Get cc() working on Windows 10

[ColeMiller1]

I have Windows 10 and am trying to use cc(). When I load R and RStudio, I have cc() already sourced:

cc()
*truncated_directory*/data.table_names_SD/src 
NULL

This is the part of cc() that I get stuck on. ret evaluates to 127:

data.table/.dev/cc.R

Lines 62 to 68 in c005296

	if (debug) {
	ret = system(sprintf("MAKEFLAGS='-j CC=%s PKG_CFLAGS=-f%sopenmp CFLAGS=-std=c99\\ -O0\\ -ggdb\\ -pedantic' R CMD SHLIB -d -o datatable.so *.c", CC, OMP))
	} else {
	ret = system(sprintf("MAKEFLAGS='-j CC=%s CFLAGS=-f%sopenmp\\ -std=c99\\ -O3\\ -pipe\\ -Wall\\ -pedantic\\ -fno-common' R CMD SHLIB -o datatable.so *.c", CC, OMP))
	# TODO add -Wextra too?
	}
	if (ret) return()

mingw_64 is downloaded with RBuildTools. I currently compile with these two lines - each c script uses the mingw_64/32 libraries for compilation:

devtools::build(vignettes = FALSE)
install.packages('data.table_1.12.9.tar.gz', repos = NULL, type="source")

C:/RBuildTools/3.5/mingw_64/bin/gcc  -I"C:/PROGRA~1/R/R-36~1.1/include" -DNDEBUG       -fopenmp   -O2 -Wall  -std=gnu99 -mtune=generic -c assign.c -o assign.o

I feel like I need to combine these two lines but am unsure of how to do it.

"MAKEFLAGS='-j CC=gcc CFLAGS=-fopenmp\\ -std=c99\\ -O3\\ -pipe\\ -Wall\\ -pedantic\\ -fno-common' R CMD SHLIB -o datatable.so *.c"

C:/RBuildTools/3.5/mingw_64/bin/gcc  -I"C:/PROGRA~1/R/R-36~1.1/include" -DNDEBUG       -fopenmp   -O2 -Wall  -std=gnu99 -mtune=generic -c assign.c -o assign.o

From #2103, I am curious if @franknarf1 has had luck on Windows with the cc() function.