From 1f6c479f806cf74573b3235bd87c9e1ecaefcd88 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Mon, 29 Jan 2024 14:51:11 -0500
Subject: [PATCH 1/3] shortcut if cycle detected in extension precompilation

---
 base/loading.jl | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/base/loading.jl b/base/loading.jl
index 8bcaa4b2ab5b3..55eeb8d076043 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -1438,6 +1438,13 @@ function run_extension_callbacks(pkgid::PkgId)
     extids = pop!(EXT_DORMITORY, pkgid, nothing)
     extids === nothing && return
     for extid in extids
+        if in(extid.id, precompilation_stack) && !isprecompiled(extid.id)
+            @debug """
+            Dependency cycle detected in extension precompilation: $(precompilation_stack_list()) > $(extid.id.name)
+            $(extid.id.name) will not be loaded here.
+            """
+            continue
+        end
         if extid.ntriggers > 0
             # indicate pkgid is loaded
             extid.ntriggers -= 1
@@ -2569,14 +2576,14 @@ function create_expr_cache(pkg::PkgId, input::String, output::String, output_o::
 end
 
 const precompilation_stack = Vector{PkgId}()
+precompilation_stack_list() = join(map(p->p.name, precompilation_stack), " > ")
 # Helpful for debugging when precompilation is unexpectedly nested.
 # Enable with `JULIA_DEBUG=nested_precomp`. Note that it expected to be nested in classical code-load precompilation
 # TODO: Add detection if extension precompilation is nested and error / return early?
 function track_nested_precomp(pkgs::Vector{PkgId})
     append!(precompilation_stack, pkgs)
     if length(precompilation_stack) > 1
-        list() = join(map(p->p.name, precompilation_stack), " > ")
-        @debug "Nested precompilation: $(list())" _group=:nested_precomp
+        @debug "Nested precompilation: $(precompilation_stack_list())" _group=:nested_precomp
     end
 end
 

From 00f7b3f4edfe6f1938cc15801afd409c2cf91f61 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Wed, 14 Feb 2024 22:27:32 -0500
Subject: [PATCH 2/3] rm isprecompiled check

---
 base/loading.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/loading.jl b/base/loading.jl
index 55eeb8d076043..16a1e12cb6c2a 100644
--- a/base/loading.jl
+++ b/base/loading.jl
@@ -1438,7 +1438,7 @@ function run_extension_callbacks(pkgid::PkgId)
     extids = pop!(EXT_DORMITORY, pkgid, nothing)
     extids === nothing && return
     for extid in extids
-        if in(extid.id, precompilation_stack) && !isprecompiled(extid.id)
+        if in(extid.id, precompilation_stack)
             @debug """
             Dependency cycle detected in extension precompilation: $(precompilation_stack_list()) > $(extid.id.name)
             $(extid.id.name) will not be loaded here.

From 33d9e2a3ca209b4bd73fd4efe5e18a35ace47b34 Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Wed, 14 Feb 2024 22:28:24 -0500
Subject: [PATCH 3/3] add test

---
 test/extensions/circular/A/Project.toml | 14 +++++++++++
 test/extensions/circular/A/ext/CExt.jl  |  3 +++
 test/extensions/circular/A/ext/DExt.jl  |  3 +++
 test/extensions/circular/A/src/A.jl     |  3 +++
 test/extensions/circular/B/Project.toml |  7 ++++++
 test/extensions/circular/B/src/B.jl     |  3 +++
 test/extensions/circular/C/Project.toml |  3 +++
 test/extensions/circular/C/src/C.jl     |  3 +++
 test/extensions/circular/D/Project.toml |  3 +++
 test/extensions/circular/D/src/D.jl     |  3 +++
 test/extensions/circular/Manifest.toml  | 32 +++++++++++++++++++++++++
 test/extensions/circular/Project.toml   |  5 ++++
 test/loading.jl                         |  7 ++++++
 13 files changed, 89 insertions(+)
 create mode 100644 test/extensions/circular/A/Project.toml
 create mode 100644 test/extensions/circular/A/ext/CExt.jl
 create mode 100644 test/extensions/circular/A/ext/DExt.jl
 create mode 100644 test/extensions/circular/A/src/A.jl
 create mode 100644 test/extensions/circular/B/Project.toml
 create mode 100644 test/extensions/circular/B/src/B.jl
 create mode 100644 test/extensions/circular/C/Project.toml
 create mode 100644 test/extensions/circular/C/src/C.jl
 create mode 100644 test/extensions/circular/D/Project.toml
 create mode 100644 test/extensions/circular/D/src/D.jl
 create mode 100644 test/extensions/circular/Manifest.toml
 create mode 100644 test/extensions/circular/Project.toml

diff --git a/test/extensions/circular/A/Project.toml b/test/extensions/circular/A/Project.toml
new file mode 100644
index 0000000000000..9b55fcbf05001
--- /dev/null
+++ b/test/extensions/circular/A/Project.toml
@@ -0,0 +1,14 @@
+name = "A"
+uuid = "c8938445-7efa-411c-ba8f-721576f9f47a"
+version = "0.1.0"
+
+[deps]
+B = "ef00b25e-dd85-47e0-9cd9-ed3c1ff51032"
+
+[weakdeps]
+C = "d95b043b-fbe6-48a2-93d2-75fba1b51518"
+D = "64e66ba5-e914-4adb-a5f6-036ef0c801f3"
+
+[extensions]
+CExt = "C"
+DExt = "D"
diff --git a/test/extensions/circular/A/ext/CExt.jl b/test/extensions/circular/A/ext/CExt.jl
new file mode 100644
index 0000000000000..33b4a5fc7cd3c
--- /dev/null
+++ b/test/extensions/circular/A/ext/CExt.jl
@@ -0,0 +1,3 @@
+module CExt
+
+end # module
diff --git a/test/extensions/circular/A/ext/DExt.jl b/test/extensions/circular/A/ext/DExt.jl
new file mode 100644
index 0000000000000..915dfc89196f2
--- /dev/null
+++ b/test/extensions/circular/A/ext/DExt.jl
@@ -0,0 +1,3 @@
+module DExt
+
+end # module
diff --git a/test/extensions/circular/A/src/A.jl b/test/extensions/circular/A/src/A.jl
new file mode 100644
index 0000000000000..b555e27e24287
--- /dev/null
+++ b/test/extensions/circular/A/src/A.jl
@@ -0,0 +1,3 @@
+module A
+
+end # module
diff --git a/test/extensions/circular/B/Project.toml b/test/extensions/circular/B/Project.toml
new file mode 100644
index 0000000000000..21205c7c345a5
--- /dev/null
+++ b/test/extensions/circular/B/Project.toml
@@ -0,0 +1,7 @@
+name = "B"
+uuid = "ef00b25e-dd85-47e0-9cd9-ed3c1ff51032"
+version = "0.1.0"
+
+[deps]
+C = "d95b043b-fbe6-48a2-93d2-75fba1b51518"
+D = "64e66ba5-e914-4adb-a5f6-036ef0c801f3"
diff --git a/test/extensions/circular/B/src/B.jl b/test/extensions/circular/B/src/B.jl
new file mode 100644
index 0000000000000..d5bdf6392c9f4
--- /dev/null
+++ b/test/extensions/circular/B/src/B.jl
@@ -0,0 +1,3 @@
+module B
+
+end # module
diff --git a/test/extensions/circular/C/Project.toml b/test/extensions/circular/C/Project.toml
new file mode 100644
index 0000000000000..a913862e5a36f
--- /dev/null
+++ b/test/extensions/circular/C/Project.toml
@@ -0,0 +1,3 @@
+name = "C"
+uuid = "d95b043b-fbe6-48a2-93d2-75fba1b51518"
+version = "0.1.0"
diff --git a/test/extensions/circular/C/src/C.jl b/test/extensions/circular/C/src/C.jl
new file mode 100644
index 0000000000000..489fa1e07ea91
--- /dev/null
+++ b/test/extensions/circular/C/src/C.jl
@@ -0,0 +1,3 @@
+module C
+
+end # module
diff --git a/test/extensions/circular/D/Project.toml b/test/extensions/circular/D/Project.toml
new file mode 100644
index 0000000000000..0e7bda4162265
--- /dev/null
+++ b/test/extensions/circular/D/Project.toml
@@ -0,0 +1,3 @@
+name = "D"
+uuid = "64e66ba5-e914-4adb-a5f6-036ef0c801f3"
+version = "0.1.0"
diff --git a/test/extensions/circular/D/src/D.jl b/test/extensions/circular/D/src/D.jl
new file mode 100644
index 0000000000000..e87de9cb2024a
--- /dev/null
+++ b/test/extensions/circular/D/src/D.jl
@@ -0,0 +1,3 @@
+module D
+
+end # module
diff --git a/test/extensions/circular/Manifest.toml b/test/extensions/circular/Manifest.toml
new file mode 100644
index 0000000000000..cd5f52f1de4ec
--- /dev/null
+++ b/test/extensions/circular/Manifest.toml
@@ -0,0 +1,32 @@
+# This file is machine-generated - editing it directly is not advised
+
+julia_version = "1.11.0-DEV"
+manifest_format = "2.0"
+project_hash = "6c189c4d9e1e9194c4a4d7627740c379ecff4942"
+
+[[deps.A]]
+deps = ["B"]
+path = "./A"
+uuid = "c8938445-7efa-411c-ba8f-721576f9f47a"
+version = "0.1.0"
+weakdeps = ["C", "D"]
+
+    [deps.A.extensions]
+    CExt = "C"
+    DExt = "D"
+
+[[deps.B]]
+deps = ["C", "D"]
+path = "./B"
+uuid = "ef00b25e-dd85-47e0-9cd9-ed3c1ff51032"
+version = "0.1.0"
+
+[[deps.C]]
+path = "./C"
+uuid = "d95b043b-fbe6-48a2-93d2-75fba1b51518"
+version = "0.1.0"
+
+[[deps.D]]
+path = "./D"
+uuid = "64e66ba5-e914-4adb-a5f6-036ef0c801f3"
+version = "0.1.0"
diff --git a/test/extensions/circular/Project.toml b/test/extensions/circular/Project.toml
new file mode 100644
index 0000000000000..beed7a9072ad4
--- /dev/null
+++ b/test/extensions/circular/Project.toml
@@ -0,0 +1,5 @@
+[deps]
+A = "c8938445-7efa-411c-ba8f-721576f9f47a"
+B = "ef00b25e-dd85-47e0-9cd9-ed3c1ff51032"
+C = "d95b043b-fbe6-48a2-93d2-75fba1b51518"
+D = "64e66ba5-e914-4adb-a5f6-036ef0c801f3"
diff --git a/test/loading.jl b/test/loading.jl
index 53e05a4a76bbc..ca39a415ade08 100644
--- a/test/loading.jl
+++ b/test/loading.jl
@@ -1143,6 +1143,13 @@ end
         finally
             copy!(LOAD_PATH, old_load_path)
         end
+
+        # issue 53081
+        @testset "avoid circular precompilation deadlock through extensions" begin
+            testenv = joinpath(@__DIR__, "extensions", "circular")
+            s = read(`$(Base.julia_cmd()) --startup-file=no --project=$testenv -e 'using A'`, String)
+            @test !occursin("Error during loading of extension", s)
+        end
     finally
         try
             rm(depot_path, force=true, recursive=true)