[Bug c++/78931] New: ICE on C++17 structured bindings from struct with reference member

[gccbugbjorn at fahller dot se]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78931

            Bug ID: 78931
           Summary: ICE on C++17 structured bindings from struct with
                    reference member
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gccbugbjorn at fahller dot se
  Target Milestone: ---

Created attachment 40413
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40413&action=edit
preprocessed t.cpp

GCC 7 snapshot build from svn rev 243933 produces this output for the attached
program:

bjorn@pteranodon /tmp $ LANG=C /opt/gcc-trunk/bin/g++ -std=c++1z t.cpp -v
-save-temps
Using built-in specs.
COLLECT_GCC=/opt/gcc-trunk/bin/g++
COLLECT_LTO_WRAPPER=/opt/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../src/gcc-trunk/configure --prefix=/opt/gcc-trunk
--with-languages=c,cpp : (reconfigured) ../src/gcc-trunk/configure
--prefix=/opt/gcc-trunk --with-languages=c,cpp : (reconfigured)
../src/gcc-trunk/configure --prefix=/opt/gcc-trunk --with-languages=c,cpp
--enable-languages=c,c++,fortran,lto,objc --no-create --no-recursion :
(reconfigured) ../src/gcc-trunk/configure --prefix=/opt/gcc-trunk
--with-languages=c,cpp --enable-languages=c,c++,fortran,lto,objc --no-create
--no-recursion : (reconfigured) ../src/gcc-trunk/configure
--prefix=/opt/gcc-trunk --with-languages=c,cpp
--enable-languages=c,c++,fortran,lto,objc --no-create --no-recursion :
(reconfigured) ../src/gcc-trunk/configure --prefix=/opt/gcc-trunk
--with-languages=c,cpp --enable-languages=c,c++,fortran,lto,objc --no-create
--no-recursion
Thread model: posix
gcc version 7.0.0 20161227 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-std=c++1z' '-v' '-save-temps' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /opt/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/cc1plus -E -quiet -v
-D_GNU_SOURCE t.cpp -mtune=generic -march=x86-64 -std=c++1z -fpch-preprocess -o
t.ii
ignoring nonexistent directory
"/opt/gcc-trunk/lib/gcc/x86_64-pc-linux-gnu/7.0.0/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /opt/gcc-trunk/lib/gcc/x86_64-pc-linux-gnu/7.0.0/../../../../include/c++/7.0.0

/opt/gcc-trunk/lib/gcc/x86_64-pc-linux-gnu/7.0.0/../../../../include/c++/7.0.0/x86_64-pc-linux-gnu

/opt/gcc-trunk/lib/gcc/x86_64-pc-linux-gnu/7.0.0/../../../../include/c++/7.0.0/backward
 /opt/gcc-trunk/lib/gcc/x86_64-pc-linux-gnu/7.0.0/include
 /usr/local/include
 /opt/gcc-trunk/include
 /opt/gcc-trunk/lib/gcc/x86_64-pc-linux-gnu/7.0.0/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-std=c++1z' '-v' '-save-temps' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /opt/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/cc1plus -fpreprocessed
t.ii -quiet -dumpbase t.cpp -mtune=generic -march=x86-64 -auxbase t -std=c++1z
-version -o t.s
GNU C++14 (GCC) version 7.0.0 20161227 (experimental) (x86_64-pc-linux-gnu)
        compiled by GNU C version 7.0.0 20161227 (experimental), GMP version
6.1.0, MPFR version 3.1.3-p4, MPC version 1.0.2, isl version 0.15
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU C++14 (GCC) version 7.0.0 20161227 (experimental) (x86_64-pc-linux-gnu)
        compiled by GNU C version 7.0.0 20161227 (experimental), GMP version
6.1.0, MPFR version 3.1.3-p4, MPC version 1.0.2, isl version 0.15
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: d72b3d35df92f054e2182b3bf4b43893
t.cpp: In function 'int main()':
t.cpp:2:5: error: invalid first operand of MEM_REF
 int main()
     ^~~~
_2
t.cpp:10:10: note: in statement
   return p;
          ^
D.2090 = MEM[(int &)_2];
t.cpp:2:5: internal compiler error: verify_gimple failed
 int main()
     ^~~~
0xdafdef verify_gimple_in_cfg(function*, bool)
        ../../src/gcc-trunk/gcc/tree-cfg.c:5266
0xc93046 execute_function_todo
        ../../src/gcc-trunk/gcc/passes.c:1965
0xc940eb execute_todo
        ../../src/gcc-trunk/gcc/passes.c:2015
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.


Changing the struct to use a value member instead of a reference works fine.