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[3.7] bpo-1875: Raise SyntaxError in invalid blocks that will be optimised away (GH-13332) #13382

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Merged
miss-islington merged 1 commit into from
May 17, 2019
Merged

[3.7] bpo-1875: Raise SyntaxError in invalid blocks that will be optimised away (GH-13332) #13382

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14 changes: 14 additions & 0 deletions Lib/test/test_syntax.py
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Original file line number Diff line number Diff line change
Expand Up @@ -650,6 +650,20 @@ def error2():
def test_break_outside_loop(self):
self._check_error("break", "outside loop")

def test_yield_outside_function(self):
self._check_error("if 0: yield", "outside function")
self._check_error("class C:\n if 0: yield", "outside function")

def test_return_outside_function(self):
self._check_error("if 0: return", "outside function")
self._check_error("class C:\n if 0: return", "outside function")

def test_break_outside_loop(self):
self._check_error("if 0: break", "outside loop")

def test_continue_outside_loop(self):
self._check_error("if 0: continue", "not properly in loop")

def test_unexpected_indent(self):
self._check_error("foo()\n bar()\n", "unexpected indent",
subclass=IndentationError)
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2019-05-15-01-29-29.bpo-1875.9oxXFX.rst
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@@ -0,0 +1,3 @@
A :exc:`SyntaxError` is now raised if a code blocks that will be optimized
away (e.g. if conditions that are always false) contains syntax errors.
Patch by Pablo Galindo.
9 changes: 4 additions & 5 deletions Python/compile.c
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Expand Up @@ -2301,13 +2301,12 @@ compiler_if(struct compiler *c, stmt_ty s)
return 0;

constant = expr_constant(s->v.If.test);
/* constant = 0: "if 0"
/* constant = 0: "if 0" Leave the optimizations to
* the pephole optimizer to check for syntax errors
* in the block.
* constant = 1: "if 1", "if 2", ...
* constant = -1: rest */
if (constant == 0) {
if (s->v.If.orelse)
VISIT_SEQ(c, stmt, s->v.If.orelse);
} else if (constant == 1) {
if (constant == 1) {
VISIT_SEQ(c, stmt, s->v.If.body);
} else {
if (asdl_seq_LEN(s->v.If.orelse)) {
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16 changes: 12 additions & 4 deletions Python/peephole.c
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Expand Up @@ -304,11 +304,19 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
case LOAD_CONST:
cumlc = lastlc + 1;
if (nextop != POP_JUMP_IF_FALSE ||
!ISBASICBLOCK(blocks, op_start, i + 1) ||
!PyObject_IsTrue(PyList_GET_ITEM(consts, get_arg(codestr, i))))
!ISBASICBLOCK(blocks, op_start, i + 1)) {
break;
fill_nops(codestr, op_start, nexti + 1);
cumlc = 0;
}
PyObject* cnt = PyList_GET_ITEM(consts, get_arg(codestr, i));
int is_true = PyObject_IsTrue(cnt);
if (is_true == 1) {
fill_nops(codestr, op_start, nexti + 1);
cumlc = 0;
} else if (is_true == 0) {
h = get_arg(codestr, nexti) / sizeof(_Py_CODEUNIT);
tgt = find_op(codestr, codelen, h);
fill_nops(codestr, op_start, tgt);
}
break;

/* Try to fold tuples of constants.
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