Traverse bytecode objects

[lionel-]

Would have helped with r-lib/coro#36 where a leak occurred via a cached bytecode object where an environment was included in the constant pool.

f <- compiler::cmpfun(inject(function() {
  !!env(x = sample(1e7))
}))

cpp11::cpp_source(code = "
  #include <Rinternals.h>
  [[cpp11::register]]
  SEXP get_body(SEXP x) {
    return BODY(x);
  }"
)

bcode <- get_body(f)
rlang:::poke_type(bcode, "pairlist")

bcode
#> [[1]]
#> [1]      12       0 8430964       1       1       0 8423560       1
#>
#> .
#>
#> [[1]]
#> {
#>     <environment>
#> }
#>
#> [[2]]
#> <environment: 0x2e2708dc0>
#>
#> [[3]]
#> !!env(x = sample(1e7))
#>
#> [[4]]
#> [1] NA  1  1  1
#> attr(,"class")
#> [1] "expressionsIndex"
#>
#> [[5]]
#> [1] NA  2  2  2
#> attr(,"class")
#> [1] "srcrefsIndex"