avoid extraneous white-space in command

Author: kevinushey

ChangeLog

@@ -1,7 +1,8 @@
 2020-03-31  Dirk Eddelbuettel  <edd@debian.org>
 
 	* docker/ci-dev/Dockerfile: Also install the 'codetools' package
-2020-03-31	Kevin Ushey	<kevin@rstudio.com>
+
+2020-03-31 Kevin Ushey  <kevin@rstudio.com>
 
 	* R/Attributes.R: Fix for sourceCpp() on Windows w/R-devel
 

R/Attributes.R

@@ -134,7 +134,7 @@ sourceCpp <- function(file = "",
         src  <- context$cppSourceFilename
 
         # prepare the command (output if we are in showOutput mode)
-        cmd <- paste(
+        args <- c(
             r, "CMD", "SHLIB",
             if (windowsDebugDLL) "-d",
             if (rebuild) "--preclean",
@@ -145,6 +145,7 @@ sourceCpp <- function(file = "",
             shQuote(src)
         )
 
+        cmd <- paste(args, collapse = " ")
         if (showOutput)
             cat(cmd, "\n")										# #nocov