From 10ead4e0544ba0a51c37f48aa21b3c3bc7e1073c Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:12:37 +0200
Subject: [PATCH 01/20] add seal_methodtable

---
 base/runtime_internals.jl | 19 +++++++++++++++++++
 src/gf.c                  | 13 ++++++++++++-
 src/jl_exported_funcs.inc |  1 +
 src/method.c              |  2 +-
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 645aa55c538b4..07dccb061d2a4 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1182,6 +1182,25 @@ function signature_type(@nospecialize(f), @nospecialize(argtypes))
     return rewrap_unionall(Tuple{ft, u.parameters...}, argtypes)
 end
 
+"""
+    delete_method(m::Method)
+
+Make method `m` uncallable and force recompilation of any methods that use(d) it.
+"""
+function delete_method(m::Method)
+    ccall(:jl_method_table_disable, Cvoid, (Any, Any), get_methodtable(m), m)
+end
+
+"""
+    seal_methodtable(m::Core.MethodTable)
+
+Disallow adding or modifyng methods of `mt`.
+"""
+function seal_methodtable(m::Core.MethodTable)
+    ccall(:jl_method_table_seal, Cvoid, (Any,), m)
+end
+seal_methodtable(m::Nothing) = nothing
+
 function get_methodtable(m::Method)
     mt = ccall(:jl_method_get_table, Any, (Any,), m)
     if mt === nothing
diff --git a/src/gf.c b/src/gf.c
index fc2e62ebff96b..8109b1cae91a1 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -772,7 +772,7 @@ static int reset_mt_caches(jl_methtable_t *mt, void *env)
 {
     // removes all method caches
     // this might not be entirely safe (GC or MT), thus we only do it very early in bootstrapping
-    if (!mt->frozen) { // make sure not to reset builtin functions
+    if (!mt->frozen) { // make sure not to reset frozen functions
         jl_atomic_store_release(&mt->leafcache, (jl_genericmemory_t*)jl_an_empty_memory_any);
         jl_atomic_store_release(&mt->cache, jl_nothing);
     }
@@ -2028,6 +2028,17 @@ JL_DLLEXPORT void jl_method_table_disable(jl_methtable_t *mt, jl_method_t *metho
     JL_UNLOCK(&world_counter_lock);
 }
 
+JL_DLLEXPORT void jl_method_table_seal(jl_methtable_t *mt)
+{
+    JL_LOCK(&world_counter_lock);
+    JL_LOCK(&mt->writelock);
+    size_t world = jl_atomic_load_relaxed(&jl_world_counter);
+    mt->frozen = 1;
+    jl_atomic_store_release(&jl_world_counter, world + 1);
+    JL_UNLOCK(&mt->writelock);
+    JL_UNLOCK(&world_counter_lock);
+}
+
 static int jl_type_intersection2(jl_value_t *t1, jl_value_t *t2, jl_value_t **isect JL_REQUIRE_ROOTED_SLOT, jl_value_t **isect2 JL_REQUIRE_ROOTED_SLOT)
 {
     *isect2 = NULL;
diff --git a/src/jl_exported_funcs.inc b/src/jl_exported_funcs.inc
index f712f154ed896..32aaf13435d84 100644
--- a/src/jl_exported_funcs.inc
+++ b/src/jl_exported_funcs.inc
@@ -305,6 +305,7 @@
     XX(jl_method_instance_add_backedge) \
     XX(jl_method_table_add_backedge) \
     XX(jl_method_table_disable) \
+    XX(jl_method_table_seal) \
     XX(jl_method_table_for) \
     XX(jl_method_table_insert) \
     XX(jl_methtable_lookup) \
diff --git a/src/method.c b/src/method.c
index 629816319b334..22c4bb4706bbf 100644
--- a/src/method.c
+++ b/src/method.c
@@ -1227,7 +1227,7 @@ JL_DLLEXPORT jl_method_t* jl_method_def(jl_svec_t *argdata,
     if ((jl_value_t*)mt == jl_nothing)
         jl_error("Method dispatch is unimplemented currently for this method signature");
     if (mt->frozen)
-        jl_error("cannot add methods to a builtin function");
+        jl_error("cannot add methods to or modify methods of a sealed function");
 
     assert(jl_is_linenode(functionloc));
     jl_sym_t *file = (jl_sym_t*)jl_linenode_file(functionloc);

From 8bef774a3c5d64041165425096a12d873a002153 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Sun, 13 Oct 2024 19:27:38 +0200
Subject: [PATCH 02/20] add test

---
 test/reflection.jl | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/test/reflection.jl b/test/reflection.jl
index 634390e0680d1..47e08542b6d75 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1298,3 +1298,11 @@ end
 @test Base.infer_return_type(code_lowered, (Any,Any)) == Vector{Core.CodeInfo}
 
 @test methods(Union{}) == Any[m.method for m in Base._methods_by_ftype(Tuple{Core.TypeofBottom, Vararg}, 1, Base.get_world_counter())] # issue #55187
+
+# sealing
+f_sealed(x::Int64) = x+1
+Base.seal_methodtable(Base.methods(f_sealed).mt)
+@test_throws(
+    ErrorException("cannot add methods to or modify methods of a sealed function"),
+    @eval f_sealed(x::Float64) = x+2
+)

From 22b224ea7c062d3c68c8d4460bcf842a9022fa6b Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:13:47 +0200
Subject: [PATCH 03/20] rm unused method

---
 base/runtime_internals.jl | 1 -
 1 file changed, 1 deletion(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 07dccb061d2a4..97ae69ce1f471 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1199,7 +1199,6 @@ Disallow adding or modifyng methods of `mt`.
 function seal_methodtable(m::Core.MethodTable)
     ccall(:jl_method_table_seal, Cvoid, (Any,), m)
 end
-seal_methodtable(m::Nothing) = nothing
 
 function get_methodtable(m::Method)
     mt = ccall(:jl_method_get_table, Any, (Any,), m)

From f39b7005760c9578f4bd872d8a9c5c9785f4e2b8 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:14:43 +0200
Subject: [PATCH 04/20] Fix typo in docstring

Co-authored-by: Alex Arslan <ararslan@comcast.net>
---
 base/runtime_internals.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 97ae69ce1f471..e690659857b61 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1194,7 +1194,7 @@ end
 """
     seal_methodtable(m::Core.MethodTable)
 
-Disallow adding or modifyng methods of `mt`.
+Disallow adding or modifying methods of `mt`.
 """
 function seal_methodtable(m::Core.MethodTable)
     ccall(:jl_method_table_seal, Cvoid, (Any,), m)

From 6580a915d7bf4f97537133cb887acd1025747bdc Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:16:12 +0200
Subject: [PATCH 05/20] rename seal_methodtable to freeze!

---
 base/runtime_internals.jl | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index e690659857b61..17b438b373190 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1192,12 +1192,12 @@ function delete_method(m::Method)
 end
 
 """
-    seal_methodtable(m::Core.MethodTable)
+    freeze!(mt::Core.MethodTable)
 
 Disallow adding or modifying methods of `mt`.
 """
-function seal_methodtable(m::Core.MethodTable)
-    ccall(:jl_method_table_seal, Cvoid, (Any,), m)
+function freeze!(mt::Core.MethodTable)
+    ccall(:jl_method_table_seal, Cvoid, (Any,), mt)
 end
 
 function get_methodtable(m::Method)

From 67830e855c4f486544c1a729d126d8627a92df55 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:17:12 +0200
Subject: [PATCH 06/20] add unfreeze! as counterpart to freeze!

---
 base/runtime_internals.jl | 15 ++++++++++++++-
 src/gf.c                  |  4 ++--
 src/jl_exported_funcs.inc |  2 +-
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 17b438b373190..30ba2def44377 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1195,9 +1195,22 @@ end
     freeze!(mt::Core.MethodTable)
 
 Disallow adding or modifying methods of `mt`.
+
+See also [`unfreeze!(mt)`](@ref unfreeze!).
 """
 function freeze!(mt::Core.MethodTable)
-    ccall(:jl_method_table_seal, Cvoid, (Any,), mt)
+    ccall(:jl_method_table_set_frozen, Cvoid, (Any,Cint), mt, 1)
+end
+
+"""
+    unfreeze!(mt::Core.MethodTable)
+
+Allow adding or modifying methods of `mt`.
+
+See also [`freeze!(mt)`](@ref freeze!).
+"""
+function unfreeze!(mt::Core.MethodTable)
+    ccall(:jl_method_table_set_frozen, Cvoid, (Any,Cint), mt, 0)
 end
 
 function get_methodtable(m::Method)
diff --git a/src/gf.c b/src/gf.c
index 8109b1cae91a1..5b6cd5f5fa9f3 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -2028,12 +2028,12 @@ JL_DLLEXPORT void jl_method_table_disable(jl_methtable_t *mt, jl_method_t *metho
     JL_UNLOCK(&world_counter_lock);
 }
 
-JL_DLLEXPORT void jl_method_table_seal(jl_methtable_t *mt)
+JL_DLLEXPORT void jl_method_table_set_frozen(jl_methtable_t *mt, int val)
 {
     JL_LOCK(&world_counter_lock);
     JL_LOCK(&mt->writelock);
     size_t world = jl_atomic_load_relaxed(&jl_world_counter);
-    mt->frozen = 1;
+    mt->frozen = val;
     jl_atomic_store_release(&jl_world_counter, world + 1);
     JL_UNLOCK(&mt->writelock);
     JL_UNLOCK(&world_counter_lock);
diff --git a/src/jl_exported_funcs.inc b/src/jl_exported_funcs.inc
index 32aaf13435d84..5ae8b661deb69 100644
--- a/src/jl_exported_funcs.inc
+++ b/src/jl_exported_funcs.inc
@@ -305,7 +305,7 @@
     XX(jl_method_instance_add_backedge) \
     XX(jl_method_table_add_backedge) \
     XX(jl_method_table_disable) \
-    XX(jl_method_table_seal) \
+    XX(jl_method_table_set_frozen) \
     XX(jl_method_table_for) \
     XX(jl_method_table_insert) \
     XX(jl_methtable_lookup) \

From c206b09e1a1decee4dee13fbe366c4a42f447f31 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:18:01 +0200
Subject: [PATCH 07/20] reword error msg

---
 base/runtime_internals.jl | 4 ++--
 src/method.c              | 2 +-
 test/reflection.jl        | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 30ba2def44377..2f69e42562972 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1199,7 +1199,7 @@ Disallow adding or modifying methods of `mt`.
 See also [`unfreeze!(mt)`](@ref unfreeze!).
 """
 function freeze!(mt::Core.MethodTable)
-    ccall(:jl_method_table_set_frozen, Cvoid, (Any,Cint), mt, 1)
+    ccall(:jl_method_table_set_frozen, Cvoid, (Any, Cint), mt, 1)
 end
 
 """
@@ -1210,7 +1210,7 @@ Allow adding or modifying methods of `mt`.
 See also [`freeze!(mt)`](@ref freeze!).
 """
 function unfreeze!(mt::Core.MethodTable)
-    ccall(:jl_method_table_set_frozen, Cvoid, (Any,Cint), mt, 0)
+    ccall(:jl_method_table_set_frozen, Cvoid, (Any, Cint), mt, 0)
 end
 
 function get_methodtable(m::Method)
diff --git a/src/method.c b/src/method.c
index 22c4bb4706bbf..10c7e3a2ddab9 100644
--- a/src/method.c
+++ b/src/method.c
@@ -1227,7 +1227,7 @@ JL_DLLEXPORT jl_method_t* jl_method_def(jl_svec_t *argdata,
     if ((jl_value_t*)mt == jl_nothing)
         jl_error("Method dispatch is unimplemented currently for this method signature");
     if (mt->frozen)
-        jl_error("cannot add methods to or modify methods of a sealed function");
+        jl_error("cannot add methods to or modify methods of a frozen function");
 
     assert(jl_is_linenode(functionloc));
     jl_sym_t *file = (jl_sym_t*)jl_linenode_file(functionloc);
diff --git a/test/reflection.jl b/test/reflection.jl
index 47e08542b6d75..d15ea8cafc456 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1303,6 +1303,6 @@ end
 f_sealed(x::Int64) = x+1
 Base.seal_methodtable(Base.methods(f_sealed).mt)
 @test_throws(
-    ErrorException("cannot add methods to or modify methods of a sealed function"),
+    ErrorException("cannot add methods to or modify methods of a frozen function"),
     @eval f_sealed(x::Float64) = x+2
 )

From e229f4fb2d347b823fac9ed04b8f03efd15a25de Mon Sep 17 00:00:00 2001
From: Florian <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 19:13:19 +0200
Subject: [PATCH 08/20] Apply suggestions from code review

Co-authored-by: Alex Arslan <ararslan@comcast.net>
---
 test/reflection.jl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/test/reflection.jl b/test/reflection.jl
index d15ea8cafc456..6632549457d0d 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1301,8 +1301,12 @@ end
 
 # sealing
 f_sealed(x::Int64) = x+1
-Base.seal_methodtable(Base.methods(f_sealed).mt)
+Base.freeze!(Base.methods(f_sealed).mt)
 @test_throws(
     ErrorException("cannot add methods to or modify methods of a frozen function"),
     @eval f_sealed(x::Float64) = x+2
 )
+Base.unfreeze!(Base.methods(f_sealed).mt)
+f_sealed(x::Float64) = x + 2
+@test f_sealed(1) == 2
+@test f_sealed(1.0) == 2.0

From 6284eab4780238e485b5aeb8d162f91d79bd5034 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 22:02:38 +0200
Subject: [PATCH 09/20] update tests

---
 test/core.jl       |  2 +-
 test/reflection.jl | 16 ++++++++--------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/test/core.jl b/test/core.jl
index 5ba0e99e730d4..1ff4afe99c687 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -2650,7 +2650,7 @@ for f in (:Any, :Function, :(Core.Builtin), :(Union{Nothing, Type}), :(Union{typ
     @test_throws ErrorException("Method dispatch is unimplemented currently for this method signature") @eval (::$f)() = 1
 end
 for f in (:(Core.getfield), :((::typeof(Core.getfield))), :((::Core.IntrinsicFunction)))
-    @test_throws ErrorException("cannot add methods to a builtin function") @eval $f() = 1
+    @test_throws ErrorException("cannot add methods to or modify methods of a frozen function") @eval $f() = 1
 end
 
 # issue #33370
diff --git a/test/reflection.jl b/test/reflection.jl
index 6632549457d0d..9bea2d5dfa58b 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1299,14 +1299,14 @@ end
 
 @test methods(Union{}) == Any[m.method for m in Base._methods_by_ftype(Tuple{Core.TypeofBottom, Vararg}, 1, Base.get_world_counter())] # issue #55187
 
-# sealing
-f_sealed(x::Int64) = x+1
-Base.freeze!(Base.methods(f_sealed).mt)
+# freezing Core.MethodTable
+f_frozen(x::Int) = x+1
+Base.freeze!(Base.methods(f_frozen).mt)
 @test_throws(
     ErrorException("cannot add methods to or modify methods of a frozen function"),
-    @eval f_sealed(x::Float64) = x+2
+    @eval f_frozen(x::Float64) = x+2
 )
-Base.unfreeze!(Base.methods(f_sealed).mt)
-f_sealed(x::Float64) = x + 2
-@test f_sealed(1) == 2
-@test f_sealed(1.0) == 2.0
+Base.unfreeze!(Base.methods(f_frozen).mt)
+f_frozen(x::Float64) = x+2
+@test f_frozen(1) == 2
+@test f_frozen(1.0) == 3.0

From f98bd1d395c0347f26bc628d3171b19b365ab6c3 Mon Sep 17 00:00:00 2001
From: Florian <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 23:22:05 +0200
Subject: [PATCH 10/20] rm unfreeze! again and rm rebase mistake

Co-authored-by: Jameson Nash <vtjnash@gmail.com>
---
 base/runtime_internals.jl | 20 --------------------
 test/reflection.jl        |  4 ----
 2 files changed, 24 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 2f69e42562972..49e749a19a789 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1182,15 +1182,6 @@ function signature_type(@nospecialize(f), @nospecialize(argtypes))
     return rewrap_unionall(Tuple{ft, u.parameters...}, argtypes)
 end
 
-"""
-    delete_method(m::Method)
-
-Make method `m` uncallable and force recompilation of any methods that use(d) it.
-"""
-function delete_method(m::Method)
-    ccall(:jl_method_table_disable, Cvoid, (Any, Any), get_methodtable(m), m)
-end
-
 """
     freeze!(mt::Core.MethodTable)
 
@@ -1202,17 +1193,6 @@ function freeze!(mt::Core.MethodTable)
     ccall(:jl_method_table_set_frozen, Cvoid, (Any, Cint), mt, 1)
 end
 
-"""
-    unfreeze!(mt::Core.MethodTable)
-
-Allow adding or modifying methods of `mt`.
-
-See also [`freeze!(mt)`](@ref freeze!).
-"""
-function unfreeze!(mt::Core.MethodTable)
-    ccall(:jl_method_table_set_frozen, Cvoid, (Any, Cint), mt, 0)
-end
-
 function get_methodtable(m::Method)
     mt = ccall(:jl_method_get_table, Any, (Any,), m)
     if mt === nothing
diff --git a/test/reflection.jl b/test/reflection.jl
index 9bea2d5dfa58b..5b5bdbba92e41 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1306,7 +1306,3 @@ Base.freeze!(Base.methods(f_frozen).mt)
     ErrorException("cannot add methods to or modify methods of a frozen function"),
     @eval f_frozen(x::Float64) = x+2
 )
-Base.unfreeze!(Base.methods(f_frozen).mt)
-f_frozen(x::Float64) = x+2
-@test f_frozen(1) == 2
-@test f_frozen(1.0) == 3.0

From a0de0b32c9d850d4a8d530c0b4fcd0731ee189c2 Mon Sep 17 00:00:00 2001
From: Florian <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 23:36:33 +0200
Subject: [PATCH 11/20] rm locking and world age increments

Co-authored-by: Jameson Nash <vtjnash@gmail.com>
---
 src/gf.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/src/gf.c b/src/gf.c
index 5b6cd5f5fa9f3..cdebc53259430 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -2030,13 +2030,7 @@ JL_DLLEXPORT void jl_method_table_disable(jl_methtable_t *mt, jl_method_t *metho
 
 JL_DLLEXPORT void jl_method_table_set_frozen(jl_methtable_t *mt, int val)
 {
-    JL_LOCK(&world_counter_lock);
-    JL_LOCK(&mt->writelock);
-    size_t world = jl_atomic_load_relaxed(&jl_world_counter);
     mt->frozen = val;
-    jl_atomic_store_release(&jl_world_counter, world + 1);
-    JL_UNLOCK(&mt->writelock);
-    JL_UNLOCK(&world_counter_lock);
 }
 
 static int jl_type_intersection2(jl_value_t *t1, jl_value_t *t2, jl_value_t **isect JL_REQUIRE_ROOTED_SLOT, jl_value_t **isect2 JL_REQUIRE_ROOTED_SLOT)

From bb5b4ab0cdb2a348f9f7882947d63c74898b084f Mon Sep 17 00:00:00 2001
From: Florian <florian.atteneder@gmail.com>
Date: Thu, 17 Oct 2024 23:37:14 +0200
Subject: [PATCH 12/20] use setfield! instead of ccall

Co-authored-by: Jameson Nash <vtjnash@gmail.com>
---
 base/runtime_internals.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 49e749a19a789..5c8e141f14e10 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1190,7 +1190,7 @@ Disallow adding or modifying methods of `mt`.
 See also [`unfreeze!(mt)`](@ref unfreeze!).
 """
 function freeze!(mt::Core.MethodTable)
-    ccall(:jl_method_table_set_frozen, Cvoid, (Any, Cint), mt, 1)
+    setfield!(mt, nfields(mt), 0x1)
 end
 
 function get_methodtable(m::Method)

From c08a509e5ca648eff8bf023715a61ea1fdb5bcf8 Mon Sep 17 00:00:00 2001
From: Florian <florian.atteneder@gmail.com>
Date: Fri, 18 Oct 2024 00:06:08 +0200
Subject: [PATCH 13/20] morph `freeze!` into `morespecific!`

Co-authored-by: Jameson Nash <vtjnash@gmail.com>
---
 base/runtime_internals.jl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 5c8e141f14e10..ac424df4be577 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -1189,7 +1189,11 @@ Disallow adding or modifying methods of `mt`.
 
 See also [`unfreeze!(mt)`](@ref unfreeze!).
 """
-function freeze!(mt::Core.MethodTable)
+function morespecific!(m::Method)
+    mt = get_methodtable(m)
+    # check that all Methods in this table are morespecific than m
+    # so we might avoid disabling a table that might get used for more than just subsets of m
+    all(m2 -> m === m2 || morespecific(m2, m), MethodList(mt)) || error("unsupported Method to disable")
     setfield!(mt, nfields(mt), 0x1)
 end
 

From 88b18a9ee2924c276732df3599e28a64789fbcd3 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Fri, 18 Oct 2024 00:05:42 +0200
Subject: [PATCH 14/20] update test

---
 test/reflection.jl | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/test/reflection.jl b/test/reflection.jl
index 5b5bdbba92e41..911e6009e80b5 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1299,10 +1299,10 @@ end
 
 @test methods(Union{}) == Any[m.method for m in Base._methods_by_ftype(Tuple{Core.TypeofBottom, Vararg}, 1, Base.get_world_counter())] # issue #55187
 
-# freezing Core.MethodTable
-f_frozen(x::Int) = x+1
-Base.freeze!(Base.methods(f_frozen).mt)
+# disallow adding new methods
+f_sealed(x::Int) = x+1
+Base.morespecific!(which(f_frozen, (Int,)))
 @test_throws(
     ErrorException("cannot add methods to or modify methods of a frozen function"),
-    @eval f_frozen(x::Float64) = x+2
+    @eval f_sealed(x::Float64) = x+2
 )

From e1232bca9db4249ba9eba1f8cbe32083fa354b10 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Fri, 18 Oct 2024 00:08:18 +0200
Subject: [PATCH 15/20] update docstring

---
 base/runtime_internals.jl | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index ac424df4be577..4471638f49ba1 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -966,6 +966,19 @@ typeintersect(@nospecialize(a), @nospecialize(b)) = (@_total_meta; ccall(:jl_typ
 morespecific(@nospecialize(a), @nospecialize(b)) = (@_total_meta; ccall(:jl_type_morespecific, Cint, (Any, Any), a::Type, b::Type) != 0)
 morespecific(a::Method, b::Method) = ccall(:jl_method_morespecific, Cint, (Any, Any), a, b) != 0
 
+"""
+    morespecific!(m::Method)
+
+Disallow adding methods more specific than `m`.
+"""
+function morespecific!(m::Method)
+    mt = get_methodtable(m)
+    # check that all Methods in this table are morespecific than m
+    # so we might avoid disabling a table that might get used for more than just subsets of m
+    all(m2 -> m === m2 || morespecific(m2, m), MethodList(mt)) || error("unsupported Method to disable")
+    setfield!(mt, nfields(mt), 0x1)
+end
+
 """
     fieldoffset(type, i)
 
@@ -1182,21 +1195,6 @@ function signature_type(@nospecialize(f), @nospecialize(argtypes))
     return rewrap_unionall(Tuple{ft, u.parameters...}, argtypes)
 end
 
-"""
-    freeze!(mt::Core.MethodTable)
-
-Disallow adding or modifying methods of `mt`.
-
-See also [`unfreeze!(mt)`](@ref unfreeze!).
-"""
-function morespecific!(m::Method)
-    mt = get_methodtable(m)
-    # check that all Methods in this table are morespecific than m
-    # so we might avoid disabling a table that might get used for more than just subsets of m
-    all(m2 -> m === m2 || morespecific(m2, m), MethodList(mt)) || error("unsupported Method to disable")
-    setfield!(mt, nfields(mt), 0x1)
-end
-
 function get_methodtable(m::Method)
     mt = ccall(:jl_method_get_table, Any, (Any,), m)
     if mt === nothing

From ed9ec6edec5d3d2e70f19b3bab6a82b4022eb4d3 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Fri, 18 Oct 2024 00:29:23 +0200
Subject: [PATCH 16/20] rm jl_method_table_set_frozen

---
 src/gf.c                  | 5 -----
 src/jl_exported_funcs.inc | 1 -
 2 files changed, 6 deletions(-)

diff --git a/src/gf.c b/src/gf.c
index cdebc53259430..abdda56730580 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -2028,11 +2028,6 @@ JL_DLLEXPORT void jl_method_table_disable(jl_methtable_t *mt, jl_method_t *metho
     JL_UNLOCK(&world_counter_lock);
 }
 
-JL_DLLEXPORT void jl_method_table_set_frozen(jl_methtable_t *mt, int val)
-{
-    mt->frozen = val;
-}
-
 static int jl_type_intersection2(jl_value_t *t1, jl_value_t *t2, jl_value_t **isect JL_REQUIRE_ROOTED_SLOT, jl_value_t **isect2 JL_REQUIRE_ROOTED_SLOT)
 {
     *isect2 = NULL;
diff --git a/src/jl_exported_funcs.inc b/src/jl_exported_funcs.inc
index 5ae8b661deb69..f712f154ed896 100644
--- a/src/jl_exported_funcs.inc
+++ b/src/jl_exported_funcs.inc
@@ -305,7 +305,6 @@
     XX(jl_method_instance_add_backedge) \
     XX(jl_method_table_add_backedge) \
     XX(jl_method_table_disable) \
-    XX(jl_method_table_set_frozen) \
     XX(jl_method_table_for) \
     XX(jl_method_table_insert) \
     XX(jl_methtable_lookup) \

From ebb41506c98ab4aae6635b38fa76839cdc6e8838 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Fri, 18 Oct 2024 01:09:09 +0200
Subject: [PATCH 17/20] add another test

---
 test/reflection.jl | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/test/reflection.jl b/test/reflection.jl
index 911e6009e80b5..6855cf969b453 100644
--- a/test/reflection.jl
+++ b/test/reflection.jl
@@ -1301,7 +1301,12 @@ end
 
 # disallow adding new methods
 f_sealed(x::Int) = x+1
-Base.morespecific!(which(f_frozen, (Int,)))
+f_sealed(x::Integer) = x+2
+@test_throws(
+    ErrorException("unsupported Method to disable"),
+    Base.morespecific!(which(f_sealed, (Int,)))
+)
+Base.morespecific!(which(f_sealed, (Integer,)))
 @test_throws(
     ErrorException("cannot add methods to or modify methods of a frozen function"),
     @eval f_sealed(x::Float64) = x+2

From b8f989c6e97e356a38b665b587e12ea1c422866c Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Fri, 18 Oct 2024 01:20:20 +0200
Subject: [PATCH 18/20] make jl_methtable_t->frozen an atomic field

---
 base/runtime_internals.jl | 2 +-
 src/datatype.c            | 2 +-
 src/gf.c                  | 4 ++--
 src/jltypes.c             | 4 ++--
 src/julia.h               | 2 +-
 src/method.c              | 2 +-
 src/staticdata.c          | 2 +-
 7 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/base/runtime_internals.jl b/base/runtime_internals.jl
index 4471638f49ba1..0765960c97ab3 100644
--- a/base/runtime_internals.jl
+++ b/base/runtime_internals.jl
@@ -976,7 +976,7 @@ function morespecific!(m::Method)
     # check that all Methods in this table are morespecific than m
     # so we might avoid disabling a table that might get used for more than just subsets of m
     all(m2 -> m === m2 || morespecific(m2, m), MethodList(mt)) || error("unsupported Method to disable")
-    setfield!(mt, nfields(mt), 0x1)
+    setfield!(mt, :frozen, 0x1, :monotonic)
 end
 
 """
diff --git a/src/datatype.c b/src/datatype.c
index c78b00fdd2245..44dedce8a3c02 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -54,7 +54,7 @@ JL_DLLEXPORT jl_methtable_t *jl_new_method_table(jl_sym_t *name, jl_module_t *mo
     mt->backedges = NULL;
     JL_MUTEX_INIT(&mt->writelock, "methodtable->writelock");
     mt->offs = 0;
-    mt->frozen = 0;
+    jl_atomic_store_relaxed(&mt->frozen, 0);
     return mt;
 }
 
diff --git a/src/gf.c b/src/gf.c
index abdda56730580..fcf25fb40dd39 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -331,7 +331,7 @@ jl_datatype_t *jl_mk_builtin_func(jl_datatype_t *dt, const char *name, jl_fptr_a
             (jl_value_t*)mi, 1, ~(size_t)0);
     jl_typemap_insert(&mt->cache, (jl_value_t*)mt, newentry, 0);
 
-    mt->frozen = 1;
+    jl_atomic_store_relaxed(&mt->frozen, 1);
     JL_GC_POP();
     return dt;
 }
@@ -772,7 +772,7 @@ static int reset_mt_caches(jl_methtable_t *mt, void *env)
 {
     // removes all method caches
     // this might not be entirely safe (GC or MT), thus we only do it very early in bootstrapping
-    if (!mt->frozen) { // make sure not to reset frozen functions
+    if (!jl_atomic_load_relaxed(&mt->frozen)) { // make sure not to reset frozen functions
         jl_atomic_store_release(&mt->leafcache, (jl_genericmemory_t*)jl_an_empty_memory_any);
         jl_atomic_store_release(&mt->cache, jl_nothing);
     }
diff --git a/src/jltypes.c b/src/jltypes.c
index 11f1d11a14edc..8b6e50dffdb8e 100644
--- a/src/jltypes.c
+++ b/src/jltypes.c
@@ -3038,9 +3038,9 @@ void jl_init_types(void) JL_GC_DISABLED
     jl_methtable_type->name->names = jl_perm_symsvec(11, "name", "defs",
                                                      "leafcache", "cache", "max_args",
                                                      "module", "backedges",
-                                                     "", "", "offs", "");
+                                                     "", "", "offs", "frozen");
     const static uint32_t methtable_constfields[1] = { 0x00000020 }; // (1<<5);
-    const static uint32_t methtable_atomicfields[1] = { 0x0000001e }; // (1<<1)|(1<<2)|(1<<3)|(1<<4);
+    const static uint32_t methtable_atomicfields[1] = { 0x00000041e }; // (1<<1)|(1<<2)|(1<<3)|(1<<4)|(1<<10);
     jl_methtable_type->name->constfields = methtable_constfields;
     jl_methtable_type->name->atomicfields = methtable_atomicfields;
     jl_precompute_memoized_dt(jl_methtable_type, 1);
diff --git a/src/julia.h b/src/julia.h
index 7bb5f31eda708..837724cc5253d 100644
--- a/src/julia.h
+++ b/src/julia.h
@@ -791,7 +791,7 @@ typedef struct _jl_methtable_t {
     jl_array_t *backedges; // (sig, caller::MethodInstance) pairs
     jl_mutex_t writelock;
     uint8_t offs;  // 0, or 1 to skip splitting typemap on first (function) argument
-    uint8_t frozen; // whether this accepts adding new methods
+    _Atomic(uint8_t) frozen; // whether this accepts adding new methods
 } jl_methtable_t;
 
 typedef struct {
diff --git a/src/method.c b/src/method.c
index 10c7e3a2ddab9..0c3b14d064b17 100644
--- a/src/method.c
+++ b/src/method.c
@@ -1226,7 +1226,7 @@ JL_DLLEXPORT jl_method_t* jl_method_def(jl_svec_t *argdata,
         mt = jl_method_table_for(argtype);
     if ((jl_value_t*)mt == jl_nothing)
         jl_error("Method dispatch is unimplemented currently for this method signature");
-    if (mt->frozen)
+    if (jl_atomic_load_acquire(&mt->frozen))
         jl_error("cannot add methods to or modify methods of a frozen function");
 
     assert(jl_is_linenode(functionloc));
diff --git a/src/staticdata.c b/src/staticdata.c
index af4527cbc143f..a432dd0ad3cde 100644
--- a/src/staticdata.c
+++ b/src/staticdata.c
@@ -975,7 +975,7 @@ static void jl_insert_into_serialization_queue(jl_serializer_state *s, jl_value_
             }
             else if (jl_typetagis(v, jl_typename_type)) {
                 jl_typename_t *tn = (jl_typename_t*)v;
-                if (tn->mt != NULL && !tn->mt->frozen) {
+                if (tn->mt != NULL && !jl_atomic_load_relaxed(&tn->mt->frozen)) {
                     jl_methtable_t * new_methtable = (jl_methtable_t *)ptrhash_get(&new_methtables, tn->mt);
                     if (new_methtable != HT_NOTFOUND)
                         record_field_change((jl_value_t **)&tn->mt, (jl_value_t*)new_methtable);

From 1de36808d673c74b7656ae5a73ef846fd55fa380 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Wed, 23 Oct 2024 20:45:10 +0200
Subject: [PATCH 19/20] update test

---
 test/core.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/core.jl b/test/core.jl
index 1ff4afe99c687..8440f4f21902a 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -35,7 +35,7 @@ for (T, c) in (
         (Core.CodeInstance, [:next, :min_world, :max_world, :inferred, :debuginfo, :ipo_purity_bits, :invoke, :specptr, :specsigflags, :precompile]),
         (Core.Method, [:primary_world, :deleted_world]),
         (Core.MethodInstance, [:cache, :flags]),
-        (Core.MethodTable, [:defs, :leafcache, :cache, :max_args]),
+        (Core.MethodTable, [:defs, :leafcache, :cache, :max_args, :frozen]),
         (Core.TypeMapEntry, [:next, :min_world, :max_world]),
         (Core.TypeMapLevel, [:arg1, :targ, :name1, :tname, :list, :any]),
         (Core.TypeName, [:cache, :linearcache]),

From 6d99ec20b19739622224395c8b0f81b40aeb0cc5 Mon Sep 17 00:00:00 2001
From: Florian Atteneder <florian.atteneder@gmail.com>
Date: Wed, 23 Oct 2024 20:53:11 +0200
Subject: [PATCH 20/20] add assert(mt != NULL) to make gc-analyzer happy

---
 src/method.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/method.c b/src/method.c
index 0c3b14d064b17..a0badc5b11e8d 100644
--- a/src/method.c
+++ b/src/method.c
@@ -1236,6 +1236,7 @@ JL_DLLEXPORT jl_method_t* jl_method_def(jl_svec_t *argdata,
     int32_t line = jl_linenode_line(functionloc);
 
     // TODO: derive our debug name from the syntax instead of the type
+    assert(mt != NULL);
     jl_methtable_t *kwmt = mt == jl_kwcall_mt ? jl_kwmethod_table_for(argtype) : mt;
     // if we have a kwcall, try to derive the name from the callee argument method table
     name = (kwmt ? kwmt : mt)->name;