Dont materialize bc expr with uninitialized data (#2253)

Author: charleskawczynski

src/Fields/broadcast.jl

@@ -177,6 +177,9 @@ function Base.similar(
     return Field(similar(todata(bc), Eltype), axes(bc))
 end
 
+Base.similar(bc::Base.Broadcast.Broadcasted{<:AbstractFieldStyle}) =
+    Base.similar(bc, eltype(bc))
+
 @inline function Base.copyto!(
     dest::Field,
     bc::Base.Broadcast.Broadcasted{<:AbstractFieldStyle},

src/MatrixFields/field_matrix_iterative_solver.jl

@@ -49,7 +49,7 @@ preconditioner generated by the `PreconditionerAlgorithm` `P_alg` for `A`.
 function preconditioner_cache(P_alg, A, b)
     is_diagonal(P_alg) && return (;)
     lazy_P = lazy_preconditioner(P_alg, A)
-    P = is_lazy(lazy_P) ? Base.Broadcast.materialize(lazy_P) : lazy_P
+    P = is_lazy(lazy_P) ? similar(lazy_P) : lazy_P
     P_if_needed = is_lazy(lazy_P) ? (; P) : (;)
     x = similar_to_x(P, b)
     alg = solver_algorithm(P_alg)

src/Operators/finitedifference.jl

@@ -4017,6 +4017,9 @@ function Base.similar(
     return Field(Eltype, sp)
 end
 
+Base.similar(bc::Base.Broadcast.Broadcasted{<:AbstractStencilStyle}) =
+    Base.similar(bc, eltype(bc))
+
 function _serial_copyto!(field_out::Field, bc, Ni::Int, Nj::Int, Nh::Int)
     space = axes(field_out)
     bounds = window_bounds(space, bc)