[Bug c++/94560] New: ICE on recursive templated alias

[pacoarjonilla at yahoo dot es]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94560

            Bug ID: 94560
           Summary: ICE on recursive templated alias
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pacoarjonilla at yahoo dot es
  Target Milestone: ---

Maybe related to Bug ID 93085

Only on GCC10 with --std=c++17 and --std=c++20

ICE with tuples and variants. Could not replicate with my own types.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

#include <tuple>

template <typename T>
using B = std::tuple<T*>;

using A = std::tuple<B<A>>;

int main()
{
    B b;
}

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Compiler output:

prueba.cc:6:24: error: ‘A’ was not declared in this scope
    6 | using A = std::tuple<B<A>>;
      |                        ^
prueba.cc:6:24: error: template argument 1 is invalid
prueba.cc:6:25: error: template argument 1 is invalid
    6 | using A = std::tuple<B<A>>;
      |                         ^~
prueba.cc:6:16: error: ‘<expression error>’ in namespace ‘std’ does not name a
type
    6 | using A = std::tuple<B<A>>;
      |                ^~~~~~~~~~~
prueba.cc: In function ‘int main()’:
prueba.cc:10:7: internal compiler error: in alias_ctad_tweaks, at cp/pt.c:28319
   10 |     B b;
      |       ^
0x674f3f alias_ctad_tweaks
        /home/paco/git/gcc/gcc/cp/pt.c:28319
0x674f3f deduction_guides_for
        /home/paco/git/gcc/gcc/cp/pt.c:28491
0x9f5ccb do_class_deduction
        /home/paco/git/gcc/gcc/cp/pt.c:28596
0x9f5ccb do_auto_deduction(tree_node*, tree_node*, tree_node*, int,
auto_deduction_context, tree_node*, int)
        /home/paco/git/gcc/gcc/cp/pt.c:28725
0x929e5c cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int)
        /home/paco/git/gcc/gcc/cp/decl.c:7503
0x9d0f69 cp_parser_init_declarator
        /home/paco/git/gcc/gcc/cp/parser.c:20906
0x9b2422 cp_parser_simple_declaration
        /home/paco/git/gcc/gcc/cp/parser.c:13731
0x9b418a cp_parser_declaration_statement
        /home/paco/git/gcc/gcc/cp/parser.c:13163
0x9b4e0d cp_parser_statement
        /home/paco/git/gcc/gcc/cp/parser.c:11469
0x9b5d38 cp_parser_statement_seq_opt
        /home/paco/git/gcc/gcc/cp/parser.c:11835
0x9b5e18 cp_parser_compound_statement
        /home/paco/git/gcc/gcc/cp/parser.c:11785
0x9cd1b5 cp_parser_function_body
        /home/paco/git/gcc/gcc/cp/parser.c:23059
0x9cd1b5 cp_parser_ctor_initializer_opt_and_function_body
        /home/paco/git/gcc/gcc/cp/parser.c:23110
0x9d050d cp_parser_function_definition_after_declarator
        /home/paco/git/gcc/gcc/cp/parser.c:28958
0x9d1589 cp_parser_function_definition_from_specifiers_and_declarator
        /home/paco/git/gcc/gcc/cp/parser.c:28874
0x9d1589 cp_parser_init_declarator
        /home/paco/git/gcc/gcc/cp/parser.c:20666
0x9b2422 cp_parser_simple_declaration
        /home/paco/git/gcc/gcc/cp/parser.c:13731
0x9db752 cp_parser_declaration
        /home/paco/git/gcc/gcc/cp/parser.c:13430
0x9dbeda cp_parser_translation_unit
        /home/paco/git/gcc/gcc/cp/parser.c:4731
0x9dbeda c_parse_file()
        /home/paco/git/gcc/gcc/cp/parser.c:43829
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