https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83167
--- Comment #3 from GCC Commits ---
The master branch has been updated by Patrick Palka :
https://gcc.gnu.org/g:d9965fef40794d548021d2e34844e5fafeca4ce5
commit r14-6350-gd9965fef40794d548021d2e34844e5fafeca4ce5
Author: Patrick Palka
Date: Fri Dec 8 16:57:13 2023 -0500
c++: decltype of (non-captured variable) [PR83167]
For decltype((x)) within a lambda where x is not captured, we dubiously
require that the lambda has a capture default, unlike for decltype(x).
But according to [expr.prim.id.unqual]/3 we should just ignore the lambda
in this case. This patch narrowly fixes this issue by disabling the
capture_decltype handling and falling back to the ordinary handling when
the innermost lambda has no capture-default. In fact, we can restrict
the special handling to only by-copy lambdas since that's what
[expr.prim.id.unqual]/3 is concerned with; for by-ref implicit captures
both code paths should give the same result anyway.
During review some other issues were discovered which are documented in
a new FIXME.
PR c++/83167
gcc/cp/ChangeLog:
* semantics.cc (capture_decltype): Inline into its only caller ...
(finish_decltype_type): ... here. Update nearby comment to refer
to recent standard. Add FIXME. Restrict uncaptured variable type
transformation to happen only for lambdas with a by-copy
capture-default.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/lambda/lambda-decltype4.C: New test.
