From c78e9849993a3e6c9feccbc6422864d9a764bd61 Mon Sep 17 00:00:00 2001
From: Neven Sajko <s@purelymail.com>
Date: Mon, 9 Jun 2025 00:27:39 +0200
Subject: [PATCH] improve inferred effects for `reshape` for `Array`

Use `LazyString` in `throw_dmrsa`.
---
 base/reshapedarray.jl |  2 +-
 test/arrayops.jl      | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/base/reshapedarray.jl b/base/reshapedarray.jl
index e831a75dfe3da..5bfa64d756a97 100644
--- a/base/reshapedarray.jl
+++ b/base/reshapedarray.jl
@@ -36,7 +36,7 @@ length(R::ReshapedArrayIterator) = length(R.iter)
 eltype(::Type{<:ReshapedArrayIterator{I}}) where {I} = @isdefined(I) ? ReshapedIndex{eltype(I)} : Any
 
 @noinline throw_dmrsa(dims, len) =
-    throw(DimensionMismatch("new dimensions $(dims) must be consistent with array length $len"))
+    throw(DimensionMismatch(LazyString("new dimensions ", dims, " must be consistent with array length ", len)))
 
 ## reshape(::Array, ::Dims) returns a new Array (to avoid conditionally aliasing the structure, only the data)
 # reshaping to same # of dimensions
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 7e2454eabd93c..5d68f70e9caf1 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -100,6 +100,18 @@ using Dates
     @test Array{eltype(a)}(a) !== a
     @test Vector(a) !== a
 end
+@testset "effect inference for `reshape` for `Array`" begin
+    for Arr ∈ (Array{<:Any, 0}, Vector, Matrix, Array{<:Any, 3})
+        for Shape ∈ (Tuple{Int}, Tuple{Int, Int})
+            effects = Base.infer_effects(reshape, Tuple{Arr{Float32}, Shape})
+            @test Base.Compiler.is_effect_free(effects)
+            @test Base.Compiler.is_terminates(effects)
+            @test Base.Compiler.is_notaskstate(effects)
+            @test Base.Compiler.is_noub(effects)
+            @test Base.Compiler.is_nortcall(effects)
+        end
+    end
+end
 @testset "reshaping SubArrays" begin
     a = Array(reshape(1:5, 1, 5))
     @testset "linearfast" begin