10000 py/emitcommon: Don't implicitly close class vars that are assigned to. · sstobbe/micropython@590de39 · GitHub
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py/emitcommon: Don't implicitly close class vars that are assigned to.
When in a class body or at the module level don't implicitly close over variables that have been assigned to. Fixes issue micropython#8603. Signed-off-by: Damien George <damien@micropython.org>
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3 files changed

+87
-4
lines changed

3 files changed

+87
-4
lines changed

‎py/emitcommon.c

Lines changed: 9 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -44,9 +44,14 @@ qstr_short_t mp_emit_common_use_qstr(mp_emit_common_t *emit, qstr qst) {
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void mp_emit_common_get_id_for_modification(scope_t *scope, qstr qst) {
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// name adding/lookup
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id_info_t *id = scope_find_or_add_id(scope, q 10000 st, ID_INFO_KIND_GLOBAL_IMPLICIT);
47-
if (SCOPE_IS_FUNC_LIKE(scope->kind) && id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT) {
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// rebind as a local variable
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id->kind = ID_INFO_KIND_LOCAL;
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if (id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT) {
48+
if (SCOPE_IS_FUNC_LIKE(scope->kind)) {
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// rebind as a local variable
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id->kind = ID_INFO_KIND_LOCAL;
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} else {
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// mark this as assigned, to prevent it from being closed over
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id->kind = ID_INFO_KIND_GLOBAL_IMPLICIT_ASSIGNED;
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}
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}
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}
5257

@@ -57,7 +62,7 @@ void mp_emit_common_id_op(emit_t *emit, const mp_emit_method_table_id_ops_t *emi
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assert(id != NULL);
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// call the emit backend with the correct code
60-
if (id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT) {
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if (id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT || id->kind == ID_INFO_KIND_GLOBAL_IMPLICIT_ASSIGNED) {
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emit_method_table->global(emit, qst, MP_EMIT_IDOP_GLOBAL_NAME);
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} else if (id->kind == ID_INFO_KIND_GLOBAL_EXPLICIT) {
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emit_method_table->global(emit, qst, MP_EMIT_IDOP_GLOBAL_GLOBAL);

‎py/scope.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -32,6 +32,7 @@
3232
typedef enum {
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ID_INFO_KIND_UNDECIDED,
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ID_INFO_KIND_GLOBAL_IMPLICIT,
35+
ID_INFO_KIND_GLOBAL_IMPLICIT_ASSIGNED,
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ID_INFO_KIND_GLOBAL_EXPLICIT,
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ID_INFO_KIND_LOCAL, // in a function f, written and only referenced by f
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ID_INFO_KIND_CELL, // in a function f, read/written by children of f

‎tests/basics/scope_class.py

Lines changed: 77 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,77 @@
1+
# test scoping rules that involve a class
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# the inner A.method should be independent to the local function called method
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def test1():
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def method():
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pass
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class A:
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def method():
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pass
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print(hasattr(A, "method"))
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print(hasattr(A(), "method"))
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test1()
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# the inner A.method is a closure and overrides the local function called method
20+
def test2():
21+
def method():
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return "outer"
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class A:
25+
nonlocal method
26+
27+
def method():
28+
return "inner"
29+
30+
print(hasattr(A, "method"))
31+
print(hasattr(A(), "method"))
32+
return method() # this is actually A.method
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print(test2())
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# a class body will capture external variables by value (not by reference)
39+
def test3(x):
40+
class A:
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local = x
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x += 1
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return x, A.local
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print(test3(42))
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# assigning to a variable in a class will implicitly prevent it from closing over a variable
51+
def test4(global_):
52+
class A:
53+
local = global_ # fetches outer global_
54+
global_ = "global2" # creates class attribute
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global_ += 1 # updates local variable
57+
return global_, A.local, A.global_
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60+
global_ = "global"
61+
print(test4(42), global_)
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# methods within a class can close over variables outside the class
65+
def test5(x):
66+
def closure():
67+
return x
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class A:
70+
def method():
71+
return x, closure()
72+
73+
closure = lambda: x + 1 # change it after A has been created
74+
return A
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77+
print(test5(42).method())

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