There is no definition for dispatch_data_t

[maleadt]

I'm trying to wrap some macOS C header, which has the following:

#ifdef __APPLE__
#import <dispatch/dispatch.h>
#endif // __APPLE__

That header apparently has issues with Clang.jl, leading to:

[ Info: Building the DAG...
┌ Warning: [CollectDependentSystemNode]: found symbols in the system headers: [:dispatch_data_t]
└ @ Clang.Generators ~/.julia/packages/Clang/uJQ2L/src/generator/passes.jl:95
ERROR: LoadError: There is no definition for dispatch_data_t's underlying type: [``] at /Users/tim/.julia/artifacts/fbb170fa64a06b66dd9a16aaa21bf12848042d9a/aarch64-apple-darwin20/sys-root/usr/include/dispatch/data.h:44:1
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] resolve_dependency!(dag::ExprDAG, node::ExprNode{Clang.Generators.TypedefElaborated, CLTypedefDecl}, options::Dict{String, Any})
   @ Clang.Generators ~/.julia/packages/Clang/uJQ2L/src/generator/resolve_deps.jl:99
 [3] (::ResolveDependency)(dag::ExprDAG, options::Dict{String, Any})
   @ Clang.Generators ~/.julia/packages/Clang/uJQ2L/src/generator/passes.jl:286
 [4] build!(ctx::Context, stage::Clang.Generators.BuildStage)
   @ Clang.Generators ~/.julia/packages/Clang/uJQ2L/src/generator/context.jl:176
 [5] wrap(name::String, headers::String; defines::Vector{Any}, include_dirs::Vector{Any}, dependents::Bool)
   @ Main ~/Julia/pkg/Metal/res/wrap/wrap.jl:27
 [6] wrap
   @ ~/Julia/pkg/Metal/res/wrap/wrap.jl:13 [inlined]
 [7] main()
   @ Main ~/Julia/pkg/Metal/res/wrap/wrap.jl:59
 [8] top-level scope
   @ ~/Julia/pkg/Metal/res/wrap/wrap.jl:64
in expression starting at /Users/tim/Julia/pkg/Metal/res/wrap/wrap.jl:64

data.h:44:

DISPATCH_DATA_DECL(dispatch_data);

With the relevant macros for that:

#define DISPATCH_GLOBAL_OBJECT(type, object) ((OS_OBJECT_BRIDGE type)&(object))
#define DISPATCH_RETURNS_RETAINED OS_OBJECT_RETURNS_RETAINED
#elif defined(__cplusplus) && !defined(__DISPATCH_BUILDING_DISPATCH__)
/*
 * Dispatch objects are NOT C++ objects. Nevertheless, we can at least keep C++
 * aware of type compatibility.
 */
typedef struct dispatch_object_s {
private:
	dispatch_object_s();
	~dispatch_object_s();
	dispatch_object_s(const dispatch_object_s &);
	void operator=(const dispatch_object_s &);
} *dispatch_object_t;
#define DISPATCH_DECL(name) \
		typedef struct name##_s : public dispatch_object_s {} *name##_t
#define DISPATCH_DECL_SUBCLASS(name, base) \
		typedef struct name##_s : public base##_s {} *name##_t
#define DISPATCH_GLOBAL_OBJECT(type, object) (static_cast<type>(&(object)))
#define DISPATCH_RETURNS_RETAINED
#else /* Plain C */
typedef union {
	struct _os_object_s *_os_obj;
	struct dispatch_object_s *_do;
	struct dispatch_queue_s *_dq;
	struct dispatch_queue_attr_s *_dqa;
	struct dispatch_group_s *_dg;
	struct dispatch_source_s *_ds;
	struct dispatch_channel_s *_dch;
	struct dispatch_mach_s *_dm;
	struct dispatch_mach_msg_s *_dmsg;
	struct dispatch_semaphore_s *_dsema;
	struct dispatch_data_s *_ddata;
	struct dispatch_io_s *_dchannel;
} dispatch_object_t DISPATCH_TRANSPARENT_UNION;
#define DISPATCH_DECL(name) typedef struct name##_s *name##_t
#define DISPATCH_DECL_SUBCLASS(name, base) typedef base##_t name##_t
#define DISPATCH_GLOBAL_OBJECT(type, object) ((type)&(object))
#define DISPATCH_RETURNS_RETAINED
#endif

#if OS_OBJECT_SWIFT3 && OS_OBJECT_USE_OBJC
#define DISPATCH_SOURCE_TYPE_DECL(name) \
		DISPATCH_EXPORT struct dispatch_source_type_s \
				_dispatch_source_type_##name; \
		OS_OBJECT_DECL_PROTOCOL(dispatch_source_##name, <OS_dispatch_source>); \
		OS_OBJECT_CLASS_IMPLEMENTS_PROTOCOL( \
				dispatch_source, dispatch_source_##name)
#define DISPATCH_SOURCE_DECL(name) \
		DISPATCH_DECL(name); \
		OS_OBJECT_DECL_PROTOCOL(name, <NSObject>); \
		OS_OBJECT_CLASS_IMPLEMENTS_PROTOCOL(name, name)
#ifndef DISPATCH_DATA_DECL
#define DISPATCH_DATA_DECL(name) OS_OBJECT_DECL_SWIFT(name)
#endif // DISPATCH_DATA_DECL
#else
#define DISPATCH_SOURCE_DECL(name) \
		DISPATCH_DECL(name);
#define DISPATCH_DATA_DECL(name) DISPATCH_DECL(name)
#define DISPATCH_SOURCE_TYPE_DECL(name) \
		DISPATCH_EXPORT const struct dispatch_source_type_s \
		_dispatch_source_type_##name
#endif

Is this a known issue, or should I try to reduce the source code involved?

[JamesWrigley]

Grokking those macros in libdispatch is quite the rabbit hole 🫠 Do you by any chance have macro_mode = "aggressive" in your generator.toml file? And if so, does setting it to basic or disable help?

[maleadt]

Yeah, I worked around it by disabling the include and ignoring that functionality, which is fine for my use case.

Setting macro mode to disable didn't help (I didn't have it customized in my toml):

[codegen.macro]
macro_mode = "disable"

[Gnimuc]

According to

https://github.com/apple/swift-corelibs-libdispatch/blob/542b7f32311680b11b6fc8fcb2576955460ba7da/dispatch/object.h#L89-L105

that macro should be as simple as #define DISPATCH_DECL(name) typedef struct name##_s *name##_t. DISPATCH_DECL(dispatch_data) is equivalent to:

typedef struct dispatch_data_s * dispatch_data_t;

But the warning from the CollectDependentSystemNode pass shows that only dispatch_data_t is collected. There might be a bug in that pass. Another possibility is that the compiler flags are not correctly configured, so DISPATCH_DECL is parsed as something else.

[ Info: Building the DAG...
┌ Warning: [CollectDependentSystemNode]: found symbols in the system headers: [:dispatch_data_t]
└ @ Clang.Generators ~/.julia/packages/Clang/uJQ2L/src/generator/passes.jl:95
ERROR: LoadError: There is no definition for dispatch_data_t's underlying type: [``] at /Users/tim/.julia/artifacts/fbb170fa64a06b66dd9a16aaa21bf12848042d9a/aarch64-apple-darwin20/sys-root/usr/include/dispatch/data.h:44:1
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35