moveconfig: Print a message for missing compiler

A common case for failed builds is a missing compiler. Print a message
for that case to tell the user concisely which compiler was expected
that was not found.

This patch also has the effect of not printing build errors any longer.
The next patch will add a switch to optionally bring that back.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>

tools/moveconfig.py

@@ -573,7 +573,8 @@ class Slot:
             return False
         cmd = list(self.make_cmd)
         cmd.append(defconfig)
-        self.ps = subprocess.Popen(cmd, stdout=self.devnull)
+        self.ps = subprocess.Popen(cmd, stdout=self.devnull,
+                                   stderr=subprocess.PIPE)
         self.defconfig = defconfig
         self.state = STATE_DEFCONFIG
         return True
@@ -598,11 +599,18 @@ class Slot:
             return False
 
         if self.ps.poll() != 0:
-
+            errmsg = 'Failed to process.'
+            errout = self.ps.stderr.read()
+            if errout.find('gcc: command not found') != -1:
+                errmsg = 'Compiler not found ('
+                errmsg += color_text(self.options.color, COLOR_YELLOW,
+                                     self.cross_compile)
+                errmsg += color_text(self.options.color, COLOR_LIGHT_RED,
+                                     ')')
             print >> sys.stderr, log_msg(self.options.color,
                                          COLOR_LIGHT_RED,
                                          self.defconfig,
-                                         "failed to process.")
+                                         errmsg),
             if self.options.exit_on_error:
                 sys.exit("Exit on error.")
             else:
@@ -620,7 +628,7 @@ class Slot:
             cmd = list(self.make_cmd)
             cmd.append('savedefconfig')
             self.ps = subprocess.Popen(cmd, stdout=self.devnull,
-                                       stderr=self.devnull)
+                                       stderr=subprocess.PIPE)
             self.state = STATE_SAVEDEFCONFIG
             return False
 
@@ -631,13 +639,17 @@ class Slot:
             self.state = STATE_IDLE
             return True
 
-        cross_compile = self.parser.get_cross_compile()
+        self.cross_compile = self.parser.get_cross_compile()
         cmd = list(self.make_cmd)
-        if cross_compile:
-            cmd.append('CROSS_COMPILE=%s' % cross_compile)
+        if self.cross_compile:
+            cmd.append('CROSS_COMPILE=%s' % self.cross_compile)
         cmd.append('KCONFIG_IGNORE_DUPLICATES=1')
         cmd.append('include/config/auto.conf')
-        self.ps = subprocess.Popen(cmd, stdout=self.devnull)
+        """This will be screen-scraped, so be sure the expected text will be
+        returned consistently on every machine by setting LANG=C"""
+        self.ps = subprocess.Popen(cmd, stdout=self.devnull,
+                                   env=dict(os.environ, LANG='C'),
+                                   stderr=subprocess.PIPE)
         self.state = STATE_AUTOCONF
         return False