Re: <SPAM> Can't build opencv : 'recursive_mutex' in namespace 'std' does not name a type

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From: Keith Marshall <[email protected]>
To: [email protected]
Message-ID: <57a33402-0ff5-e13c-f084-3ae66ebf78e4-JlWs9+JhQMeJPt80KsDg5Q@public.gmane.org>
Subject: Re: <SPAM> [MinGW-Users] Can't build opencv : 'recursive_mutex' in
 namespace 'std' does not name a type
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On 26/12/2020 03:50, Roy Qu wrote:
> I'm trying to build opencv using mingw gcc 9.2, and i got the following=

> message:
>=20
> [...snip...]
> error: 'recursive_mutex' in namespace 'std' does not name a type
> =C2=A0 706 | typedef std::recursive_mutex Mutex;
> =C2=A0 =C2=A0 =C2=A0 | =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
^~~~~~~~~~~~~~~
> F:/Temp/test/opencv-4.5.1/modules/core/include/opencv2/core/utility.hpp=
:63:1:
> note: 'std::recursive_mutex' is defined in header '<mutex>'; did you
> forget to '#include <mutex>'?

Presumably, you have checked that <mutex> has been included?  Even if it
has been, I believe that std::recursive_mutex is unsupported, when GCC
itself has been compiled to use the Win32 threads model, (as ours is).

> So what should I do to get it worked?

This will not be the answer you are hoping for, but unless you build GCC
to use the POSIX threads model, (or find a third-party build elsewhere),
you will need to port the application, to substitute a Windows-native
alternative for std::recursive_mutex.

--=20
Regards,
Keith.

Public key available from keys.gnupg.net
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