Fix serialization of code instances.

If they are encountered in a Julia object directly, as opposed to
e.g. during serialization of a method instance, we'll have first
populated the backref table as part of jl_serialize_value, so we
need to skip that check during code instance serialization.

Author: maleadt

src/dump.c

@@ -653,13 +653,15 @@ static int jl_serialize_generic(jl_serializer_state *s, jl_value_t *v) JL_GC_DIS
     return 0;
 }
 
-static void jl_serialize_code_instance(jl_serializer_state *s, jl_code_instance_t *codeinst, int skip_partial_opaque, int internal) JL_GC_DISABLED
+static void jl_serialize_code_instance(jl_serializer_state *s, jl_code_instance_t *codeinst,
+                                       int skip_partial_opaque, int internal,
+                                       int force) JL_GC_DISABLED
 {
     if (internal > 2) {
         while (codeinst && !codeinst->relocatability)
             codeinst = codeinst->next;
     }
-    if (jl_serialize_generic(s, (jl_value_t*)codeinst)) {
+    if (!force && jl_serialize_generic(s, (jl_value_t*)codeinst)) {
         return;
     }
     assert(codeinst != NULL); // handle by jl_serialize_generic, but this makes clang-sa happy
@@ -680,7 +682,7 @@ static void jl_serialize_code_instance(jl_serializer_state *s, jl_code_instance_
     if (write_ret_type && codeinst->rettype_const &&
             jl_typeis(codeinst->rettype_const, jl_partial_opaque_type)) {
         if (skip_partial_opaque) {
-            jl_serialize_code_instance(s, codeinst->next, skip_partial_opaque, internal);
+            jl_serialize_code_instance(s, codeinst->next, skip_partial_opaque, internal, 0);
             return;
         }
         else {
@@ -707,7 +709,7 @@ static void jl_serialize_code_instance(jl_serializer_state *s, jl_code_instance_
         jl_serialize_value(s, jl_nothing);
     }
     write_uint8(s->s, codeinst->relocatability);
-    jl_serialize_code_instance(s, codeinst->next, skip_partial_opaque, internal);
+    jl_serialize_code_instance(s, codeinst->next, skip_partial_opaque, internal, 0);
 }
 
 enum METHOD_SERIALIZATION_MODE {
@@ -968,10 +970,10 @@ static void jl_serialize_value_(jl_serializer_state *s, jl_value_t *v, int as_li
         }
         jl_serialize_value(s, (jl_value_t*)backedges);
         jl_serialize_value(s, (jl_value_t*)NULL); //callbacks
-        jl_serialize_code_instance(s, mi->cache, 1, internal);
+        jl_serialize_code_instance(s, mi->cache, 1, internal, 0);
     }
     else if (jl_is_code_instance(v)) {
-        jl_serialize_code_instance(s, (jl_code_instance_t*)v, 0, 2);
+        jl_serialize_code_instance(s, (jl_code_instance_t*)v, 0, 2, 1);
     }
     else if (jl_typeis(v, jl_module_type)) {
         jl_serialize_module(s, (jl_module_t*)v);

test/precompile.jl

@@ -1488,5 +1488,27 @@ precompile_test_harness("Issue #46558") do load_path
     @test (@eval $Foo.foo(1)) == 2
 end
 
+precompile_test_harness("issue #46296") do load_path
+    write(joinpath(load_path, "CodeInstancePrecompile.jl"),
+        """
+        module CodeInstancePrecompile
+
+        sig = Tuple{typeof(identity), Nothing}
+        meth = which(sig)
+        ti, env = ccall(:jl_type_intersection_with_env, Any,
+                    (Any, Any), meth.sig, sig)
+        mi = ccall(:jl_specializations_get_linfo, Ref{Core.MethodInstance},
+                (Any, Any, Any, UInt), meth, ti, env, 1)
+        ci = Core.CodeInstance(mi, Any, nothing, nothing, zero(Int32), typemin(UInt64),
+                            typemax(UInt64), zero(UInt32), zero(UInt32), nothing, 0x00)
+
+        __init__() = @assert ci isa Core.CodeInstance
+
+        end
+        """)
+    Base.compilecache(Base.PkgId("CodeInstancePrecompile"))
+    (@eval (using CodeInstancePrecompile))
+end
+
 empty!(Base.DEPOT_PATH)
 append!(Base.DEPOT_PATH, original_depot_path)