The cfunction 1.0 deserves

base/c.jl

@@ -16,24 +16,56 @@ respectively.
 """
 cglobal
 
+struct CFunction
+    ptr::Ptr{Cvoid}
+    f::Any
+    _1::Ptr{Cvoid}
+    _2::Ptr{Cvoid}
+    let construtor = false end
+end
+unsafe_convert(::Type{Ptr{Cvoid}}, cf::CFunction) = cf.ptr
+
 """
-    cfunction(f::Function, returntype::Type, argtypes::Type) -> Ptr{Cvoid}
+    @cfunction(callable, ReturnType, (ArgumentTypes...,)) -> Ptr{Cvoid}
+    @cfunction(\$callable, ReturnType, (ArgumentTypes...,)) -> CFunction
+
+Generate a C-callable function pointer from the Julia function `closure`
+for the given type signature.
+
+Note that the argument type tuple must be a literal tuple, and not a tuple-valued variable or expression
+(although it can include a splat expression). And that these arguments will be evaluated in global scope
+during compile-time (not deferred until runtime).
+Adding a `\$` in front of the function argument changes this to instead create a runtime closure
+over the local variable `callable`.
 
-Generate C-callable function pointer from the Julia function `f`. Type annotation of the return
-value in the callback function is a must for situations where Julia cannot infer the return
-type automatically.
+See [manual section on ccall and cfunction usage](@ref Calling-C-and-Fortran-Code).
 
 # Examples
 ```julia-repl
 julia> function foo(x::Int, y::Int)
            return x + y
        end
 
-julia> cfunction(foo, Int, Tuple{Int,Int})
+julia> @cfunction(foo, Int, (Int, Int))
 Ptr{Cvoid} @0x000000001b82fcd0
 ```
 """
-cfunction(f, r, a) = ccall(:jl_function_ptr, Ptr{Cvoid}, (Any, Any, Any), f, r, a)
+macro cfunction(f, at, rt)
+    if !(isa(rt, Expr) && rt.head === :tuple)
+        throw(ArgumentError("@cfunction argument types must be a literal tuple"))
+    end
+    rt.head = :call
+    pushfirst!(rt.args, GlobalRef(Core, :svec))
+    if isa(f, Expr) && f.head === :$
+        fptr = f.args[1]
+        typ = CFunction
+    else
+        fptr = QuoteNode(f)
+        typ = Ptr{Cvoid}
+    end
+    cfun = Expr(:cfunction, typ, fptr, at, rt, QuoteNode(:ccall))
+    return esc(cfun)
+end
 
 if ccall(:jl_is_char_signed, Ref{Bool}, ())
     const Cchar = Int8

base/compiler/abstractinterpretation.jl

@@ -663,8 +663,8 @@ function abstract_call(@nospecialize(f), fargs::Union{Tuple{},Vector{Any}}, argt
     return abstract_call_gf_by_type(f, argtypes, atype, sv)
 end
 
-function abstract_eval_call(e::Expr, vtypes::VarTable, sv::InferenceState)
-    argtypes = Any[abstract_eval(a, vtypes, sv) for a in e.args]
+# wrapper around `abstract_call` for first computing if `f` is available
+function abstract_eval_call(fargs::Union{Tuple{},Vector{Any}}, argtypes::Vector{Any}, vtypes::VarTable, sv::InferenceState)
     #print("call ", e.args[1], argtypes, "\n\n")
     for x in argtypes
         x === Bottom && return Bottom
@@ -689,7 +689,7 @@ function abstract_eval_call(e::Expr, vtypes::VarTable, sv::InferenceState)
         end
         return abstract_call_gf_by_type(nothing, argtypes, argtypes_to_type(argtypes), sv)
     end
-    return abstract_call(f, e.args, argtypes, vtypes, sv)
+    return abstract_call(f, fargs, argtypes, vtypes, sv)
 end
 
 function sp_type_rewrap(@nospecialize(T), linfo::MethodInstance, isreturn::Bool)
@@ -730,6 +730,18 @@ function sp_type_rewrap(@nospecialize(T), linfo::MethodInstance, isreturn::Bool)
     return T
 end
 
+function abstract_eval_cfunction(e::Expr, vtypes::VarTable, sv::InferenceState)
+    f = abstract_eval(e.args[2], vtypes, sv)
+    # rt = sp_type_rewrap(e.args[3], sv.linfo, true)
+    at = Any[ sp_type_rewrap(argt, sv.linfo, false) for argt in e.args[4]::SimpleVector ]
+    pushfirst!(at, f)
+    # this may be the wrong world for the call,
+    # but some of the result is likely to be valid anyways
+    # and that may help generate better codegen
+    abstract_eval_call((), at, vtypes, sv)
+    nothing
+end
+
 function abstract_eval(@nospecialize(e), vtypes::VarTable, sv::InferenceState)
     if isa(e, QuoteNode)
         return AbstractEvalConstant((e::QuoteNode).value)
@@ -748,7 +760,8 @@ function abstract_eval(@nospecialize(e), vtypes::VarTable, sv::InferenceState)
     end
     e = e::Expr
     if e.head === :call
-        t = abstract_eval_call(e, vtypes, sv)
+        argtypes = Any[ abstract_eval(a, vtypes, sv) for a in e.args ]
+        t = abstract_eval_call(e.args, argtypes, vtypes, sv)
     elseif e.head === :new
         t = instanceof_tfunc(abstract_eval(e.args[1], vtypes, sv))[1]
         for i = 2:length(e.args)
@@ -767,6 +780,10 @@ function abstract_eval(@nospecialize(e), vtypes::VarTable, sv::InferenceState)
                 t = Bottom
             end
         end
+    elseif e.head === :cfunction
+        t = e.args[1]
+        isa(t, Type) || (t = Any)
+        abstract_eval_cfunction(e, vtypes, sv)
     elseif e.head === :static_parameter
         n = e.args[1]
         t = Any

base/compiler/optimize.jl

@@ -769,17 +769,26 @@ function substitute!(
         head = e.head
         if head === :static_parameter
             return quoted(spvals[e.args[1]])
+        elseif head === :cfunction
+            @assert !isa(spsig, UnionAll) || !isempty(spvals)
+            if !(e.args[2] isa QuoteNode) # very common no-op
+                e.args[2] = substitute!(e.args[2], na, argexprs, spsig, spvals, offset, boundscheck)
+            end
+            e.args[3] = ccall(:jl_instantiate_type_in_env, Any, (Any, Any, Ptr{Any}), e.args[3], spsig, spvals)
+            e.args[4] = svec(Any[
+                ccall(:jl_instantiate_type_in_env, Any, (Any, Any, Ptr{Any}), argt, spsig, spvals)
+                for argt
+                in e.args[4] ]...)
         elseif head === :foreigncall
             @assert !isa(spsig, UnionAll) || !isempty(spvals)
             for i = 1:length(e.args)
                 if i == 2
                     e.args[2] = ccall(:jl_instantiate_type_in_env, Any, (Any, Any, Ptr{Any}), e.args[2], spsig, spvals)
                 elseif i == 3
-                    argtuple = Any[
+                    e.args[3] = svec(Any[
                         ccall(:jl_instantiate_type_in_env, Any, (Any, Any, Ptr{Any}), argt, spsig, spvals)
                         for argt
-                        in e.args[3] ]
-                    e.args[3] = svec(argtuple...)
+                        in e.args[3] ]...)
                 elseif i == 4
                     @assert isa((e.args[4]::QuoteNode).value, Symbol)
                 elseif i == 5

base/compiler/validation.jl

@@ -22,6 +22,7 @@ const VALID_EXPR_HEADS = IdDict{Any,Any}(
     :meta => 0:typemax(Int),
     :global => 1:1,
     :foreigncall => 3:typemax(Int),
+    :cfunction => 6:6,
     :isdefined => 1:1,
     :simdloop => 0:0,
     :gc_preserve_begin => 0:typemax(Int),
@@ -139,9 +140,11 @@ function validate_code!(errors::Vector{>:InvalidCodeError}, c::CodeInfo, is_top_
                 end
                 validate_val!(x.args[1])
             elseif head === :call || head === :invoke || head == :gc_preserve_end || head === :meta ||
-                head === :inbounds || head === :foreigncall || head === :const || head === :enter ||
-                head === :leave || head === :method || head === :global || head === :static_parameter ||
-                head === :new || head === :thunk || head === :simdloop || head === :throw_undef_if_not || head === :unreachable
+                head === :inbounds || head === :foreigncall || head === :cfunction ||
+                head === :const || head === :enter || head === :leave ||
+                head === :method || head === :global || head === :static_parameter ||
+                head === :new || head === :thunk || head === :simdloop ||
+                head === :throw_undef_if_not || head === :unreachable
                 validate_val!(x)
             else
                 push!(errors, InvalidCodeError("invalid statement", x))
@@ -221,7 +224,7 @@ end
 
 function is_valid_rvalue(lhs, x)
     is_valid_argument(x) && return true
-    if isa(x, Expr) && x.head in (:new, :the_exception, :isdefined, :call, :invoke, :foreigncall, :gc_preserve_begin)
+    if isa(x, Expr) && x.head in (:new, :the_exception, :isdefined, :call, :invoke, :foreigncall, :cfunction, :gc_preserve_begin)
         return true
         # TODO: disallow `globalref = call` when .typ field is removed
         #return isa(lhs, SSAValue) || isa(lhs, Slot)

base/deprecated.jl

@@ -495,6 +495,12 @@ end
 
 # PR #23066
 @deprecate cfunction(f, r, a::Tuple) cfunction(f, r, Tuple{a...})
+@noinline function cfunction(f, r, a)
+    @nospecialize(f, r, a)
+    depwarn("The function `cfunction` is now written as a macro `@cfunction`.", :cfunction)
+    return ccall(:jl_function_ptr, Ptr{Cvoid}, (Any, Any, Any), f, r, a)
+end
+export cfunction
 
 # PR 23341
 @eval GMP @deprecate gmp_version() version() false

base/exports.jl

@@ -924,7 +924,7 @@ export
     withenv,
 
 # C interface
-    cfunction,
+    @cfunction,
     cglobal,
     disable_sigint,
     pointer,

base/libuv.jl

@@ -85,13 +85,20 @@ function process_events(block::Bool)
     end
 end
 
+function uv_alloc_buf end
+function uv_readcb end
+function uv_writecb_task end
+function uv_return_spawn end
+function uv_asynccb end
+function uv_timercb end
+
 function reinit_stdio()
-    global uv_jl_alloc_buf     = cfunction(uv_alloc_buf, Cvoid, Tuple{Ptr{Cvoid}, Csize_t, Ptr{Cvoid}})
-    global uv_jl_readcb        = cfunction(uv_readcb, Cvoid, Tuple{Ptr{Cvoid}, Cssize_t, Ptr{Cvoid}})
-    global uv_jl_writecb_task  = cfunction(uv_writecb_task, Cvoid, Tuple{Ptr{Cvoid}, Cint})
-    global uv_jl_return_spawn  = cfunction(uv_return_spawn, Cvoid, Tuple{Ptr{Cvoid}, Int64, Int32})
-    global uv_jl_asynccb       = cfunction(uv_asynccb, Cvoid, Tuple{Ptr{Cvoid}})
-    global uv_jl_timercb       = cfunction(uv_timercb, Cvoid, Tuple{Ptr{Cvoid}})
+    global uv_jl_alloc_buf     = @cfunction(uv_alloc_buf, Cvoid, (Ptr{Cvoid}, Csize_t, Ptr{Cvoid}))
+    global uv_jl_readcb        = @cfunction(uv_readcb, Cvoid, (Ptr{Cvoid}, Cssize_t, Ptr{Cvoid}))
+    global uv_jl_writecb_task  = @cfunction(uv_writecb_task, Cvoid, (Ptr{Cvoid}, Cint))
+    global uv_jl_return_spawn  = @cfunction(uv_return_spawn, Cvoid, (Ptr{Cvoid}, Int64, Int32))
+    global uv_jl_asynccb       = @cfunction(uv_asynccb, Cvoid, (Ptr{Cvoid},))
+    global uv_jl_timercb       = @cfunction(uv_timercb, Cvoid, (Ptr{Cvoid},))
 
     global uv_eventloop = ccall(:jl_global_event_loop, Ptr{Cvoid}, ())
     global stdin = init_stdio(ccall(:jl_stdin_stream, Ptr{Cvoid}, ()))

base/threadcall.jl

@@ -4,12 +4,6 @@ const max_ccall_threads = parse(Int, get(ENV, "UV_THREADPOOL_SIZE", "4"))
 const thread_notifiers = Union{Condition, Nothing}[nothing for i in 1:max_ccall_threads]
 const threadcall_restrictor = Semaphore(max_ccall_threads)
 
-function notify_fun(idx)
-    global thread_notifiers
-    notify(thread_notifiers[idx])
-    return
-end
-
 """
     @threadcall((cfunc, clib), rettype, (argtypes...), argvals...)
 
@@ -36,62 +30,71 @@ macro threadcall(f, rettype, argtypes, argvals...)
     argvals = map(esc, argvals)
 
     # construct non-allocating wrapper to call C function
-    wrapper = :(function wrapper(args_ptr::Ptr{Cvoid}, retval_ptr::Ptr{Cvoid})
+    wrapper = :(function (args_ptr::Ptr{Cvoid}, retval_ptr::Ptr{Cvoid})
         p = args_ptr
+        # the rest of the body is created below
     end)
     body = wrapper.args[2].args
     args = Symbol[]
-    for (i,T) in enumerate(argtypes)
+    for (i, T) in enumerate(argtypes)
         arg = Symbol("arg", i)
         push!(body, :($arg = unsafe_load(convert(Ptr{$T}, p))))
-        push!(body, :(p += sizeof($T)))
+        push!(body, :(p += Core.sizeof($T)))
         push!(args, arg)
     end
     push!(body, :(ret = ccall($f, $rettype, ($(argtypes...),), $(args...))))
     push!(body, :(unsafe_store!(convert(Ptr{$rettype}, retval_ptr), ret)))
-    push!(body, :(return sizeof($rettype)))
+    push!(body, :(return Int(Core.sizeof($rettype))))
 
     # return code to generate wrapper function and send work request thread queue
-    :(let
-        $wrapper
-        do_threadcall(wrapper, $rettype, Any[$(argtypes...)], Any[$(argvals...)])
+    wrapper = Expr(Symbol("hygienic-scope"), wrapper, @__MODULE__)
+    return :(let fun_ptr = @cfunction($wrapper, Int, (Ptr{Cvoid}, Ptr{Cvoid}))
+        do_threadcall(fun_ptr, $rettype, Any[$(argtypes...)], Any[$(argvals...)])
     end)
 end
 
-function do_threadcall(wrapper::Function, rettype::Type, argtypes::Vector, argvals::Vector)
+function do_threadcall(fun_ptr::Ptr{Cvoid}, rettype::Type, argtypes::Vector, argvals::Vector)
     # generate function pointer
-    fun_ptr = cfunction(wrapper, Int, Tuple{Ptr{Cvoid}, Ptr{Cvoid}})
-    c_notify_fun = cfunction(notify_fun, Cvoid, Tuple{Cint})
+    c_notify_fun = @cfunction(
+        function notify_fun(idx)
+            global thread_notifiers
+            notify(thread_notifiers[idx])
+            return
+        end, Cvoid, (Cint,))
 
     # cconvert, root and unsafe_convert arguments
     roots = Any[]
-    args_size = isempty(argtypes) ? 0 : sum(sizeof, argtypes)
+    args_size = isempty(argtypes) ? 0 : sum(Core.sizeof, argtypes)
     args_arr = Vector{UInt8}(undef, args_size)
     ptr = pointer(args_arr)
     for (T, x) in zip(argtypes, argvals)
+        isbits(T) || throw(ArgumentError("threadcall requires isbits argument types"))
         y = cconvert(T, x)
         push!(roots, y)
-        unsafe_store!(convert(Ptr{T}, ptr), unsafe_convert(T, y))
-        ptr += sizeof(T)
+        unsafe_store!(convert(Ptr{T}, ptr), unsafe_convert(T, y)::T)
+        ptr += Core.sizeof(T)
     end
 
     # create return buffer
-    ret_arr = Vector{UInt8}(undef, sizeof(rettype))
+    ret_arr = Vector{UInt8}(undef, Core.sizeof(rettype))
 
     # wait for a worker thread to be available
     acquire(threadcall_restrictor)
     idx = findfirst(isequal(nothing), thread_notifiers)::Int
     thread_notifiers[idx] = Condition()
 
-    # queue up the work to be done
-    ccall(:jl_queue_work, Cvoid,
-        (Ptr{Cvoid}, Ptr{UInt8}, Ptr{UInt8}, Ptr{Cvoid}, Cint),
-        fun_ptr, args_arr, ret_arr, c_notify_fun, idx)
+    GC.@preserve args_arr ret_arr roots begin
+        # queue up the work to be done
+        ccall(:jl_queue_work, Cvoid,
+            (Ptr{Cvoid}, Ptr{UInt8}, Ptr{UInt8}, Ptr{Cvoid}, Cint),
+            fun_ptr, args_arr, ret_arr, c_notify_fun, idx)
 
-    # wait for a result & return it
-    wait(thread_notifiers[idx])
-    thread_notifiers[idx] = nothing
-    release(threadcall_restrictor)
+        # wait for a result & return it
+        wait(thread_notifiers[idx])
+        thread_notifiers[idx] = nothing
+        release(threadcall_restrictor)
 
-    unsafe_load(convert(Ptr{rettype}, pointer(ret_arr)))
+        r = unsafe_load(convert(Ptr{rettype}, pointer(ret_arr)))
+    end
+    return r
 end

doc/src/base/c.md

@@ -3,7 +3,7 @@
 ```@docs
 ccall
 Core.Intrinsics.cglobal
-Base.cfunction
+Base.@cfunction
 Base.unsafe_convert
 Base.cconvert
 Base.unsafe_load