fix map! undefined value exposure

base/abstractarray.jl

@@ -3355,9 +3355,9 @@ concatenate_setindex!(R, X::AbstractArray, I...) = (R[I...] = X)
 ## 1 argument
 
 function map!(f::F, dest::AbstractArray, A::AbstractArray) where F
-    for (i,j) in zip(eachindex(dest),eachindex(A))
-        val = f(@inbounds A[j])
-        @inbounds dest[i] = val
+    inds = LinearIndices(A)
+    for i = inds
+        dest[i] = f(A[i])
     end
     return dest
 end
@@ -3400,10 +3400,11 @@ map(f, ::AbstractSet) = error("map is not defined on sets")
 
 ## 2 argument
 function map!(f::F, dest::AbstractArray, A::AbstractArray, B::AbstractArray) where F
-    for (i, j, k) in zip(eachindex(dest), eachindex(A), eachindex(B))
-        @inbounds a, b = A[j], B[k]
-        val = f(a, b)
-        @inbounds dest[i] = val
+    IL = IndexLinear()
+    inds = intersect(eachindex(IL, A), eachindex(IL, B))
+    @boundscheck checkbounds(dest, inds)
+    for i = inds
+        dest[i] = f(A[i], B[i])
     end
     return dest
 end
@@ -3417,12 +3418,10 @@ function ith_all(i, as)
 end
 
 function map_n!(f::F, dest::AbstractArray, As) where F
-    idxs1 = LinearIndices(As[1])
-    @boundscheck LinearIndices(dest) == idxs1 && all(x -> LinearIndices(x) == idxs1, As)
-    for i = idxs1
-        @inbounds I = ith_all(i, As)
-        val = f(I...)
-        @inbounds dest[i] = val
+    inds = mapreduce(Fix1(eachindex, IndexLinear()), intersect, As)
+    @boundscheck checkbounds(dest, inds)
+    for i = inds
+        dest[i] = f(ith_all(i, As)...)
     end
     return dest
 end

base/reducedim.jl

@@ -238,7 +238,7 @@ copyfirst!(R::AbstractArray, A::AbstractArray) = mapfirst!(identity, R, A)
 function mapfirst!(f::F, R::AbstractArray, A::AbstractArray{<:Any,N}) where {N, F}
     lsiz = check_reducedims(R, A)
     t = _firstreducedslice(axes(R), axes(A))
-    map!(f, R, view(A, t...))
+    map!(f, view(R, firstindex(R):lastindex(R)), view(A, t...))
 end
 # We know that the axes of R and A are compatible, but R might have a different number of
 # dimensions than A, which is trickier than it seems due to offset arrays and type stability

test/abstractarray.jl

@@ -910,6 +910,25 @@ include("generic_map_tests.jl")
 generic_map_tests(map, map!)
 @test map!(-, [1]) == [-1]
 
+@testset "#30624" begin
+    ### unstructured
+    @test map!(+, ones(3), ones(3), ones(3), [1]) == [3, 1, 1]
+    @test map!(+, ones(3), [1], ones(3), ones(3)) == [3, 1, 1]
+    @test map!(+, [1], [1], [], []) == [1]
+    @test map!(+, [[1]], [1], [], []) == [[1]]
+
+    @test_throws BoundsError map!(+, ones(1), ones(2))
+    @test_throws BoundsError map!(+, ones(1), ones(2, 2))
+
+    @test map!(+, ones(3), view(ones(2, 3), 1:2, 2:3), ones(3)) == [2, 2, 2]
+    @test map!(+, ones(3), ones(2, 2), ones(3)) == [2, 2, 2]
+
+    ### structured (all mapped arguments are <:AbstractArray equal ndims > 1)
+    @test map!(+, ones(4), ones(2, 2), ones(2, 2)) == [2, 2, 2, 2]
+    @test map!(+, ones(4), ones(2, 2), ones(1, 2)) == [2, 2, 1, 1]
+    @test_throws BoundsError map!(+, ones(3), ones(2, 2), ones(2, 2))
+end
+
 test_UInt_indexing(TestAbstractArray)
 test_13315(TestAbstractArray)
 test_checksquare()

test/offsetarray.jl

@@ -344,6 +344,8 @@ map!(+, dest, am, am)
 am = map(identity, a)
 @test isa(am, OffsetArray)
 @test am == a
+@test_throws BoundsError map!(identity, fill(0, 1:3), fill(1, 2:4))
+
 
 # https://github.com/JuliaArrays/OffsetArrays.jl/issues/106
 @test isequal(map(!, OffsetArray([true,missing],2)), OffsetArray([false, missing], 2))