https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93296
Bug ID: 93296
Summary: Compiler error when assigning array to const reference
with implicit constructor call.
Product: gcc
Version: 9.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: benjamin at readyatdawn dot com
Target Milestone: ---
I'm seeing this error running godbolt.org compiler explorer. I don't have gcc
installed on my PC so I have not attached a preprocessed file, but the bug is
very simple to reproduce. I see the issue with all versions of gcc available on
compiler explorer.
This is the simplest repro I ended up with:
<code>
struct Container {
Container(int (&)[3]) { }
};
int main() {
int data[3];
const Container& container = data;
return 0;
}
</code>
error: invalid initialization of reference of type 'const Container&' from
expression of type 'int*'
A few changes avoid the issue, these both work:
<code>
const Container container = data; // no reference
const Container& container { data }; // explicit construction
</code>
Compiler output with '-v':
Using built-in specs.
COLLECT_GCC=/opt/compiler-explorer/gcc-9.2.0/bin/g++
Target: x86_64-linux-gnu
Configured with: ../gcc-9.2.0/configure
--prefix=/opt/compiler-explorer/gcc-build/staging --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --enable-clocale=gnu --enable-languages=c,c++,fortran,ada,d
--enable-ld=yes --enable-gold=yes --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-linker-build-id --enable-lto
--enable-plugins --enable-threads=posix
--with-pkgversion=Compiler-Explorer-Build
Thread model: posix
gcc version 9.2.0 (Compiler-Explorer-Build)
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' './output.s'
'-masm=intel' '-S' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/opt/compiler-explorer/gcc-9.2.0/bin/../libexec/gcc/x86_64-linux-gnu/9.2.0/cc1plus
-quiet -v -imultiarch x86_64-linux-gnu -iprefix
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/
-D_GNU_SOURCE <source> -quiet -dumpbase example.cpp -masm=intel -mtune=generic
-march=x86-64 -auxbase-strip ./output.s -g -version -fdiagnostics-color=always
-o ./output.s
GNU C++14 (Compiler-Explorer-Build) version 9.2.0 (x86_64-linux-gnu)
compiled by GNU C version 7.4.0, GMP version 6.1.0, MPFR version 3.1.4,
MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../x86_64-linux-gnu/include"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/backward"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/include"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/include-fixed"
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/x86_64-linux-gnu
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/backward
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/include
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/include-fixed
/usr/local/include
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++14 (Compiler-Explorer-Build) version 9.2.0 (x86_64-linux-gnu)
compiled by GNU C version 7.4.0, GMP version 6.1.0, MPFR version 3.1.4,
MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 35bcd684e0bc8b3378dcc1f162909bba
<source>: In function 'int main()':
<source>:7:34: error: invalid initialization of reference of type 'const
Container&' from expression of type 'int*'
7 | const Container& container = data;
| ^~~~
ASM generation compiler returned: 1
Using built-in specs.
COLLECT_GCC=/opt/compiler-explorer/gcc-9.2.0/bin/g++
COLLECT_LTO_WRAPPER=/opt/compiler-explorer/gcc-9.2.0/bin/../libexec/gcc/x86_64-linux-gnu/9.2.0/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../gcc-9.2.0/configure
--prefix=/opt/compiler-explorer/gcc-build/staging --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --enable-clocale=gnu --enable-languages=c,c++,fortran,ada,d
--enable-ld=yes --enable-gold=yes --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-linker-build-id --enable-lto
--enable-plugins --enable-threads=posix
--with-pkgversion=Compiler-Explorer-Build
Thread model: posix
gcc version 9.2.0 (Compiler-Explorer-Build)
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' './output.s' '-v'
'-shared-libgcc' '-mtune=generic' '-march=x86-64'
/opt/compiler-explorer/gcc-9.2.0/bin/../libexec/gcc/x86_64-linux-gnu/9.2.0/cc1plus
-quiet -v -imultiarch x86_64-linux-gnu -iprefix
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/
-D_GNU_SOURCE <source> -quiet -dumpbase example.cpp -mtune=generic
-march=x86-64 -auxbase example -g -version -fdiagnostics-color=always -o
/tmp/cc5PFAVP.s
GNU C++14 (Compiler-Explorer-Build) version 9.2.0 (x86_64-linux-gnu)
compiled by GNU C version 7.4.0, GMP version 6.1.0, MPFR version 3.1.4,
MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../x86_64-linux-gnu/include"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/backward"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/include"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/include-fixed"
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/x86_64-linux-gnu
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/../../../../include/c++/9.2.0/backward
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/include
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/x86_64-linux-gnu/9.2.0/include-fixed
/usr/local/include
/opt/compiler-explorer/gcc-9.2.0/bin/../lib/gcc/../../include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++14 (Compiler-Explorer-Build) version 9.2.0 (x86_64-linux-gnu)
compiled by GNU C version 7.4.0, GMP version 6.1.0, MPFR version 3.1.4,
MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 35bcd684e0bc8b3378dcc1f162909bba
<source>: In function 'int main()':
<source>:7:34: error: invalid initialization of reference of type 'const
Container&' from expression of type 'int*'
7 | const Container& container = data;
| ^~~~
Execution build compiler returned: 1
