[Bug 1924219] Re: internal compiler error on certain variably sized 3d arrays

[Matthias Klose]

fixed in GCC 11 and newer versions

** Changed in: gcc-10 (Ubuntu)
       Status: New => Fix Released

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Title:
  internal compiler error on certain variably sized 3d arrays

Status in gcc-10 package in Ubuntu:
  Fix Released

Bug description:
  WSL2:
  Ubuntu 20.04.2 LTS (GNU/Linux 5.4.72-microsoft-standard-WSL2 x86_64)

  $ lsb_release -rd
  Description:    Ubuntu 20.04.2 LTS
  Release:        20.04

  $ apt-cache policy gcc-10
  gcc-10:
    Installed: 10.2.0-5ubuntu1~20.04
    Candidate: 10.2.0-5ubuntu1~20.04
    Version table:
   *** 10.2.0-5ubuntu1~20.04 500
          500 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages
          500 http://security.ubuntu.com/ubuntu focal-security/universe amd64 Packages
          100 /var/lib/dpkg/status
       10-20200411-0ubuntu1 500
          500 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages

  $ g++-10 -v
  COLLECT_GCC=g++-10
  COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper
  OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa
  OFFLOAD_TARGET_DEFAULT=1
  Target: x86_64-linux-gnu
  Configured with: ../src/configure -v --with-pkgversion='Ubuntu 10.2.0-5ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --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-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --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=/build/gcc-10-WJNXnb/gcc-10-10.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-10-WJNXnb/gcc-10-10.2.0/debian/tmp-gcn/usr,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
  Thread model: posix
  Supported LTO compression algorithms: zlib zstd
  gcc version 10.2.0 (Ubuntu 10.2.0-5ubuntu1~20.04)

  $ cat main.cpp
  int main() {
  	int n;
  	bool arr[3][n][n] {};
  	if(arr[0][0][0]) {
  	    // don't optimize this out
  	    return 1;
  	}
  }

  $ g++-10 main.cpp
  during RTL pass: expand
  main.cpp: In function ‘int main()’:
  main.cpp:3:7: internal compiler error: in make_decl_rtl, at varasm.c:1342
      3 |  bool arr[3][n][n] {};
        |       ^~~
  Please submit a full bug report,
  with preprocessed source if appropriate.
  See <file:///usr/share/doc/gcc-10/README.Bugs> for instructions.

  The type of arr can be any primitive (could possibly include more
  types, didn't check). arr must be initialized with brackets. At least
  one of the first two dimensions of arr must be a constant, while the
  last dimension must be of variable length. I've repeated this behavior
  with versions 5.1.0, 6.4.0, 7.3.0, 9.2.0 on online compilers.

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