From 567c6ffb1e6cbd49e4e87ecf71cdc4093eafe4c6 Mon Sep 17 00:00:00 2001
From: Cody Tapscott <topolarity@tapscott.me>
Date: Thu, 5 Feb 2026 20:55:52 -0500
Subject: [PATCH] codegen: Mark resolved `const` `GlobalRef` as method root

This allows `--trim` to safely* prune bindings without dropping
the root required for the generated machine code.

* uninferred GlobalRefs can lead to missing bindings at runtime,
  but these do not directly trigger UB / crash and they are
  relatively rare
---
 src/codegen.cpp               |  4 ++++
 test/trimming/trimmability.jl | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/src/codegen.cpp b/src/codegen.cpp
index 5bf292bc44427..4e2a796dd2eb7 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -3505,6 +3505,10 @@ static jl_cgval_t emit_globalref(jl_codectx_t &ctx, jl_module_t *mod, jl_sym_t *
             undef_var_error_ifnot(ctx, ConstantInt::get(getInt1Ty(ctx.builder.getContext()), 0), name, (jl_value_t*)mod);
             return jl_cgval_t();
         }
+        if (jl_generating_output()) {
+            // root is required to allow bindings to be pruned, especially by `--trim`
+            jl_temporary_root(ctx, constval);
+        }
         return mark_julia_const(ctx, constval);
     }
     if (rkp.kind != PARTITION_KIND_GLOBAL) {
diff --git a/test/trimming/trimmability.jl b/test/trimming/trimmability.jl
index 209a27343d18d..0fd9eedc6999d 100644
--- a/test/trimming/trimmability.jl
+++ b/test/trimming/trimmability.jl
@@ -19,6 +19,13 @@ area(c::Circle) = pi*c.radius^2
 
 sum_areas(v::Vector{Shape}) = sum(area, v)
 
+mutable struct Foo; x::Int; end
+const storage = Foo[]
+function add_one(x::Cint)::Cint
+    push!(storage, Foo(x))
+    return x + 1
+end
+
 function @main(args::Vector{String})::Cint
     println(Core.stdout, str())
     println(Core.stdout, PROGRAM_FILE)
@@ -38,6 +45,12 @@ function @main(args::Vector{String})::Cint
     d = mapreduce(x -> x^2, +, sorted_arr)
     # e = reduce(xor, rand(Int, 10))
 
+    for i = 1:10
+        # https://github.com/JuliaLang/julia/issues/60846
+        add_one(Cint(i))
+        GC.gc()
+    end
+
     try
         sock = connect("localhost", 4900)
         if isopen(sock)