[Bug c++/67210] New: [concepts] Error parsing ">>" after a template-id that names a concept

[Casey at Carter dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67210

            Bug ID: 67210
           Summary: [concepts] Error parsing ">>" after a template-id that
                    names a concept
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Casey at Carter dot net
  Target Milestone: ---

Created attachment 36183
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36183&action=edit
Test case

r226833 ICEs compiling this correct TU:

template <class T, class U>
concept bool C = true;

template <class T>
struct A {};

void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)

with error:

~/gcc6-r226833/bin/g++ -std=gnu++1z foo.cpp -c
foo.cpp:7:10: error: type/value mismatch at argument 1 in template parameter
list for ‘template<class T> struct A’
 void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)
          ^
foo.cpp:7:10: note:   expected a type, got ‘C<int>’
foo.cpp:7:10: error: type/value mismatch at argument 1 in template parameter
list for ‘template<class T> struct A’
foo.cpp:7:10: note:   expected a type, got ‘C<int>’
foo.cpp:7:10: error: type/value mismatch at argument 1 in template parameter
list for ‘template<class T> struct A’
foo.cpp:7:10: note:   expected a type, got ‘C<int>’
foo.cpp:7:8: error: variable or field ‘f’ declared void
 void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)
        ^
foo.cpp:7:10: error: wrong number of template arguments (1, should be 2)
 void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)
          ^
foo.cpp:2:14: note: provided for ‘template<class T, class U> constexpr const
bool C<T, U>’
 concept bool C = true;
              ^
foo.cpp:7:10: error: wrong number of template arguments (1, should be 2)
 void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)
          ^
foo.cpp:2:14: note: provided for ‘template<class T, class U> constexpr const
bool C<T, U>’
 concept bool C = true;
              ^
foo.cpp:7:10: error: type/value mismatch at argument 1 in template parameter
list for ‘template<class T> struct A’
 void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)
          ^
foo.cpp:7:10: note:   expected a type, got ‘true’
foo.cpp:7:17: internal compiler error: tree check: expected tree that contains
‘decl minimal’ structure, have ‘error_mark’ in cp_parser_init_declarator, at
cp/parser.c:17813
 void f(A<C<int>>) {} // Error ("void f(A<C<int> >)" works fine)
                 ^
0xf05fc4 tree_contains_struct_check_failed(tree_node const*,
tree_node_structure_enum, char const*, int, char const*)
        ../../gcc/tree.c:9667
0x71d266 contains_struct_check(tree_node*, tree_node_structure_enum, char
const*, int, char const*)
        ../../gcc/tree.h:2972
0x71d266 cp_parser_init_declarator
        ../../gcc/cp/parser.c:17813
0x71f6e5 cp_parser_simple_declaration
        ../../gcc/cp/parser.c:11681
0x718e83 cp_parser_block_declaration
        ../../gcc/cp/parser.c:11555
0x724cc7 cp_parser_declaration
        ../../gcc/cp/parser.c:11452
0x72346a cp_parser_declaration_seq_opt
        ../../gcc/cp/parser.c:11334
0x723789 cp_parser_translation_unit
        ../../gcc/cp/parser.c:4154
0x723789 c_parse_file()
        ../../gcc/cp/parser.c:34271
0x86d1a2 c_common_parse_file()
        ../../gcc/c-family/c-opts.c:1058
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