execute_process: Improve stdout/stderr merging

Use the KWSys Process "MergeOutput" option to give the child process
the same pipe (or file) for both stdout and stderr.  This allows
natural merging of stdout and stderr together instead of merging
on arbitrary buffered read boundaries as before.

1 files changed, 19 insertions, 5 deletions

diff --git a/Source/cmExecuteProcessCommand.cxx b/Source/cmExecuteProcessCommand.cxx
index 1225992..a371390 100644
--- a/Source/cmExecuteProcessCommand.cxx
+++ b/Source/cmExecuteProcessCommand.cxx
@@ -255,7 +255,7 @@ bool cmExecuteProcessCommand
   cmsysProcess_SetOption(cp, cmsysProcess_Option_HideWindow, 1);
 
   // Check the output variables.
-  bool merge_output = (output_variable == error_variable);
+  bool merge_output = false;
   if(!input_file.empty())
     {
     cmsysProcess_SetPipeFile(cp, cmsysProcess_Pipe_STDIN, input_file.c_str());
@@ -267,8 +267,23 @@ bool cmExecuteProcessCommand
     }
   if(!error_file.empty())
     {
-    cmsysProcess_SetPipeFile(cp, cmsysProcess_Pipe_STDERR,
-                             error_file.c_str());
+    if (error_file == output_file)
+      {
+      merge_output = true;
+      }
+    else
+      {
+      cmsysProcess_SetPipeFile(cp, cmsysProcess_Pipe_STDERR,
+                               error_file.c_str());
+      }
+    }
+  if (!output_variable.empty() && output_variable == error_variable)
+    {
+    merge_output = true;
+    }
+  if (merge_output)
+    {
+    cmsysProcess_SetOption(cp, cmsysProcess_Option_MergeOutput, 1);
     }
 
   // Set the timeout if any.
@@ -289,8 +304,7 @@ bool cmExecuteProcessCommand
   while((p = cmsysProcess_WaitForData(cp, &data, &length, 0), p))
     {
     // Put the output in the right place.
-    if((p == cmsysProcess_Pipe_STDOUT && !output_quiet) ||
-       (p == cmsysProcess_Pipe_STDERR && !error_quiet && merge_output))
+    if (p == cmsysProcess_Pipe_STDOUT && !output_quiet)
       {
       if(output_variable.empty())
         {