RunSingleCommand: Add a OUTPUT_NORMAL flag.

OUTPUT_NORMAL does no processing of the output streams, it just passes
them through the same streams as they were received on.

Source/cmSystemTools.cxx

@@ -247,6 +247,12 @@ void cmSystemTools::Stdout(const char* s)
     }
 }
 
+void cmSystemTools::Stderr(const char* s, int length)
+{
+    std::cerr.write(s, length);
+    std::cerr.flush();
+}
+
 void cmSystemTools::Stdout(const char* s, int length)
 {
   if(s_StdoutCallback)
@@ -630,7 +636,21 @@ bool cmSystemTools::RunSingleCommand(std::vector<cmStdString>const& command,
         }
       if(outputflag != OUTPUT_NONE)
         {
-        cmSystemTools::Stdout(data, length);
+        if(outputflag == OUTPUT_MERGE)
+          {
+          cmSystemTools::Stdout(data, length);
+          }
+        else
+          {
+          if(pipe == cmsysProcess_Pipe_STDERR)
+            {
+            cmSystemTools::Stderr(data, length);
+            }
+          else if(pipe == cmsysProcess_Pipe_STDOUT)
+            {
+            cmSystemTools::Stdout(data, length);
+            }
+          }
         }
       }
     }

Source/cmSystemTools.h

@@ -75,6 +75,9 @@ public:
   typedef  void (*StdoutCallback)(const char*, int length, void*);
   static void SetStdoutCallback(StdoutCallback, void* clientData=0);
 
+  ///! Send a string to stderr. Stdout callbacks will not be invoced.
+  static void Stderr(const char* s, int length);
+
   ///! Return true if there was an error at any point.
   static bool GetErrorOccuredFlag()
     {
@@ -196,7 +199,8 @@ public:
    * Output is controlled with outputflag. If outputflag is OUTPUT_NONE, no
    * user-viewable output from the program being run will be generated.
    * OUTPUT_MERGE is the legacy behaviour where stdout and stderr are merged
-   * into stdout.
+   * into stdout.  OUTPUT_NORMAL passes through the output to stdout/stderr as
+   * it was received.
    *
    * If timeout is specified, the command will be terminated after
    * timeout expires. Timeout is specified in seconds.
@@ -214,7 +218,8 @@ public:
    enum OutputOption
    {
      OUTPUT_NONE = 0,
-     OUTPUT_MERGE
+     OUTPUT_MERGE,
+     OUTPUT_NORMAL
    };
   static bool RunSingleCommand(const char* command, std::string* output = 0,
                                int* retVal = 0, const char* dir = 0,

Source/cmake.cxx

@@ -4296,7 +4296,8 @@ int cmake::Build(const std::string& dir,
                  const std::string& target,
                  const std::string& config,
                  const std::vector<std::string>& nativeOptions,
-                 bool clean)
+                 bool clean,
+                 cmSystemTools::OutputOption outputflag)
 {
   if(!cmSystemTools::FileIsDirectory(dir.c_str()))
     {
@@ -4338,8 +4339,7 @@ int cmake::Build(const std::string& dir,
                     projName.c_str(), target.c_str(),
                     &output,
                     makeProgram.c_str(),
-                    config.c_str(), clean, false, 0,
-                    cmSystemTools::OUTPUT_MERGE,
+                    config.c_str(), clean, false, 0, outputflag,
                     0, nativeOptions);
 }
 

Source/cmake.h

@@ -364,7 +364,8 @@ class cmake
             const std::string& target,
             const std::string& config,
             const std::vector<std::string>& nativeOptions,
-            bool clean);
+            bool clean,
+            cmSystemTools::OutputOption outputflag);
 
   void UnwatchUnusedCli(const char* var);
   void WatchUnusedCli(const char* var);

Source/cmakemain.cxx

@@ -62,6 +62,7 @@ static const char * cmDocumentationDescription[][3] =
   "  --config <cfg> = For multi-configuration tools, choose <cfg>.\n"   \
   "  --clean-first  = Build target 'clean' first, then build.\n"        \
   "                   (To clean only, use --target 'clean'.)\n"         \
+  "  --use-stderr  =  Don't merge stdout/stderr.\n"                     \
   "  --             = Pass remaining options to the native tool.\n"
 
 //----------------------------------------------------------------------------
@@ -568,6 +569,7 @@ static int do_build(int ac, char** av)
   std::string dir;
   std::vector<std::string> nativeOptions;
   bool clean = false;
+  cmSystemTools::OutputOption outputflag = cmSystemTools::OUTPUT_MERGE;
 
   enum Doing { DoingNone, DoingDir, DoingTarget, DoingConfig, DoingNative};
   Doing doing = DoingDir;
@@ -590,6 +592,10 @@ static int do_build(int ac, char** av)
       clean = true;
       doing = DoingNone;
       }
+    else if(strcmp(av[i], "--use-stderr") == 0)
+      {
+        outputflag = cmSystemTools::OUTPUT_NORMAL;
+      }
     else if(strcmp(av[i], "--") == 0)
       {
       doing = DoingNative;
@@ -635,6 +641,6 @@ static int do_build(int ac, char** av)
     }
 
   cmake cm;
-  return cm.Build(dir, target, config, nativeOptions, clean);
+  return cm.Build(dir, target, config, nativeOptions, clean, outputflag);
 #endif
 }