From 7a25348ab838a10a0aa1ec043f76dfbdca7db02f Mon Sep 17 00:00:00 2001
From: JamesWrigley <james@puiterwijk.org>
Date: Thu, 19 Mar 2026 23:22:14 +0100
Subject: [PATCH] Change `isassigned()` to match the Base definition

ScopedValues.jl previously used `isassigned()` to check if a `ScopedValue` had a
default value, but this differs from Base which uses `isassigned()` to check if
a `ScopedValue` is initialized in the current scope.
---
 src/ScopedValues.jl | 9 +++++++--
 test/runtests.jl    | 7 +++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/ScopedValues.jl b/src/ScopedValues.jl
index f98b319..9d721da 100644
--- a/src/ScopedValues.jl
+++ b/src/ScopedValues.jl
@@ -66,9 +66,14 @@ Base.eltype(::ScopedValue{T}) where {T} = T
 """
     isassigned(val::ScopedValue)
 
-Test if the ScopedValue has a default value.
+Test if the ScopedValue has an assigned value.
 """
-Base.isassigned(val::ScopedValue) = val.has_default
+function Base.isassigned(val::ScopedValue)
+    val.has_default && return true
+    scope = current_scope()::Union{Scope, Nothing}
+    scope === nothing && return false
+    return haskey((scope::Scope).values, val)
+end
 
 const ScopeStorage = HAMT{ScopedValue, Any}
 
diff --git a/test/runtests.jl b/test/runtests.jl
index 8d51b1d..f7123a1 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -131,6 +131,13 @@ end
     @test ret == 1.23
 end
 
+const sval_uninitialized = ScopedValue{Int}()
+
+@testset "isassigned()" begin
+    @test !isassigned(sval_uninitialized)
+    @with sval_uninitialized => 42 @test isassigned(sval_uninitialized)
+end
+
 @testset "ScopedThunk" begin
     function check_svals()
         @test sval[] == 8