This is the alternative patch as discussed with jon_y on IRC.
-- Best regards, LIU Hao
From 1d0e08852d702232eca5edd885187b7db3074348 Mon Sep 17 00:00:00 2001 From: LIU Hao <[email protected]> Date: Sat, 30 Apr 2022 21:17:38 +0800 Subject: [PATCH] winpthreads: Do not use `dllimport` when building 3rd-party DLLs When using libtool to build a 3rd-party DLL that attempts to link against winpthreads statically, `DLL_EXPORT` is defined when compiling 3rd-party source files, which used to cause winpthreads functions to be decorated as `dllimport`. As static libraries do not export functions, this would end up with undefined references. We only ever need `dllexport` on winpthreads functions when building winpthreads itself. GNU LD can import them even without the `dllimport` attribute, so it's unnecessary. Note: This is not a satisfactory solution. We can see that after this commit, user code will always see `WINPTHREAD_API` as empty. I prefer to move it from headers to source files. Reference: https://sourceforge.net/p/mingw-w64/mailman/message/37647350/ Signed-off-by: LIU Hao <[email protected]> --- mingw-w64-libraries/winpthreads/README | 10 ++++++++++ .../winpthreads/include/pthread.h | 16 ++++++++++------ mingw-w64-libraries/winpthreads/include/sched.h | 16 ++++++++++------ .../winpthreads/include/semaphore.h | 16 ++++++++++------ 4 files changed, 40 insertions(+), 18 deletions(-) create mode 100644 mingw-w64-libraries/winpthreads/README diff --git a/mingw-w64-libraries/winpthreads/README b/mingw-w64-libraries/winpthreads/README new file mode 100644 index 000000000..e5451e20f --- /dev/null +++ b/mingw-w64-libraries/winpthreads/README @@ -0,0 +1,10 @@ +The Winpthreads Library +----------------------- + +This library provides POSIX threading APIs for mingw-w64. + +Programs are usually linked against the winpthreads DLL, and winpthreads +headers expose `dllexport` APIs by default. When linking against the +static library, especially when building a user DLL with libtool, it is +necessary to define the `WINPTHREAD_STATIC` macro to avoid undefined +references. diff --git a/mingw-w64-libraries/winpthreads/include/pthread.h b/mingw-w64-libraries/winpthreads/include/pthread.h index 5aadb1cfa..d17df3352 100644 --- a/mingw-w64-libraries/winpthreads/include/pthread.h +++ b/mingw-w64-libraries/winpthreads/include/pthread.h @@ -83,14 +83,18 @@ extern "C" { /* MSB 8-bit major version, 8-bit minor version, 16-bit patch level. */ #define __WINPTHREADS_VERSION 0x00050000 -#if defined DLL_EXPORT #ifdef IN_WINPTHREAD -#define WINPTHREAD_API __declspec(dllexport) +# ifdef DLL_EXPORT +# define WINPTHREAD_API __declspec(dllexport) +# else +# define WINPTHREAD_API +# endif #else -#define WINPTHREAD_API __declspec(dllimport) -#endif -#else -#define WINPTHREAD_API +# ifdef WINPTHREAD_STATIC +# define WINPTHREAD_API +# else +# define WINPTHREAD_API __declspec(dllimport) +# endif #endif /* #define WINPTHREAD_DBG 1 */ diff --git a/mingw-w64-libraries/winpthreads/include/sched.h b/mingw-w64-libraries/winpthreads/include/sched.h index e77bf4cc3..2f6ce7c49 100644 --- a/mingw-w64-libraries/winpthreads/include/sched.h +++ b/mingw-w64-libraries/winpthreads/include/sched.h @@ -49,14 +49,18 @@ struct sched_param { extern "C" { #endif -#if defined DLL_EXPORT && !defined (WINPTHREAD_EXPORT_ALL_DEBUG) #ifdef IN_WINPTHREAD -#define WINPTHREAD_SCHED_API __declspec(dllexport) +# if defined(DLL_EXPORT) && !defined(WINPTHREAD_EXPORT_ALL_DEBUG) +# define WINPTHREAD_SCHED_API __declspec(dllexport) +# else +# define WINPTHREAD_SCHED_API +# endif #else -#define WINPTHREAD_SCHED_API __declspec(dllimport) -#endif -#else -#define WINPTHREAD_SCHED_API +# ifdef WINPTHREAD_STATIC +# define WINPTHREAD_SCHED_API +# else +# define WINPTHREAD_SCHED_API __declspec(dllimport) +# endif #endif int WINPTHREAD_SCHED_API sched_yield(void); diff --git a/mingw-w64-libraries/winpthreads/include/semaphore.h b/mingw-w64-libraries/winpthreads/include/semaphore.h index 14cb70371..fb08d58d7 100644 --- a/mingw-w64-libraries/winpthreads/include/semaphore.h +++ b/mingw-w64-libraries/winpthreads/include/semaphore.h @@ -27,14 +27,18 @@ extern "C" { #endif -#if defined DLL_EXPORT && !defined (WINPTHREAD_EXPORT_ALL_DEBUG) #ifdef IN_WINPTHREAD -#define WINPTHREAD_SEMA_API __declspec(dllexport) +# if defined(DLL_EXPORT) && !defined(WINPTHREAD_EXPORT_ALL_DEBUG) +# define WINPTHREAD_SEMA_API __declspec(dllexport) +# else +# define WINPTHREAD_SEMA_API +# endif #else -#define WINPTHREAD_SEMA_API __declspec(dllimport) -#endif -#else -#define WINPTHREAD_SEMA_API +# ifdef WINPTHREAD_STATIC +# define WINPTHREAD_SEMA_API +# else +# define WINPTHREAD_SEMA_API __declspec(dllimport) +# endif #endif /* Set this to 0 to disable it */ -- 2.35.3
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