gccgo: internal compiler error in do_get_backend (2)

[dvyukov]

gccgo crashes on the following program:

package a
var _, _ = <-chan int(n)

go1: internal compiler error: in do_get_backend, at go/gofrontend/expressions.cc:3450
0x5e2224 Unsafe_type_conversion_expression::do_get_backend(Translate_context*)
    ../../gcc/go/gofrontend/expressions.cc:3450
0x5fb6ca Call_expression::do_get_backend(Translate_context*)
    ../../gcc/go/gofrontend/expressions.cc:9299
0x64de42 Temporary_statement::do_get_backend(Translate_context*)
    ../../gcc/go/gofrontend/statements.cc:487
0x61c5b7 Block::get_backend(Translate_context*)
    ../../gcc/go/gofrontend/gogo.cc:5862
0x64b65c Block_statement::do_get_backend(Translate_context*)
    ../../gcc/go/gofrontend/statements.cc:1836
0x61c5b7 Block::get_backend(Translate_context*)
    ../../gcc/go/gofrontend/gogo.cc:5862
0x61c763 Variable::get_init_block(Gogo*, Named_object*, Bvariable*)
    ../../gcc/go/gofrontend/gogo.cc:6426
0x624f57 Gogo::write_globals()
    ../../gcc/go/gofrontend/gogo.cc:1418

gofrontend is on commit 81810917af7ba19e1f9f8efc8b1989f7d6419d30

[dvyukov]

@ianlancetaylor

[paranoiacblack]

This is a duplicate of #12320 and the same fix applies.