Fixed #5666 (False positive when modifiying std::string by pointer)

Author: danmar

lib/tokenize.cpp

@@ -6249,7 +6249,7 @@ bool Tokenizer::simplifyKnownVariables()
                      (Token::Match(tok2, "%name% = %bool%|%char%|%num%|%str%|%name% ;") ||
                       Token::Match(tok2, "%name% [ %num%| ] = %str% ;") ||
                       Token::Match(tok2, "%name% = & %name% ;") ||
-                      Token::Match(tok2, "%name% = & %name% [ 0 ] ;"))) {
+                      (Token::Match(tok2, "%name% = & %name% [ 0 ] ;") && arrays.find(tok2->tokAt(3)->varId()) != arrays.end()))) {
                 const unsigned int varid = tok2->varId();
                 if (varid == 0)
                     continue;

test/testtokenize.cpp

@@ -179,6 +179,7 @@ class TestTokenizer : public TestFixture {
         TEST_CASE(simplifyKnownVariables59);    // skip for header
         TEST_CASE(simplifyKnownVariables60);    // #6829
         TEST_CASE(simplifyKnownVariables61);    // #7805
+        TEST_CASE(simplifyKnownVariables62);    // #5666 - p=&str[0]
         TEST_CASE(simplifyKnownVariablesBailOutAssign1);
         TEST_CASE(simplifyKnownVariablesBailOutAssign2);
         TEST_CASE(simplifyKnownVariablesBailOutAssign3); // #4395 - nested assignments
@@ -2663,6 +2664,17 @@ class TestTokenizer : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void simplifyKnownVariables62() { // #5666
+        ASSERT_EQUALS("void foo ( std :: string str ) {\n"
+                      "char * p ; p = & str [ 0 ] ;\n"
+                      "* p = 0 ;\n"
+                      "}",
+                      tokenizeAndStringify("void foo(std::string str) {\n"
+                                           "  char *p = &str[0];\n"
+                                           "  *p = 0;\n"
+                                           "}", /*simplify=*/true));
+    }
+
     void simplifyKnownVariablesBailOutAssign1() {
         const char code[] = "int foo() {\n"
                             "    int i; i = 0;\n"