https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93400
Bug ID: 93400
Summary: [10 Regression] ICE: in tsubst, at cp/pt.c:15142 on
friends with concepts
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gcc-bugs at marehr dot dialup.fu-berlin.de
Target Milestone: ---
The following code ICEs on a recent gcc-10 build, but worked in gcc 9 and
below:
```
template <typename> bool a = true;
template <typename i> concept b = a<i>;
template <int> struct f { template <b c> friend auto g(c, f); };
auto d = f<1>{};
auto e = f<0>{};
```
https://godbolt.org/z/A5xXyR
With the following error:
```
> g++-git -std=c++2a -c ice.cpp // and -std=c++17 -fconcepts
ice.cpp: In instantiation of ‘struct f<0>’:
ice.cpp:5:15: required from here
ice.cpp:3:54: internal compiler error: in tsubst, at cp/pt.c:15142
3 | template <int> struct f { template <b c> friend auto g(c, f); };
| ^
0x602fb4 tsubst(tree_node*, tree_node*, int, tree_node*)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:15142
0x7723f5 tsubst_template_args(tree_node*, tree_node*, int, tree_node*)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:13125
0x76a73c tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:19022
0x7630c4 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:18955
0x7630c4 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:18590
0x6825f6 tsubst_constraint(tree_node*, tree_node*, int, tree_node*)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/constraint.cc:2349
0x781d6f tsubst_friend_function
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:10846
0x781d6f instantiate_class_template_1
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:11975
0x7823e2 instantiate_class_template(tree_node*)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/pt.c:12040
0x7b242d complete_type(tree_node*)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/typeck.c:137
0x7b242d complete_type(tree_node*)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/typeck.c:111
0x790cb9 finish_compound_literal(tree_node*, tree_node*, int, fcl_t)
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/semantics.c:2929
0x71cf1d cp_parser_functional_cast
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:29405
0x734044 cp_parser_postfix_expression
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:7134
0x718aca cp_parser_binary_expression
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:9508
0x71a12c cp_parser_assignment_expression
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:9813
0x71927d cp_parser_constant_expression
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:10107
0x7197e1 cp_parser_initializer_clause
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:23108
0x71d04f cp_parser_initializer
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:23046
0x742b94 cp_parser_init_declarator
/home/marehr/Packages/gcc-git/src/gcc/gcc/cp/parser.c:20752
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://bugs.archlinux.org/> for instructions.
```
gcc version being:
```
g++-git -v
Using built-in specs.
COLLECT_GCC=g++-git
COLLECT_LTO_WRAPPER=/opt/gcc/gcc-git/bin/../lib/gcc/x86_64-pc-linux-gnu/10.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/marehr/Packages/gcc-git/src/gcc/configure --prefix=/usr
--libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++ --enable-shared --enable-threads=posix
--with-system-zlib --with-isl --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-lto --enable-plugin --enable-install-libiberty
--with-linker-hash-style=gnu --enable-gnu-indirect-function --enable-multilib
--disable-werror --enable-checking=release --enable-default-pie
--enable-default-ssp --enable-cet=auto --disable-boostrap
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.0.1 20200123 (experimental) (GCC)
```
