Compiler Warning C4750
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Compiler Warning C4750

Visual Studio 2005

Error Message

'identifier': function with _alloca() inlined into a loop

The 'identifier' function forces inline expansion of the _alloca function within a loop, which might cause a stack overflow when the loop is executed.

To correct this error

  1. Ensure that the 'identifier' function is not modified with the __forceinline specifier.

  2. Ensure that the 'identifier' function does not contain a _alloca function that is contained in a loop.

  3. Do not specify the /O1, /O2, /Ox, or /Og compilation switch.

  4. Place the _alloca function in a try-except statement that will catch a stack overflow.


The following code example calls MyFunction in a loop, and MyFunction calls the _alloca function. The __forceinline modifier causes the inline expansion of the _alloca function.

// c4750.cpp
// compile with: /O2 /W2 /c
#include <intrin.h>

char * volatile newstr;

__forceinline void myFunction(void) // C4750
// The _alloca function does not require a __try/__except 
// block because the example uses compiler option /c.
    newstr = (char * volatile) _alloca(1000);

int main(void)
    for (int i=0; i<50000; i++)
    return 0;
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