Fix insert and deleteat boundscheck for tuples. Improve unsafe_deleteat performance for single- and two-element tuples.

Author: chriselrod

src/ArrayInterface.jl

@@ -617,8 +617,8 @@ Base.@propagate_inbounds function insert(collection, index, item)
   return ret
 end
 
-function insert(x::Tuple, index::Integer, item)
-  @boundscheck if !checkindex(Bool, static_first(x):static_last(x), index)
+function insert(x::Tuple{Vararg{Any,N}}, index::Integer, item) where {N}
+  @boundscheck if !checkindex(Bool, StaticInt{1}():StaticInt{N}(), index)
     throw(BoundsError(x, index))
   end
   return unsafe_insert(x, Int(index), item)
@@ -643,8 +643,8 @@ Return a new instance of `collection` with the item at the given `index` removed
   end
   return unsafe_deleteat(collection, index)
 end
-@propagate_inbounds function deleteat(collection::Tuple, index)
-  @boundscheck if !checkindex(Bool, static_first(collection):static_last(collection), index)
+@propagate_inbounds function deleteat(collection::Tuple{Vararg{Any,N}}, index) where {N}
+  @boundscheck if !checkindex(Bool, StaticInt{1}():StaticInt{N}(), index)
     throw(BoundsError(collection, index))
   end
   return unsafe_deleteat(collection, index)
@@ -686,6 +686,8 @@ end
   return Tuple(dst)
 end
 
+@inline unsafe_deleteat(x::Tuple{T}, i::Integer) where {T} = ()
+@inline unsafe_deleteat(x::Tuple{T1,T2}, i::Integer) where {T1,T2} = isone(i) ? (x[2],) : (x[1],)
 @inline function unsafe_deleteat(x::Tuple, i::Integer)
   if i === one(i)
     return Base.tail(x)

test/runtests.jl

@@ -463,13 +463,13 @@ end
     @test @inferred(ArrayInterface.deleteat([1, 2, 3], [2, 3])) == [1]
 
 
-    @test @inferred(ArrayInterface.insert((1,2,3), 1, -2)) == (-2, 1, 2, 3)
-    @test @inferred(ArrayInterface.insert((1,2,3), 2, -2)) == (1, -2, 2, 3)
-    @test @inferred(ArrayInterface.insert((1,2,3), 3, -2)) == (1, 2, -2, 3)
+    @test @inferred(ArrayInterface.insert((2,3,4), 1, -2)) == (-2, 2, 3, 4)
+    @test @inferred(ArrayInterface.insert((2,3,4), 2, -2)) == (2, -2, 3, 4)
+    @test @inferred(ArrayInterface.insert((2,3,4), 3, -2)) == (2, 3, -2, 4)
 
-    @test @inferred(ArrayInterface.deleteat((1, 2, 3), 1)) == (2, 3)
-    @test @inferred(ArrayInterface.deleteat((1, 2, 3), 2)) == (1, 3)
-    @test @inferred(ArrayInterface.deleteat((1, 2, 3), 3)) == (1, 2)
+    @test @inferred(ArrayInterface.deleteat((2, 3, 4), 1)) == (3, 4)
+    @test @inferred(ArrayInterface.deleteat((2, 3, 4), 2)) == (2, 4)
+    @test @inferred(ArrayInterface.deleteat((2, 3, 4), 3)) == (2, 3)
     @test ArrayInterface.deleteat((1, 2, 3), [1, 2]) == (3,)
 end