Refactorized check for dead pointers after throw:

- Less bailouts for inconclusive checking
- Support for static variables
- Changed severity to warning (error is not certain)

lib/checkexceptionsafety.cpp

@@ -58,6 +58,9 @@ void CheckExceptionSafety::destructors()
 
 void CheckExceptionSafety::deallocThrow()
 {
+    if (!_settings->isEnabled("style"))
+        return;
+
     const SymbolDatabase* const symbolDatabase = _tokenizer->getSymbolDatabase();
 
     // Deallocate a global/member pointer and then throw exception
@@ -81,7 +84,7 @@ void CheckExceptionSafety::deallocThrow()
 
         // we only look for global variables
         const Variable* var = symbolDatabase->getVariableFromVarId(varid);
-        if (!var || !var->isGlobal())
+        if (!var || !(var->isGlobal() || var->isStatic()))
             continue;
 
         // indentlevel..
@@ -100,16 +103,24 @@ void CheckExceptionSafety::deallocThrow()
                 --indentlevel;
             }
 
-            else if (tok2->str() == "throw")
-                ThrowToken = tok2;
-
-            // if the variable is not assigned after the throw then it
-            // is assumed that it is not the intention that it is a dead pointer.
-            else if (Token::Match(tok2, "%varid% =", varid)) {
-                if (ThrowToken)
-                    deallocThrowError(ThrowToken, tok->str());
+            // Throw after delete -> Dead pointer
+            else if (tok2->str() == "throw") {
+                if (_settings->inconclusive) { // For inconclusive checking, throw directly.
+                    deallocThrowError(tok2, tok->str());
                     break;
                 }
+                ThrowToken = tok2;
+            }
+
+            // Variable is assigned -> Bail out
+            else if (Token::Match(tok2, "%varid% =", varid)) {
+                if (ThrowToken) // For non-inconclusive checking, wait until we find an assignement to it. Otherwise we assume it is safe to leave a dead pointer.
+                    deallocThrowError(ThrowToken, tok2->str());
+                break;
+            }
+            // Variable passed to function. Assume it becomes assigned -> Bail out
+            else if (Token::Match(tok2, "[,(] &| %varid% [,)]", varid)) // TODO: No bailout if passed by value or as const reference
+                break;
         }
     }
 }

lib/checkexceptionsafety.h

@@ -74,7 +74,7 @@ private:
     }
 
     void deallocThrowError(const Token * const tok, const std::string &varname) {
-        reportError(tok, Severity::error, "exceptDeallocThrow", "Throwing exception in invalid state, " + varname + " points at deallocated memory");
+        reportError(tok, Severity::warning, "exceptDeallocThrow", "Throwing exception in invalid state, " + varname + " points at deallocated memory");
     }
 
     void rethrowCopyError(const Token * const tok, const std::string &varname) {

test/testexceptionsafety.cpp

@@ -35,24 +35,25 @@ private:
         TEST_CASE(destructors);
         TEST_CASE(deallocThrow1);
         TEST_CASE(deallocThrow2);
+        TEST_CASE(deallocThrow3);
         TEST_CASE(rethrowCopy1);
         TEST_CASE(rethrowCopy2);
         TEST_CASE(rethrowCopy3);
         TEST_CASE(rethrowCopy4);
     }
 
-    void check(const std::string &code) {
+    void check(const std::string &code, bool inconclusive = false) {
         // Clear the error buffer..
         errout.str("");
 
         Settings settings;
         settings.addEnabled("all");
+        settings.inconclusive = inconclusive;
 
         // Tokenize..
         Tokenizer tokenizer(&settings, this);
         std::istringstream istr(code);
         tokenizer.tokenize(istr, "test.cpp");
-        tokenizer.simplifyTokenList();
 
         // Check char variable usage..
         CheckExceptionSafety checkExceptionSafety(&tokenizer, &settings, this);
@@ -83,24 +84,57 @@ private:
 
     void deallocThrow1() {
         check("int * p;\n"
-              "void f(int x)\n"
-              "{\n"
+              "void f(int x) {\n"
               "    delete p;\n"
               "    if (x)\n"
               "        throw 123;\n"
               "    p = 0;\n"
-              "}\n");
-        ASSERT_EQUALS("[test.cpp:6]: (error) Throwing exception in invalid state, p points at deallocated memory\n", errout.str());
+              "}");
+        ASSERT_EQUALS("[test.cpp:5]: (warning) Throwing exception in invalid state, p points at deallocated memory\n", errout.str());
+
+        check("void f() {\n"
+              "    static int* p = foo;\n"
+              "    delete p;\n"
+              "    if (foo)\n"
+              "        throw 1;\n"
+              "    p = 0;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:5]: (warning) Throwing exception in invalid state, p points at deallocated memory\n", errout.str());
     }
 
     void deallocThrow2() {
         check("void f() {\n"
               "    int* p = 0;\n"
               "    delete p;\n"
+              "    if (foo)\n"
               "        throw 1;\n"
               "    p = new int;\n"
-              "}\n");
+              "}", true);
         ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n"
+              "    static int* p = 0;\n"
+              "    delete p;\n"
+              "    reset(p);\n"
+              "    throw 1;\n"
+              "}", true);
+        ASSERT_EQUALS("", errout.str());
+    }
+
+    void deallocThrow3() {
+        check("void f() {\n"
+              "    static int* p = 0;\n"
+              "    delete p;\n"
+              "    throw 1;\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n"
+              "    static int* p = 0;\n"
+              "    delete p;\n"
+              "    throw 1;\n"
+              "}", true);
+        ASSERT_EQUALS("[test.cpp:4]: (warning) Throwing exception in invalid state, p points at deallocated memory\n", errout.str());
     }
 
     void rethrowCopy1() {