fix #40249, reshaping SharedArray on another process (#40286)

(cherry picked from commit 79e198b)

Author: JeffBezanson

stdlib/SharedArrays/src/SharedArrays.jl

@@ -295,14 +295,21 @@ size(S::SharedArray) = S.dims
 elsize(::Type{SharedArray{T,N}}) where {T,N} = elsize(Array{T,N}) # aka fieldtype(T, :s)
 IndexStyle(::Type{<:SharedArray}) = IndexLinear()
 
+function local_array_by_id(refid)
+    if isa(refid, Future)
+        refid = remoteref_id(refid)
+    end
+    fetch(channel_from_id(refid))
+end
+
 function reshape(a::SharedArray{T}, dims::NTuple{N,Int}) where {T,N}
     if length(a) != prod(dims)
         throw(DimensionMismatch("dimensions must be consistent with array size"))
     end
     refs = Vector{Future}(undef, length(a.pids))
     for (i, p) in enumerate(a.pids)
-        refs[i] = remotecall(p, a.refs[i], dims) do r,d
-            reshape(fetch(r),d)
+        refs[i] = remotecall(p, a.refs[i], dims) do r, d
+            reshape(local_array_by_id(r), d)
         end
     end
 
@@ -382,7 +389,7 @@ function shared_pids(pids)
         # only use workers on the current host
         pids = procs(myid())
         if length(pids) > 1
-            pids = filter(x -> x != 1, pids)
+            pids = filter(!=(1), pids)
         end
 
         onlocalhost = true
@@ -419,13 +426,7 @@ sub_1dim(S::SharedArray, pidx) = view(S.s, range_1dim(S, pidx))
 function init_loc_flds(S::SharedArray{T,N}, empty_local=false) where T where N
     if myid() in S.pids
         S.pidx = findfirst(isequal(myid()), S.pids)
-        if isa(S.refs[1], Future)
-            refid = remoteref_id(S.refs[S.pidx])
-        else
-            refid = S.refs[S.pidx]
-        end
-        c = channel_from_id(refid)
-        S.s = fetch(c)
+        S.s = local_array_by_id(S.refs[S.pidx])
         S.loc_subarr_1d = sub_1dim(S, S.pidx)
     else
         S.pidx = 0

stdlib/SharedArrays/test/runtests.jl

@@ -176,6 +176,12 @@ d = SharedArrays.shmem_fill(1.0, (10,10,10))
 @test fill(1., 100, 10) == reshape(d,(100,10))
 d = SharedArrays.shmem_fill(1.0, (10,10,10))
 @test_throws DimensionMismatch reshape(d,(50,))
+# issue #40249, reshaping on another process
+let m = SharedArray{ComplexF64}(10, 20, 30)
+    m2 = remotecall_fetch(() -> reshape(m, (100, :)), id_other)
+    @test size(m2) == (100, 60)
+    @test m2 isa SharedArray
+end
 
 # rand, randn
 d = SharedArrays.shmem_rand(dims)