https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92625
Bug ID: 92625
Summary: Internal compiler error accessing element in static
constexpr char array in template class using alias
Product: gcc
Version: 9.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: haoranni at terpmail dot umd.edu
Target Milestone: ---
The internal compiler error can be reproduced by the following minimal example
that I was able to boil down to.
//------ te.cpp
template< typename T >
struct G {
using my_int = char;
static constexpr my_int my_array[1] {0};
};
void work() {
G<double>::my_array[0];
}
//------ end
Compiling command:
g++ -std=c++17 -c -o te.o -save-temps te.cpp
My GCC information (from g++ -v):
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/afs/glue.umd.edu/software/gcc/9.1.0/sys/bin/../libexec/gcc/x86_64-pc-linux-gnu/9.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../src/configure
--prefix=/cell_root/software/gcc/9.1.0/sys --enable-languages=c,c++,fortran
--with-gmp=/usr/local/gmp --with-isl=/usr/local/isl --with-mpfr=/usr/local/mpfr
--with-mpc=/usr/local/mpc --with-as=/usr/local/binutils/2.26/bin/as
--with-ld=/usr/local/binutils/2.26/bin/ld
Thread model: posix
gcc version 9.1.0 (GCC)
My OS information:
Red Hat Enterprise Linux Server release 6.10 (Santiago)
Compiler output:
//------ start output
te.cpp: In instantiation of 'constexpr const my_int G<double>::my_array [1]':
te.cpp:11:16: required from here
te.cpp:6:29: internal compiler error: in tsubst_copy, at cp/pt.c:16155
6 | static constexpr my_int my_array[1] {0};
| ^~~~~~~~
0x593dca tsubst_copy
../../src/gcc/cp/pt.c:16155
0x6c8770 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../src/gcc/cp/pt.c:19611
0x6d0284 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../src/gcc/cp/pt.c:18241
0x6d0284 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
../../src/gcc/cp/pt.c:17917
0x6d260c tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
../../src/gcc/cp/pt.c:15482
0x6d260c tsubst_init
../../src/gcc/cp/pt.c:15486
0x6ce322 regenerate_decl_from_template
../../src/gcc/cp/pt.c:24155
0x6ce322 instantiate_decl(tree_node*, bool, bool)
../../src/gcc/cp/pt.c:24699
0x63be13 maybe_instantiate_decl
../../src/gcc/cp/decl2.c:5300
0x63be13 maybe_instantiate_decl
../../src/gcc/cp/decl2.c:5284
0x63d958 mark_used(tree_node*, int)
../../src/gcc/cp/decl2.c:5456
0x6fa5af finish_id_expression_1
../../src/gcc/cp/semantics.c:3777
0x6fa5af finish_id_expression(tree_node*, tree_node*, tree_node*, cp_id_kind*,
bool, bool, bool*, bool, bool, bool, bool, char const**, unsigned int)
../../src/gcc/cp/semantics.c:3925
0x6980f9 cp_parser_primary_expression
../../src/gcc/cp/parser.c:5723
0x69becb cp_parser_postfix_expression
../../src/gcc/cp/parser.c:7178
0x6a89f9 cp_parser_unary_expression
../../src/gcc/cp/parser.c:8472
0x68696f cp_parser_cast_expression
../../src/gcc/cp/parser.c:9357
0x68715a cp_parser_binary_expression
../../src/gcc/cp/parser.c:9460
0x687ef7 cp_parser_assignment_expression
../../src/gcc/cp/parser.c:9758
0x68821a cp_parser_expression
../../src/gcc/cp/parser.c:9925
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.
//------ end
More information and tests:
In the original code, doing any of the following removes the internal error.
1. remove the template and make "G" a normal struct;
2. use "char" directly instead of "my_int" in the array definition;
3. replace "char" with "int" in the alias declaration;
4. remove the usage of the array in the work() function.
Moreover, I am able to reproduce the same error on a completely different
version and OS and the info is as follows.
//------ start another environment
$> g++ -v
Using built-in specs.
COLLECT_GCC=g++-9
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/9.2.0_1/libexec/gcc/x86_64-apple-darwin18/9.2.0/lto-wrapper
Target: x86_64-apple-darwin18
Configured with: ../configure --build=x86_64-apple-darwin18
--prefix=/usr/local/Cellar/gcc/9.2.0_1
--libdir=/usr/local/Cellar/gcc/9.2.0_1/lib/gcc/9 --disable-nls
--enable-checking=release --enable-languages=c,c++,objc,obj-c++,fortran
--program-suffix=-9 --with-gmp=/usr/local/opt/gmp
--with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc
--with-isl=/usr/local/opt/isl --with-system-zlib --with-pkgversion='Homebrew
GCC 9.2.0_1' --with-bugurl=https://github.com/Homebrew/homebrew-core/issues
--disable-multilib --with-native-system-header-dir=/usr/include
--with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
Thread model: posix
gcc version 9.2.0 (Homebrew GCC 9.2.0_1)
//------ end
