gccgo: internal compiler error in do_flatten (2)

[dvyukov]

gccgo crashes on the following program:

package a
var e, v = 0, complex(e, v)

go1: internal compiler error: in do_flatten, at go/gofrontend/expressions.cc:6828
0x5eb26c Builtin_call_expression::do_flatten(Gogo*, Named_object*, Statement_inserter*)
    ../../gcc/go/gofrontend/expressions.cc:6828
0x60f3e3 Expression::flatten(Gogo*, Named_object*, Statement_inserter*)
    ../../gcc/go/gofrontend/expressions.h:813
0x60f3e3 Flatten::expression(Expression**)
    ../../gcc/go/gofrontend/gogo.cc:3899
0x611076 Gogo::flatten_expression(Named_object*, Statement_inserter*, Expression**)
    ../../gcc/go/gofrontend/gogo.cc:3926
0x61ea90 Variable::flatten_init_expression(Gogo*, Named_object*, Statement_inserter*)
    ../../gcc/go/gofrontend/gogo.cc:6071
0x61eb6b Flatten::variable(Named_object*)
    ../../gcc/go/gofrontend/gogo.cc:3815
0x615439 Bindings::traverse(Traverse*, bool)
    ../../gcc/go/gofrontend/gogo.cc:7538
0x6155c1 Gogo::traverse(Traverse*)
    ../../gcc/go/gofrontend/gogo.cc:2491
0x61581f Gogo::flatten()
    ../../gcc/go/gofrontend/gogo.cc:3933
0x60efab go_parse_input_files(char const**, unsigned int, bool, bool)
    ../../gcc/go/gofrontend/go.cc:139
0x60accf go_langhook_parse_file
    ../../gcc/go/go-lang.c:304

gofrontend is on commit 81810917af7ba19e1f9f8efc8b1989f7d6419d30

[dvyukov]

@ianlancetaylor

[gopherbot]

CL https://golang.org/cl/13931 mentions this issue.