All 4.8.x and later ICE, but not 4.7.x.  

The code is correctly accepted by Clang. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto --prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.1 20170203 (experimental) [trunk revision 245148] (GCC) 
$ 
$ clang++ -c -std=c++11 small.cpp
$ 
$ g++-trunk -c -std=c++11 small.cpp
small.cpp: In lambda function:
small.cpp:6:5: error: Local declaration from a different function
   [&] { decltype (b) c; } ();
     ^
D.2056
small.cpp:6:22: note: in statement
   [&] { decltype (b) c; } ();
                      ^
_1 = (sizetype) D.2056;
small.cpp:6:5: error: Local declaration from a different function
   [&] { decltype (b) c; } ();
     ^
D.2056
small.cpp:6:22: note: in statement
   [&] { decltype (b) c; } ();
                      ^
_5 = (sizetype) D.2056;
small.cpp:6:5: internal compiler error: verify_gimple failed
   [&] { decltype (b) c; } ();
     ^
0xe5e15d verify_gimple_in_cfg(function*, bool)
	../../gcc-source-trunk/gcc/tree-cfg.c:5266
0xd3ac27 execute_function_todo
	../../gcc-source-trunk/gcc/passes.c:1966
0xd3b595 execute_todo
	../../gcc-source-trunk/gcc/passes.c:2016
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.
$ 


-----------------------------------


int a = 1;

void foo ()
{
  int b[a];
  [&] { decltype (b) c; } ();
}