search for: clear_vector_elt

...nment. The bug relies on `x` not being IS_GROWABLE(), which may explain why a plain x[[4]] <- list() sometimes doesn't fail. The future assignment result `x` is now expression(a, b, c, NULL), and the old `x` set to expression(NULL, NULL, NULL) by SET_VECTOR_ELT(newx, i, VECTOR_ELT(x, i)); CLEAR_VECTOR_ELT(x, i); during EnlargeVector(). 4. But then the assignment fails, raising the error back in do_subassign2_dflt(), because the assignment kind is invalid: there is no way to put data.frames into an expression vector. The new resized `x` is lost, and the old overwritten `x` stays there. Not sure wha...

...on `x` not being IS_GROWABLE(), which may explain > why a plain x[[4]] <- list() sometimes doesn't fail. > > The future assignment result `x` is now expression(a, b, c, NULL), and > the old `x` set to expression(NULL, NULL, NULL) by SET_VECTOR_ELT(newx, > i, VECTOR_ELT(x, i)); CLEAR_VECTOR_ELT(x, i); during EnlargeVector(). > > 4. But then the assignment fails, raising the error back in > do_subassign2_dflt(), because the assignment kind is invalid: there is > no way to put data.frames into an expression vector. The new resized > `x` is lost, and the old overwritten `x` st...

There seems to be a bug in out-of-bounds assignment of list objects to an expression() vector. Tested on release and devel. (Many thanks to folks over at Mastodon for the help narrowing down this bug) When assigning a list into an existing index, it correctly errors on incompatible type, and the expression vector is unchanged: ``` x <- expression(a,b,c) x[[3]] <- list() # Error x #>