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Always disallow assignments to constants #57567

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merged 1 commit into from
Feb 28, 2025
+13 −13
Merged

Always disallow assignments to constants #57567

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19 changes: 7 additions & 12 deletions src/module.c
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Original file line number Diff line number Diff line change
Expand Up @@ -545,14 +545,19 @@ JL_DLLEXPORT void jl_check_binding_currently_writable(jl_binding_t *b, jl_module
{
jl_binding_partition_t *bpart = jl_get_binding_partition(b, jl_current_task->world_age);
enum jl_partition_kind kind = jl_binding_kind(bpart);
if (kind != BINDING_KIND_GLOBAL && kind != BINDING_KIND_DECLARED && !jl_bkind_is_some_constant(kind)) {
if (kind != BINDING_KIND_GLOBAL && kind != BINDING_KIND_DECLARED) {
if (jl_bkind_is_some_guard(kind)) {
jl_errorf("Global %s.%s does not exist and cannot be assigned.\n"
"Note: Julia 1.9 and 1.10 inadvertently omitted this error check (#56933).\n"
"Hint: Declare it using `global %s` inside `%s` before attempting assignment.",
jl_symbol_name(m->name), jl_symbol_name(s),
jl_symbol_name(s), jl_symbol_name(m->name));
} else {
}
else if (jl_bkind_is_some_constant(kind)) {
jl_errorf("invalid assignment to constant %s.%s. This redefinition may be permitted using the `const` keyword.",
jl_symbol_name(m->name), jl_symbol_name(s));
}
else {
jl_module_t *from = jl_binding_dbgmodule(b, m, s);
if (from == m)
jl_errorf("cannot assign a value to imported variable %s.%s",
Expand Down Expand Up @@ -1449,16 +1454,6 @@ jl_value_t *jl_check_binding_assign_value(jl_binding_t *b JL_PROPAGATES_ROOT, jl
JL_GC_PUSH1(&rhs); // callee-rooted
jl_binding_partition_t *bpart = jl_get_binding_partition(b, jl_current_task->world_age);
enum jl_partition_kind kind = jl_binding_kind(bpart);
if (jl_bkind_is_some_constant(kind)) {
jl_value_t *old = bpart->restriction;
JL_GC_PROMISE_ROOTED(old);
if (jl_egal(rhs, old)) {
JL_GC_POP();
return NULL;
}
jl_errorf("invalid assignment to constant %s.%s. This redefinition may be permitted using the `const` keyword.",
jl_symbol_name(mod->name), jl_symbol_name(var));
}
assert(kind == BINDING_KIND_DECLARED || kind == BINDING_KIND_GLOBAL);
jl_value_t *old_ty = kind == BINDING_KIND_DECLARED ? (jl_value_t*)jl_any_type : bpart->restriction;
JL_GC_PROMISE_ROOTED(old_ty);
Expand Down
7 changes: 6 additions & 1 deletion test/syntax.jl
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Expand Up @@ -3969,8 +3969,13 @@ end

# Test trying to define a constant and then trying to assign to the same value
module AssignConstValueTest
using Test
const x = 1
x = 1
@test_throws ErrorException @eval x = 1
@test_throws ErrorException @eval begin
@Base.Experimental.force_compile
global x = 1
end
end
@test isconst(AssignConstValueTest, :x)

Expand Down