Require all arrays in eachindex to have the same axes. Fixes #13310 (#…

…25108)

NEWS.md

@@ -324,6 +324,9 @@ This section lists changes that do not have deprecation warnings.
     points in reverse order; any string type overrides `reverse` to return a different
     type of string must also override `reverseind` to compute reversed indices correctly.
 
+  * `eachindex(A, B...)` now requires that all inputs have the same number of elements.
+    When the chosen indexing is Cartesian, they must have the same axes.
+
 Library improvements
 --------------------
 

base/abstractarray.jl

@@ -843,12 +843,9 @@ end
 eachindex(::IndexLinear, A::AbstractArray) = linearindices(A)
 function eachindex(::IndexLinear, A::AbstractArray, B::AbstractArray...)
     @_inline_meta
-    1:_maxlength(A, B...)
-end
-_maxlength(A) = length(A)
-function _maxlength(A, B, C...)
-    @_inline_meta
-    max(length(A), _maxlength(B, C...))
+    indsA = linearindices(A)
+    all(x->linearindices(x) == indsA, B) || throw_eachindex_mismatch(IndexLinear(), A, B...)
+    indsA
 end
 
 isempty(a::AbstractArray) = (_length(a) == 0)

base/multidimensional.jl

@@ -228,15 +228,11 @@ module IteratorsMD
 
     eachindex(::IndexCartesian, A::AbstractArray) = CartesianRange(axes(A))
 
-    @inline eachindex(::IndexCartesian, A::AbstractArray, B::AbstractArray...) =
-        CartesianRange(maxsize(A, B...))
-    maxsize() = ()
-    @inline maxsize(A) = size(A)
-    @inline maxsize(A, B...) = maxt(size(A), maxsize(B...))
-    @inline maxt(a::Tuple{}, b::Tuple{}) = ()
-    @inline maxt(a::Tuple{}, b::Tuple)   = b
-    @inline maxt(a::Tuple,   b::Tuple{}) = a
-    @inline maxt(a::Tuple,   b::Tuple)   = (max(a[1], b[1]), maxt(tail(a), tail(b))...)
+    @inline function eachindex(::IndexCartesian, A::AbstractArray, B::AbstractArray...)
+        axsA = axes(A)
+        all(x->axes(x) == axsA, B) || Base.throw_eachindex_mismatch(IndexCartesian(), A, B...)
+        CartesianRange(axsA)
+    end
 
     eltype(R::CartesianRange) = eltype(typeof(R))
     eltype(::Type{CartesianRange{N}}) where {N} = CartesianIndex{N}

base/replutil.jl

@@ -713,3 +713,10 @@ Such a method is usually undesirable to be displayed to the user in the REPL.
 function is_default_method(m::Method)
     return m.module == Base && m.file == Symbol("sysimg.jl") && m.sig == Tuple{Type{T},Any} where T
 end
+
+@noinline function throw_eachindex_mismatch(::IndexLinear, A...)
+    throw(DimensionMismatch("all inputs to eachindex must have the same indices, got $(join(linearindices.(A), ", ", " and "))"))
+end
+@noinline function throw_eachindex_mismatch(::IndexCartesian, A...)
+    throw(DimensionMismatch("all inputs to eachindex must have the same axes, got $(join(axes.(A), ", ", " and "))"))
+end

test/arrayops.jl

@@ -1636,10 +1636,16 @@ R = CartesianRange((0,3))
 R = CartesianRange((3,0))
 @test done(R, start(R)) == true
 
-@test @inferred(eachindex(Base.IndexCartesian(),zeros(3),zeros(2,2),zeros(2,2,2),zeros(2,2))) == CartesianRange((3,2,2))
-@test @inferred(eachindex(Base.IndexLinear(),zeros(3),zeros(2,2),zeros(2,2,2),zeros(2,2))) == 1:8
-@test @inferred(eachindex(zeros(3),view(zeros(3,3),1:2,1:2),zeros(2,2,2),zeros(2,2))) == CartesianRange((3,2,2))
-@test @inferred(eachindex(zeros(3),zeros(2,2),zeros(2,2,2),zeros(2,2))) == 1:8
+@testset "multi-array eachindex" begin
+    local a = zeros(2,2)
+    local b = view(zeros(3,2), 1:2, :)
+    @test @inferred(eachindex(Base.IndexCartesian(), a, b)) == CartesianRange((2,2))
+    @test @inferred(eachindex(Base.IndexLinear(), a, b)) == 1:4
+    @test @inferred(eachindex(a, b)) == CartesianRange((2,2))
+    @test @inferred(eachindex(a, a)) == 1:4
+    @test_throws DimensionMismatch eachindex(a, rand(3,3))
+    @test_throws DimensionMismatch eachindex(b, rand(3,3))
+end
 
 @testset "rotates" begin
     a = [1 0 0; 0 0 0]