util: Add verifier for opening braces of classes

Make sure that opening braces of classes are not declared
in the same line of the class name.

This does not work for multi-line classes.

Change-Id: I232df1a9ebd974b9f4f66e1d96d03b12513bd49f
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39016
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Gabe Black <gabe.black@gmail.com>

util/style/verifiers.py

@@ -456,6 +456,33 @@ class BoolCompare(LineVerifier):
                               "comparisons with false/False.\n")
         return line
 
+class ClassBraces(LineVerifier):
+    """ Check if the opening braces of classes are not on the same line of
+        the class name.
+
+        @todo Make this work for multi-line class declarations. e.g.,
+
+            class MultiLineClass
+              : public BaseClass {
+    """
+
+    languages = set(('C', 'C++'))
+    test_name = 'class opening brace position'
+    opt_name = 'classbrace'
+
+    regex = re.compile(r'\A(\s*)(class\s+[A-Z].*\S)\s*\{')
+
+    def check_line(self, line, **kwargs):
+        return self.regex.search(line) == None
+
+    def fix_line(self, line, **kwargs):
+        match = self.regex.search(line)
+        if match:
+            # Group 1 is indentation, group 2 is class declaration
+            line = match.group(1) + match.group(2) + "\n" + \
+                match.group(1) + "{"
+        return line
+
 def is_verifier(cls):
     """Determine if a class is a Verifier that can be instantiated"""