Update to LightBoundsError

Author: Jakob Nybo Andersen

CHANGELOG.md

@@ -15,6 +15,11 @@ not be mentioned here, because they do not impact how the package is to be used.
 * `Matrix` and other `Array` types with a different dimensionality than 1 is now
   `NotMemory`, since it is not equal to its own memory view, due to shape mismatch.
 
+* Out of bounds access now throws a `LightBoundsError` from the LightBoundsErrors
+  package, instead of `Base.BoundsError`.
+  This improves codegen slightly, as it enables escape analysis of the array,
+  and outlines error paths slightly more aggressively.
+
 * `MemoryView(::SubArray)` now accepts fewer subarray types. However, it is unlikely
   that any instance that is now no longer accepted worked previously, so it is
   unlikely to be breaking in practice.

src/MemoryViews.jl

@@ -110,7 +110,7 @@ Create a mutable memory view from its parts.
 ```jldoctest
 julia> v = [1,2,3,4];
 
-julia> ref = Base.memoryref(v);
+julia> ref = Base.cconvert(Ptr, v);
 
 julia> view = unsafe_from_parts(ref, 3)
 3-element MutableMemoryView{Int64}:

src/basic.jl

@@ -410,7 +410,7 @@ end
 
 Return the first element of `v` and all other elements as a new memory view.
 
-This function will throw a `BoundsError` if `v` is empty.
+This function will throw a `LightBoundsError` if `v` is empty.
 
 See also: [`split_last`](@ref)
 
@@ -425,7 +425,7 @@ julia> split_first(v[1:1])
 (0x01, UInt8[])
 
 julia> split_first(v[1:0])
-ERROR: BoundsError: attempt to access 0-element MutableMemoryView{UInt8} at index [1]
+ERROR: LightBoundsErrors.LightBoundsError: out-of-bounds indexing: `collection[1]`, where:
 [...]
 ```
 """
@@ -439,7 +439,7 @@ end
 
 Return the last element of `v` and all other elements as a new memory view.
 
-This function will throw a `BoundsError` if `v` is empty.
+This function will throw a `LightBoundsError` if `v` is empty.
 
 See also: [`split_first`](@ref)
 
@@ -454,7 +454,7 @@ julia> split_last(v[1:1])
 (0x01, UInt8[])
 
 julia> split_last(v[1:0])
-ERROR: BoundsError: attempt to access 0-element MutableMemoryView{UInt8} at index [1]
+ERROR: LightBoundsErrors.LightBoundsError: out-of-bounds indexing: `collection[1]`, where:
 [...]
 ```
 """
@@ -469,10 +469,10 @@ end
 Split a memory view into two at an index.
 
 The first will contain all indices in `1:i-1`, the second `i:end`.
-This function will throw a `BoundsError` if `i` is not in `1:end+1`.
+This function will throw a `LightBoundsError` if `i` is not in `1:end+1`.
 
 # Examples
-```jldocstest
+```jldoctest
 julia> split_at(MemoryView([1,2,3,4,5]), 2)
 ([1], [2, 3, 4, 5])
 
@@ -481,7 +481,9 @@ julia> split_at(MemoryView(Int8[1, 2, 3]), 4)
 ```
 """
 function split_at(v::MemoryView, i::Int)
-    @boundscheck checkbounds(1:(lastindex(v) + 1), i)
+    @boundscheck if i ∉ 1:lastindex(v) + 1
+        throw_lightboundserror(v, i)
+    end
     return (@inbounds(truncate(v, i - 1)), @inbounds(truncate_start(v, i)))
 end
 

test/runtests.jl

@@ -485,6 +485,8 @@ end
             @test split_at(mem, 2) == (mem[1:1], mem[2:end])
             @test split_at(mem, lastindex(mem)) == (mem[1:(end - 1)], mem[end:end])
             @test split_at(mem, lastindex(mem) + 1) == (mem[1:end], mem[1:0])
+            @test_throws LightBoundsError split_at(mem, 0)
+            @test_throws LightBoundsError split_at(mem, lastindex(mem) + 2)
             mem = mem[2:2]
             @test split_first(mem) == (mem[1], mem[2:end])
             @test split_last(mem) == (mem[end], mem[1:(end - 1)])
@@ -498,6 +500,8 @@ end
         (v1, v2) = split_at(mem, 1)
         @test v1 == v2
         @test isempty(v1)
+        @test_throws LightBoundsError split_at(mem, 0)
+        @test_throws LightBoundsError split_at(mem, 2)
     end
 
     @testset "Split unaligned" begin