Public bug reported:
I have just encountered an "internal compiler error" while using gcc-7.
```cpp source code
#include <cstdio>
int main()
{
int N = 100;
int K = 100;
int dp[N][2][K] = {0};
printf("%d\n", dp[0][0][0]);
return 0;
}
```
After executing
g++ test.cc
Output is
test.cc: In function ‘int main()’:
test.cc:7:25: internal compiler error: in make_decl_rtl, at varasm.c:1310
int dp[N][2][K] = {0};
^
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-7/README.Bugs> for instructions.
which is exectly same with these three options: "-std=c++11",
"-std=c++14", "-std=c++17".
With executing
g++ test.cc -std=c++98
the binary is produced normally.
With executing
g++ test.cc -std=c++98 -ansi -pedantic -Wextra -Werror
Output is
test.cc: In function ‘int main()’:
test.cc:7:19: error: ISO C++ forbids variable length array ‘dp’ [-Werror=vla]
int dp[N][2][K] = {0};
^
test.cc:7:19: error: ISO C++ forbids variable length array ‘dp’ [-Werror=vla]
cc1plus: all warnings being treated as errors
which is expected.
According to my observation, this seems to be the issue related to the order of
'N','2','K',
if I write
int dp[N][K][2] = {0};
then everything is fine.
Here is my gcc version (gcc -v):
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
7.5.0-3ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-7
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
BTW, the preprocessed file 'test.ii' can be found in the 'Attachment' in case
you need it.
** Affects: gcc-7 (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "test.ii"
https://bugs.launchpad.net/bugs/1895372/+attachment/5410020/+files/test.ii
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https://bugs.launchpad.net/bugs/1895372
Title:
C++11 with GNU VLA extention results in ICE
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