From 794764bf6c9a2c15f361199257864e2db647c3a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Fri, 18 Apr 2025 12:39:14 -0400
Subject: [PATCH 01/18] Revise external method tables

---
 src/lowered.jl    |   6 +--
 src/packagedef.jl |  33 +++++++-------
 test/runtests.jl  | 107 ++++++++++++++++++++++++++++++++++++++++------
 3 files changed, 113 insertions(+), 33 deletions(-)

diff --git a/src/lowered.jl b/src/lowered.jl
index 083ec6a2..5e308788 100644
--- a/src/lowered.jl
+++ b/src/lowered.jl
@@ -16,7 +16,7 @@ end
 # This defines the API needed to store signatures using methods_by_execution!
 # This default version is simple and only used for testing purposes.
 # The "real" one is CodeTrackingMethodInfo in Revise.jl.
-const MethodInfo = IdDict{Type,LineNumberNode}
+const MethodInfo = IdDict{Pair{<:Union{Nothing, MethodTable},<:Type},LineNumberNode}
 add_signature!(methodinfo::MethodInfo, @nospecialize(sig), ln) = push!(methodinfo, sig=>ln)
 push_expr!(methodinfo::MethodInfo, mod::Module, ex::Expr) = methodinfo
 pop_expr!(methodinfo::MethodInfo) = methodinfo
@@ -464,13 +464,13 @@ function methods_by_execution!(@nospecialize(recurse), methodinfo, docexprs, fra
                         uT = Base.unwrap_unionall(T)::DataType
                         ft = uT.types
                         sig1 = Tuple{Base.rewrap_unionall(Type{uT}, T), Any[Any for i in 1:length(ft)]...}
-                        push!(signatures, sig1)
+                        push!(signatures, nothing => sig1)
                         sig2 = Base.rewrap_unionall(Tuple{Type{T}, ft...}, T)
                         while T isa UnionAll
                             sig2 isa UnionAll || (sig2 = sig1; break) # sig2 doesn't define all parameters, so drop it
                             T = T.body
                         end
-                        sig1 == sig2 || push!(signatures, sig2)
+                        sig1 == sig2 || push!(signatures, nothing => sig2)
                         for sig in signatures
                             add_signature!(methodinfo, sig, lnn)
                         end
diff --git a/src/packagedef.jl b/src/packagedef.jl
index 813cf982..f404c891 100644
--- a/src/packagedef.jl
+++ b/src/packagedef.jl
@@ -4,7 +4,7 @@ using FileWatching, REPL, UUIDs
 import LibGit2
 using Base: PkgId
 using Base.Meta: isexpr
-using Core: CodeInfo
+using Core: CodeInfo, MethodTable
 
 export revise, includet, entr, MethodSummary
 
@@ -286,14 +286,14 @@ function delete_missing!(exs_sigs_old::ExprsSigs, exs_sigs_new)
             haskey(exs_sigs_new, ex) && continue
             # ex was deleted
             sigs === nothing && continue
-            for sig in sigs
-                ret = Base._methods_by_ftype(sig, -1, Base.get_world_counter())
+            for (mt, sig) in sigs
+                ret = Base._methods_by_ftype(sig, mt, -1, Base.get_world_counter())
                 success = false
                 if !isempty(ret)
                     m = get_method_from_match(ret[end])   # the last method returned is the least-specific that matches, and thus most likely to be type-equal
                     methsig = m.sig
                     if sig <: methsig && methsig <: sig
-                        locdefs = get(CodeTracking.method_info, sig, nothing)
+                        locdefs = get(CodeTracking.method_info, mt => sig, nothing)
                         if isa(locdefs, Vector{Tuple{LineNumberNode,Expr}})
                             if length(locdefs) > 1
                                 # Just delete this reference but keep the method
@@ -312,14 +312,14 @@ function delete_missing!(exs_sigs_old::ExprsSigs, exs_sigs_new)
                         for get_workers in workers_functions
                             for p in @invokelatest get_workers()
                                 try  # guard against serialization errors if the type isn't defined on the worker
-                                    @invokelatest remotecall_impl(Core.eval, p, Main, :(delete_method_by_sig($sig)))
+                                    @invokelatest remotecall_impl(Core.eval, p, Main, :(delete_method_by_sig($mt, $sig)))
                                 catch
                                 end
                             end
                         end
                         Base.delete_method(m)
                         # Remove the entries from CodeTracking data
-                        delete!(CodeTracking.method_info, sig)
+                        delete!(CodeTracking.method_info, mt => sig)
                         # Remove frame from JuliaInterpreter, if applicable. Otherwise debuggers
                         # may erroneously work with outdated code (265-like problems)
                         if haskey(JuliaInterpreter.framedict, m)
@@ -1161,7 +1161,7 @@ function get_def(method::Method; modified_files=revision_queue)
     # We need to find the right file.
     if method.module == Base || method.module == Core || method.module == Core.Compiler
         @warn "skipping $method to avoid parsing too much code"
-        CodeTracking.invoked_setindex!(CodeTracking.method_info, method.sig, missing)
+        CodeTracking.invoked_setindex!(CodeTracking.method_info, CodeTracking.method_info_key(method), missing)
         return false
     end
     parentfile, included_files = modulefiles(method.module)
@@ -1178,15 +1178,15 @@ function get_def(method::Method; modified_files=revision_queue)
         def = get_def(method, pkgdata, file)
         def !== nothing && return true
     end
-    @warn "$(method.sig) was not found"
+    @warn "$(method.sig)$(isdefined(method, :external_mt) ? " (overlayed)" : "") was not found"
     # So that we don't call it again, store missingness info in CodeTracking
-    CodeTracking.invoked_setindex!(CodeTracking.method_info, method.sig, missing)
+    CodeTracking.invoked_setindex!(CodeTracking.method_info, CodeTracking.method_info_key(method), missing)
     return false
 end
 
 function get_def(method, pkgdata, filename)
     maybe_extract_sigs!(maybe_parse_from_cache!(pkgdata, filename))
-    return get(CodeTracking.method_info, method.sig, nothing)
+    return get(CodeTracking.method_info, CodeTracking.method_info_key(method), nothing)
 end
 
 function get_tracked_id(id::PkgId; modified_files=revision_queue)
@@ -1245,10 +1245,9 @@ function update_stacktrace_lineno!(trace)
         end
         if linfo isa Core.MethodInstance
             m = linfo.def
-            sigt = m.sig
             # Why not just call `whereis`? Because that forces tracking. This is being
             # clever by recognizing that these entries exist only if there have been updates.
-            updated = get(CodeTracking.method_info, sigt, nothing)
+            updated = get(CodeTracking.method_info, CodeTracking.method_info_key(m), nothing)
             if updated !== nothing
                 lnn = updated[1][1]     # choose the first entry by default
                 lineoffset = lnn.line - m.line
@@ -1263,7 +1262,7 @@ end
 function method_location(method::Method)
     # Why not just call `whereis`? Because that forces tracking. This is being
     # clever by recognizing that these entries exist only if there have been updates.
-    updated = get(CodeTracking.method_info, method.sig, nothing)
+    updated = get(CodeTracking.method_info, CodeTracking.method_info_key(method), nothing)
     if updated !== nothing
         lnn = updated[1][1]
         return lnn.file, lnn.line
@@ -1321,16 +1320,16 @@ Revise itself does not need to be running on `p`.
 """
 function init_worker(p::AbstractWorker)
     @invokelatest remotecall_impl(Core.eval, p, Main, quote
-        function whichtt(@nospecialize sig)
-            ret = Base._methods_by_ftype(sig, -1, Base.get_world_counter())
+        function whichtt(mt::Union{Nothing, MethodTable}, @nospecialize sig)
+            ret = Base._methods_by_ftype(sig, mt, -1, Base.get_world_counter())
             isempty(ret) && return nothing
             m = ret[end][3]::Method   # the last method returned is the least-specific that matches, and thus most likely to be type-equal
             methsig = m.sig
             (sig <: methsig && methsig <: sig) || return nothing
             return m
         end
-        function delete_method_by_sig(@nospecialize sig)
-            m = whichtt(sig)
+        function delete_method_by_sig(mt::Union{Nothing, MethodTable}, @nospecialize sig)
+            m = whichtt(mt, sig)
             isa(m, Method) && Base.delete_method(m)
         end
     end)
diff --git a/test/runtests.jl b/test/runtests.jl
index a8c6c1b5..528561ae 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -266,7 +266,7 @@ end
         @test length(dvs) == 3
         (def, val) = dvs[1]
         @test isequal(Revise.unwrap(def), Revise.RelocatableExpr(:(square(x) = x^2)))
-        @test val == [Tuple{typeof(ReviseTest.square),Any}]
+        @test val == [nothing => Tuple{typeof(ReviseTest.square),Any}]
         @test Revise.firstline(Revise.unwrap(def)).line == 5
         m = @which ReviseTest.square(1)
         @test m.line == 5
@@ -274,14 +274,14 @@ end
         @test Revise.RelocatableExpr(definition(m)) == Revise.unwrap(def)
         (def, val) = dvs[2]
         @test isequal(Revise.unwrap(def), Revise.RelocatableExpr(:(cube(x) = x^3)))
-        @test val == [Tuple{typeof(ReviseTest.cube),Any}]
+        @test val == [nothing => Tuple{typeof(ReviseTest.cube),Any}]
         m = @which ReviseTest.cube(1)
         @test m.line == 7
         @test whereis(m) == (tmpfile, 7)
         @test Revise.RelocatableExpr(definition(m)) == Revise.unwrap(def)
         (def, val) = dvs[3]
         @test isequal(Revise.unwrap(def), Revise.RelocatableExpr(:(fourth(x) = x^4)))
-        @test val == [Tuple{typeof(ReviseTest.fourth),Any}]
+        @test val == [nothing => Tuple{typeof(ReviseTest.fourth),Any}]
         m = @which ReviseTest.fourth(1)
         @test m.line == 9
         @test whereis(m) == (tmpfile, 9)
@@ -291,7 +291,7 @@ end
         @test length(dvs) == 5
         (def, val) = dvs[1]
         @test isequal(Revise.unwrap(def),  Revise.RelocatableExpr(:(mult2(x) = 2*x)))
-        @test val == [Tuple{typeof(ReviseTest.Internal.mult2),Any}]
+        @test val == [nothing => Tuple{typeof(ReviseTest.Internal.mult2),Any}]
         @test Revise.firstline(Revise.unwrap(def)).line == 13
         m = @which ReviseTest.Internal.mult2(1)
         @test m.line == 11
@@ -299,7 +299,7 @@ end
         @test Revise.RelocatableExpr(definition(m)) == Revise.unwrap(def)
         (def, val) = dvs[2]
         @test isequal(Revise.unwrap(def), Revise.RelocatableExpr(:(mult3(x) = 3*x)))
-        @test val == [Tuple{typeof(ReviseTest.Internal.mult3),Any}]
+        @test val == [nothing => Tuple{typeof(ReviseTest.Internal.mult3),Any}]
         m = @which ReviseTest.Internal.mult3(1)
         @test m.line == 14
         @test whereis(m) == (tmpfile, 14)
@@ -327,10 +327,10 @@ end
         cmpdiff(logs[4], "Eval"; deltainfo=(ReviseTest, :(cube(x) = x^3)))
         cmpdiff(logs[5], "Eval"; deltainfo=(ReviseTest, :(fourth(x) = x^4)))
         stmpfile = Symbol(tmpfile)
-        cmpdiff(logs[6], "LineOffset"; deltainfo=(Any[Tuple{typeof(ReviseTest.Internal.mult2),Any}], LineNumberNode(11,stmpfile)=>LineNumberNode(13,stmpfile)))
+        cmpdiff(logs[6], "LineOffset"; deltainfo=(Any[nothing => Tuple{typeof(ReviseTest.Internal.mult2),Any}], LineNumberNode(11,stmpfile)=>LineNumberNode(13,stmpfile)))
         cmpdiff(logs[7], "Eval"; deltainfo=(ReviseTest.Internal, :(mult3(x) = 3*x)))
-        cmpdiff(logs[8], "LineOffset"; deltainfo=(Any[Tuple{typeof(ReviseTest.Internal.unchanged),Any}], LineNumberNode(18,stmpfile)=>LineNumberNode(19,stmpfile)))
-        cmpdiff(logs[9], "LineOffset"; deltainfo=(Any[Tuple{typeof(ReviseTest.Internal.unchanged2),Any}], LineNumberNode(20,stmpfile)=>LineNumberNode(21,stmpfile)))
+        cmpdiff(logs[8], "LineOffset"; deltainfo=(Any[nothing => Tuple{typeof(ReviseTest.Internal.unchanged),Any}], LineNumberNode(18,stmpfile)=>LineNumberNode(19,stmpfile)))
+        cmpdiff(logs[9], "LineOffset"; deltainfo=(Any[nothing => Tuple{typeof(ReviseTest.Internal.unchanged2),Any}], LineNumberNode(20,stmpfile)=>LineNumberNode(21,stmpfile)))
         @test length(Revise.actions(rlogger)) == 6  # by default LineOffset is skipped
         @test length(Revise.actions(rlogger; line=true)) == 9
         @test_broken length(Revise.diffs(rlogger)) == 2
@@ -503,8 +503,8 @@ end
                 m3 = first(methods(eval(fn3)))
                 m3file = joinpath(dn, "subdir", "file3.jl")
                 @test whereis(m3) == (m3file, 1)
-                @test signatures_at(m3file, 1) == [m3.sig]
-                @test signatures_at(eval(Symbol(modname)), joinpath("src", "subdir", "file3.jl"), 1) == [m3.sig]
+                @test signatures_at(m3file, 1) == [nothing => m3.sig]
+                @test signatures_at(eval(Symbol(modname)), joinpath("src", "subdir", "file3.jl"), 1) == [nothing => m3.sig]
 
                 id = Base.PkgId(eval(Symbol(modname)))   # for testing #596
                 pkgdata = Revise.pkgdatas[id]
@@ -1398,7 +1398,7 @@ end
             """)
         @yry()
         @test MacroSigs.blah() == 1
-        @test haskey(CodeTracking.method_info, (@which MacroSigs.blah()).sig)
+        @test haskey(CodeTracking.method_info, CodeTracking.method_info_key(@which MacroSigs.blah()))
         rm_precompile("MacroSigs")
 
         # Issue #568 (a macro *execution* bug)
@@ -1896,8 +1896,8 @@ end
         ex2 = :(methspecificity(x::Integer) = 2)
         Core.eval(ReviseTestPrivate, ex1)
         Core.eval(ReviseTestPrivate, ex2)
-        exsig1 = Revise.RelocatableExpr(ex1)=>[Tuple{typeof(ReviseTestPrivate.methspecificity),Int}]
-        exsig2 = Revise.RelocatableExpr(ex2)=>[Tuple{typeof(ReviseTestPrivate.methspecificity),Integer}]
+        exsig1 = Revise.RelocatableExpr(ex1) => [nothing => Tuple{typeof(ReviseTestPrivate.methspecificity),Int}]
+        exsig2 = Revise.RelocatableExpr(ex2) => [nothing => Tuple{typeof(ReviseTestPrivate.methspecificity),Integer}]
         f_old, f_new = Revise.ExprsSigs(exsig1, exsig2), Revise.ExprsSigs(exsig2)
         Revise.delete_missing!(f_old, f_new)
         m = @which ReviseTestPrivate.methspecificity(1)
@@ -3085,6 +3085,87 @@ end
         @test B670.y == 7
         rm_precompile("B670")
     end
+
+    do_test("External method tables") && @testset "External method tables" begin
+        function retval(m)
+            src = Base.uncompressed_ast(m)
+            node = src.code[1]::Core.ReturnNode
+            node.val
+        end
+
+        testdir = newtestdir()
+
+        unique_name(base) = Symbol(replace(lstrip(String(gensym(base)), '#'), '#' => '_'))
+        first_revision(name) = """
+            module $name
+
+            Base.Experimental.@MethodTable(method_table)
+
+            foo() = 1
+            Base.Experimental.@overlay method_table foo() = 2
+
+            bar() = foo()
+
+            end
+            """
+        second_revision(name) = """
+            module $name
+
+            Base.Experimental.@MethodTable(method_table)
+
+            foo() = 1
+            Base.Experimental.@overlay method_table foo() = 3
+
+            bar() = foo() + 1
+
+            end
+            """
+
+        name = unique_name(:ExternalMT)
+        dn = joinpath(testdir, "$name", "src")
+        mkpath(dn)
+        write(joinpath(dn, "$name.jl"), first_revision(name))
+        sleep(mtimedelay)
+        @eval import $name
+        ExternalMT = @eval $name
+        foo, bar, mt = ExternalMT.foo, ExternalMT.bar, ExternalMT.method_table
+        sleep(mtimedelay)
+        @test foo() == 1
+        @test bar() == 1
+        (; ms) = Base.MethodList(mt)
+        @test retval(first(ms)) == 2
+        write(joinpath(dn, "$name.jl"), second_revision(name))
+        sleep(mtimedelay)
+        @yry()
+        @test foo() == 1
+        @test bar() == 2
+        (; ms) = Base.MethodList(mt)
+        @test retval(first(ms)) == 3
+
+        file = tempname() * ".jl"
+        name = unique_name(:ExternalMT_includet)
+        write(file, first_revision(name))
+        sleep(mtimedelay)
+        Revise.track(@__MODULE__(), file; mode=:includet)
+        sleep(mtimedelay)
+        @eval import .$name
+        ExternalMT = @eval $name
+        foo, bar, mt = ExternalMT.foo, ExternalMT.bar, ExternalMT.method_table
+        sleep(mtimedelay)
+        @test foo() == 1
+        @test bar() == 1
+        (; ms) = Base.MethodList(mt)
+        @test retval(first(ms)) == 2
+        rm(file)
+        sleep(mtimedelay)
+        write(file, second_revision(name))
+        sleep(mtimedelay)
+        @yry()
+        @test foo() == 1
+        @test bar() == 2
+        (; ms) = Base.MethodList(mt)
+        @test retval(first(ms)) == 3
+    end
 end
 
 do_test("Utilities") && @testset "Utilities" begin

From e148172881d259168d27194ccb51a3a09e45d348 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Mon, 21 Apr 2025 13:37:57 -0400
Subject: [PATCH 02/18] Bump compat for CodeTracking

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 2677999f..d1298355 100644
--- a/Project.toml
+++ b/Project.toml
@@ -21,7 +21,7 @@ Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 DistributedExt = "Distributed"
 
 [compat]
-CodeTracking = "1.2"
+CodeTracking = "2"
 Distributed = "1"
 JuliaInterpreter = "0.9"
 LoweredCodeUtils = "3.2"

From 5a38f9ca3a95b11d9e48c822b8e9c74fb3efdb24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Mon, 21 Apr 2025 14:44:58 -0400
Subject: [PATCH 03/18] Use MethodInfoKey, rename a few `sigs` to `mt_sigs`

---
 src/Revise.jl     |  2 +-
 src/lowered.jl    |  4 ++--
 src/packagedef.jl | 49 ++++++++++++++++++++++++-----------------------
 src/types.jl      |  2 +-
 test/runtests.jl  |  5 +++--
 5 files changed, 32 insertions(+), 30 deletions(-)

diff --git a/src/Revise.jl b/src/Revise.jl
index 78cacd8e..d904cb03 100644
--- a/src/Revise.jl
+++ b/src/Revise.jl
@@ -35,7 +35,7 @@ module Revise
 
 using OrderedCollections, CodeTracking, JuliaInterpreter, LoweredCodeUtils
 
-using CodeTracking: PkgFiles, basedir, srcfiles, basepath
+using CodeTracking: PkgFiles, basedir, srcfiles, basepath, MethodInfoKey
 using JuliaInterpreter: whichtt, is_doc_expr, step_expr!, finish_and_return!, get_return,
                         @lookup, moduleof, scopeof, pc_expr, is_quotenode_egal,
                         linetable, codelocs, LineTypes, isassign, isidentical
diff --git a/src/lowered.jl b/src/lowered.jl
index 28bcbb25..947d0123 100644
--- a/src/lowered.jl
+++ b/src/lowered.jl
@@ -16,7 +16,7 @@ end
 # This defines the API needed to store signatures using methods_by_execution!
 # This default version is simple and only used for testing purposes.
 # The "real" one is CodeTrackingMethodInfo in Revise.jl.
-const MethodInfo = IdDict{Pair{<:Union{Nothing, MethodTable},<:Type},LineNumberNode}
+const MethodInfo = IdDict{MethodInfoKey,LineNumberNode}
 add_signature!(methodinfo::MethodInfo, @nospecialize(sig), ln) = push!(methodinfo, sig=>ln)
 push_expr!(methodinfo::MethodInfo, mod::Module, ex::Expr) = methodinfo
 pop_expr!(methodinfo::MethodInfo) = methodinfo
@@ -320,7 +320,7 @@ function methods_by_execution!(@nospecialize(recurse), methodinfo, docexprs, fra
     mod = moduleof(frame)
     # Hoist this lookup for performance. Don't throw even when `mod` is a baremodule:
     modinclude = isdefined(mod, :include) ? getfield(mod, :include) : nothing
-    signatures = []  # temporary for method signature storage
+    signatures = MethodInfoKey[]  # temporary for method signature storage
     pc = frame.pc
     while true
         JuliaInterpreter.is_leaf(frame) || (@warn("not a leaf"); break)
diff --git a/src/packagedef.jl b/src/packagedef.jl
index f404c891..4dd0470d 100644
--- a/src/packagedef.jl
+++ b/src/packagedef.jl
@@ -282,18 +282,19 @@ get_method_from_match(mm::Core.MethodMatch) = mm.method
 
 function delete_missing!(exs_sigs_old::ExprsSigs, exs_sigs_new)
     with_logger(_debug_logger) do
-        for (ex, sigs) in exs_sigs_old
+        for (ex, mt_sigs) in exs_sigs_old
             haskey(exs_sigs_new, ex) && continue
             # ex was deleted
-            sigs === nothing && continue
-            for (mt, sig) in sigs
+            mt_sigs === nothing && continue
+            for mt_sig in mt_sigs
+                mt, sig = mt_sig
                 ret = Base._methods_by_ftype(sig, mt, -1, Base.get_world_counter())
                 success = false
                 if !isempty(ret)
                     m = get_method_from_match(ret[end])   # the last method returned is the least-specific that matches, and thus most likely to be type-equal
                     methsig = m.sig
                     if sig <: methsig && methsig <: sig
-                        locdefs = get(CodeTracking.method_info, mt => sig, nothing)
+                        locdefs = get(CodeTracking.method_info, mt_sig, nothing)
                         if isa(locdefs, Vector{Tuple{LineNumberNode,Expr}})
                             if length(locdefs) > 1
                                 # Just delete this reference but keep the method
@@ -319,7 +320,7 @@ function delete_missing!(exs_sigs_old::ExprsSigs, exs_sigs_new)
                         end
                         Base.delete_method(m)
                         # Remove the entries from CodeTracking data
-                        delete!(CodeTracking.method_info, mt => sig)
+                        delete!(CodeTracking.method_info, mt_sig)
                         # Remove frame from JuliaInterpreter, if applicable. Otherwise debuggers
                         # may erroneously work with outdated code (265-like problems)
                         if haskey(JuliaInterpreter.framedict, m)
@@ -352,14 +353,14 @@ end
 
 function eval_rex(rex::RelocatableExpr, exs_sigs_old::ExprsSigs, mod::Module; mode::Symbol=:eval)
     return with_logger(_debug_logger) do
-        sigs, includes = nothing, nothing
+        mt_sigs, includes = nothing, nothing
         rexo = getkey(exs_sigs_old, rex, nothing)
         # extract the signatures and update the line info
         if rexo === nothing
             ex = rex.ex
             # ex is not present in old
             @debug "Eval" _group="Action" time=time() deltainfo=(mod, ex)
-            sigs, deps, includes, thunk = eval_with_signatures(mod, ex; mode=mode)  # All signatures defined by `ex`
+            mt_sigs, deps, includes, thunk = eval_with_signatures(mod, ex; mode=mode)  # All signatures defined by `ex`
             if !isexpr(thunk, :thunk)
                 thunk = ex
             end
@@ -376,14 +377,14 @@ function eval_rex(rex::RelocatableExpr, exs_sigs_old::ExprsSigs, mod::Module; mo
             end
             storedeps(deps, rex, mod)
         else
-            sigs = exs_sigs_old[rexo]
+            mt_sigs = exs_sigs_old[rexo]
             # Update location info
             ln, lno = firstline(unwrap(rex)), firstline(unwrap(rexo))
-            if sigs !== nothing && !isempty(sigs) && ln != lno
+            if mt_sigs !== nothing && !isempty(mt_sigs) && ln != lno
                 ln, lno = ln::LineNumberNode, lno::LineNumberNode
-                @debug "LineOffset" _group="Action" time=time() deltainfo=(sigs, lno=>ln)
-                for sig in sigs
-                    locdefs = CodeTracking.method_info[sig]::AbstractVector
+                @debug "LineOffset" _group="Action" time=time() deltainfo=(mt_sigs, lno=>ln)
+                for mt_sig in mt_sigs
+                    locdefs = CodeTracking.method_info[mt_sig]::AbstractVector
                     ld = let lno=lno
                         map(pr->linediff(lno, pr[1]), locdefs)
                     end
@@ -397,7 +398,7 @@ function eval_rex(rex::RelocatableExpr, exs_sigs_old::ExprsSigs, mod::Module; mo
                 end
             end
         end
-        return sigs, includes
+        return mt_sigs, includes
     end
 end
 
@@ -453,20 +454,20 @@ It also has the following fields:
 """
 struct CodeTrackingMethodInfo
     exprstack::Vector{Expr}
-    allsigs::Vector{Any}
+    allsigs::Vector{Pair{Union{Nothing, MethodTable}, Type}}
     deps::Set{Union{GlobalRef,Symbol}}
     includes::Vector{Pair{Module,String}}
 end
 CodeTrackingMethodInfo(ex::Expr) = CodeTrackingMethodInfo([ex], Any[], Set{Union{GlobalRef,Symbol}}(), Pair{Module,String}[])
 
-function add_signature!(methodinfo::CodeTrackingMethodInfo, @nospecialize(sig), ln)
-    locdefs = CodeTracking.invoked_get!(Vector{Tuple{LineNumberNode,Expr}}, CodeTracking.method_info, sig)
+function add_signature!(methodinfo::CodeTrackingMethodInfo, mt_sig::MethodInfoKey, ln)
+    locdefs = CodeTracking.invoked_get!(Vector{Tuple{LineNumberNode,Expr}}, CodeTracking.method_info, mt_sig)
     newdef = unwrap(methodinfo.exprstack[end])
     if newdef !== nothing
         if !any(locdef->locdef[1] == ln && isequal(RelocatableExpr(locdef[2]), RelocatableExpr(newdef)), locdefs)
             push!(locdefs, (fixpath(ln), newdef))
         end
-        push!(methodinfo.allsigs, sig)
+        push!(methodinfo.allsigs, mt_sig)
     end
     return methodinfo
 end
@@ -1161,7 +1162,7 @@ function get_def(method::Method; modified_files=revision_queue)
     # We need to find the right file.
     if method.module == Base || method.module == Core || method.module == Core.Compiler
         @warn "skipping $method to avoid parsing too much code"
-        CodeTracking.invoked_setindex!(CodeTracking.method_info, CodeTracking.method_info_key(method), missing)
+        CodeTracking.invoked_setindex!(CodeTracking.method_info, missing, MethodInfoKey(method))
         return false
     end
     parentfile, included_files = modulefiles(method.module)
@@ -1180,13 +1181,13 @@ function get_def(method::Method; modified_files=revision_queue)
     end
     @warn "$(method.sig)$(isdefined(method, :external_mt) ? " (overlayed)" : "") was not found"
     # So that we don't call it again, store missingness info in CodeTracking
-    CodeTracking.invoked_setindex!(CodeTracking.method_info, CodeTracking.method_info_key(method), missing)
+    CodeTracking.invoked_setindex!(CodeTracking.method_info, missing, MethodInfoKey(method))
     return false
 end
 
 function get_def(method, pkgdata, filename)
     maybe_extract_sigs!(maybe_parse_from_cache!(pkgdata, filename))
-    return get(CodeTracking.method_info, CodeTracking.method_info_key(method), nothing)
+    return get(CodeTracking.method_info, MethodInfoKey(method), nothing)
 end
 
 function get_tracked_id(id::PkgId; modified_files=revision_queue)
@@ -1247,7 +1248,7 @@ function update_stacktrace_lineno!(trace)
             m = linfo.def
             # Why not just call `whereis`? Because that forces tracking. This is being
             # clever by recognizing that these entries exist only if there have been updates.
-            updated = get(CodeTracking.method_info, CodeTracking.method_info_key(m), nothing)
+            updated = get(CodeTracking.method_info, MethodInfoKey(m), nothing)
             if updated !== nothing
                 lnn = updated[1][1]     # choose the first entry by default
                 lineoffset = lnn.line - m.line
@@ -1262,7 +1263,7 @@ end
 function method_location(method::Method)
     # Why not just call `whereis`? Because that forces tracking. This is being
     # clever by recognizing that these entries exist only if there have been updates.
-    updated = get(CodeTracking.method_info, CodeTracking.method_info_key(method), nothing)
+    updated = get(CodeTracking.method_info, MethodInfoKey(method), nothing)
     if updated !== nothing
         lnn = updated[1][1]
         return lnn.file, lnn.line
@@ -1320,7 +1321,7 @@ Revise itself does not need to be running on `p`.
 """
 function init_worker(p::AbstractWorker)
     @invokelatest remotecall_impl(Core.eval, p, Main, quote
-        function whichtt(mt::Union{Nothing, MethodTable}, @nospecialize sig)
+        function whichtt(mt::Union{Nothing, Core.MethodTable}, @nospecialize sig)
             ret = Base._methods_by_ftype(sig, mt, -1, Base.get_world_counter())
             isempty(ret) && return nothing
             m = ret[end][3]::Method   # the last method returned is the least-specific that matches, and thus most likely to be type-equal
@@ -1328,7 +1329,7 @@ function init_worker(p::AbstractWorker)
             (sig <: methsig && methsig <: sig) || return nothing
             return m
         end
-        function delete_method_by_sig(mt::Union{Nothing, MethodTable}, @nospecialize sig)
+        function delete_method_by_sig(mt::Union{Nothing, Core.MethodTable}, @nospecialize sig)
             m = whichtt(mt, sig)
             isa(m, Method) && Base.delete_method(m)
         end
diff --git a/src/types.jl b/src/types.jl
index 011f0a7c..5ad7f2f7 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -16,7 +16,7 @@ mutable struct WatchList
 end
 
 const DocExprs = Dict{Module,Vector{Expr}}
-const ExprsSigs = OrderedDict{RelocatableExpr,Union{Nothing,Vector{Any}}}
+const ExprsSigs = OrderedDict{RelocatableExpr,Union{Nothing,Vector{Pair{Union{Nothing, MethodTable}, Type}}}}
 const DepDictVals = Tuple{Module,RelocatableExpr}
 const DepDict = Dict{Symbol,Set{DepDictVals}}
 
diff --git a/test/runtests.jl b/test/runtests.jl
index 589e4b0f..8119c733 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,6 +1,7 @@
 # REVISE: DO NOT PARSE   # For people with JULIA_REVISE_INCLUDE=1
 using Revise
 using Revise.CodeTracking
+using Revise.CodeTracking: MethodInfoKey
 using Revise.JuliaInterpreter
 using Test
 
@@ -1408,7 +1409,7 @@ end
             """)
         @yry()
         @test MacroSigs.blah() == 1
-        @test haskey(CodeTracking.method_info, CodeTracking.method_info_key(@which MacroSigs.blah()))
+        @test haskey(CodeTracking.method_info, MethodInfoKey(@which MacroSigs.blah()))
         rm_precompile("MacroSigs")
 
         # Issue #568 (a macro *execution* bug)
@@ -2945,7 +2946,7 @@ end
     do_test("Recipes") && @testset "Recipes" begin
         # https://github.com/JunoLab/Juno.jl/issues/257#issuecomment-473856452
         meth = @which gcd(10, 20)
-        sigs = signatures_at(Base.find_source_file(String(meth.file)), meth.line)  # this should track Base
+        signatures_at(Base.find_source_file(String(meth.file)), meth.line)  # this should track Base
 
         # Tracking Base
         # issue #250

From 9cac5356d4258200dd8c5e95ca855889ee9a0cc5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Mon, 21 Apr 2025 14:49:45 -0400
Subject: [PATCH 04/18] Start updating docs a bit

---
 docs/src/internals.md | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/docs/src/internals.md b/docs/src/internals.md
index 3ff9388b..76422c9c 100644
--- a/docs/src/internals.md
+++ b/docs/src/internals.md
@@ -226,9 +226,9 @@ Most of Revise's magic comes down to just three internal variables:
 
 Two "maps" are central to Revise's inner workings: `ExprsSigs` maps link
 definition=>signature-types (the forward workflow), while `CodeTracking` (specifically,
-its internal variable `method_info`) links from
-signature-type=>definition (the backward workflow).
-Concretely, `CodeTracking.method_info` is just an `IdDict` mapping `sigt=>(locationinfo, def)`.
+its internal variable `method_info`) links from a
+method table/signature-type pair to the corresponding definition (the backward workflow).
+Concretely, `CodeTracking.method_info` is just an `IdDict` mapping `(mt => sigt) => (locationinfo, def)`.
 Of note, a stack frame typically contains a link to a method, which stores the equivalent
 of `sigt`; consequently, this information allows one to look up the corresponding
 `locationinfo` and `def`. (When methods move, the location information stored by CodeTracking
@@ -237,8 +237,8 @@ gets updated by Revise.)
 Some additional notes about Revise's `ExprsSigs` maps:
 
 - For expressions that do not define a method, it is just `def=>nothing`
-- For expressions that do define a method, it is `def=>[sigt1, ...]`.
-  `[sigt1, ...]` is the list of signature-types generated from `def` (often just one,
+- For expressions that do define a method, it is `def=>[mt_sigt1, ...]`.
+  `[mt_sigt1, ...]` is the list of method table/signature-type pairs generated from `def` (often just one,
   but more in the case of methods with default arguments or keyword arguments).
 - They are represented as an `OrderedDict` so as to preserve the sequence in which expressions
   occur in the file.
@@ -255,7 +255,7 @@ Some additional notes about Revise's `ExprsSigs` maps:
   the location information stored by `CodeTracking`.
 
 `ExprsSigs` are organized by module and then file, so that one can map
-`filename`=>`module`=>`def`=>`sigts`.
+`filename`=>`module`=>`def`=>`mt_sigts`.
 Importantly, single-file modules can be "reconstructed" from the keys of the corresponding
 `ExprsSigs` (and multi-file modules from a collection of such items), since they hold
 the complete ordered set of expressions that would be `eval`ed to define the module.
@@ -334,13 +334,13 @@ FileInfo(Items=>ExprsSigs with the following expressions:
       end), )
 ```
 
-This is just a summary; to see the actual `def=>sigts` map, do the following:
+This is just a summary; to see the actual `def=>mt_sigts` map, do the following:
 
 ```julia
 julia> pkgdata.fileinfos[2].modexsigs[Items]
-OrderedCollections.OrderedDict{Revise.RelocatableExpr,Union{Nothing, Array{Any,1}}} with 2 entries:
-  :(indent(::UInt16) = begin…                       => Any[Tuple{typeof(indent),UInt16}]
-  :(indent(::UInt8) = begin…                        => Any[Tuple{typeof(indent),UInt8}]
+OrderedCollections.OrderedDict{Module, OrderedCollections.OrderedDict{Revise.RelocatableExpr, Union{Nothing, Vector{Pair{Union{Nothing, Core.MethodTable}, Type}}}}} with 2 entries:
+  :(indent(::UInt16) = begin…                       => Pair{Union{Nothing, MethodTable}, Type}[nothing => Tuple{typeof(indent),UInt16}]
+  :(indent(::UInt8) = begin…                        => Pair{Union{Nothing, MethodTable}, Type}[nothing => Tuple{typeof(indent),UInt8}]
 ```
 
 These are populated now because we specified `__precompile__(false)`, which forces

From fe7acd4a1f22e90e1626008bc5b6adabd653d498 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Mon, 21 Apr 2025 14:52:28 -0400
Subject: [PATCH 05/18] Patch CI to test with upstream dependencies

---
 .github/workflows/Documenter.yml | 2 ++
 .github/workflows/ci.yml         | 1 +
 2 files changed, 3 insertions(+)

diff --git a/.github/workflows/Documenter.yml b/.github/workflows/Documenter.yml
index b91b123b..2b5ed12b 100644
--- a/.github/workflows/Documenter.yml
+++ b/.github/workflows/Documenter.yml
@@ -11,6 +11,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
+      - run: cd docs && julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
       - uses: julia-actions/julia-buildpkg@latest
       - uses: julia-actions/julia-docdeploy@latest
         env:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 476a13c7..e5aaf05c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -39,6 +39,7 @@ jobs:
         version: ${{ matrix.version }}
         show-versioninfo: ${{ matrix.version == 'nightly' }}
     - uses: julia-actions/cache@v2
+    - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
     - uses: julia-actions/julia-buildpkg@latest
     # Revise's tests need significant customization
     # Populate the precompile cache with an extraneous file, to catch issues like in #460

From 27d82f7beeaea3563477855c904e08d9492f2e86 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Mon, 21 Apr 2025 14:59:50 -0400
Subject: [PATCH 06/18] Update outdated comment

---
 src/lowered.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lowered.jl b/src/lowered.jl
index 947d0123..f4c85d11 100644
--- a/src/lowered.jl
+++ b/src/lowered.jl
@@ -15,7 +15,7 @@ end
 
 # This defines the API needed to store signatures using methods_by_execution!
 # This default version is simple and only used for testing purposes.
-# The "real" one is CodeTrackingMethodInfo in Revise.jl.
+# The "real" one is CodeTrackingMethodInfo in packagedef.jl.
 const MethodInfo = IdDict{MethodInfoKey,LineNumberNode}
 add_signature!(methodinfo::MethodInfo, @nospecialize(sig), ln) = push!(methodinfo, sig=>ln)
 push_expr!(methodinfo::MethodInfo, mod::Module, ex::Expr) = methodinfo

From da595896f79bab3c0961f8e0f12e7724c90f9786 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Mon, 21 Apr 2025 15:23:55 -0400
Subject: [PATCH 07/18] Attempt to fix Git tests

---
 .github/workflows/ci.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e5aaf05c..0ff5491d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -81,6 +81,7 @@ jobs:
         # We also need to pick up the Git tests, but for that we need to `dev` the package
         echo "Git tests"
         julia --code-coverage=user -e '
+          using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"
           using Pkg; Pkg.develop(PackageSpec(path="."))
           include(joinpath("test", "runtests.jl"))
         ' "Git"

From 1c03d7d31a2c2ee7ab33afcace30cfc38540a14e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Thu, 24 Apr 2025 12:36:30 -0400
Subject: [PATCH 08/18] Refactor tests and increase coverage

---
 test/runtests.jl | 79 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 52 insertions(+), 27 deletions(-)

diff --git a/test/runtests.jl b/test/runtests.jl
index 8119c733..f2ce9a8c 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -3100,7 +3100,8 @@ end
     do_test("External method tables") && @testset "External method tables" begin
         function retval(m)
             src = Base.uncompressed_ast(m)
-            node = src.code[1]::Core.ReturnNode
+            i = findfirst(!isnothing, src.code)
+            node = src.code[i]::Core.ReturnNode
             node.val
         end
 
@@ -3111,9 +3112,20 @@ end
             module $name
 
             Base.Experimental.@MethodTable(method_table)
+            Base.Experimental.@MethodTable(method_table_2)
+            get_method_table() = method_table
+
+            macro override(ex) esc(:(Base.Experimental.@overlay \$method_table \$ex)) end
+            macro override_2(ex) esc(:(Base.Experimental.@overlay $name.method_table \$ex)) end
+            macro override_3(ex) esc(:(Base.Experimental.@overlay get_method_table() \$ex)) end
 
             foo() = 1
-            Base.Experimental.@overlay method_table foo() = 2
+
+            @override print(x) = "print"
+            @override cos(x) = "cos"
+            @override_2 sin(x) = "sin"
+            @override_3 sincos(x) = "sincos"
+            Base.Experimental.@overlay method_table_2 foo() = 2
 
             bar() = foo()
 
@@ -3123,35 +3135,59 @@ end
             module $name
 
             Base.Experimental.@MethodTable(method_table)
+            Base.Experimental.@MethodTable(method_table_2)
+            get_method_table() = method_table
+
+            macro override(ex) esc(:(Base.Experimental.@overlay \$method_table \$ex)) end
+            macro override_2(ex) esc(:(Base.Experimental.@overlay $name.method_table \$ex)) end
+            macro override_3(ex) esc(:(Base.Experimental.@overlay get_method_table() \$ex)) end
 
             foo() = 1
-            Base.Experimental.@overlay method_table foo() = 3
+
+            @override print(x) = "print"
+            @override cos(x) = "sin"
+            @override_2 sin(x) = "cos"
+            @override_3 sincos(x) = "cossin"
+            Base.Experimental.@overlay method_table_2 foo() = 3
 
             bar() = foo() + 1
 
             end
             """
 
+        function test_first_revision(mod)
+            foo, bar, mt, mt2 = mod.foo, mod.bar, mod.method_table, mod.method_table_2
+            @test foo() == 1
+            @test bar() == 1
+            (; ms) = Base.MethodList(mt)
+            @test length(ms) == 4 # cos/sin/sincos/print
+            (; ms) = Base.MethodList(mt2)
+            @test length(ms) == 1 # foo
+            @test retval(first(ms)) == 2
+        end
+
+        function test_second_revision(mod)
+            foo, bar, mt, mt2 = mod.foo, mod.bar, mod.method_table, mod.method_table_2
+            @test foo() == 1
+            @test bar() == 2
+            (; ms) = Base.MethodList(mt)
+            @test length(ms) == 7 # cos/sin/sincos x2 + print x1
+            (; ms) = Base.MethodList(mt2)
+            @test length(ms) == 2 # foo x2
+            @test retval(first(ms)) == 3
+        end
+
         name = unique_name(:ExternalMT)
         dn = joinpath(testdir, "$name", "src")
         mkpath(dn)
         write(joinpath(dn, "$name.jl"), first_revision(name))
         sleep(mtimedelay)
         @eval import $name
-        ExternalMT = @eval $name
-        foo, bar, mt = ExternalMT.foo, ExternalMT.bar, ExternalMT.method_table
         sleep(mtimedelay)
-        @test foo() == 1
-        @test bar() == 1
-        (; ms) = Base.MethodList(mt)
-        @test retval(first(ms)) == 2
+        test_first_revision(@eval $name)
         write(joinpath(dn, "$name.jl"), second_revision(name))
-        sleep(mtimedelay)
         @yry()
-        @test foo() == 1
-        @test bar() == 2
-        (; ms) = Base.MethodList(mt)
-        @test retval(first(ms)) == 3
+        test_second_revision(@eval $name)
 
         file = tempname() * ".jl"
         name = unique_name(:ExternalMT_includet)
@@ -3160,22 +3196,11 @@ end
         Revise.track(@__MODULE__(), file; mode=:includet)
         sleep(mtimedelay)
         @eval import .$name
-        ExternalMT = @eval $name
-        foo, bar, mt = ExternalMT.foo, ExternalMT.bar, ExternalMT.method_table
-        sleep(mtimedelay)
-        @test foo() == 1
-        @test bar() == 1
-        (; ms) = Base.MethodList(mt)
-        @test retval(first(ms)) == 2
-        rm(file)
         sleep(mtimedelay)
+        test_first_revision(@eval $name)
         write(file, second_revision(name))
-        sleep(mtimedelay)
         @yry()
-        @test foo() == 1
-        @test bar() == 2
-        (; ms) = Base.MethodList(mt)
-        @test retval(first(ms)) == 3
+        test_second_revision(@eval $name)
     end
 end
 

From 83c5eb9cd9e259189e5cfb1785c11a44e774a3d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Thu, 24 Apr 2025 14:00:02 -0400
Subject: [PATCH 09/18] Add tests for method deletion

---
 test/runtests.jl | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/test/runtests.jl b/test/runtests.jl
index f2ce9a8c..e2ddf1ca 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -3122,12 +3122,14 @@ end
             foo() = 1
 
             @override print(x) = "print"
+            @override show(x) = "show"
             @override cos(x) = "cos"
             @override_2 sin(x) = "sin"
             @override_3 sincos(x) = "sincos"
             Base.Experimental.@overlay method_table_2 foo() = 2
 
             bar() = foo()
+            baz() = bar()
 
             end
             """
@@ -3145,35 +3147,39 @@ end
             foo() = 1
 
             @override print(x) = "print"
+            # @override show(x) = "show"
             @override cos(x) = "sin"
             @override_2 sin(x) = "cos"
             @override_3 sincos(x) = "cossin"
             Base.Experimental.@overlay method_table_2 foo() = 3
 
             bar() = foo() + 1
+            # baz() = bar()
 
             end
             """
 
-        function test_first_revision(mod)
-            foo, bar, mt, mt2 = mod.foo, mod.bar, mod.method_table, mod.method_table_2
-            @test foo() == 1
-            @test bar() == 1
-            (; ms) = Base.MethodList(mt)
-            @test length(ms) == 4 # cos/sin/sincos/print
-            (; ms) = Base.MethodList(mt2)
+        function test_first_revision(mod::Module)
+            @test mod.foo() == 1
+            @test mod.bar() == 1
+            @test length(methods(mod.baz)) == 1
+            (; ms) = Base.MethodList(mod.method_table)
+            @test length(ms) == 5 # cos/sin/sincos/print/show
+            (; ms) = Base.MethodList(mod.method_table_2)
             @test length(ms) == 1 # foo
             @test retval(first(ms)) == 2
         end
 
-        function test_second_revision(mod)
-            foo, bar, mt, mt2 = mod.foo, mod.bar, mod.method_table, mod.method_table_2
-            @test foo() == 1
-            @test bar() == 2
-            (; ms) = Base.MethodList(mt)
-            @test length(ms) == 7 # cos/sin/sincos x2 + print x1
-            (; ms) = Base.MethodList(mt2)
+        function test_second_revision(mod::Module)
+            @test mod.foo() == 1
+            @test mod.bar() == 2
+            @test isempty(methods(mod.baz))
+            (; ms) = Base.MethodList(mod.method_table)
+            @test length(ms) == 8 # cos/sin/sincos x2 + print/show
+            @test count(x -> x.deleted_world < Base.tls_world_age(), ms) == 4 # deleted cos/sin/sincos/show
+            (; ms) = Base.MethodList(mod.method_table_2)
             @test length(ms) == 2 # foo x2
+            @test count(x -> x.deleted_world < Base.tls_world_age(), ms) == 1 # deleted foo
             @test retval(first(ms)) == 3
         end
 

From bb750c95c262e969c07193b193512cdbb3e05b5d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Thu, 24 Apr 2025 14:18:10 -0400
Subject: [PATCH 10/18] Bump JuliaInterpreter compat bound

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index d1298355..9dd26315 100644
--- a/Project.toml
+++ b/Project.toml
@@ -23,7 +23,7 @@ DistributedExt = "Distributed"
 [compat]
 CodeTracking = "2"
 Distributed = "1"
-JuliaInterpreter = "0.9"
+JuliaInterpreter = "0.10"
 LoweredCodeUtils = "3.2"
 OrderedCollections = "1"
 # Exclude Requires-1.1.0 - see https://github.com/JuliaPackaging/Requires.jl/issues/94

From b90f43044395309b41e306047ccbca66dc1c6712 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Thu, 24 Apr 2025 16:59:24 -0400
Subject: [PATCH 11/18] Fix tests for 1.10

---
 test/runtests.jl | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/test/runtests.jl b/test/runtests.jl
index 7db7ea78..8837ce45 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -3171,15 +3171,16 @@ end
         end
 
         function test_second_revision(mod::Module)
+            current_world_age = isdefined(Base, :tls_world_age) ? Base.tls_world_age() : Base.get_world_counter()
             @test mod.foo() == 1
             @test mod.bar() == 2
             @test isempty(methods(mod.baz))
             (; ms) = Base.MethodList(mod.method_table)
             @test length(ms) == 8 # cos/sin/sincos x2 + print/show
-            @test count(x -> x.deleted_world < Base.tls_world_age(), ms) == 4 # deleted cos/sin/sincos/show
+            @test count(x -> x.deleted_world < current_world_age, ms) == 4 # deleted cos/sin/sincos/show
             (; ms) = Base.MethodList(mod.method_table_2)
             @test length(ms) == 2 # foo x2
-            @test count(x -> x.deleted_world < Base.tls_world_age(), ms) == 1 # deleted foo
+            @test count(x -> x.deleted_world < current_world_age, ms) == 1 # deleted foo
             @test retval(first(ms)) == 3
         end
 

From a20db58ed6ec320a85ad785ec08468bdce1ca574 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Fri, 25 Apr 2025 13:27:49 -0400
Subject: [PATCH 12/18] Update documentation, more `mt_sigs` renames

---
 docs/src/debugging.md |  6 +++---
 docs/src/internals.md |  1 +
 src/packagedef.jl     | 22 +++++++++++-----------
 src/types.jl          | 18 +++++++++---------
 test/sigtest.jl       |  4 ++--
 5 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/docs/src/debugging.md b/docs/src/debugging.md
index 93dcc9c7..e373f26d 100644
--- a/docs/src/debugging.md
+++ b/docs/src/debugging.md
@@ -159,13 +159,13 @@ julia> rlogger.logs
           #= /tmp/revisetest.jl:9 =#
           x ^ 4
       end))))
- Revise.LogRecord(Debug, LineOffset, Action, Revise_fb38a7f7, "/home/tim/.julia/dev/Revise/src/Revise.jl", 296, (time=1.557996459331061e9, deltainfo=(Any[Tuple{typeof(mult2),Any}], :(#= /tmp/revisetest.jl:11 =#) => :(#= /tmp/revisetest.jl:13 =#))))
+ Revise.LogRecord(Debug, LineOffset, Action, Revise_fb38a7f7, "/home/tim/.julia/dev/Revise/src/Revise.jl", 296, (time=1.557996459331061e9, deltainfo=(Pair{Union{Nothing, MethodTable}, Type}[nothing => Tuple{typeof(mult2),Any}], :(#= /tmp/revisetest.jl:11 =#) => :(#= /tmp/revisetest.jl:13 =#))))
  Revise.LogRecord(Debug, Eval, Action, Revise_9147188b, "/home/tim/.julia/dev/Revise/src/Revise.jl", 276, (time=1.557996459391182e9, deltainfo=(Main.ReviseTest.Internal, :(mult3(x) = begin
           #= /tmp/revisetest.jl:14 =#
           3x
       end))))
- Revise.LogRecord(Debug, LineOffset, Action, Revise_fb38a7f7, "/home/tim/.julia/dev/Revise/src/Revise.jl", 296, (time=1.557996459391642e9, deltainfo=(Any[Tuple{typeof(unchanged),Any}], :(#= /tmp/revisetest.jl:18 =#) => :(#= /tmp/revisetest.jl:19 =#))))
- Revise.LogRecord(Debug, LineOffset, Action, Revise_fb38a7f7, "/home/tim/.julia/dev/Revise/src/Revise.jl", 296, (time=1.557996459391695e9, deltainfo=(Any[Tuple{typeof(unchanged2),Any}], :(#= /tmp/revisetest.jl:20 =#) => :(#= /tmp/revisetest.jl:21 =#))))
+ Revise.LogRecord(Debug, LineOffset, Action, Revise_fb38a7f7, "/home/tim/.julia/dev/Revise/src/Revise.jl", 296, (time=1.557996459391642e9, deltainfo=(Pair{Union{Nothing, MethodTable}, Type}[nothing => Tuple{typeof(unchanged),Any}], :(#= /tmp/revisetest.jl:18 =#) => :(#= /tmp/revisetest.jl:19 =#))))
+ Revise.LogRecord(Debug, LineOffset, Action, Revise_fb38a7f7, "/home/tim/.julia/dev/Revise/src/Revise.jl", 296, (time=1.557996459391695e9, deltainfo=(Pair{Union{Nothing, MethodTable}, Type}[nothing => Tuple{typeof(unchanged2),Any}], :(#= /tmp/revisetest.jl:20 =#) => :(#= /tmp/revisetest.jl:21 =#))))
 ```
 
 You can see that Revise started by deleting three methods, followed by evaluating three new versions of those methods. Interspersed are various changes to the line numbering.
diff --git a/docs/src/internals.md b/docs/src/internals.md
index 76422c9c..4406f155 100644
--- a/docs/src/internals.md
+++ b/docs/src/internals.md
@@ -137,6 +137,7 @@ Tuple{typeof(print_item),IO,Any,Integer,String}     # print_item(io, item, 2, "
 ```
 
 In Revise's internal code, a definition is often represented with a variable `def`, and a signature-type with `sigt`.
+The method table for which the method was defined is also represented, to form a `mt_sigt` pair.
 Recent versions of Revise do not make extensive use of signature expressions.
 
 ### Computing signatures
diff --git a/src/packagedef.jl b/src/packagedef.jl
index b7c72f52..51e971fe 100644
--- a/src/packagedef.jl
+++ b/src/packagedef.jl
@@ -264,7 +264,7 @@ const silencefile = Ref(joinpath(depsdir, "silence.txt"))  # Ref so that tests d
 ##     + add to the ModuleExprsSigs
 ##     + add to CodeTracking.method_info
 ##
-## Interestingly, the ex=>sigs link may not be the same as the sigs=>ex link.
+## Interestingly, the ex=>mt_sigs link may not be the same as the mt_sigs=>ex link.
 ## Consider a conditional block,
 ##     if Sys.islinux()
 ##         f() = 1
@@ -407,9 +407,9 @@ end
 function eval_new!(exs_sigs_new::ExprsSigs, exs_sigs_old, mod::Module; mode::Symbol=:eval)
     includes = Vector{Pair{Module,String}}()
     for rex in keys(exs_sigs_new)
-        sigs, _includes = eval_rex(rex, exs_sigs_old, mod; mode=mode)
-        if sigs !== nothing
-            exs_sigs_new[rex] = sigs
+        mt_sigs, _includes = eval_rex(rex, exs_sigs_old, mod; mode=mode)
+        if mt_sigs !== nothing
+            exs_sigs_new[rex] = mt_sigs
         end
         if _includes !== nothing
             append!(includes, _includes)
@@ -524,8 +524,8 @@ function instantiate_sigs!(modexsigs::ModuleExprsSigs; mode=:sigs, kwargs...)
     for (mod, exsigs) in modexsigs
         for rex in keys(exsigs)
             is_doc_expr(rex.ex) && continue
-            sigs, deps, _ = eval_with_signatures(mod, rex.ex; mode=mode, kwargs...)
-            exsigs[rex] = sigs
+            mt_sigs, deps, _ = eval_with_signatures(mod, rex.ex; mode=mode, kwargs...)
+            exsigs[rex] = mt_sigs
             storedeps(deps, rex, mod)
         end
     end
@@ -848,9 +848,9 @@ function revise(; throw=false)
                         mode ∈ (:sigs, :eval, :evalmeth, :evalassign) || error("unsupported mode ", mode)
                         exsold = get(fi.modexsigs, mod, empty_exs_sigs)
                         for rex in keys(exsnew)
-                            sigs, includes = eval_rex(rex, exsold, mod; mode=mode)
-                            if sigs !== nothing
-                                exsnew[rex] = sigs
+                            mt_sigs, includes = eval_rex(rex, exsold, mod; mode=mode)
+                            if mt_sigs !== nothing
+                                exsnew[rex] = mt_sigs
                             end
                             if includes !== nothing
                                 maybe_add_includes_to_pkgdata!(pkgdata, file, includes; eval_now=true)
@@ -1144,8 +1144,8 @@ function get_def(method::Method; modified_files=revision_queue)
         fi = add_definitions_from_repl(filename)
         hassig = false
         for (mod, exs) in fi.modexsigs
-            for sigs in values(exs)
-                hassig |= !isempty(sigs)
+            for mt_sigs in values(exs)
+                hassig |= !isempty(mt_sigs)
             end
         end
         return hassig
diff --git a/src/types.jl b/src/types.jl
index 5ad7f2f7..cf111aa3 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -24,9 +24,9 @@ function Base.show(io::IO, exsigs::ExprsSigs)
     compact = get(io, :compact, false)
     if compact
         n = 0
-        for (rex, sigs) in exsigs
-            sigs === nothing && continue
-            n += length(sigs)
+        for (rex, mt_sigs) in exsigs
+            mt_sigs === nothing && continue
+            n += length(mt_sigs)
         end
         print(io, "ExprsSigs(<$(length(exsigs)) expressions>, <$n signatures>)")
     else
@@ -42,11 +42,11 @@ end
     ModuleExprsSigs
 
 For a particular source file, the corresponding `ModuleExprsSigs` is a mapping
-`mod=>exprs=>sigs` of the expressions `exprs` found in `mod` and the signatures `sigs`
+`mod=>exprs=>mt_sigs` of the expressions `exprs` found in `mod` and the method table/signature pairs `mt_sigs`
 that arise from them. Specifically, if `mes` is a `ModuleExprsSigs`, then `mes[mod][ex]`
-is a list of signatures that result from evaluating `ex` in `mod`. It is possible that
+is a list of method table/signature pairs that result from evaluating `ex` in `mod`. It is possible that
 this returns `nothing`, which can mean either that `ex` does not define any methods
-or that the signatures have not yet been cached.
+or that the method table/signature pairs have not yet been cached.
 
 The first `mod` key is guaranteed to be the module into which this file was `include`d.
 
@@ -186,10 +186,10 @@ function Base.show(io::IO, pkgdata::PkgData)
         for fi in pkgdata.fileinfos
             thisnexs, thisnsigs = 0, 0
             for (mod, exsigs) in fi.modexsigs
-                for (rex, sigs) in exsigs
+                for (rex, mt_sigs) in exsigs
                     thisnexs += 1
-                    sigs === nothing && continue
-                    thisnsigs += length(sigs)
+                    mt_sigs === nothing && continue
+                    thisnsigs += length(mt_sigs)
                 end
             end
             nexs += thisnexs
diff --git a/test/sigtest.jl b/test/sigtest.jl
index 500d9360..d7609337 100644
--- a/test/sigtest.jl
+++ b/test/sigtest.jl
@@ -88,8 +88,8 @@ module Lowering end
             end
         end
     end
-    sigs, _ = Revise.eval_with_signatures(Lowering, ex)
-    @test length(sigs) >= 2
+    mt_sigs, _ = Revise.eval_with_signatures(Lowering, ex)
+    @test length(mt_sigs) >= 2
 end
 
 try # Suppress world age increments, since the instantiation messes with base

From 4f92e45186f7eb5a3975b1c93d98a2f7c007bd1c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Fri, 25 Apr 2025 15:37:07 -0400
Subject: [PATCH 13/18] Add NEWS.md entry

---
 NEWS.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/NEWS.md b/NEWS.md
index 0fe8bf2d..ef25c1ae 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -3,6 +3,10 @@
 This file describes only major changes, and does not include bug fixes,
 cleanups, or minor enhancements.
 
+## Revise 3.8
+
+* Methods defined on external method tables via `Base.Experimental.@overlay` can now be correctly revised ([#904]).
+
 ## Revise 3.3
 
 * Upgrade to JuliaInterpreter 0.9 and drop support for Julia prior to 1.6 (the new LTS).
@@ -151,3 +155,4 @@ New features:
 [#243]: https://github.com/timholy/Revise.jl/pull/243
 [#245]: https://github.com/timholy/Revise.jl/pull/245
 [#278]: https://github.com/timholy/Revise.jl/pull/278
+[#904]: https://github.com/timholy/Revise.jl/pull/904

From f3a9e9983d93960eeef58623290d3230046483e3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Fri, 25 Apr 2025 15:37:19 -0400
Subject: [PATCH 14/18] Bump package version to 3.8.0

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 1f44822c..35c72b3f 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "Revise"
 uuid = "295af30f-e4ad-537b-8983-00126c2a3abe"
-version = "3.7.6"
+version = "3.8.0"
 
 [deps]
 CodeTracking = "da1fd8a2-8d9e-5ec2-8556-3022fb5608a2"

From 024f45cab45c2673bc2f2dde4a96ee2688e024ea Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Belmant?= <cedric.belmant@juliahub.com>
Date: Fri, 25 Apr 2025 15:43:10 -0400
Subject: [PATCH 15/18] Update CI patches

---
 .github/workflows/Documenter.yml | 4 ++--
 .github/workflows/ci.yml         | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/Documenter.yml b/.github/workflows/Documenter.yml
index 2b5ed12b..53d719d5 100644
--- a/.github/workflows/Documenter.yml
+++ b/.github/workflows/Documenter.yml
@@ -11,8 +11,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
-      - run: cd docs && julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
+      - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/timholy/CodeTracking.jl#master https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
+      - run: cd docs && julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/timholy/CodeTracking.jl#master https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
       - uses: julia-actions/julia-buildpkg@latest
       - uses: julia-actions/julia-docdeploy@latest
         env:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0ff5491d..4db9539e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -39,7 +39,7 @@ jobs:
         version: ${{ matrix.version }}
         show-versioninfo: ${{ matrix.version == 'nightly' }}
     - uses: julia-actions/cache@v2
-    - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
+    - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/timholy/CodeTracking.jl#master https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
     - uses: julia-actions/julia-buildpkg@latest
     # Revise's tests need significant customization
     # Populate the precompile cache with an extraneous file, to catch issues like in #460
@@ -81,7 +81,7 @@ jobs:
         # We also need to pick up the Git tests, but for that we need to `dev` the package
         echo "Git tests"
         julia --code-coverage=user -e '
-          using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/serenity4/CodeTracking.jl#parametrize-by-mt https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"
+          using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/timholy/CodeTracking.jl#master https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"
           using Pkg; Pkg.develop(PackageSpec(path="."))
           include(joinpath("test", "runtests.jl"))
         ' "Git"

From d3024453622a41677a53c388077d320a046ba6f0 Mon Sep 17 00:00:00 2001
From: serenity4 <cedric.bel@hotmail.fr>
Date: Tue, 10 Jun 2025 15:27:35 +0200
Subject: [PATCH 16/18] Update CI dependency patch

---
 .github/workflows/ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4db9539e..d4006aed 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -39,7 +39,7 @@ jobs:
         version: ${{ matrix.version }}
         show-versioninfo: ${{ matrix.version == 'nightly' }}
     - uses: julia-actions/cache@v2
-    - run: julia --project -e 'using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/timholy/CodeTracking.jl#master https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"'
+    - run: julia --project -e 'using Pkg; using Pkg; Pkg.add([PackageSpec(; url="https://github.com/serenity4/JuliaInterpreter.jl", rev="codetracking-v2"), PackageSpec(; name = "CodeTracking", rev="master"), PackageSpec(; url = "https://github.com/serenity4/LoweredCodeUtils.jl", rev = "support-external-methodtables")])'
     - uses: julia-actions/julia-buildpkg@latest
     # Revise's tests need significant customization
     # Populate the precompile cache with an extraneous file, to catch issues like in #460
@@ -81,7 +81,7 @@ jobs:
         # We also need to pick up the Git tests, but for that we need to `dev` the package
         echo "Git tests"
         julia --code-coverage=user -e '
-          using Pkg; pkg"add https://github.com/serenity4/JuliaInterpreter.jl#codetracking-v2 https://github.com/timholy/CodeTracking.jl#master https://github.com/serenity4/LoweredCodeUtils.jl#support-external-methodtables"
+          using Pkg; using Pkg; using Pkg; Pkg.add([PackageSpec(; url="https://github.com/serenity4/JuliaInterpreter.jl", rev="codetracking-v2"), PackageSpec(; name = "CodeTracking", rev="master"), PackageSpec(; url = "https://github.com/serenity4/LoweredCodeUtils.jl", rev = "support-external-methodtables")])
           using Pkg; Pkg.develop(PackageSpec(path="."))
           include(joinpath("test", "runtests.jl"))
         ' "Git"

From 13b67a18406fdf54d89b0ff11f3e604fb8ff593e Mon Sep 17 00:00:00 2001
From: serenity4 <cedric.bel@hotmail.fr>
Date: Tue, 10 Jun 2025 15:51:39 +0200
Subject: [PATCH 17/18] Don't test `(::Method).deleted_world` on 1.12+

---
 test/runtests.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/runtests.jl b/test/runtests.jl
index 68453776..fac401c6 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -3165,10 +3165,10 @@ const issue639report = []
             @test isempty(methods(mod.baz))
             (; ms) = Base.MethodList(mod.method_table)
             @test length(ms) == 8 # cos/sin/sincos x2 + print/show
-            @test count(x -> x.deleted_world < current_world_age, ms) == 4 # deleted cos/sin/sincos/show
+            VERSION < v"1.12-" && @test count(x -> x.deleted_world < current_world_age, ms) == 4 # deleted cos/sin/sincos/show
             (; ms) = Base.MethodList(mod.method_table_2)
             @test length(ms) == 2 # foo x2
-            @test count(x -> x.deleted_world < current_world_age, ms) == 1 # deleted foo
+            VERSION < v"1.12-" && @test count(x -> x.deleted_world < current_world_age, ms) == 1 # deleted foo
             @test retval(first(ms)) == 3
         end
 

From 552ceea078a6a5c50e636efd4eb36cac36ec59ab Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Thu, 24 Jul 2025 06:41:19 -0500
Subject: [PATCH 18/18] Preliminary support for `include(mapexpr, file)`

In conjunction with `CodeTracking.MapFile`, this allows Revise to track
changes in files that are included with `include(mapexpr, file)`. This
PR supports the implementation of revisions for such files, properly
applying the `mapexpr` transformation to the included file's
expressions.

What's missing:
- Revise can't correctly populate the internal data structures needed to
  initiate `mapexpr` without help. The problem is that Revise only
  parses files that get edited, but discovering that `file2.jl` gets
  included from `file1.jl` via a `mapexpr` requires parsing `file1.jl`,
  which may not have been edited and therefore never scanned via Revise.
  The right way to fix this is in Julia itself, writing additional info
  to the package cache header. This will not land before Julia 1.13.
- `include(mapexpr, file)` is well-suited to include the same file more
  than once with different `mapexpr`s. While it hasn't been tested, this
  seems unlikely to work for now, and the anticipated problems stem all
  the way back to Julia itself (again, issues that should be fixed in
  the package cache header).

Package authors who want to use this in their packages can add a call to
`Revise.parseall(@__MODULE__)` in their `__init__` function to
ensure that the `mapexpr` files are parsed and tracked by Revise.

Fixes #820, #634
---
 src/Revise.jl     |  2 +-
 src/callbacks.jl  |  2 +-
 src/lowered.jl    |  9 +++++++--
 src/packagedef.jl | 29 ++++++++++++++++++++---------
 src/parsing.jl    | 15 +++++++++++++++
 src/pkgs.jl       | 26 +++++++++++++++++++++++---
 src/types.jl      |  8 ++++++--
 test/runtests.jl  | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 8 files changed, 120 insertions(+), 18 deletions(-)

diff --git a/src/Revise.jl b/src/Revise.jl
index 0bde5773..bd7bcedb 100644
--- a/src/Revise.jl
+++ b/src/Revise.jl
@@ -35,7 +35,7 @@ module Revise
 
 using OrderedCollections, CodeTracking, JuliaInterpreter, LoweredCodeUtils
 
-using CodeTracking: PkgFiles, basedir, srcfiles, basepath, MethodInfoKey
+using CodeTracking: PkgFiles, MethodInfoKey, MapExprFile, basedir, srcfiles, basepath
 using JuliaInterpreter: Compiled, Frame, Interpreter, LineTypes, RecursiveInterpreter
 using JuliaInterpreter: codelocs, finish_and_return!, get_return, is_doc_expr, isassign,
                         isidentical, is_quotenode_egal, linetable, lookup, moduleof,
diff --git a/src/callbacks.jl b/src/callbacks.jl
index 5c258594..a42d69a1 100644
--- a/src/callbacks.jl
+++ b/src/callbacks.jl
@@ -21,7 +21,7 @@ const user_callbacks_queue = Set{Any}()
 Global variable, maps files (identified by their absolute path) to the set of
 callback keys registered for them.
 """
-const user_callbacks_by_file = Dict{String, Set{Any}}()
+const user_callbacks_by_file = Dict{Union{String, MapExprFile}, Set{Any}}()
 
 """
     Revise.user_callbacks_by_key
diff --git a/src/lowered.jl b/src/lowered.jl
index 2741be42..fcb4491d 100644
--- a/src/lowered.jl
+++ b/src/lowered.jl
@@ -495,7 +495,12 @@ function _methods_by_execution!(interp::Interpreter, methodinfo, frame::Frame, i
                     if length(stmt.args) == 2
                         add_includes!(methodinfo, mod, lookup(interp, frame, stmt.args[2]))
                     elseif length(stmt.args) == 3
-                        add_includes!(methodinfo, lookup(interp, frame, stmt.args[2]), lookup(interp, frame, stmt.args[3]))
+                        mod_or_mapexpr = lookup(interp, frame, stmt.args[2])
+                        if isa(mod_or_mapexpr, Module)
+                            add_includes!(methodinfo, mod_or_mapexpr, lookup(interp, frame, stmt.args[3]))
+                        else
+                            add_includes!(methodinfo, mod, MapExprFile(mod_or_mapexpr, lookup(interp, frame, stmt.args[3])))
+                        end
                     else
                         error("Bad call to Core.include")
                     end
@@ -509,7 +514,7 @@ function _methods_by_execution!(interp::Interpreter, methodinfo, frame::Frame, i
                         if isa(mod_or_mapexpr, Module)
                             add_includes!(methodinfo, mod_or_mapexpr, lookup(interp, frame, stmt.args[3]))
                         else
-                            error("include(mapexpr, path) is not supported") # TODO (issue #634)
+                            add_includes!(methodinfo, mod, MapExprFile(mod_or_mapexpr, lookup(interp, frame, stmt.args[3])))
                         end
                     end
                     assign_this!(frame, nothing)  # FIXME: the file might return something different from `nothing`
diff --git a/src/packagedef.jl b/src/packagedef.jl
index 393cae3e..959fceac 100644
--- a/src/packagedef.jl
+++ b/src/packagedef.jl
@@ -436,9 +436,9 @@ It also has the following fields:
 struct CodeTrackingMethodInfo
     exprstack::Vector{Expr}
     allsigs::Vector{Pair{Union{Nothing, MethodTable}, Type}}
-    includes::Vector{Pair{Module,String}}
+    includes::Vector{Pair{Module,Union{String, MapExprFile}}}
 end
-CodeTrackingMethodInfo(ex::Expr) = CodeTrackingMethodInfo([ex], Pair{Union{Nothing, MethodTable}, Type}[], Pair{Module,String}[])
+CodeTrackingMethodInfo(ex::Expr) = CodeTrackingMethodInfo([ex], Pair{Union{Nothing, MethodTable}, Type}[], Pair{Module,Union{String, MapExprFile}}[])
 
 function add_signature!(methodinfo::CodeTrackingMethodInfo, mt_sig::MethodInfoKey, ln)
     locdefs = CodeTracking.invoked_get!(Vector{Tuple{LineNumberNode,Expr}}, CodeTracking.method_info, mt_sig)
@@ -466,14 +466,16 @@ function eval_with_signatures(mod, ex::Expr; mode=:eval, kwargs...)
 end
 
 function instantiate_sigs!(modexsigs::ModuleExprsSigs; mode=:sigs, kwargs...)
+    includes = Pair{Module,Union{String, MapExprFile}}[]
     for (mod, exsigs) in modexsigs
         for rex in keys(exsigs)
             is_doc_expr(rex.ex) && continue
-            mt_sigs, _ = eval_with_signatures(mod, rex.ex; mode=mode, kwargs...)
+            mt_sigs, _includes = eval_with_signatures(mod, rex.ex; mode=mode, kwargs...)
+            append!(includes, _includes)
             exsigs[rex] = mt_sigs
         end
     end
-    return modexsigs
+    return includes
 end
 
 # This is intended for testing purposes, but not general use. The key problem is
@@ -485,6 +487,7 @@ function eval_revised(mod_exs_sigs_new, mod_exs_sigs_old)
     delete_missing!(mod_exs_sigs_old, mod_exs_sigs_new)
     eval_new!(mod_exs_sigs_new, mod_exs_sigs_old)  # note: drops `includes`
     instantiate_sigs!(mod_exs_sigs_new)
+    return mod_exs_sigs_new
 end
 
 """
@@ -631,16 +634,24 @@ function handle_deletions(pkgdata, file)
     maybe_extract_sigs!(fi)
     mexsold = fi.modexsigs
     idx = fileindex(pkgdata, file)
-    filep = pkgdata.info.files[idx]
-    if isa(filep, AbstractString)
+    filename = filep = pkgdata.info.files[idx]
+    if isa(filep, MapExprFile)
+        filename = String(filep.filename)::String
+    end
+    if isa(filename, AbstractString)
         if file ≠ "."
-            filep = normpath(basedir(pkgdata), file)
+            filename = normpath(basedir(pkgdata), file)
         else
-            filep = normpath(basedir(pkgdata))
+            filename = normpath(basedir(pkgdata))
         end
     end
+    if isa(filep, MapExprFile)
+        filep = MapExprFile(filep.mapexpr, filename)
+    else
+        filep = filename
+    end
     topmod = first(keys(mexsold))
-    fileok = file_exists(String(filep)::String)
+    fileok = file_exists(filename)
     mexsnew = fileok ? parse_source(filep, topmod) : ModuleExprsSigs(topmod)
     if mexsnew !== nothing && mexsnew !== DoNotParse()
         delete_missing!(mexsold, mexsnew)
diff --git a/src/parsing.jl b/src/parsing.jl
index 0e053286..95b48fd5 100644
--- a/src/parsing.jl
+++ b/src/parsing.jl
@@ -43,6 +43,21 @@ function parse_source!(mod_exprs_sigs::ModuleExprsSigs, src::AbstractString, fil
     end
 end
 
+function parse_source!(mod_exprs_sigs::ModuleExprsSigs, src::AbstractString, mapfile::MapExprFile, mod::Module; kwargs...)
+    if startswith(src, "# REVISE: DO NOT PARSE")
+        return DoNotParse()
+    end
+    (; mapexpr, filename) = mapfile
+    ex = Base.parse_input_line(src; filename)
+    if ex === nothing
+        return mod_exprs_sigs
+    elseif ex isa Expr
+        return process_ex!(mod_exprs_sigs, mapexpr(ex), filename, mod; kwargs...)
+    else # literals
+        return nothing
+    end
+end
+
 function process_ex!(mod_exprs_sigs::ModuleExprsSigs, ex::Expr, filename::AbstractString, mod::Module; mode::Symbol=:sigs)
     if isexpr(ex, :error) || isexpr(ex, :incomplete)
         return eval(ex)
diff --git a/src/pkgs.jl b/src/pkgs.jl
index 716effd4..f0ad8f3d 100644
--- a/src/pkgs.jl
+++ b/src/pkgs.jl
@@ -78,7 +78,7 @@ function read_from_cache(pkgdata::PkgData, file::AbstractString)
             Base._read_dependency_src(io, filec)
         end
     end
-    Base.read_dependency_src(fi.cachefile, filep)
+    Base.read_dependency_src(fi.cachefile, String(filep))
 end
 
 function maybe_parse_from_cache!(pkgdata::PkgData, file::AbstractString)
@@ -105,6 +105,25 @@ function maybe_parse_from_cache!(pkgdata::PkgData, file::AbstractString)
     return fi
 end
 
+function parseall!(pkgdata::PkgData)
+    # Parse all files in the package
+    for file in srcfiles(pkgdata)
+        fi = maybe_parse_from_cache!(pkgdata, file)
+        includes = maybe_extract_sigs!(fi)
+        for (mod, filename) in includes
+            if isa(filename, MapExprFile)
+                fn = joinpath(dirname(file), String(filename))
+                i = fileindex(pkgdata, fn)
+                if i !== nothing
+                    pkgdata.info.files[i] = MapExprFile(filename.mapexpr, fn)
+                end
+            end
+        end
+    end
+end
+parseall(pkgid::PkgId) = parseall!(pkgdatas[pkgid])
+parseall(m::Module) = parseall!(pkgdatas[PkgId(m)])
+
 function add_modexs!(fi::FileInfo, modexs)
     for (mod, rex) in modexs
         exsigs = get(fi.modexsigs, mod, nothing)
@@ -117,11 +136,12 @@ function add_modexs!(fi::FileInfo, modexs)
 end
 
 function maybe_extract_sigs!(fi::FileInfo)
+    includes = nothing
     if !fi.extracted[]
-        instantiate_sigs!(fi.modexsigs)
+        includes = instantiate_sigs!(fi.modexsigs)
         fi.extracted[] = true
     end
-    return fi
+    return includes
 end
 maybe_extract_sigs!(pkgdata::PkgData, file::AbstractString) = maybe_extract_sigs!(fileinfo(pkgdata, file))
 
diff --git a/src/types.jl b/src/types.jl
index 85dd6935..f66bc64e 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -150,7 +150,11 @@ CodeTracking.srcfiles(pkgdata::PkgData) = srcfiles(pkgdata.info)
 
 function fileindex(info::PkgData, file::AbstractString)
     for (i, f) in enumerate(srcfiles(info))
-        String(f) == String(file) && return i
+        f == file && return i
+        # FIXME: what if the file gets included twice with different mapexprs?
+        if isa(f, MapExprFile) && !isa(file, MapExprFile)
+            f.filename == file && return i
+        end
     end
     return nothing
 end
@@ -162,7 +166,7 @@ function hasfile(info::PkgData, file::AbstractString)
     fileindex(info, file) !== nothing
 end
 
-function fileinfo(pkgdata::PkgData, file::String)
+function fileinfo(pkgdata::PkgData, file::Union{String, MapExprFile})
     i = fileindex(pkgdata, file)
     i === nothing && error("file ", file, " not found")
     return pkgdata.fileinfos[i]
diff --git a/test/runtests.jl b/test/runtests.jl
index fac401c6..fff4f743 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -3197,6 +3197,53 @@ const issue639report = []
         @yry()
         test_second_revision(@eval $name)
     end
+
+    do_test("mapexpr include") && @testset "mapexpr include" begin
+        # Test is inspired by #634, modified to simplify testing
+        # Changes all appearances of `c` in the right-hand side of an assignment
+        # to `11 * c`
+        testdir = newtestdir()
+        dn = joinpath(testdir, "MapExprInclude", "src")
+        mkpath(dn)
+        write(joinpath(dn, "MapExprInclude.jl"), """
+            module MapExprInclude
+            function c211c!(expr)
+                expr0 = expr
+                while expr.head !== :(=)
+                    expr = expr.args[end]
+                end
+                if expr.head === :(=)
+                    lhs, rhs = expr.args
+                    while rhs.args[end] !== :c
+                        rhs = rhs.args[end]
+                    end
+                    if rhs.args[end] === :c
+                        rhs.args[end] = :(11 * c)
+                    else
+                        error("unexpected rhs: ", rhs)
+                    end
+                end
+                return expr0
+            end
+
+            include(c211c!, "getsmapped.jl")
+            end
+            """)
+        write(joinpath(dn, "getsmapped.jl"), """
+            foo(a, b, c) = a * b + c
+            """)
+        sleep(mtimedelay)
+        @eval using MapExprInclude
+        sleep(mtimedelay)
+        @test MapExprInclude.foo(1.0, 2.0, 3.0) == 35.0
+        Revise.parseall(MapExprInclude)   # DELETEME Julia 1.13
+        write(joinpath(dn, "getsmapped.jl"), """
+            foo(a, b, c) = a + b * c
+            """)
+        @yry()
+        @test MapExprInclude.foo(1.0, 2.0, 3.0) == 67.0
+        rm_precompile("MapExprInclude")
+    end
 end
 
 do_test("Utilities") && @testset "Utilities" begin