Issue with dllexport/dllimport inline function

[LIU Hao]

在 2022-10-11 22:26, xclaesse@gmail.com 写道:
> #ifdef GLIB_COMPILATION
> #  define _GLIB_API _GLIB_EXPORT
> #  define GLIB_INLINE __attribute__((__dllexport__)) __attribute__((__gnu_inline__)) extern inline

This is not correct. Typically, `dllexport` indicates that 'I want an external definition' but 
`gnu_inline` indicates that 'I do not want an external definition', so it's a contradiction: you get 
either multiple definitions, or none (which causes undefined references).


To user code which imports such a function, it should be seen as

    ```
    __attribute__((__gnu_inline__))
    extern inline
    int g_strcmp0(const char*, const char*)
    ```

This has the desired effect: The function can be inlined where appropriate. And if not, a call to 
the external thunk is emitted; no weak definition is emitted in either case.


To the library itself which exports it, it should be seen as

    ```
    __attribute__((__dllexport__))
    extern inline
    int g_strcmp0(const char*, const char*)
    ```

There is no `gnu_inline` in this case. GCC always generates a COMDAT/weak/linkonce definition, which 
will not cause multiple definition errors.



-- 
Best regards,
LIU Hao

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