Remove redundant convert in _setindex! (JuliaLang#56178)

Follow up to JuliaLang#56034, ref:
JuliaLang#56034 (comment).

---------

Co-authored-by: Cody Tapscott <[email protected]>

Author: giordano

base/array.jl

@@ -999,11 +999,11 @@ function setindex!(A::Array{T}, x, i1::Int, i2::Int, I::Int...) where {T}
     x = x isa T ? x : convert(T, x)::T
     return _setindex!(A, x, i1, i2, I...)
 end
-function _setindex!(A::Array{T}, x, i1::Int, i2::Int, I::Int...) where {T}
+function _setindex!(A::Array{T}, x::T, i1::Int, i2::Int, I::Int...) where {T}
     @inline
     @_noub_if_noinbounds_meta
     @boundscheck checkbounds(A, i1, i2, I...) # generally _to_linear_index requires bounds checking
-    memoryrefset!(memoryrefnew(A.ref, _to_linear_index(A, i1, i2, I...), false), x isa T ? x : convert(T,x)::T, :not_atomic, false)
+    memoryrefset!(memoryrefnew(A.ref, _to_linear_index(A, i1, i2, I...), false), x, :not_atomic, false)
     return A
 end
 

base/genericmemory.jl

@@ -235,13 +235,18 @@ getindex(A::Memory, c::Colon) = copy(A)
 
 ## Indexing: setindex! ##
 
-function setindex!(A::Memory{T}, x, i1::Int) where {T}
-    val = x isa T ? x : convert(T,x)::T
+function _setindex!(A::Memory{T}, x::T, i1::Int) where {T}
     ref = memoryrefnew(memoryref(A), i1, @_boundscheck)
-    memoryrefset!(ref, val, :not_atomic, @_boundscheck)
+    memoryrefset!(ref, x, :not_atomic, @_boundscheck)
     return A
 end
 
+function setindex!(A::Memory{T}, x, i1::Int) where {T}
+    @_propagate_inbounds_meta
+    val = x isa T ? x : convert(T,x)::T
+    return _setindex!(A, val, i1)
+end
+
 function setindex!(A::Memory{T}, x, i1::Int, i2::Int, I::Int...) where {T}
     @inline
     @boundscheck (i2 == 1 && all(==(1), I)) || throw_boundserror(A, (i1, i2, I...))