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authorFelipe Magno de Almeida <felipe@expertise.dev>2021-05-23 20:08:33 +0100
committerCarsten Haitzler (Rasterman) <raster@rasterman.com>2021-05-23 20:47:23 +0100
commitc02b796fdb0960411b24576f654a03f0e765a842 (patch)
tree513b0a1162e770a867b405223b08341639550a6f /src/lib/elementary/Elementary.h
parent6c969f6b7d59e64e8bdf09a5e535de9561d77535 (diff)
elementary: Add EOAPI definition in Elementary to allow removal in other libraries
Summary: Patch from a series of patches to rename EAPI symbols to specific library DSOs. = The Rationale = 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, raster Reviewed By: raster Subscribers: raster, cedric, #reviewers, #committers Tags: #efl Differential Revision: https://phab.enlightenment.org/D12273
Diffstat (limited to '')
-rw-r--r--src/lib/elementary/Elementary.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/src/lib/elementary/Elementary.h b/src/lib/elementary/Elementary.h
index a64406de43..6d0a33a643 100644
--- a/src/lib/elementary/Elementary.h
+++ b/src/lib/elementary/Elementary.h
@@ -88,6 +88,9 @@
88#ifdef EAPI_WEAK 88#ifdef EAPI_WEAK
89# undef EAPI_WEAK 89# undef EAPI_WEAK
90#endif 90#endif
91#ifdef EOAPI
92# undef EOAPI
93#endif
91 94
92#ifdef _WIN32 95#ifdef _WIN32
93# ifdef EFL_BUILD 96# ifdef EFL_BUILD
@@ -116,7 +119,7 @@
116#endif 119#endif
117 120
118#define EWAPI EAPI EAPI_WEAK 121#define EWAPI EAPI EAPI_WEAK
119 122#define EOAPI EAPI
120 123
121/* allow usage from c++ */ 124/* allow usage from c++ */
122#ifdef __cplusplus 125#ifdef __cplusplus