fix isconst definition/accessor issues with binding partitions

The problem was that isconst was declaring true when it was actually a
back-dated (e.g. mutable) value, which confuses the runtime (e.g.
show_datatype) into emitting warnings that are not warranted.

Author: vtjnash

src/codegen.cpp

@@ -3199,7 +3199,7 @@ static jl_cgval_t emit_globalref(jl_codectx_t &ctx, jl_module_t *mod, jl_sym_t *
     if (!jl_get_binding_leaf_partitions_restriction_kind(bnd, &rkp, ctx.min_world, ctx.max_world)) {
         return emit_globalref_runtime(ctx, bnd, mod, name);
     }
-    if (jl_bkind_is_some_constant(rkp.kind) && rkp.kind != PARTITION_KIND_BACKDATED_CONST) {
+    if (jl_bkind_is_real_constant(rkp.kind) || rkp.kind == PARTITION_KIND_UNDEF_CONST) {
         if (rkp.maybe_depwarn) {
             Value *bp = julia_binding_gv(ctx, bnd);
             ctx.builder.CreateCall(prepare_call(jldepcheck_func), { bp });
@@ -3789,7 +3789,7 @@ static jl_cgval_t emit_isdefinedglobal(jl_codectx_t &ctx, jl_module_t *modu, jl_
     jl_binding_t *bnd = allow_import ? jl_get_binding(modu, name) : jl_get_module_binding(modu, name, 0);
     struct restriction_kind_pair rkp = { NULL, NULL, PARTITION_KIND_GUARD, 0 };
     if (allow_import && jl_get_binding_leaf_partitions_restriction_kind(bnd, &rkp, ctx.min_world, ctx.max_world)) {
-        if (jl_bkind_is_some_constant(rkp.kind) && rkp.restriction)
+        if (jl_bkind_is_real_constant(rkp.kind))
             return mark_julia_const(ctx, jl_true);
         if (rkp.kind == PARTITION_KIND_GLOBAL) {
             Value *bp = julia_binding_gv(ctx, rkp.binding_if_global);

src/gf.c

@@ -771,7 +771,7 @@ int foreach_mtable_in_module(
         if ((void*)b == jl_nothing)
             break;
         jl_sym_t *name = b->globalref->name;
-        jl_value_t *v = jl_get_binding_value_if_const(b);
+        jl_value_t *v = jl_get_latest_binding_value_if_const(b);
         if (v) {
             jl_value_t *uw = jl_unwrap_unionall(v);
             if (jl_is_datatype(uw)) {

src/julia.h

@@ -1942,9 +1942,9 @@ JL_DLLEXPORT jl_sym_t *jl_tagged_gensym(const char *str, size_t len);
 JL_DLLEXPORT jl_sym_t *jl_get_root_symbol(void);
 JL_DLLEXPORT jl_value_t *jl_get_binding_value(jl_binding_t *b JL_PROPAGATES_ROOT);
 JL_DLLEXPORT jl_value_t *jl_get_binding_value_in_world(jl_binding_t *b JL_PROPAGATES_ROOT, size_t world);
-JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_const(jl_binding_t *b JL_PROPAGATES_ROOT);
-JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_resolved_debug_only(jl_binding_t *b JL_PROPAGATES_ROOT) JL_NOTSAFEPOINT;
-JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_latest_resolved_and_const_debug_only(jl_binding_t *b JL_PROPAGATES_ROOT) JL_NOTSAFEPOINT;
+JL_DLLEXPORT jl_value_t *jl_get_latest_binding_value_if_const(jl_binding_t *b JL_PROPAGATES_ROOT);
+JL_DLLEXPORT jl_value_t *jl_get_latest_binding_value_if_resolved_debug_only(jl_binding_t *b JL_PROPAGATES_ROOT) JL_NOTSAFEPOINT;
+JL_DLLEXPORT jl_value_t *jl_get_latest_binding_value_if_resolved_and_const_debug_only(jl_binding_t *b JL_PROPAGATES_ROOT) JL_NOTSAFEPOINT;
 JL_DLLEXPORT jl_value_t *jl_declare_const_gf(jl_module_t *mod, jl_sym_t *name);
 JL_DLLEXPORT jl_method_t *jl_method_def(jl_svec_t *argdata, jl_methtable_t *mt, jl_code_info_t *f, jl_module_t *module);
 JL_DLLEXPORT jl_code_info_t *jl_code_for_staged(jl_method_instance_t *linfo, size_t world, jl_code_instance_t **cache);

src/julia_internal.h

@@ -982,6 +982,10 @@ STATIC_INLINE int jl_bkind_is_defined_constant(enum jl_partition_kind kind) JL_N
     return kind == PARTITION_KIND_IMPLICIT_CONST || kind == PARTITION_KIND_CONST || kind == PARTITION_KIND_CONST_IMPORT || kind == PARTITION_KIND_BACKDATED_CONST;
 }
 
+STATIC_INLINE int jl_bkind_is_real_constant(enum jl_partition_kind kind) JL_NOTSAFEPOINT {
+    return kind == PARTITION_KIND_IMPLICIT_CONST || kind == PARTITION_KIND_CONST || kind == PARTITION_KIND_CONST_IMPORT;
+}
+
 JL_DLLEXPORT jl_binding_partition_t *jl_get_binding_partition(jl_binding_t *b JL_PROPAGATES_ROOT, size_t world) JL_GLOBALLY_ROOTED;
 JL_DLLEXPORT jl_binding_partition_t *jl_get_binding_partition_with_hint(jl_binding_t *b JL_PROPAGATES_ROOT, jl_binding_partition_t *previous_part, size_t world) JL_GLOBALLY_ROOTED;
 JL_DLLEXPORT jl_binding_partition_t *jl_get_binding_partition_all(jl_binding_t *b JL_PROPAGATES_ROOT, size_t min_world, size_t max_world) JL_GLOBALLY_ROOTED;

src/method.c

@@ -224,7 +224,7 @@ static jl_value_t *resolve_definition_effects(jl_value_t *expr, jl_module_t *mod
         jl_sym_t *fe_sym = jl_globalref_name(fe);
         // look at some known called functions
         jl_binding_t *b = jl_get_binding(fe_mod, fe_sym);
-        if (jl_get_binding_value_if_const(b) == BUILTIN(tuple)) {
+        if (jl_get_latest_binding_value_if_const(b) == BUILTIN(tuple)) {
             size_t j;
             for (j = 1; j < nargs; j++) {
                 if (!jl_is_quotenode(jl_exprarg(e, j)))

src/module.c

@@ -461,7 +461,7 @@ JL_DLLEXPORT jl_value_t *jl_get_binding_leaf_partitions_value_if_const(jl_bindin
     struct restriction_kind_pair rkp = { NULL, NULL, PARTITION_KIND_GUARD, 0 };
     if (!jl_get_binding_leaf_partitions_restriction_kind(b, &rkp, min_world, max_world))
         return NULL;
-    if (jl_bkind_is_some_constant(rkp.kind) && rkp.kind != PARTITION_KIND_BACKDATED_CONST) {
+    if (jl_bkind_is_real_constant(rkp.kind)) {
         *maybe_depwarn = rkp.maybe_depwarn;
         return rkp.restriction;
     }
@@ -578,7 +578,7 @@ JL_DLLEXPORT jl_binding_partition_t *jl_declare_constant_val3(
             for (;;) {
                 enum jl_partition_kind prev_kind = jl_binding_kind(prev_bpart);
                 if (jl_bkind_is_some_constant(prev_kind) || prev_kind == PARTITION_KIND_GLOBAL ||
-                    (jl_bkind_is_some_import(prev_kind))) {
+                    jl_bkind_is_some_import(prev_kind)) {
                     need_backdate = 0;
                     break;
                 }
@@ -917,22 +917,23 @@ JL_DLLEXPORT jl_value_t *jl_get_binding_value_seqcst(jl_binding_t *b)
     return jl_atomic_load(&b->value);
 }
 
-JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_const(jl_binding_t *b)
+JL_DLLEXPORT jl_value_t *jl_get_latest_binding_value_if_const(jl_binding_t *b)
 {
-    jl_binding_partition_t *bpart = jl_get_binding_partition(b, jl_current_task->world_age);
-    jl_walk_binding_inplace(&b, &bpart, jl_current_task->world_age);
+    // See note below. Note that this is for some deprecated uses, and should not be added to new code.
+    size_t world = jl_atomic_load_relaxed(&jl_world_counter);
+    jl_binding_partition_t *bpart = jl_get_binding_partition(b, world);
+    jl_walk_binding_inplace(&b, &bpart, world);
     enum jl_partition_kind kind = jl_binding_kind(bpart);
     if (jl_bkind_is_some_guard(kind))
         return NULL;
-    if (!jl_bkind_is_some_constant(kind))
+    if (!jl_bkind_is_real_constant(kind))
         return NULL;
-    check_backdated_binding(b, kind);
     return bpart->restriction;
 }
 
-JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_latest_resolved_and_const_debug_only(jl_binding_t *b)
+JL_DLLEXPORT jl_value_t *jl_get_latest_binding_value_if_resolved_and_const_debug_only(jl_binding_t *b)
 {
-    // Unlike jl_get_binding_value_if_const this doesn't try to allocate new binding partitions if they
+    // Unlike jl_get_latest_binding_value_if_const this doesn't try to allocate new binding partitions if they
     // don't already exist, making this JL_NOTSAFEPOINT. However, as a result, this may fail to return
     // a value - even if one does exist. It should only be used for reflection/debugging when the integrity
     // of the runtime is not guaranteed.
@@ -942,18 +943,17 @@ JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_latest_resolved_and_const_debug
     if (!bpart)
         return NULL;
     size_t max_world = jl_atomic_load_relaxed(&bpart->max_world);
-    if (jl_atomic_load_relaxed(&bpart->min_world) > jl_current_task->world_age || jl_current_task->world_age > max_world)
+    if (max_world != ~(size_t)0)
         return NULL;
     enum jl_partition_kind kind = jl_binding_kind(bpart);
     if (jl_bkind_is_some_guard(kind))
         return NULL;
-    if (!jl_bkind_is_some_constant(kind))
+    if (!jl_bkind_is_real_constant(kind))
         return NULL;
-    check_backdated_binding(b, kind);
     return bpart->restriction;
 }
 
-JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_resolved_debug_only(jl_binding_t *b)
+JL_DLLEXPORT jl_value_t *jl_get_latest_binding_value_if_resolved_debug_only(jl_binding_t *b)
 {
     // See note above. Use for debug/reflection purposes only.
     if (!b)
@@ -962,15 +962,14 @@ JL_DLLEXPORT jl_value_t *jl_get_binding_value_if_resolved_debug_only(jl_binding_
     if (!bpart)
         return NULL;
     size_t max_world = jl_atomic_load_relaxed(&bpart->max_world);
-    if (jl_atomic_load_relaxed(&bpart->min_world) > jl_current_task->world_age || jl_current_task->world_age > max_world)
+    if (max_world != ~(size_t)0)
         return NULL;
     enum jl_partition_kind kind = jl_binding_kind(bpart);
     if (jl_bkind_is_some_guard(kind))
         return NULL;
     if (jl_bkind_is_some_import(kind))
         return NULL;
     if (jl_bkind_is_some_constant(kind)) {
-        check_backdated_binding(b, kind);
         return bpart->restriction;
     }
     return jl_atomic_load_relaxed(&b->value);
@@ -1005,6 +1004,7 @@ static jl_module_t *jl_binding_dbgmodule(jl_binding_t *b)
 // along the way.
 JL_DLLEXPORT jl_value_t *jl_get_existing_strong_gf(jl_binding_t *b, size_t new_world)
 {
+    assert(new_world > jl_atomic_load_relaxed(&jl_world_counter));
     jl_binding_partition_t *bpart = jl_get_binding_partition(b, new_world);
     enum jl_partition_kind kind = jl_binding_kind(bpart);
     if (jl_bkind_is_some_constant(kind) && kind != PARTITION_KIND_IMPLICIT_CONST)
@@ -1026,7 +1026,7 @@ JL_DLLEXPORT jl_value_t *jl_get_existing_strong_gf(jl_binding_t *b, size_t new_w
             check_safe_newbinding(b->globalref->mod, b->globalref->name);
             return NULL;
         }
-        jl_module_t *from = jl_binding_dbgmodule(b);\
+        jl_module_t *from = jl_binding_dbgmodule(b);
         assert(from); // Can only be NULL if implicit, which we excluded above
         jl_errorf("invalid method definition in %s: exported function %s.%s does not exist",
                     jl_module_debug_name(b->globalref->mod), jl_module_debug_name(from), jl_symbol_name(b->globalref->name));
@@ -1722,7 +1722,7 @@ JL_DLLEXPORT int jl_globalref_is_const(jl_globalref_t *gr)
         b = jl_get_module_binding(gr->mod, gr->name, 1);
     jl_binding_partition_t *bpart = jl_get_binding_partition(b, jl_current_task->world_age);
     jl_walk_binding_inplace(&b, &bpart, jl_current_task->world_age);
-    return jl_bkind_is_some_constant(jl_binding_kind(bpart));
+    return jl_bkind_is_real_constant(jl_binding_kind(bpart));
 }
 
 JL_DLLEXPORT void jl_disable_binding(jl_globalref_t *gr)
@@ -1751,7 +1751,7 @@ JL_DLLEXPORT int jl_is_const(jl_module_t *m, jl_sym_t *var)
     jl_binding_t *b = jl_get_binding(m, var);
     jl_binding_partition_t *bpart = jl_get_binding_partition(b, jl_current_task->world_age);
     jl_walk_binding_inplace(&b, &bpart, jl_current_task->world_age);
-    return b && jl_bkind_is_some_constant(jl_binding_kind(bpart));
+    return b && jl_bkind_is_real_constant(jl_binding_kind(bpart));
 }
 
 // set the deprecated flag for a binding:

src/rtutils.c

@@ -579,7 +579,7 @@ JL_DLLEXPORT jl_value_t *jl_stderr_obj(void) JL_NOTSAFEPOINT
     if (jl_base_module == NULL)
         return NULL;
     jl_binding_t *stderr_obj = jl_get_module_binding(jl_base_module, jl_symbol("stderr"), 0);
-    return stderr_obj ? jl_get_binding_value_if_resolved_debug_only(stderr_obj) : NULL;
+    return stderr_obj ? jl_get_latest_binding_value_if_resolved_debug_only(stderr_obj) : NULL;
 }
 
 // toys for debugging ---------------------------------------------------------
@@ -674,7 +674,7 @@ static int is_globname_binding(jl_value_t *v, jl_datatype_t *dv) JL_NOTSAFEPOINT
     jl_sym_t *globname = dv->name->mt != NULL ? dv->name->mt->name : NULL;
     if (globname && dv->name->module) {
         jl_binding_t *b = jl_get_module_binding(dv->name->module, globname, 0);
-        jl_value_t *bv = jl_get_binding_value_if_latest_resolved_and_const_debug_only(b);
+        jl_value_t *bv = jl_get_latest_binding_value_if_resolved_and_const_debug_only(b);
         if (bv && ((jl_value_t*)dv == v ? jl_typeof(bv) == v : bv == v))
             return 1;
     }

src/toplevel.c

@@ -417,7 +417,7 @@ static void expr_attributes(jl_value_t *v, jl_array_t *body, int *has_ccall, int
             jl_module_t *mod = jl_globalref_mod(f);
             jl_sym_t *name = jl_globalref_name(f);
             jl_binding_t *b = jl_get_binding(mod, name);
-            called = jl_get_binding_value_if_const(b);
+            called = jl_get_latest_binding_value_if_const(b);
         }
         else if (jl_is_quotenode(f)) {
             called = jl_quotenode_value(f);

test/syntax.jl

@@ -1939,7 +1939,7 @@ end
 # eval'ing :const exprs
 eval(Expr(:const, :_var_30877))
 @test !isdefined(@__MODULE__, :_var_30877)
-@test isconst(@__MODULE__, :_var_30877)
+@test !isconst(@__MODULE__, :_var_30877)
 
 # anonymous kw function in value position at top level
 f30926 = function (;k=0)