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efl/src/lib/eolian/eolian_api.h

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eolian: Rename EAPI macro to EOLIAN_API in Eolian library Summary: Patch from a series of patches to rename EAPI symbols to specific library DSOs. EAPI was designed to be able to pass `__attribute__ ((visibility ("default")))` for symbols with GCC, which would mean that even if -fvisibility=hidden was used when compiling the library, the needed symbols would get exported. MSVC __almost__ works like GCC (or mingw) in which you can declare everything as export and it will just work (slower, but it will work). But there's a caveat: global variables will not work the same way for MSVC, but works for mingw and GCC. For global variables (as opposed to functions), MSVC requires correct DSO visibility for MSVC: instead of declaring a symbol as export for everything, you need to declare it as import when importing from another DSO and export when defining it locally. With current EAPI definitions, we get the following example working in mingw and MSVC (observe it doesn't define any global variables as exported symbols). Example 1: dll1: ``` EAPI void foo(void); EAPI void bar() { foo(); } ``` dll2: ``` EAPI void foo() { printf ("foo\n"); } ``` This works fine with API defined as __declspec(dllexport) in both cases and for gcc defining as `__atttribute__((visibility("default")))`. However, the following: Example 2: dll1: ``` EAPI extern int foo; EAPI void foobar(void); EAPI void bar() { foo = 5; foobar(); } ``` dll2: ``` EAPI int foo = 0; EAPI void foobar() { printf ("foo %d\n", foo); } ``` This will work on mingw but will not work for MSVC. And that's why EAPI is the only solution that worked for MSVC. Co-authored-by: João Paulo Taylor Ienczak Zanette <jpaulotiz@gmail.com> Co-authored-by: Ricardo Campos <ricardo.campos@expertise.dev> Co-authored-by: Lucas Cavalcante de Sousa <lucks.sousa@gmail.com> Reviewers: vtorri, woohyun, jptiz, lucas Reviewed By: vtorri Subscribers: cedric, #reviewers, #committers Tags: #efl Differential Revision: https://phab.enlightenment.org/D12196
2020-11-25 06:39:05 -08:00
#ifndef _EFL_EOLIAN_API_H
#define _EFL_EOLIAN_API_H
#ifdef EOLIAN_API
#error EOLIAN_API should not be already defined
#endif
#ifdef _WIN32
# ifndef EOLIAN_STATIC
# ifdef EOLIAN_BUILD
# define EOLIAN_API __declspec(dllexport)
# else
# define EOLIAN_API __declspec(dllimport)
# endif
# else
# define EOLIAN_API
# endif
# define EOLIAN_API_WEAK
#else
# ifdef __GNUC__
# if __GNUC__ >= 4
# define EOLIAN_API __attribute__ ((visibility("default")))
# define EOLIAN_API_WEAK __attribute__ ((weak))
# else
# define EOLIAN_API
# define EOLIAN_API_WEAK
# endif
# else
# define EOLIAN_API
# define EOLIAN_API_WEAK
# endif
#endif
#endif