[PATCH] D86049: RFC: Implement optional exportable wrapper function generation for objc_direct methods.

[Puyan Lotfi via Phabricator via cfe-commits]

plotfi added inline comments.


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Comment at: clang/include/clang/Basic/Attr.td:2251-2256
+def ObjCDirectVisible : Attr {
+  let Spellings = [Clang<"objc_direct_visible">];
+  let Subjects = SubjectList<[ObjCMethod], ErrorDiag>;
+  let LangOpts = [ObjC];
+  let Documentation = [ObjCDirectVisibleDocs];
+}
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mwyman wrote:
> Should this inherit `ObjCDirect`, to include both objc_direct and the visibility aspect? I don't see any reason we would want to add `objc_direct_visible` without also having `objc_direct`, so why make developers add both?
> 
> As an alternative, would it make sense to allow adding `__attribute__((visibility("default")))` on direct methods?
> 
> Also, it doesn't seem like this allows making `@property`s visible, so should there be a similar attribute for properties?
I'd prefer to do `@property`s in a separate commit, but I suppose you are thinking like a `objc_direct_members_visible` attribute? I think I can add that in a subsequent commit. 

I took a look at how to make things inherit and I think the most straightforward way is to have `handleObjCDirectVisibleAttr` set the objc_direct attribute if it is not set already.

As for `__attribute__((visibility("default")))` I think the trouble lies in what we want the default visibility behavior for objc methods to be and if we want the behavior to be controlled by `-fvisibility=`. I tried going by attribute visibility before and had some trouble too (I forget exactly what though). 




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Comment at: clang/lib/CodeGen/CGObjCMac.cpp:4025-4036
+  if (OMD->isDirectMethodVisible() && Fn->getName().str()[0] == '\1') {
+    // Drop '\1' to work with dlsym.
+    std::string Name = Fn->getName().str().substr(1);
+
+    assert(Name[0] == '-' || Name[0] == '+');
+    assert(Name[1] == '[' && Name[Name.length() - 1] == ']');
+
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mwyman wrote:
> Should this move to clang/lib/AST/Mangle.cpp's mangleObjCMethodName?
I like this idea. I will look into doing it next.


Repository:
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  https://reviews.llvm.org/D86049/new/

https://reviews.llvm.org/D86049