attempt to accommodate CRAN's lack of cygpath

Author: kevinushey

src/Makevars.in

@@ -9,8 +9,8 @@ ifeq ($(OS), Windows_NT)
   MAKE = make -e
   MAKE_CMD =                                  \
     CYGWIN=nodosfilewarning                   \
-    CONLY="$(shell cygpath -m "@CC@")"        \
-    CPLUS="$(shell cygpath -m "@CXX11@")"     \
+    CONLY="@WINDOWS_CC@"                      \
+    CPLUS="@WINDOWS_CXX11@"                   \
     CXXFLAGS="@CXX11FLAGS@ -DTBB_NO_LEGACY=1" \
     PIC_KEY="@CXX11PICFLAGS@"                 \
     WARNING_SUPPRESS=""                       \

tools/config/configure.R

@@ -54,6 +54,19 @@ switch(
    stop("Failed to infer C / C++ compilation flags")
 )
 
+# define special flags for Windows
+db <- configure_database()
+if (Sys.info()[["sysname"]] == "Windows") {
+   
+   cygpath <- nzchar(Sys.which("cygpath"))
+   fmt <- if (cygpath) "$(shell cygpath -m \"%s\")" else "%s"
+   define(
+      WINDOWS_CC    = sprintf(fmt, db$CC),
+      WINDOWS_CXX11 = sprintf(fmt, db$CXX11)
+   )
+
+}
+
 # use c++0x for compatibility with older compilers
 define(STDVER = "c++0x")