gccgo: internal compiler error in Builtin_call_expression

[dvyukov]

package a
var a = (complex^0)(0

go1: internal compiler error: in Builtin_call_expression, at go/gofrontend/expressions.cc:6630
0x5e7c03 Builtin_call_expression::Builtin_call_expression(Gogo*, Expression*, Expression_list*, bool, Location)
    ../../gcc/go/gofrontend/expressions.cc:6630
0x5f9798 Call_expression::do_lower(Gogo*, Named_object*, Statement_inserter*, int)
    ../../gcc/go/gofrontend/expressions.cc:8600
0x6109ae Expression::lower(Gogo*, Named_object*, Statement_inserter*, int)
    ../../gcc/go/gofrontend/expressions.h:791
0x6109ae Lower_parse_tree::expression(Expression**)
    ../../gcc/go/gofrontend/gogo.cc:2740
0x61255e Gogo::lower_expression(Named_object*, Statement_inserter*, Expression**)
    ../../gcc/go/gofrontend/gogo.cc:2779
0x61bf5c Variable::lower_init_expression(Gogo*, Named_object*, Statement_inserter*)
    ../../gcc/go/gofrontend/gogo.cc:5985
0x61bfac Lower_parse_tree::variable(Named_object*)
    ../../gcc/go/gofrontend/gogo.cc:2609
0x6169e9 Bindings::traverse(Traverse*, bool)
    ../../gcc/go/gofrontend/gogo.cc:7493
0x616b71 Gogo::traverse(Traverse*)
    ../../gcc/go/gofrontend/gogo.cc:2491
0x616f97 Gogo::lower_parse_tree()
    ../../gcc/go/gofrontend/gogo.cc:2757
0x61052c go_parse_input_files(char const**, unsigned int, bool, bool)
    ../../gcc/go/gofrontend/go.cc:95
0x60c32f go_langhook_parse_file
    ../../gcc/go/go-lang.c:304

gcc version 6.0.0 2015070 (experimental) (GCC)

[dvyukov]

@paranoiacblack

[gopherbot]

CL https://golang.org/cl/13893 mentions this issue.