Add module dependency check to CPP-LINT

To use it just put a module_dependencies.txt into a directory,
which lists all modules that it is allowed to include header
files from.

Author: peterschrammel

scripts/cpplint.py

@@ -4981,7 +4981,7 @@ def _ClassifyInclude(fileinfo, include, is_system):
 
 
 
-def CheckIncludeLine(filename, clean_lines, linenum, include_state, error):
+def CheckIncludeLine(filename, clean_lines, linenum, include_state, error, module_deps):
   """Check rules that are applicable to #include lines.
 
   Strings on #include lines are NOT removed from elided line, to make
@@ -5029,6 +5029,18 @@ def CheckIncludeLine(filename, clean_lines, linenum, include_state, error):
     elif not _THIRD_PARTY_HEADERS_PATTERN.match(include):
       include_state.include_list[-1].append((include, linenum))
 
+    # Check module dependencies
+    module_name = os.path.dirname(filename)
+    has_src = module_name.find('src/')
+    if has_src >= 0:
+        module_name = module_name[has_src+4:]
+    deps_name = os.path.dirname(include)
+    if deps_name and module_deps:
+        may_use = any(deps_name.startswith(module) for module in module_deps)
+        if not may_use:
+            error(filename, linenum, 'build/include', 4,
+                  'Module `'+module_name+'` must not use `'+include+'`')
+
       # We want to ensure that headers appear in the right order:
       # 1) for foo.cc, foo.h  (preferred location)
       # 2) c system files
@@ -5141,7 +5153,7 @@ def _GetTextInside(text, start_pattern):
 
 
 def CheckLanguage(filename, clean_lines, linenum, file_extension,
-                  include_state, nesting_state, error):
+                  include_state, nesting_state, error, module_deps):
   """Checks rules from the 'C++ language rules' section of cppguide.html.
 
   Some of these rules are hard to test (function overloading, using
@@ -5165,7 +5177,7 @@ def CheckLanguage(filename, clean_lines, linenum, file_extension,
 
   match = _RE_PATTERN_INCLUDE.search(line)
   if match:
-    CheckIncludeLine(filename, clean_lines, linenum, include_state, error)
+    CheckIncludeLine(filename, clean_lines, linenum, include_state, error, module_deps)
     return
 
   # Reset include state across preprocessor directives.  This is meant
@@ -6246,7 +6258,7 @@ def CheckForEndl(filename, clean_lines, linenum, error):
     error(filename, linenum, 'runtime/endl', 4, 'Do not use std::endl')
 
 def ProcessLine(filename, file_extension, clean_lines, line,
-                include_state, function_state, nesting_state, error,
+                include_state, function_state, nesting_state, error, module_deps,
                 extra_check_functions=[]):
   """Processes a single line in the file.
 
@@ -6276,7 +6288,7 @@ def ProcessLine(filename, file_extension, clean_lines, line,
   CheckForMultilineCommentsAndStrings(filename, clean_lines, line, error)
   CheckStyle(filename, clean_lines, line, file_extension, nesting_state, error)
   CheckLanguage(filename, clean_lines, line, file_extension, include_state,
-                nesting_state, error)
+                nesting_state, error, module_deps)
   CheckForNonConstReference(filename, clean_lines, line, nesting_state, error)
   CheckForNonStandardConstructs(filename, clean_lines, line,
                                 nesting_state, error)
@@ -6370,6 +6382,27 @@ def ProcessFileData(filename, file_extension, lines, error,
 
   ResetNolintSuppressions()
 
+  # Load module dependencies
+  module_deps_file = os.path.join(os.path.dirname(filename), 'module_dependencies.txt')
+  module_deps = []
+  if os.path.isfile(module_deps_file):
+      with open(module_deps_file, 'r') as f:
+          module_deps = f.read().splitlines()
+      # strip off comments and whitespace
+      def strip_off_comments(s):
+          comment_index = s.find('#')
+          if comment_index >= 0:
+              s = s[:comment_index]
+          s = s.strip()
+          return s
+      module_deps = [strip_off_comments(module) for module in module_deps]
+      # remove empty lines
+      module_deps = [module for module in module_deps if len(module) != 0]
+  else:
+      error(filename, 0, 'build/include', 4,
+            'module_dependencies.txt not found in `' +
+                os.path.dirname(filename) + '`')
+
   CheckForCopyright(filename, lines, error)
   CheckForFunctionCommentHeaders(filename, lines, error)
   ProcessGlobalSuppresions(lines)
@@ -6381,7 +6414,7 @@ def ProcessFileData(filename, file_extension, lines, error,
 
   for line in xrange(clean_lines.NumLines()):
     ProcessLine(filename, file_extension, clean_lines, line,
-                include_state, function_state, nesting_state, error,
+                include_state, function_state, nesting_state, error, module_deps,
                 extra_check_functions)
     FlagCxx11Features(filename, clean_lines, line, error)
   nesting_state.CheckCompletedBlocks(filename, error)