Fix #11195 Add redundantContinue check (#4283)

lib/checkother.cpp

@@ -829,6 +829,9 @@ void CheckOther::checkUnreachableCode()
                     if (!labelInFollowingLoop && !silencedCompilerWarningOnly)
                         unreachableCodeError(secondBreak, inconclusive);
                     tok = Token::findmatch(secondBreak, "[}:]");
+                } else if (secondBreak->scope() && secondBreak->scope()->isLoopScope() && secondBreak->str() == "}" && tok->str() == "continue") {
+                    redundantContinueError(tok);
+                    tok = secondBreak;
                 } else
                     tok = secondBreak;
 
@@ -854,6 +857,12 @@ void CheckOther::unreachableCodeError(const Token *tok, bool inconclusive)
                 "Statements following return, break, continue, goto or throw will never be executed.", CWE561, inconclusive ? Certainty::inconclusive : Certainty::normal);
 }
 
+void CheckOther::redundantContinueError(const Token *tok)
+{
+    reportError(tok, Severity::style, "redundantContinue",
+                "'continue' is redundant since it is the last statement in a loop.", CWE561, Certainty::normal);
+}
+
 //---------------------------------------------------------------------------
 // Check scope of variables..
 //---------------------------------------------------------------------------

lib/checkother.h

@@ -260,6 +260,7 @@ private:
     void duplicateExpressionTernaryError(const Token *tok, ErrorPath errors);
     void duplicateBreakError(const Token *tok, bool inconclusive);
     void unreachableCodeError(const Token* tok, bool inconclusive);
+    void redundantContinueError(const Token* tok);
     void unsignedLessThanZeroError(const Token *tok, const ValueFlow::Value *v, const std::string &varname);
     void pointerLessThanZeroError(const Token *tok, const ValueFlow::Value *v);
     void unsignedPositiveError(const Token *tok, const ValueFlow::Value *v, const std::string &varname);

test/testother.cpp

@@ -117,6 +117,7 @@ private:
         TEST_CASE(switchRedundantOperationTest);
         TEST_CASE(switchRedundantBitwiseOperationTest);
         TEST_CASE(unreachableCode);
+        TEST_CASE(redundantContinue);
 
         TEST_CASE(suspiciousCase);
         TEST_CASE(suspiciousEqualityComparison);
@@ -4449,6 +4450,26 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void redundantContinue() {
+        check("void f() {\n" // #11195
+              "    for (int i = 0; i < 10; ++i) {\n"
+              "        printf(\"i = %d\\n\", i);\n"
+              "        continue;\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:4]: (style) 'continue' is redundant since it is the last statement in a loop.\n", errout.str());
+
+        check("void f() {\n"
+              "    int i = 0;"
+              "    do {\n"
+              "        ++i;\n"
+              "        printf(\"i = %d\\n\", i);\n"
+              "        continue;\n"
+              "    } while (i < 10);\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:5]: (style) 'continue' is redundant since it is the last statement in a loop.\n", errout.str());
+    }
+
 
     void suspiciousCase() {
         check("void foo() {\n"