Close... VC++ .NET allows it, gcc 2.95.4 forbids it.

a.cpp

#include <stdio.h>

int main() {
   for (int i=0; i<5; i++) {
      printf("%d\n", i);
   }

   printf("%d\n", i);

   return 0;
}
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VC++ .NET

>cl a.cpp
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 13.10.3077 for 
+80x86
Copyright (C) Microsoft Corporation 1984-2002. All rights reserved.

a.cpp
Microsoft (R) Incremental Linker Version 7.10.3077
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:a.exe
a.obj

>a
0
1
2
3
4
5
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gcc 2.95.4

$ gcc a.cpp -o a
a.cpp: In function `int main()':
a.cpp:9: name lookup of `i' changed for new ANSI `for' scoping
a.cpp:5:   using obsolete binding at `i'
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