The build system for libbson and libmongoc must keep straight the distinction between "compiling on Windows" and "compiling with Microsoft Visual C". There are many ifdefs that check for BSON_OS_WIN32 and then include MSVC-specific code. This breaks under MinGW since BSON_OS_WIN32 is true in MinGW but mostly, compiling with MinGW is the same as compiling on Unix.

Most ifdefs that currently check for BSON_OS_WIN32 should instead check for _MSC_VER to

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Original report:

bson-stdint.h not found when using MinGW:

The bson.h requires including bson-stdint.h which is renamed to bson-stdint-win32.h on Windows.

This is because the _MSC_VER is not defined (and is only defined with MSVC).

I propose to change the following code :

#ifdef _MSC_VER
# include "bson-stdint-win32.h"
// ... as before

to something like this :

#if defined(_WIN32)
#  include "bson-stdint.h-win32.h"
#endif

#if defined(_MSC_VER)
// ... as before specific for MSVC
#endif