[LyX/master] Fix CAS input on windows (bug 10262)

[Georg Baum]

commit 6dfc255088ecd3393c4c5dc3d2c5357a3fbabfc0
Author: Georg Baum <b...@lyx.org>
Date:   Sat Jul 2 18:58:30 2016 +0200

    Fix CAS input on windows (bug 10262)
    
    This is the well known file locking problem: The TempFile class keeps the
    created file locked for the own process, and this prevents the CAS to read 
it.
---
 src/mathed/MathExtern.cpp |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/mathed/MathExtern.cpp b/src/mathed/MathExtern.cpp
index b3443fa..8b1e0f0 100644
--- a/src/mathed/MathExtern.cpp
+++ b/src/mathed/MathExtern.cpp
@@ -1001,8 +1001,13 @@ namespace {
        {
                // In order to avoid parsing problems with command interpreters
                // we pass input data through a file
-               TempFile tempfile("casinput");
-               FileName const cas_tmpfile = tempfile.name();
+               // Since the CAS is supposed to read the temp file we need
+               // to unlock it on windows (bug 10262).
+               unique_ptr<TempFile> tempfile(new TempFile("casinput"));
+               tempfile->setAutoRemove(false);
+               FileName const cas_tmpfile = tempfile->name();
+               tempfile.reset();
+
                if (cas_tmpfile.empty()) {
                        lyxerr << "Warning: cannot create temporary file."
                               << endl;