How to compile C code containing extern "C" directive?

Question

In Visual Studio 2008, there's a nice debug heap coded in file dbgheap.c. It implements functions such as _CrtDumpMemoryLeaks().

I note the file includes extern "C" directives that don't seem to be allowed by Microsoft's own compiler. Code like:

extern "C" _CRTIMP int __cdecl _CrtDumpMemoryLeaks(
    void
    )
{
    /* only dump leaks when there are in fact leaks */

Simply produces errors if you try to compile it yourself. Obviously there are compiler flags to allow this syntax, but anyone know what the flags are?

Answer 1

In this case, it turns out that while the code is otherwise 100% legal C, except for these extern "C" qualifiers, it also compiles perfectly with flag /TP which means, "compile as C++ disregarding the file name."

So, I imagine that's what they did.

I think MSFT just overlooked putting the extern "C" qualifiers in some sort of conditional compilation dependent on the __cplusplus flag or something.