c++: lambda in function template signature [PR119401]

Here we instantiate the lambda three times in producing A<0>::f:
1) in tsubst_function_type, substituting the type of A<>::f
2) in tsubst_function_decl, substituting the parameters of A<>::f
3) in regenerate_decl_from_template when instantiating A<>::f

The first one gets thrown away by maybe_rebuild_function_decl_type.  Before
r15-7202, we happily built all of them and mangled the result wrongly as
lambda #3.  After r15-7202, we try to mangle #3 as #1, which breaks because
 #1 is already mangled as #1.

This patch avoids building #3 by suppressing regenerate_decl_from_template
if the template signature includes a lambda, fixing the ICE.

We now mangle the lambda as #2, which is still wrong.  Addressing that
should involve not calling tsubst_function_type from tsubst_function_decl,
and building the type from the parms types in the first place rather than
fixing it up in maybe_rebuild_function_decl_type.

	PR c++/119401

gcc/cp/ChangeLog:

	* pt.cc (regenerate_decl_from_template): Don't regenerate if the
	signature involves a lambda.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp2a/lambda-targ11.C: New test.

0 files changed, 0 insertions, 0 deletions