Fixed #2841 (False positive: Array index out of bounds, can't compare ints to chars)

lib/checkbufferoverrun.cpp

@@ -662,9 +662,16 @@ void CheckBufferOverrun::checkFunctionParameter(const Token &tok, unsigned int p
                 }
                 else if (ftok2->str() == ")")
                     break;
-                else if (parameter == par && Token::Match(ftok2, "%var% ,|)"))
+                else if (parameter == par && Token::Match(ftok2, "%var% ,|)|["))
+                {
+                    // check type..
+                    const Token *type = ftok2->previous();
+                    while (Token::Match(type, "*|const"))
+                        type = type->previous();
+                    if (type && _tokenizer->sizeOfType(type) == arrayInfo.element_size())
                         parameterVarId = ftok2->varId();
                 }
+            }
 
             // No parameterVarId => bail out
             if (parameterVarId == 0)

test/testbufferoverrun.cpp

@@ -118,6 +118,7 @@ private:
         TEST_CASE(array_index_for_neq);    // #2211: Using != in condition
         TEST_CASE(array_index_for_question);	// #2561: for, ?:
         TEST_CASE(array_index_extern);      // FP when using 'extern'. #1684
+        TEST_CASE(array_index_cast);       // FP after cast. #2841
 
         TEST_CASE(buffer_overrun_1);
         TEST_CASE(buffer_overrun_2);
@@ -1390,6 +1391,31 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void array_index_cast()
+    {
+        // Ticket #2841. FP when using cast.
+
+        // Different types => no error
+        check("void f1(char *buf) {\n"
+              "    buf[4] = 0;\n"
+              "}\n"
+              "void f2() {\n"
+              "    int x[2];\n"
+              "    f1(x);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        // Same type => error
+        check("void f1(const char buf[]) {\n"
+              "    char c = buf[4];\n"
+              "}\n"
+              "void f2() {\n"
+              "    char x[2];\n"
+              "    f1(x);\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:6] -> [test.cpp:2]: (error) Array 'x[2]' index 4 out of bounds\n", errout.str());
+    }
+
     void buffer_overrun_1()
     {
         check("void f()\n"