Add %td check to CRAN_Release

Author: MichaelChirico

.dev/CRAN_Release.cmd

@@ -95,16 +95,18 @@ grep "PROTECT_PTR" ./src/*.c
 # No use of long long, instead use int64_t. TODO
 # grep "long long" ./src/*.c
 
-// No use of llu, lld, zd or zu
-grep -nE "(llu|lld|zd|zu)" src/*.[hc]
+// No use of llu, lld, td or tu
+grep -nE "%(ll|t)[ud]\b" src/*.[hc]
 // Comment moved here from fread.c on 19 Nov 2019
 // [Moved from fread.c on 19 Nov 2019] On Windows variables of type `size_t` cannot be printed
-// with "%zu" in the `snprintf()` function. For those variables we used to cast them into
-// `unsigned long long int` before printing, and defined (llu) to make the cast shorter.
-// We're now observing warnings from gcc-8 with -Wformat-extra-args, #4062. So
-// now we're more strict and cast to [u]int64_t and use PRIu64/PRId64 from <inttypes.h>
-// In many cases the format specifier is passed to our own macro (e.g. DTPRINT) or to Rprintf(),
-// error() etc, and even if they don't call sprintf() now, they could in future.
+//   with "%zu" in the `snprintf()` function. For those variables we used to cast them into
+//   `unsigned long long int` before printing, and defined (llu) to make the cast shorter.
+//   We're now observing warnings from gcc-8 with -Wformat-extra-args, #4062. So
+//   now we're more strict and cast to [u]int64_t and use PRIu64/PRId64 from <inttypes.h>
+//   In many cases the format specifier is passed to our own macro (e.g. DTPRINT) or to Rprintf(),
+//   error() etc, and even if they don't call sprintf() now, they could in future.
+// td is for ptrdiff_t from C99; it's not available in old versions of Rtools (e.g. for R<4.2.0),
+//   see https://github.com/Rdatatable/data.table/pull/6970#issuecomment-2877636459.
 
 # No tabs in C or R code (sorry, Richard Hendricks)
 grep -P "\t" ./R/*.R