CPP: Add a test of common mistakes using locking classes.

cpp/ql/test/examples/BadLocking/AV Rule 107.expected

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+| UnintendedDeclaration.cpp:51:2:51:22 | declaration | Functions should be declared at file scope, not inside blocks. |
+| UnintendedDeclaration.cpp:72:2:72:27 | declaration | Functions should be declared at file scope, not inside blocks. |

cpp/ql/test/examples/BadLocking/AV Rule 107.qlref

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+jsf/4.13 Functions/AV Rule 107.ql

cpp/ql/test/examples/BadLocking/DeclStmts.expected

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+| UnintendedDeclaration.cpp:44:2:44:29 | declaration | myLock | Variable |
+| UnintendedDeclaration.cpp:51:2:51:22 | declaration | myLock | Function |
+| UnintendedDeclaration.cpp:58:2:58:20 | declaration | myLock | Variable |
+| UnintendedDeclaration.cpp:65:2:65:22 | declaration | myMutex | Variable |
+| UnintendedDeclaration.cpp:72:2:72:27 | declaration | myLock | Function |
+| UnintendedDeclaration.cpp:82:3:82:34 | declaration | myLock | Variable |
+| UnintendedDeclaration.cpp:89:3:89:27 | declaration | memberMutex | Variable |

cpp/ql/test/examples/BadLocking/DeclStmts.ql

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+import cpp
+
+string describe(Declaration d)
+{
+	(
+		d instanceof Variable and
+		result = "Variable"
+	) or (
+		d instanceof Function and
+		result = "Function"
+	)
+}
+
+from DeclStmt ds, Declaration d
+where
+	ds.getADeclaration() = d
+select
+	ds, concat(d.getName(), ", "), concat(describe(d), ", ")

cpp/ql/test/examples/BadLocking/LocalVariableHidesGlobalVariable.expected

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+| UnintendedDeclaration.cpp:65:14:65:20 | definition of myMutex | Local variable myMutex hides $@ with the same name. | UnintendedDeclaration.cpp:40:7:40:13 | myMutex | a global variable |

cpp/ql/test/examples/BadLocking/LocalVariableHidesGlobalVariable.qlref

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+Best Practices/Hiding/LocalVariableHidesGlobalVariable.ql

cpp/ql/test/examples/BadLocking/UnintendedDeclaration.cpp

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+
+class Mutex
+{
+public:
+	Mutex();
+	~Mutex();
+
+	void lock();
+	void unlock();
+
+private:
+	// ...
+};
+
+template<class T>
+class Lock
+{
+public:
+	Lock() : m(0)
+	{
+	}
+
+	Lock(T &_m) : m(&_m)
+	{
+		m->lock();
+	}
+
+	~Lock()
+	{
+		if (m)
+		{
+			m->unlock();
+		}
+	}
+
+private:
+	T *m;
+};
+
+Mutex myMutex;
+
+void test1()
+{
+	Lock<Mutex> myLock(myMutex); // GOOD (creates `myLock` on `myMutex`)
+
+	// ...
+}
+
+void test2()
+{
+	Lock<Mutex> myLock(); // BAD (interpreted as a function declaration, this does nothing)
+
+	// ...
+}
+
+void test3()
+{
+	Lock<Mutex> myLock; // GOOD (creates an uninitialized variable called `myLock`, probably intended)
+
+	// ...
+}
+
+void test4()
+{
+	Lock<Mutex>(myMutex); // BAD (creates an uninitialized variable called `myMutex`, probably not intended)
+
+	// ...
+}
+
+void test5()
+{
+	Lock<Mutex> myLock(Mutex); // BAD (interpreted as a function declaration, this does nothing)
+
+	// ...
+}
+
+class MyTestClass
+{
+public:
+	void test6()
+	{
+		Lock<Mutex> myLock(memberMutex); // GOOD (creates `myLock` on `memberMutex`)
+
+		// ...
+	}
+
+	void test7()
+	{
+		Lock<Mutex>(memberMutex); // BAD (creates an uninitialized variable called `memberMutex`, probably not intended) [NOT DETECTED]
+
+		// ...
+	}
+
+private:
+	Mutex memberMutex;
+};