[Rd] [SPAM Warning!] Suggestion to emphasize Rboolean is unrelated to LGLSXP in R-exts

[Ivan Krylov]

On Thu, 30 Jan 2025 13:07:31 -0800
Michael Chirico <michaelchirico4 using gmail.com> wrote:

> There are at least dozens of other cases on CRAN [2],[3].

Some of these involve casting an int to Rboolean. Best case, the int is
compared against NA_LOGICAL beforehand, avoiding any mistake (there's
at least one like that). Worst case, NA_LOGICAL is not considered before
the cast, so NA will now be interpreted as TRUE. This is hard to check
without actually reading the code.

Some packages compare an Rboolean expression against NA_LOGICAL [1].
This implies having stored an int in an Rboolean value as in the
previous paragraph. I think that it wasn't disallowed according to the
C standard to store NA_LOGICAL in an enumeration type wide enough to
fit it (and it evidently worked in practice). With typedef bool
Rboolean, storing NA_LOGICAL in an Rboolean converts it to 'true', so
the comparison will definitely fail:

DPQ src/pnchisq-it.c:530,532
Rmpfr src/convert.c:535
checkmate src/helper.c:102
chron src/unpaste.c:21
collapse src/data.table_rbindlist.c:208,258,383,384,408,431
data.table (many; fixed in Git)
ff src/ordermerge.c:5074 (one declaration, many comparisons)
networkDynamic src/Rinit.c:209 src/is.active.c:75,76,96-98
slam src/util.c:258
this.path src/get_file_from_closure.h:13,43 src/thispath.c:14,17,19,39
 src/ext.c:25 src/setsyspath.c:8 src/get_file_from_closure.h:13,43

Four packages cast int* pointers returned by LOGICAL() to Rboolean* or
use sizeof(Rboolean) to calculate buffer sizes in calls to memcpy()
with LOGICAL() buffers [2]. With typedef bool Rboolean, this is a
serious mistake, because the memory layout of the types is no longer
compatible:

bit64 src/integer64.c:576,603,914,929,942,955,968,981,994
collapse src/data.table_rbindlist.c:19,67,105
data.table (many; fixed in Git)
kit src/utils.c:390

I don't know Coccinelle that well and there may be additional cases I
failed to consider. At which point is it appropriate to start notifying
maintainers of the bugs not caught by their test suites?

-- 
Best regards,
Ivan

[1] Coccinelle script:
@@
typedef Rboolean;
Rboolean E;
@@
* E == NA_LOGICAL

[2] Coccinelle scripts:

@@
typedef Rboolean;
int* E;
@@
* (Rboolean*)E

This one will offer a diff to fix the bug:

@@
int *E1;
int *E2;
typedef Rboolean;
@@
(
 memcpy
|
 memmove
)
 (E1, E2,
 <+...
-sizeof(Rboolean)
+sizeof(int)
 ...+>
 )