Shim Type#fully_qualified_name for libclang < 21#135
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clang_getFullyQualifiedName landed in libclang 21. Earlier versions have no equivalent native API, so users on those versions hit a NoMethodError when calling the wrapper. Add a Ruby shim that composes existing libclang APIs (declaration, qualified_name, template arguments, pointer/array/reference unwrapping). Type#fully_qualified_name now dispatches: * libclang 21+ → clang_getFullyQualifiedName (native) * libclang < 21 → fqn_impl shim The shim covers approximately 95% of the native API's behavior. Known limitation: STL container typedefs that depend on default template arguments (e.g. std::vector<T>::iterator) don't expand the defaults, so the output is shorter than native but still valid C++. Code is lifted from ruby-bindgen, which has been carrying the shim as a refinement on Type and where it has been battle-tested generating Rice C++ bindings for OpenCV (1k+ classes). Closes #131.
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Description
clang_getFullyQualifiedNamelanded in libclang 21. Earlier versions have no equivalent native API, so callingType#fully_qualified_nameon those versions raisesNoMethodError(the FFI symbol isn't attached).Add a Ruby shim that composes existing libclang APIs (
declaration,qualified_name,template_argument_type, pointer/array/reference unwrapping) to produce equivalent output.Type#fully_qualified_namenow dispatches:clang_getFullyQualifiedName(native, unchanged)fqn_implshim (new)Known limitation
STL container typedefs that depend on default template arguments (e.g.
std::vector<T>::iterator) don't expand the defaults — the shim producesstd::vector<Pixel>::iteratorwhere native producesstd::vector<Pixel, std::allocator<Pixel>>::iterator. Output is valid C++ either way; this is the only known semantic gap.Provenance
The shim is lifted from ruby-bindgen, where it has been carried as a refinement on
Typeand battle-tested generating Rice C++ bindings for OpenCV (1k+ classes, 10k+ method signatures across multiple libclang versions). Lifting it into ffi-clang lets ruby-bindgen retire its refinement and makes the same fallback available to other consumers.Tests
The existing
#fully_qualified_namespecs no longer skip on libclang < 21 (they now go through the shim and produce the expected output). A newshim implementation (fqn_impl)describe block exercises the shim directly viafqn_impl(nil), so the shim gets coverage on libclang 21+ CI as well as on older libclang.Eight new examples covering:
Closes
Closes #131.
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