variable usage: fix false positives when __attribute__ is used. Ticket: #1792

lib/token.cpp

@@ -104,6 +104,7 @@ void Token::deleteThis()
         _isName = _next->_isName;
         _isNumber = _next->_isNumber;
         _isBoolean = _next->_isBoolean;
+        _isUnused = _next->_isUnused;
         _varId = _next->_varId;
         _fileIndex = _next->_fileIndex;
         _linenr = _next->_linenr;

lib/tokenize.cpp

@@ -7688,6 +7688,10 @@ void Tokenizer::simplifyAttribute()
                     if (Token::Match(tok->previous(), "%type%"))
                         tok->previous()->isUnused(true);
                 }
+
+                // check if before variable name
+                else if (Token::Match(tok->next()->link()->next(), "%type%"))
+                    tok->next()->link()->next()->isUnused(true);
             }
 
             Token::eraseTokens(tok, tok->next()->link()->next());

test/testunusedvar.cpp

@@ -1935,6 +1935,18 @@ private:
                               "    bool test __attribute__((unused)) = true;\n"
                               "}\n");
         ASSERT_EQUALS(std::string(""), errout.str());
+
+        functionVariableUsage("int foo()\n"
+                              "{\n"
+                              "    bool __attribute__((unused)) test;\n"
+                              "}\n");
+        ASSERT_EQUALS(std::string(""), errout.str());
+
+        functionVariableUsage("int foo()\n"
+                              "{\n"
+                              "    bool __attribute__((unused)) test = true;\n"
+                              "}\n");
+        ASSERT_EQUALS(std::string(""), errout.str());
     }
 };