.
This also unifies almost all of the different versions of
FinishTemplateArgumentDeduction (except the function template case).
This makes sure they all follow the rules consistently, instantiating
the parameters and comparing those with the argument.
Fixes#132562
This appears to be the only template argument deduction context where we were
missing this check. Surprisingly, other implementations also appear to miss
the check in this case; it may turn out that important code is relying on
the widespread non-conformance here, in which case we'll need to reconsider.
llvm-svn: 295277
The rules around typechecking deduced template arguments during partial
ordering are not clear, and while the prior behavior does not seem to be
correct (it doesn't follow the general model of partial ordering where each
template parameter is replaced by a non-dependent but unique value), the new
behavior is also not clearly right and breaks some existing idioms.
The new behavior is retained for dealing with non-type template parameters
with 'auto' types, as without it even the most basic uses of that feature
don't work. We can revisit this once CWG has come to an agreement on how
partial ordering with 'auto' non-type template parameters is supposed to
work.
llvm-svn: 292183
