add a regression test for fixed dcast fun.aggregate issue

NEWS.md

@@ -135,6 +135,8 @@
 
 4. `cube(DT, by="a")` now gives a more helpful error that `j` is missing, [#4282](https://github.com/Rdatatable/data.table/pull/4282).
 
+5. v1.13.0 (July 2020) fixed a segfault/corruption/error (depending on version of R and circumstances) in `dcast()` when `fun.aggregate` returned `NA` (type `logical`) in an otherwise `character` result, [#2394](https://github.com/Rdatatable/data.table/issues/2394). This fix was the result of other internal rework and there was no news item at the time. A new test to cover this case has now been added. Thanks Vadim Khotilovich for reporting, and Michael Chirico for investigating, pinpointing when the fix occurred and adding the test.
+
 
 # data.table [v1.14.0](https://github.com/Rdatatable/data.table/milestone/23?closed=1)  (21 Feb 2021)
 
@@ -340,7 +342,6 @@ has a better chance of working on Mac.
 11. `copy()` now overallocates deeply nested lists of `data.table`s, [#4205](https://github.com/Rdatatable/data.table/issues/4205). Thanks to @d-sci for reporting and the PR.
 
 12. `rbindlist` no longer errors when coercing complex vectors to character vectors, [#4202](https://github.com/Rdatatable/data.table/issues/4202). Thanks to @sritchie73 for reporting and the PR.
-
 13. A relatively rare case of segfault when combining non-equi joins with `by=.EACHI` is now fixed, closes [#4388](https://github.com/Rdatatable/data.table/issues/4388).
 
 14. Selecting key columns could incur a large speed penalty, [#4498](https://github.com/Rdatatable/data.table/issues/4498). Thanks to @Jesper on Stack Overflow for the report.
@@ -355,7 +356,7 @@ has a better chance of working on Mac.
 
 19. Matrices resulting from logical operators or comparisons on `data.table`s, e.g. in `dta == dtb`, can no longer have their colnames changed by reference later, [#4323](https://github.com/Rdatatable/data.table/issues/4323). Thanks to @eyherabh for reporting and @tlapak for the PR.
 
-20. The environment variable `R_DATATABLE_NUM_THREADS` was being limited by `R_DATATABLE_NUM_PROCS_PERCENT` (by default 50%), [#4514](https://github.com/Rdatatable/data.table/issues/4514). It is now consistent with `setDTthreads()` and only limited by the full number of logical CPUs. For example, on a machine with 8 logical CPUs, `R_DATATABLE_NUM_THREADS=6` now results in 6 threads rather than 4 (50% of 8).
+20. The environment variable `R_DATATABLE_NUM_THREADS` was being limited by `R_DATATABLE_NUM_PROCS_PERCENT` (by default 50%), [#4514](https://github.com/Rdatatable/data.table/issues/4514). It is now consistent with `setDTthreads()` and only limited by the full number of logical CPUs. For example, on a machine with 8 logical CPUs, `R_DATATABLE_NUM_THREADS=6` now results in 6 threads rather than 4 (50% of 8).r
 
 ## NOTES
 

inst/tests/tests.Rraw

@@ -17577,3 +17577,10 @@ vr = "Species"
 IDT[, virginca := get(vr) == "virginica"]
 ans = data.table(round = c(3, 3, 3, 2, 2, 4, 2, 4), k = c(6, 7, 8, 5, 7, 7, 6, 8), kar = structure(c(3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("setosa", "versicolor", "virginica"), class = "factor"), N = c(24L, 14L, 4L, 1L, 1L, 1L, 3L, 2L))
 test(2184.5, IDT[(virginca), .N, by = .(round(Sepal.Width), k = round(Sepal.Length), kar = get(vr))] , ans)
+
+# dcast() segfault or 'STRING_ELT() can only be applied to character not logical' fixed in v1.13.0, #2394
+agg = function(x) if(length(x) > 0) min(x) else NA
+DT = data.table(id=c(1,1,2,2), x=c('y','y','y','z'), v=c('a','b','c','d'))
+test(2185, dcast(DT, formula=id~x, fun.aggregate=agg, value.var='v'),
+           data.table(id=c(1,2), y=c('a','c'), z=c(NA,'d'), key="id"))
+