The following code...

import std.stdio;

immutable char c = void; 

void main()
{
   writeln(c);
}

.. causes GDC to ICE:

internal compiler error: in gimplify_init_constructor, at gimplify.c:4269
0x7b3be3 gimplify_init_constructor
	../../gcc-4.8.2/gcc/gimplify.c:4269
0x7b445b gimplify_modify_expr_rhs
	../../gcc-4.8.2/gcc/gimplify.c:4468
0x7b47af gimplify_modify_expr
	../../gcc-4.8.2/gcc/gimplify.c:4861
0x7af1ab gimplify_expr(tree_node**, gimple_statement_d**, gimple_statement_d**, bool (*)(tree_node*), int)
	../../gcc-4.8.2/gcc/gimplify.c:7193
0x7b0f86 gimplify_stmt(tree_node**, gimple_statement_d**)
	../../gcc-4.8.2/gcc/gimplify.c:5725
0x7b1d25 gimplify_and_add
	../../gcc-4.8.2/gcc/gimplify.c:370
0x7b1d25 internal_get_tmp_var
	../../gcc-4.8.2/gcc/gimplify.c:636
0x7ae668 gimplify_expr(tree_node**, gimple_statement_d**, gimple_statement_d**, bool (*)(tree_node*), int)
	../../gcc-4.8.2/gcc/gimplify.c:8023
0x7b329b gimplify_call_expr
	../../gcc-4.8.2/gcc/gimplify.c:2669
0x7aec6d gimplify_expr(tree_node**, gimple_statement_d**, gimple_statement_d**, bool (*)(tree_node*), int)
	../../gcc-4.8.2/gcc/gimplify.c:7164
0x7b0f86 gimplify_stmt(tree_node**, gimple_statement_d**)
	../../gcc-4.8.2/gcc/gimplify.c:5725
0x7aedbb gimplify_statement_list
	../../gcc-4.8.2/gcc/gimplify.c:1561
0x7aedbb gimplify_expr(tree_node**, gimple_statement_d**, gimple_statement_d**, bool (*)(tree_node*), int)
	../../gcc-4.8.2/gcc/gimplify.c:7582
0x7b0f86 gimplify_stmt(tree_node**, gimple_statement_d**)
	../../gcc-4.8.2/gcc/gimplify.c:5725
0x7b1652 gimplify_bind_expr
	../../gcc-4.8.2/gcc/gimplify.c:1253
0x7aec4a gimplify_expr(tree_node**, gimple_statement_d**, gimple_statement_d**, bool (*)(tree_node*), int)
	../../gcc-4.8.2/gcc/gimplify.c:7364
0x7b0f86 gimplify_stmt(tree_node**, gimple_statement_d**)
	../../gcc-4.8.2/gcc/gimplify.c:5725
0x7aedbb gimplify_statement_list
	../../gcc-4.8.2/gcc/gimplify.c:1561
0x7aedbb gimplify_expr(tree_node**, gimple_statement_d**, gimple_statement_d**, bool (*)(tree_node*), int)
	../../gcc-4.8.2/gcc/gimplify.c:7582
0x7b0f86 gimplify_stmt(tree_node**, gimple_statement_d**)
	../../gcc-4.8.2/gcc/gimplify.c:5725


I was creating use cases to try and figure out what section the compiler puts variables in when I found this bug.  I don't know why anyone would want to do such a thing, but the compiler shouldn't crash.  DMD 2.065 handles it fine.