https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79118
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> --- The original preprocessed file started ICEing with -Wall -std=gnu++14 with r219268: In file included from /mnt/g/boostish/outcome/test/../include/boost/outcome/v1.0/monad.hpp:98:0, from /mnt/g/boostish/outcome/test/../include/boost/outcome/outcome.hpp:15, from /mnt/g/boostish/outcome/test/unittests.cpp:41: /mnt/g/boostish/outcome/test/../include/boost/outcome/v1.0/value_storage.hpp:181:123: internal compiler error: in retrieve_specialization, at cp/pt.c:1050 0x713f4d retrieve_specialization ../../gcc/cp/pt.c:1047 0x762268 instantiate_template_1 ../../gcc/cp/pt.c:15859 0x76293a instantiate_template(tree_node*, tree_node*, int) ../../gcc/cp/pt.c:15972 0x892805 finish_template_variable(tree_node*) ../../gcc/cp/semantics.c:2457 0x896b60 finish_id_expression(tree_node*, tree_node*, tree_node*, cp_id_kind*, bool, bool, bool*, bool, bool, bool, bool, char const**, unsigned int) ../../gcc/cp/semantics.c:3570 0x7f02ed cp_parser_primary_expression ../../gcc/cp/parser.c:4766 0x7f2d8e cp_parser_postfix_expression ../../gcc/cp/parser.c:6120 0x7f5569 cp_parser_unary_expression ../../gcc/cp/parser.c:7401 0x7f60af cp_parser_cast_expression ../../gcc/cp/parser.c:8034 0x7f6148 cp_parser_binary_expression ../../gcc/cp/parser.c:8136 0x7f6892 cp_parser_assignment_expression ../../gcc/cp/parser.c:8378 0x7f6d28 cp_parser_constant_expression ../../gcc/cp/parser.c:8624 0x80941a cp_parser_initializer_clause ../../gcc/cp/parser.c:19288 0x8092b1 cp_parser_initializer ../../gcc/cp/parser.c:19229 0x805527 cp_parser_init_declarator ../../gcc/cp/parser.c:17192 0x811c3a cp_parser_single_declaration ../../gcc/cp/parser.c:23755 0x8111de cp_parser_template_declaration_after_export ../../gcc/cp/parser.c:23550 0x7fe9c7 cp_parser_template_declaration ../../gcc/cp/parser.c:13199 0x80c68e cp_parser_member_declaration ../../gcc/cp/parser.c:20672 0x80c582 cp_parser_member_specification_opt ../../gcc/cp/parser.c:20599 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <http://gcc.gnu.org/bugs.html> for instructions.