Suppress "unused import" for abstract param/return types #1486
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When we generate a non-wrapped function or method binding that takes or returns an abstract (i.e. pure virtual) type not referenced elsewhere, we get an erroneous "unused import" warning for the user-visible re-export of that abstract type. This happens because the only use of the type is emitted by cxx and thus references the binding in "cxxbridge" instead of the re-export in "output". [See the unqualify_params_minisyn() and unqualify_ret_type() calls in codegen_rs::fun_codegen::gen_function().] The warning is erroneous because the re-export is the only way for users to name the type, and we don't want to generate an API that takes or returns types the user can't name. So let's just suppress it, like we did for non-abstract types in commit 5dd9a00 ("Fix unused import warnings.").
tchebb
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Since autocxx subclasses don't support multiple inheritance, we have to subclass all the ContentDecryptionModule_NN versions in C++ and then subclass a second time in Rust. This means we do now have some C++ in our tree (hence the Chromium-derived .clang-format), but it's cleaner than the other options. For Host_NN, we can do dynamic dispatch in Rust. I've added a macro to reduce the boilerplate, but there's still some. Even though the code's not the cleanest, I think this feature is important enough to justify the added complexity. The new C++ header exposed a bug in autocxx, which I've fixed in [1] and incorporated into our fork. Note that, while Chromium parses the "x-cdm-*-versions" manifest keys as comma-separated lists, Firefox parses each as a single number. I've put the comma-separated versions in the Firefox manifest too because the bug might get fixed by the time Firefox drops interface 10 support. [1] google/autocxx#1486
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When we generate a non-wrapped function or method binding that takes or returns an abstract (i.e. pure virtual) type not referenced elsewhere, we get an erroneous "unused import" warning for the user-visible re-export of that abstract type. This happens because the only use of the type is emitted by cxx and thus references the binding in
cxxbridgeinstead of the re-export inoutput. [See theunqualify_params_minisyn()andunqualify_ret_type()calls incodegen_rs::fun_codegen::gen_function().]The warning is erroneous because the re-export is the only way for users to name the type, and we don't want to generate an API that takes or returns types the user can't name. So let's just suppress it, like we did for non-abstract types in #1345.