get(A::AbstractArray, (), default) should get A[] (#30270)

NEWS.md

@@ -83,6 +83,8 @@ Standard library changes
   * New `ncodeunits(c::Char)` method as a fast equivalent to `ncodeunits(string(c))` ([#29153]).
   * New `sort!(::AbstractArray; dims)` method that can sort the array along the `dims` dimension ([#28902]).
   * `range` now accept `stop` as a positional argument ([#28708]).
+  * `get(A::AbstractArray, (), default)` now returns the result of `A[]` if it can instead of always
+    returning an empty array ([#30270]).
   * `parse(Bool, str)` is now supported ([#29997]).
   * `copyto!(::AbstractMatrix, ::UniformScaling)` supports rectangular matrices now ([#28790]).
   * In `put!(c::Channel{T}, v)`, `v` now gets converted to `T` as `put!` is being called ([#29092]).

base/abstractarray.jl

@@ -1166,7 +1166,7 @@ RangeVecIntList{A<:AbstractVector{Int}} = Union{Tuple{Vararg{Union{AbstractRange
     AbstractVector{UnitRange{Int}}, AbstractVector{AbstractRange{Int}}, AbstractVector{A}}
 
 get(A::AbstractArray, i::Integer, default) = checkbounds(Bool, A, i) ? A[i] : default
-get(A::AbstractArray, I::Tuple{}, default) = similar(A, typeof(default), 0)
+get(A::AbstractArray, I::Tuple{}, default) = checkbounds(Bool, A) ? A[] : default
 get(A::AbstractArray, I::Dims, default) = checkbounds(Bool, A, I...) ? A[I...] : default
 
 function get!(X::AbstractVector{T}, A::AbstractVector, I::Union{AbstractRange,AbstractVector{Int}}, default::T) where T

test/abstractarray.jl

@@ -584,11 +584,23 @@ function test_setindex!_internals(::Type{TestAbstractArray})
 end
 
 function test_get(::Type{TestAbstractArray})
-    A = T24Linear([1:24...])
-    B = TSlow([1:24...])
-
-    @test get(A, (), 0) == Int[]
-    @test get(B, (), 0) == TSlow(Int, 0)
+    A = T24Linear(reshape([1:24...], 4, 3, 2))
+    B = TSlow(reshape([1:24...], 4, 3, 2))
+
+    @test get(A, (), 0) == 0
+    @test get(B, (), 0) == 0
+    @test get(A, (1,), 0) == get(A, 1, 0) == A[1] == 1
+    @test get(B, (1,), 0) == get(B, 1, 0) == B[1] == 1
+    @test get(A, (25,), 0) == get(A, 25, 0) == 0
+    @test get(B, (25,), 0) == get(B, 25, 0) == 0
+    @test get(A, (1,1,1), 0) == A[1,1,1] == 1
+    @test get(B, (1,1,1), 0) == B[1,1,1] == 1
+    @test get(A, (1,1,3), 0) == 0
+    @test get(B, (1,1,3), 0) == 0
+
+    @test get(TSlow([]), (), 0) == 0
+    @test get(TSlow([1]), (), 0) == 1
+    @test get(TSlow(fill(1)), (), 0) == 1
 end
 
 function test_cat(::Type{TestAbstractArray})