Fix slash escaping in cwrapper.c

Summary: Escape `\` in paths on Windows in `cwapper.c` when we re-output the paths.

Test Plan: ./validate

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #13666

Differential Revision: https://phabricator.haskell.org/D3628

1 files changed, 1 insertions, 1 deletions

diff --git a/driver/utils/cwrapper.c b/driver/utils/cwrapper.c
index da6cec4bc3..5a30274ba7 100644
--- a/driver/utils/cwrapper.c
+++ b/driver/utils/cwrapper.c
@@ -59,7 +59,7 @@ char *flattenAndQuoteArgs(char *ptr, int argc, char *argv[])
         *ptr++ = '"';
         src = argv[i];
         while(*src) {
-            if (*src == '"') {
+            if (*src == '"' || *src == '\\') {
                 *ptr++ = '\\';
             }
             *ptr++ = *src++;