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https://issues.apache.org/jira/browse/LUCY-231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13259151#comment-13259151
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Marvin Humphrey commented on LUCY-231:
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> With the reworked patchset 03-06 I was able to successfully build a compiled
> extension on Windows 7 64-bit with ActivePerl and MSVC. And we're down to
> 9553 exported symbols in Lucy.so.
Sweet!!
* 0003-Unify-method-data-for-initialization-and-callbacks.patch looks good and
suggests an interesting direction outside the scope of this issue, which I
will post about on the dev list. FWIW, I'd suggest "cfish_Method" for the
name of the struct, or possibly "cfish_MetaData" or "cfish_MetaMethod", and
"_META" for the variables. Auxillary suggestion: eventually, it would be
handy to have the host alias stored alongside the rest of the method
introspection data -- that would allow us to simplify some code in VTable.c
and might eventually enable us to improve certain error messages by spelling
the method name as documented in the host language binding docs.
* 0004-Preliminary-Charmonizer-support-for-symbol-export.patch looks perfect.
* 0005-Switch-to-fvisibility-hidden-and-start-using-CHY_EXP.patch looks good,
thought I have one comment. It took me a while to figure out the reasoning
behind changing up the export symbols in the autogenerated .h files based on
whether the .cfh file was "included". Up until now the output of CFC has
been deterministic for a given set of .cfh files; after this patch, that's
no longer true. My first instinct would have been to use an #ifdef chain as
described above; I think you chose to do things this way so that the
extension author wouldn't have to add an extra pound-define to to their C
files, right?
* 0006-Install-import-library-on-Windows.patch looks good.
+1 to commit the patch series!
> Symbol visibility
> -----------------
>
> Key: LUCY-231
> URL: https://issues.apache.org/jira/browse/LUCY-231
> Project: Lucy
> Issue Type: Task
> Components: Clownfish
> Reporter: Nick Wellnhofer
> Assignee: Nick Wellnhofer
> Attachments:
> 0001-Preliminary-Charmonizer-support-for-symbol-export.patch,
> 0002-Switch-to-fvisibility-hidden-and-start-using-CHY_EXP.patch,
> 0003-Unify-method-data-for-initialization-and-callbacks.patch,
> 0004-Preliminary-Charmonizer-support-for-symbol-export.patch,
> 0005-Switch-to-fvisibility-hidden-and-start-using-CHY_EXP.patch,
> 0006-Install-import-library-on-Windows.patch
>
>
> In order to get compiled extension working on Windows, we'll have to define
> the visibility of our extern variables and functions. On Windows every
> exported symbol of a DLL has to be marked with __declspec(dllexport) when
> compiling the DLL. If you're linking against a DLL, every symbol imported
> from the DLL has to be marked __declspec(dllimport)
> On UNIX, every symbol is exported by default, so defining visibility is not
> strictly necessary. But hiding symbols that don't have to be exported has the
> benefit of reducing size and speeding up loading of a DLL. Hidden symbols
> also allow the compiler to generate more optimized code.
> The standard approach is to compile with the GCC option -fvisibility=hidden
> which emulates the Windows behavior. Then a macro is defined roughly like
> that (should probably be handled by charmonizer):
> {noformat}
> #if defined __GNUC__
> # if defined _WIN32 || defined __CYGWIN__
> # define CHY_EXPORT __attribute__ ((dllexport))
> # elif __GNUC__ >= 4
> # define CHY_EXPORT __attribute__ ((visibility ("default")))
> # else
> # define CHY_EXPORT
> # endif
> #elif defined _MFC_VER
> # define CHY_EXPORT __declspec(dllexport)
> #else
> # define CHY_EXPORT
> #endif
> {noformat}
> This macro can then be used like that:
> {noformat}
> CHY_EXPORT void
> exported_function();
> extern CHY_EXPORT int exported_variable;
> {noformat}
> When compiling an extension, we also have to handle __declspec(dllimport) on
> Windows. For the generated headers, we could define CHY_IMPORT and use it
> instead of CHY_EXPORT for "included" headers. For the code in XSBind.[ch], we
> could define BUILDING_XSBIND only during compilation of XSBind.c and then use
> something like that:
> {noformat}
> #if defined __GNUC__
> # if defined _WIN32 || defined __CYGWIN__
> # if BUILDING_XSBIND
> # define XSBIND_EXPORT __attribute__ ((dllexport))
> # else
> # define XSBIND_EXPORT __attribute__ ((dllimport))
> # endif
> # elif __GNUC__ >= 4
> # define XSBIND_EXPORT __attribute__ ((visibility ("default")))
> # else
> # define XSBIND_EXPORT
> # endif
> #elif defined _MFC_VER
> # if BUILDING_XSBIND
> # define XSBIND_EXPORT __declspec(dllexport)
> # else
> # define XSBIND_EXPORT __declspec(dllimport)
> # endif
> #else
> # define XSBIND_EXPORT
> #endif
> XSBIND_EXPORT cfish_Obj*
> cfish_XSBind_new_blank_obj(SV *either_sv);
> {noformat}
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