Add a presubmit check to look for duplicate Valgrind/Heapchecker suppression name...

tools/valgrind/memcheck/PRESUBMIT.py

Index: tools/valgrind/memcheck/PRESUBMIT.py
===================================================================
--- tools/valgrind/memcheck/PRESUBMIT.py	(revision 59155)
+++ tools/valgrind/memcheck/PRESUBMIT.py	(working copy)
@@ -9,7 +9,12 @@
 
 def CheckChange(input_api, output_api):
   """Checks the memcheck suppressions files for bad data."""
+  suppressions = {}
   errors = []
+  # skip_next_line has 3 possible values:
+  # - False: don't skip the next line.
+  # - 'skip_suppression_name': the next line is a suppression name, skip.
+  # - 'skip_param': the next line is a system call parameter error, skip.
   skip_next_line = False
   func_re = input_api.re.compile('[a-z_.]+\(.+\)$')
   for f, line_num, line in input_api.RightHandSideLines(lambda x:
@@ -19,11 +24,23 @@
       continue
 
     if skip_next_line:
+      if skip_next_line == 'skip_suppression_name':
+        if suppressions.has_key(line):
+          errors.append('suppression with name "%s" at %s line %s has already '
+                        'been defined at line %s' % (line, f.LocalPath(),
+                                                     line_num,
+                                                     suppressions[line][1]))
+        else:
+          suppressions[line] = (f, line_num)
       skip_next_line = False
       continue
-    if line == '{' or line == "Memcheck:Param":
-      skip_next_line = True
+    if line == '{':
+      skip_next_line = 'skip_suppression_name'
       continue
+    if line == "Memcheck:Param":
+      skip_next_line = 'skip_param'
+      continue
+
     if (line.startswith('fun:') or line.startswith('obj:') or
         line.startswith('Memcheck:') or line == '}' or
         line == '...'):