84     VARIABLE = re.compile(r"^([A-Z0-9_]+)\s*((\+|:|)=)")  variable in OverriddenVariable
105         m = self.VARIABLE.search(text)
108         variable, assignment = m.group(1, 2)
111             if variable in self.conditionally_set:
112                 self.unconditionally_set.append(variable)
114 …                return ["{}:{}: unconditional override of variable {} previously conditionally set"
115                             .format(self.filename, lineno, variable),
118             if variable not in self.unconditionally_set:
119                 self.unconditionally_set.append(variable)
122                 return ["{}:{}: unconditional override of variable {}"
123                         .format(self.filename, lineno, variable),
126             if variable not in self.unconditionally_set:
127                 self.conditionally_set.append(variable)
130                 return ["{}:{}: immediate assignment to append to variable {}"
131                         .format(self.filename, lineno, variable),
136                 return ["{}:{}: conditional override of variable {}"
137                         .format(self.filename, lineno, variable),
187             return ["{}:{}: remove default value of _SOURCE variable "
245     VARIABLE = re.compile(r"^([A-Z0-9_]+_[A-Z0-9_]+)\s*(\+|)=")  variable in TypoInPackageVariable
261         m = self.VARIABLE.search(text)
265         variable = m.group(1)
273             if variable.startswith("{}_".format(virtual)):
276         if self.ALLOWED.match(variable):
280                     .format(self.filename, lineno, variable, self.package),