prevent loading other extensions when precompiling an extension

base/loading.jl

@@ -1332,7 +1332,9 @@ function run_module_init(mod::Module, i::Int=1)
 end
 
 function run_package_callbacks(modkey::PkgId)
-    run_extension_callbacks(modkey)
+    if !precompiling_extension
+        run_extension_callbacks(modkey)
+    end
     assert_havelock(require_lock)
     unlock(require_lock)
     try
@@ -2805,7 +2807,7 @@ end
 
 const PRECOMPILE_TRACE_COMPILE = Ref{String}()
 function create_expr_cache(pkg::PkgId, input::String, output::String, output_o::Union{Nothing, String},
-                           concrete_deps::typeof(_concrete_dependencies), flags::Cmd=``, internal_stderr::IO = stderr, internal_stdout::IO = stdout)
+                           concrete_deps::typeof(_concrete_dependencies), flags::Cmd=``, internal_stderr::IO = stderr, internal_stdout::IO = stdout, isext::Bool=false)
     @nospecialize internal_stderr internal_stdout
     rm(output, force=true)   # Remove file if it exists
     output_o === nothing || rm(output_o, force=true)
@@ -2874,7 +2876,7 @@ function create_expr_cache(pkg::PkgId, input::String, output::String, output_o::
     write(io.in, """
         empty!(Base.EXT_DORMITORY) # If we have a custom sysimage with `EXT_DORMITORY` prepopulated
         Base.track_nested_precomp($precomp_stack)
-        Base.precompiling_extension = $(loading_extension)
+        Base.precompiling_extension = $(loading_extension | isext)
         Base.include_package_for_output($(pkg_str(pkg)), $(repr(abspath(input))), $(repr(depot_path)), $(repr(dl_load_path)),
             $(repr(load_path)), $deps, $(repr(source_path(nothing))))
         """)
@@ -2931,18 +2933,18 @@ This can be used to reduce package load times. Cache files are stored in
 `DEPOT_PATH[1]/compiled`. See [Module initialization and precompilation](@ref)
 for important notes.
 """
-function compilecache(pkg::PkgId, internal_stderr::IO = stderr, internal_stdout::IO = stdout; flags::Cmd=``, reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}())
+function compilecache(pkg::PkgId, internal_stderr::IO = stderr, internal_stdout::IO = stdout; flags::Cmd=``, reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}(), isext::Bool=false)
     @nospecialize internal_stderr internal_stdout
     path = locate_package(pkg)
     path === nothing && throw(ArgumentError("$(repr("text/plain", pkg)) not found during precompilation"))
-    return compilecache(pkg, path, internal_stderr, internal_stdout; flags, reasons)
+    return compilecache(pkg, path, internal_stderr, internal_stdout; flags, reasons, isext)
 end
 
 const MAX_NUM_PRECOMPILE_FILES = Ref(10)
 
 function compilecache(pkg::PkgId, path::String, internal_stderr::IO = stderr, internal_stdout::IO = stdout,
                       keep_loaded_modules::Bool = true; flags::Cmd=``, cacheflags::CacheFlags=CacheFlags(),
-                      reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}())
+                      reasons::Union{Dict{String,Int},Nothing}=Dict{String,Int}(), isext::Bool=false)
 
     @nospecialize internal_stderr internal_stdout
     # decide where to put the resulting cache file
@@ -2982,7 +2984,7 @@ function compilecache(pkg::PkgId, path::String, internal_stderr::IO = stderr, in
             close(tmpio_o)
             close(tmpio_so)
         end
-        p = create_expr_cache(pkg, path, tmppath, tmppath_o, concrete_deps, flags, internal_stderr, internal_stdout)
+        p = create_expr_cache(pkg, path, tmppath, tmppath_o, concrete_deps, flags, internal_stderr, internal_stdout, isext)
 
         if success(p)
             if cache_objects

base/precompilation.jl

@@ -471,7 +471,10 @@ function precompilepkgs(pkgs::Vector{String}=String[];
                     extension_1 == extension_2 && continue
                     deps_ext_2 = depsmap_transitive[extension_2]
                     if issubset(deps_ext_2, deps_ext_1)
-                        push!(depsmap[extension_1], extension_2)
+                        # extensions do not depend on each other
+                        if !haskey(exts, extension_2)
+                            push!(depsmap[extension_1], extension_2)
+                        end
                     end
                 end
             end
@@ -849,7 +852,7 @@ function precompilepkgs(pkgs::Vector{String}=String[];
                             t = @elapsed ret = precompile_pkgs_maybe_cachefile_lock(io, print_lock, fancyprint, pkg_config, pkgspidlocked, hascolor) do
                                 Base.with_logger(Base.NullLogger()) do
                                     # The false here means we ignore loaded modules, so precompile for a fresh session
-                                    Base.compilecache(pkg, sourcepath, std_pipe, std_pipe, false; flags, cacheflags)
+                                    Base.compilecache(pkg, sourcepath, std_pipe, std_pipe, false; flags, cacheflags, isext = haskey(exts, pkg))
                                 end
                             end
                             if ret isa Base.PrecompilableError

test/loading.jl

@@ -1147,6 +1147,19 @@ end
         finally
             copy!(LOAD_PATH, old_load_path)
         end
+
+        # Extension with cycles in dependencies
+        code = """
+        using CyclicExtensions
+        Base.get_extension(CyclicExtensions, :ExtA) isa Module || error("expected extension to load")
+        Base.get_extension(CyclicExtensions, :ExtB) isa Module || error("expected extension to load")
+        CyclicExtensions.greet()
+        """
+        proj = joinpath(@__DIR__, "project", "Extensions", "CyclicExtensions")
+        cmd =  `$(Base.julia_cmd()) --startup-file=no -e $code`
+        cmd = addenv(cmd, "JULIA_LOAD_PATH" => proj)
+        @test occursin("Hello Cycles!", String(read(cmd)))
+
     finally
         try
             rm(depot_path, force=true, recursive=true)

test/project/Extensions/CyclicExtensions/Manifest.toml

@@ -0,0 +1,21 @@
+# This file is machine-generated - editing it directly is not advised
+
+julia_version = "1.10.4"
+manifest_format = "2.0"
+project_hash = "ec25ff8df3a5e2212a173c3de2c7d716cc47cd36"
+
+[[deps.ExtDep]]
+deps = ["SomePackage"]
+path = "../ExtDep.jl"
+uuid = "fa069be4-f60b-4d4c-8b95-f8008775090c"
+version = "0.1.0"
+
+[[deps.ExtDep2]]
+path = "../ExtDep2"
+uuid = "55982ee5-2ad5-4c40-8cfe-5e9e1b01500d"
+version = "0.1.0"
+
+[[deps.SomePackage]]
+path = "../SomePackage"
+uuid = "678608ae-7bb3-42c7-98b1-82102067a3d8"
+version = "0.1.0"

test/project/Extensions/CyclicExtensions/Project.toml

@@ -0,0 +1,13 @@
+name = "CyclicExtensions"
+uuid = "17d4f0df-b55c-4714-ac4b-55fa23f7355c"
+version = "0.1.0"
+
+[deps]
+ExtDep = "fa069be4-f60b-4d4c-8b95-f8008775090c"
+
+[weakdeps]
+SomePackage = "678608ae-7bb3-42c7-98b1-82102067a3d8"
+
+[extensions]
+ExtA = ["SomePackage"]
+ExtB = ["SomePackage"]

test/project/Extensions/CyclicExtensions/ext/ExtA.jl

@@ -0,0 +1,6 @@
+module ExtA
+
+using CyclicExtensions
+using SomePackage
+
+end

test/project/Extensions/CyclicExtensions/ext/ExtB.jl

@@ -0,0 +1,6 @@
+module ExtB
+
+using CyclicExtensions
+using SomePackage
+
+end

test/project/Extensions/CyclicExtensions/src/CyclicExtensions.jl

@@ -0,0 +1,7 @@
+module CyclicExtensions
+
+using ExtDep
+
+greet() = print("Hello Cycles!")
+
+end # module CyclicExtensions