Fixed danmar#4487 (False positive: variable is not assigned a value (pointer alias))

danmar · danmar · commit dd155b57e422 · 2013-03-20T06:38:53.000+01:00
diff --git a/lib/checkunusedvar.cpp b/lib/checkunusedvar.cpp
@@ -605,6 +605,16 @@ static const Token* doAssignment(Variables &variables, const Token *tok, bool de
         }
     }
 
+    // Possible pointer alias
+    else if (Token::Match(tok, "%var% = %var% ;")) {
+        const unsigned int varid2 = tok->tokAt(2)->varId();
+        Variables::VariableUsage *var2 = variables.find(varid2);
+        if (var2 && (var2->_type == Variables::array ||
+                     var2->_type == Variables::pointer)) {
+            variables.use(varid2,tok);
+        }
+    }
+
     return tok;
 }
 
diff --git a/test/testunusedvar.cpp b/test/testunusedvar.cpp
@@ -104,6 +104,7 @@ class TestUnusedVar : public TestFixture {
         TEST_CASE(localvaralias10); // ticket #2004
         TEST_CASE(localvaralias11); // ticket #4423 - iterator
         TEST_CASE(localvaralias12); // ticket #4394
+        TEST_CASE(localvaralias13); // ticket #4487
         TEST_CASE(localvarasm);
         TEST_CASE(localvarstatic);
         TEST_CASE(localvarextern);
@@ -2744,6 +2745,22 @@ class TestUnusedVar : public TestFixture {
         ASSERT_EQUALS("", errout.str());
     }
 
+    void localvaralias13() { // #4487
+        functionVariableUsage("void f(char *p) {\n"
+                              "    char a[4];\n"
+                              "    p = a;\n"
+                              "    strcpy(p, \"x\");\n"
+                              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("void f(char *p) {\n"
+                              "    char a[4];\n"
+                              "    p = a;\n"
+                              "    strcpy(p, \"x\");\n"
+                              "}");
+        TODO_ASSERT_EQUALS("a is assigned value that is never used", "", errout.str());
+    }
+
     void localvarasm() {
         functionVariableUsage("void foo(int &b)\n"
                               "{\n"

Original file line number	Diff line number	Diff line change
`@@ -605,6 +605,16 @@ static const Token* doAssignment(Variables &variables, const Token *tok, bool de`
`605`	`605`	`}`
`606`	`606`	`}`
`607`	`607`
	`608`	`+ // Possible pointer alias`
	`609`	`+ else if (Token::Match(tok, "%var% = %var% ;")) {`
	`610`	`+ const unsigned int varid2 = tok->tokAt(2)->varId();`
	`611`	`+ Variables::VariableUsage *var2 = variables.find(varid2);`
	`612`	`+ if (var2 && (var2->_type == Variables::array \|\|`
	`613`	`+ var2->_type == Variables::pointer)) {`
	`614`	`+ variables.use(varid2,tok);`
	`615`	`+ }`
	`616`	`+ }`
	`617`	`+`
`608`	`618`	`return tok;`
`609`	`619`	`}`
`610`	`620`