New check: Ensure that the return value of std::remove() is used.

lib/checkstl.cpp

@@ -1340,6 +1340,8 @@ void CheckStl::uselessCalls()
                 uselessCallsSubstrError(tok, true);
         } else if (Token::Match(tok, "[{}:;] %var% . empty ( ) ;") && style)
             uselessCallsEmptyError(tok->next());
+        else if (Token::Match(tok, "[{};] std :: remove ("))
+            uselessCallsRemoveError(tok->next());
     }
 }
 
@@ -1377,3 +1379,10 @@ void CheckStl::uselessCallsEmptyError(const Token *tok)
 {
     reportError(tok, Severity::warning, "uselessCallsEmpty", "Useless call of function 'empty()'. Did you intend to call 'clear()' instead?");
 }
+
+void CheckStl::uselessCallsRemoveError(const Token *tok)
+{
+    reportError(tok, Severity::warning, "uselessCallsRemove", "Return value of std::remove() ignored. Elements remain in container.\n"
+                "The return value of std::remove() is ignored. This function returns an iterator to the end of the range containing those elements that should be kept. "
+                "Elements past new end remain valid but with unspecified values. Use the erase method of the container to delete them.");
+}

lib/checkstl.h

@@ -62,7 +62,6 @@ public:
         checkStl.size();
         checkStl.redundantCondition();
         checkStl.missingComparison();
-
     }
 
 
@@ -176,6 +175,7 @@ private:
     void uselessCallsSwapError(const Token *tok, const std::string &varname);
     void uselessCallsSubstrError(const Token *tok, bool empty);
     void uselessCallsEmptyError(const Token *tok);
+    void uselessCallsRemoveError(const Token *tok);
 
     void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const {
         CheckStl c(0, settings, errorLogger);
@@ -202,6 +202,7 @@ private:
         c.uselessCallsSwapError(0, "str");
         c.uselessCallsSubstrError(0, false);
         c.uselessCallsEmptyError(0);
+        c.uselessCallsRemoveError(0);
     }
 
     static std::string myName() {

test/teststl.cpp

@@ -1925,6 +1925,13 @@ private:
               "        std::cout << greeting.substr(0, npos) << std::endl;\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n"
+              "    std::remove(a.begin(), a.end(), val);\n"
+              "    x = std::remove(a.begin(), a.end(), val);\n"
+              "    a.erase(std::remove(a.begin(), a.end(), val));\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2]: (warning) Return value of std::remove() ignored. Elements remain in container.\n", errout.str());
     }
 };