c++: lambda and the current instantiation [PR82980]
authorJason Merrill <jason@redhat.com>
Thu, 14 Apr 2022 12:16:45 +0000 (08:16 -0400)
committerJason Merrill <jason@redhat.com>
Thu, 14 Apr 2022 18:51:49 +0000 (14:51 -0400)
commit74b2e20222cf4fb24b90561ddb6f0989738bb722
tree4497f32f6a794c993200be3df9b3b86cc504e3a9
parentd634c5d7c78c6ec0fa39d96984460475564519c8
c++: lambda and the current instantiation [PR82980]

When a captured variable is type-dependent, we've expressed the type of the
capture field and proxy with a decltype variant.  But if the type is "the
current instantiation", we need to be able to see that so that we can do
lookup inside it just like we could with the captured variable itself.

I also tried looking through lambda capture in
cp_parser_postfix_dot_deref_expression, but this way seems cleaner.  I plan
to treat more types as deducible in stage 1.

I considered also using this in do_auto_deduction, but think that would be
wrong: [temp.dep.expr] says an id-expression is type-dependent if it is
"associated by name lookup with a variable declared with a type that
contains a placeholder type where the initializer is type-dependent".  That
doesn't clearly exclude deducing a dependent type from the initializer, but
it seems like a barrier, and other implementations agree.

PR c++/82980

gcc/cp/ChangeLog:

* lambda.cc (type_deducible_expression_p): New.
(lambda_capture_field_type): Check it.

gcc/testsuite/ChangeLog:

* g++.dg/cpp0x/lambda/lambda-current-inst1.C: New test.
gcc/cp/lambda.cc
gcc/testsuite/g++.dg/cpp0x/lambda/lambda-current-inst1.C [new file with mode: 0644]