[Bug c++/71814] New: ICE on valid C++11 code: in write_type, at cp/mangle.c:2158

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71814

            Bug ID: 71814
           Summary: ICE on valid C++11 code: in write_type, at
                    cp/mangle.c:2158
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following C++11 code causes an ICE when compiled with the current GCC trunk
on x86_64-linux-gnu in both 32-bit and 64-bit modes.  

It also affects 6.1.x and is a regression from 5.4.x. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160707 (experimental) [trunk revision 238117] (GCC)
$
$ g++-5.4 -std=c++11 -c small.cpp
$ clang++-3.8 -std=c++11 -c small.cpp
$
$ g++-trunk -std=c++11 -c small.cpp
small.cpp: In instantiation of ‘void foo(int (&)[sizeof (int, U ..., int,
typename U::type ...)]) [with U = {A<int>, A<float>}; TN<int, U ..., int,
typename U::type ...> = int [6]]’:
small.cpp:8:57:   required from here
small.cpp:6:6: internal compiler error: in write_type, at cp/mangle.c:2158
 void foo (TN < int, U ..., int, typename U::type ... >&) {}
      ^~~
0x861088 write_type
        ../../gcc-source-trunk/gcc/cp/mangle.c:2158
0x8622aa write_array_type
        ../../gcc-source-trunk/gcc/cp/mangle.c:3319
0x8622aa write_type
        ../../gcc-source-trunk/gcc/cp/mangle.c:1935
0x861411 write_type
        ../../gcc-source-trunk/gcc/cp/mangle.c:2082
0x8639d7 write_method_parms
        ../../gcc-source-trunk/gcc/cp/mangle.c:2602
0x863d70 write_bare_function_type
        ../../gcc-source-trunk/gcc/cp/mangle.c:2544
0x865f25 mangle_decl_string
        ../../gcc-source-trunk/gcc/cp/mangle.c:3515
0x866078 get_mangled_id
        ../../gcc-source-trunk/gcc/cp/mangle.c:3537
0x866348 mangle_decl(tree_node*)
        ../../gcc-source-trunk/gcc/cp/mangle.c:3607
0x10605b0 decl_assembler_name(tree_node*)
        ../../gcc-source-trunk/gcc/tree.c:669
0x10b1d68 notice_global_symbol(tree_node*)
        ../../gcc-source-trunk/gcc/varasm.c:1654
0x9c2149 cgraph_node::finalize_function(tree_node*, bool)
        ../../gcc-source-trunk/gcc/cgraphunit.c:426
0x81a96f expand_or_defer_fn(tree_node*)
        ../../gcc-source-trunk/gcc/cp/semantics.c:4223
0x6d4c1a instantiate_decl(tree_node*, int, bool)
        ../../gcc-source-trunk/gcc/cp/pt.c:22118
0x721842 instantiate_pending_templates(int)
        ../../gcc-source-trunk/gcc/cp/pt.c:22214
0x764975 c_parse_final_cleanups()
        ../../gcc-source-trunk/gcc/cp/decl2.c:4600
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.


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


template < typename > struct A {  using type = int;  };

template < typename ... T > using TN = int[sizeof ... (T)];

template < typename ... U >
void foo (TN < int, U ..., int, typename U::type ... >&) {}

template void foo < A < int >, A < float > > (int (&)[6]);