mention compatibility implications of wxExecute() quoting changes; don't change quoting of already quoted arguments in 2.8 for compatibility; also fix handling of empty arguments as a side effect (see #4115)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54695 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -99,6 +99,8 @@ Changes in behaviour not resulting in compilation errors, please read this!
   your code if you overrode these functions and change the functions in the
   derived classes to use const reference as well.
 
+- Under MSW wxExecute() arguments are now always properly quoted, as under
+  Unix, and so shouldn't contain quotes unless they are part of the argument.
 
 Changes in behaviour which may result in compilation errors
 -----------------------------------------------------------

src/msw/utilsexc.cpp

@@ -1032,16 +1032,28 @@ long wxExecuteImpl(CharType **argv, int flags, wxProcess *handler)
     {
         arg = *argv++;
 
-        // escape any quotes present in the string to avoid interfering with
-        // the command line parsing in the child process
-        arg.Replace("\"", "\\\"", true /* replace all */);
+        bool quote;
+        if ( arg.empty() )
+        {
+            // we need to quote empty arguments, otherwise they'd just
+            // disappear
+            quote = true;
+        }
+        else // non-empty
+        {
+            // escape any quotes present in the string to avoid interfering
+            // with the command line parsing in the child process
+            arg.Replace("\"", "\\\"", true /* replace all */);
 
-        // and quote any arguments containing the spaces to prevent them from
-        // being broken down
-        if ( arg.find_first_of(" \t") == wxString::npos )
-            command += arg;
-        else
+            // and quote any arguments containing the spaces to prevent them from
+            // being broken down
+            quote = arg.find_first_of(" \t") != wxString::npos;
+        }
+
+        if ( quote )
             command += '\"' + arg + '\"';
+        else
+            command += arg;
 
         if ( !*argv )
             break;