GH-95921: Fix positions for some chained comparisons (GH-96968)

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index 3ed57c2a5d2763eb331a93bef595f737889f6b4d..4b35cce5612a6e9018424562cfd03a50ef21b4a3 100644 (file)
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -1077,6 +1077,31 @@ if 1:
         check_op_count(aug, "STORE_SLICE", 1)
         check_op_count(aug, "BUILD_SLICE", 0)
 
+    def test_compare_positions(self):
+        for opname, op in [
+            ("COMPARE_OP", "<"),
+            ("COMPARE_OP", "<="),
+            ("COMPARE_OP", ">"),
+            ("COMPARE_OP", ">="),
+            ("CONTAINS_OP", "in"),
+            ("CONTAINS_OP", "not in"),
+            ("IS_OP", "is"),
+            ("IS_OP", "is not"),
+        ]:
+            expr = f'a {op} b {op} c'
+            expected_positions = 2 * [(2, 2, 0, len(expr))]
+            for source in [
+                f"\\\n{expr}", f'if \\\n{expr}: x', f"x if \\\n{expr} else y"
+            ]:
+                code = compile(source, "<test>", "exec")
+                actual_positions = [
+                    instruction.positions
+                    for instruction in dis.get_instructions(code)
+                    if instruction.opname == opname
+                ]
+                with self.subTest(source):
+                    self.assertEqual(actual_positions, expected_positions)
+
 
 @requires_debug_ranges()
 class TestSourcePositions(unittest.TestCase):

diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-09-20-11-06-45.gh-issue-95921.dkcRQn.rst b/Misc/NEWS.d/next/Core and Builtins/2022-09-20-11-06-45.gh-issue-95921.dkcRQn.rst
new file mode 100644 (file)
index 0000000..0c8b704
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-09-20-11-06-45.gh-issue-95921.dkcRQn.rst
@@ -0,0 +1,2 @@
+Fix overly-broad source position information for chained comparisons used as
+branching conditions.

diff --git a/Python/compile.c b/Python/compile.c
index 1f1ef56e7b1b075892b6c036eb544622e89d0098..507fd040a89d7d2dd755b21625532b8e96c375cf 100644 (file)
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2905,6 +2905,7 @@ compiler_jump_if(struct compiler *c, expr_ty e, jump_target_label next, int cond
         return 1;
     }
     case Compare_kind: {
+        SET_LOC(c, e);
         Py_ssize_t i, n = asdl_seq_LEN(e->v.Compare.ops) - 1;
         if (n > 0) {
             if (!check_compare(c, e)) {