Fixed #920 (new style check: find empty catch blocks)

lib/checkother.cpp

@@ -3565,7 +3565,24 @@ void CheckOther::postIncrement()
     }
 }
 
+void CheckOther::checkEmptyCatchBlock()
+{
+    if (!_settings->_checkCodingStyle)
+        return;
 
+    const char pattern[] = "} catch (";
+    for (const Token *tok = Token::findmatch(_tokenizer->tokens(), pattern); tok;
+         tok = Token::findmatch(tok, pattern))
+    {
+        tok = tok->tokAt(2);
+
+        if (Token::Match(tok, "( const| %type% *|&| %var% ) { }") ||
+            Token::simpleMatch(tok, "( . . . ) { }"))
+        {
+            emptyCatchBlockError(tok);
+        }
+    }
+}
 
 
 void CheckOther::cstyleCastError(const Token *tok)
@@ -3712,6 +3729,10 @@ void CheckOther::fflushOnInputStreamError(const Token *tok, const std::string &v
                 "fflushOnInputStream", "fflush() called on input stream \"" + varname + "\" may result in undefined behaviour");
 }
 
+void CheckOther::emptyCatchBlockError(const Token *tok)
+{
+    reportError(tok, Severity::style, "emptyCatchBlock", "Empty catch block");
+}
 
 void CheckOther::sizeofsizeof()
 {

lib/checkother.h

@@ -61,6 +61,7 @@ public:
         checkOther.checkStructMemberUsage();
         checkOther.strPlusChar();
         checkOther.sizeofsizeof();
+        checkOther.checkEmptyCatchBlock();
     }
 
     /** @brief Run checks against the simplified token list */
@@ -170,6 +171,9 @@ public:
     /** @brief %Check for using fflush() on an input stream*/
     void checkFflushOnInputStream();
 
+    /** @brief %Check for empty catch() blocks*/
+    void checkEmptyCatchBlock();
+
     /** @brief %Check for 'sizeof sizeof ..' */
     void sizeofsizeof();
     void sizeofsizeofError(const Token *tok);
@@ -200,6 +204,7 @@ public:
     void postIncrementError(const Token *tok, const std::string &var_name, const bool isIncrement);
     void emptyStringTestError(const Token *tok, const std::string &var_name, const bool isTestForEmpty);
     void fflushOnInputStreamError(const Token *tok, const std::string &varname);
+    void emptyCatchBlockError(const Token *tok);
 
     void getErrorMessages()
     {
@@ -228,6 +233,7 @@ public:
         conditionAlwaysTrueFalse(0, "true/false");
         strPlusChar(0);
         sizeofsizeofError(0);
+        emptyCatchBlockError(0);
 
         // optimisations
         postIncrementError(0, "varname", true);
@@ -262,6 +268,7 @@ public:
                "* variable scope can be limited\n"
                "* condition that is always true/false\n"
                "* unusal pointer arithmetic. For example: \"abc\" + 'd'\n"
+               "* empty catch() block\n"
 
                // optimisations
                "* optimisation: detect post increment/decrement\n"

test/testother.cpp

@@ -98,6 +98,8 @@ private:
         TEST_CASE(fflushOnInputStreamTest);
 
         TEST_CASE(sizeofsizeof);
+
+        TEST_CASE(emptyCatchBlock);
     }
 
     void check(const char code[])
@@ -116,6 +118,7 @@ private:
         errout.str("");
 
         checkOther.sizeofsizeof();
+        checkOther.checkEmptyCatchBlock();
 
         // Simplify token list..
         tokenizer.simplifyTokenList();
@@ -2631,6 +2634,70 @@ private:
               "}\n");
         ASSERT_EQUALS("[test.cpp:3]: (style) Suspicios code 'sizeof sizeof ..', most likely there should only be one sizeof. The current code is equivalent with 'sizeof(size_t)'.\n", errout.str());
     }
+
+    void emptyCatchBlock()
+    {
+        check("void Open(String name)\n"
+              "{\n"
+              "  try\n"
+              "  {\n"
+              "    foo();\n"
+              "  }\n"
+              "  catch (FileNotFoundException e)\n"
+              "  {\n"
+              "  }\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Empty catch block\n", errout.str());
+
+        check("void Open(String name)\n"
+              "{\n"
+              "  try\n"
+              "  {\n"
+              "    foo();\n"
+              "  }\n"
+              "  catch (char *errorMsg)\n"
+              "  {\n"
+              "  }\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Empty catch block\n", errout.str());
+
+        check("void Open(String name)\n"
+              "{\n"
+              "  try\n"
+              "  {\n"
+              "    foo();\n"
+              "  }\n"
+              "  catch (const FileNotFoundException& e)\n"
+              "  {\n"
+              "  }\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Empty catch block\n", errout.str());
+
+        check("void Open(String name)\n"
+              "{\n"
+              "  try\n"
+              "  {\n"
+              "    foo();\n"
+              "  }\n"
+              "  catch (...)\n"
+              "  {\n"
+              "  }\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:7]: (style) Empty catch block\n", errout.str());
+
+        check("void Open(String name)\n"
+              "{\n"
+              "  try\n"
+              "  {\n"
+              "    foo();\n"
+              "  }\n"
+              "  catch (const FileNotFoundException& e)\n"
+              "  {\n"
+              "    prinf(\"File not found\");\n"
+              "  }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
 };
 
 REGISTER_TEST(TestOther)