[Bug c++/83947] New: ICE on invalid C++ code with auto: in tsubst_decl, at cp/pt.c:13046

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83947

            Bug ID: 83947
           Summary: ICE on invalid C++ code with auto: in tsubst_decl, at
                    cp/pt.c:13046
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

This appears to be a recent regression. 

$ g++tk -v
Using built-in specs.
COLLECT_GCC=g++tk
COLLECT_LTO_WRAPPER=/home/su/software/tmp/gcc/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/8.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/home/su/software/tmp/gcc/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 8.0.1 20180117 (experimental) [trunk revision 256779] (GCC)
$
$ g++-7.2.0 -c tmp.cpp
tmp.cpp: In instantiation of ‘auto g<0>’:
tmp.cpp:3:10:   required from here
tmp.cpp:2:23: error: use of ‘auto f()’ before deduction of ‘auto’
 template < int > auto g (f);
                       ^
$
$ g++tk -c tmp.cpp
tmp.cpp:2:23: internal compiler error: in tsubst_decl, at cp/pt.c:13046
 template < int > auto g (f);
                       ^
0x86faa0 tsubst_decl
        ../../gcc-source-trunk/gcc/cp/pt.c:13046
0x876996 tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../gcc-source-trunk/gcc/cp/pt.c:13562
0x8749b5 instantiate_template_1
        ../../gcc-source-trunk/gcc/cp/pt.c:18569
0x8749b5 instantiate_template(tree_node*, tree_node*, int)
        ../../gcc-source-trunk/gcc/cp/pt.c:18625
0x8c81b6 finish_id_expression(tree_node*, tree_node*, tree_node*, cp_id_kind*,
bool, bool, bool*, bool, bool, bool, bool, char const**, unsigned int)
        ../../gcc-source-trunk/gcc/cp/semantics.c:3679
0x80a1a2 cp_parser_primary_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:5615
0x817443 cp_parser_postfix_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:7029
0x82087c cp_parser_unary_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:8281
0x7fa8a9 cp_parser_cast_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:9049
0x7fafa5 cp_parser_binary_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:9151
0x7fb890 cp_parser_assignment_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:9439
0x7fc883 cp_parser_constant_expression
        ../../gcc-source-trunk/gcc/cp/parser.c:9721
0x7fcd67 cp_parser_initializer_clause
        ../../gcc-source-trunk/gcc/cp/parser.c:21842
0x7ffcfb cp_parser_initializer
        ../../gcc-source-trunk/gcc/cp/parser.c:21780
0x8227a4 cp_parser_init_declarator
        ../../gcc-source-trunk/gcc/cp/parser.c:19601
0x824248 cp_parser_simple_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12997
0x8250cf cp_parser_block_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12815
0x830770 cp_parser_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12712
0x82f3b4 cp_parser_declaration_seq_opt
        ../../gcc-source-trunk/gcc/cp/parser.c:12588
0x82f6f7 cp_parser_translation_unit
        ../../gcc-source-trunk/gcc/cp/parser.c:4559
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
$


-------------------------------


auto f ();
template < int > auto g (f);
auto h = g < 0 > ();