rust-bindgen: Incorrect layout with large bitfield

Looks like g++ agrees with clang++ on a size of 80:

$ cat big-bitfield.cpp 
struct HasBigBitfield {
    unsigned : 632;
};

int f(HasBigBitfield*);

int main() {
    HasBigBitfield b;
    return f(&b);
}
$ g++ -g -c big-bitfield.cpp -o big-bitfield.o
big-bitfield.cpp:2:16: warning: width of ‘HasBigBitfield::<anonymous>’ exceeds its type
     unsigned : 632;
                ^~~
$ dwarfdump big-bitfield.o
...
< 1><0x0000002d>    DW_TAG_structure_type
                      DW_AT_name                  HasBigBitfield
                      DW_AT_byte_size             0x00000050
                      DW_AT_decl_file             0x00000001 /home/fitzgen/scratch/big-bitfield.cpp
                      DW_AT_decl_line             0x00000001
...
$