Q120243 - BUG: L2025 With Static Object in Inline Function

BUG: L2025 With Static Object in Inline Function

Q120243

1.00 1.50 WINDOWS kbprg kbbuglist ----------------------------------------------------------------- The information in this article applies to: The Microsoft C Run-time (CRT), included with - Microsoft Visual C++ for Windows, versions 1.0 and 1.5 ----------------------------------------------------------------- SYMPTOMS ======== When an inline function with a local static object is called from two different object modules, two different objects are created, generating the following error message: L2025: symbol: symbol defined more than once where symbol is the mangled function name. This problem only occurs when the following two conditions are met: - The function with the static object is inline. - The two calls are from separate files (object modules). CAUSE ===== For a local static object of an inline function, the compiler does not take into account that the function may be called from other files. RESOLUTION ========== To work around this problem, use one of the following methods: - Make sure that the function with the static object is not inlined. -or- - Move all calls of the static member function into one file. STATUS ====== Microsoft has confirmed this to be a bug in the products listed above. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available. This is not a problem in Visual C++ 32-bit Edition. MORE INFORMATION ================ The following sample code demonstrates this problem: Sample Code ----------- /* Compile options needed : none */ // test.h #include <iostream.h> void TestFunctionA(); void TestFunctionB(); class Object { public: int data; // Will track the number of accesses to an // object of class Object. Object(); // Provides screen output each time // constructor is called. ~Object(); // Provides screen output each time // destructor is called. }; inline int staticFunc() { static Object objectA; // This object should be // created only once. return objectA.data++; // Increment objectA's // access counter. } // test1.cpp #include "test.h" void main() { TestFunctionA(); // Should construct objectA. TestFunctionB(); // Should increment objectA.data. } void TestFunctionA() { cout << "objectA.data = " << staticFunc() << endl; } // test2.cpp #include "test.h" Object::Object() { data=1; // Initialize access count to 1. cout << "Constructor call" << endl; } Object::~Object() { cout << "Destructor call" << endl; } void TestFunctionB() { cout << "objectA.data = " << staticFunc() << endl; } Additional reference words: 1.00 1.50 inline static object KBCategory: kbprg kbbuglist KBSubcategory: CPPLngIss

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