[3.10] GH-95921: Fix positions for some chained comparisons (GH-96968) (GH-96974)

(cherry picked from commit dfc73b5)

Automerge-Triggered-By: GH:brandtbucher

Author: brandtbucher

Lib/test/test_compile.py

@@ -984,6 +984,38 @@ def if_else_break():
             elif instr.opname in HANDLED_JUMPS:
                 self.assertNotEqual(instr.arg, (line + 1)*INSTR_SIZE)
 
+    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_lines = 2 * [2]
+            for source in [
+                f"\\\n{expr}", f'if \\\n{expr}: x', f"x if \\\n{expr} else y"
+            ]:
+                code = compile(source, "<test>", "exec")
+                all_lines = (
+                    line
+                    for start, stop, line in code.co_lines()
+                    for _ in range(start, stop, 2)
+                )
+                actual_lines = [
+                    line
+                    for instruction, line in zip(
+                        dis.get_instructions(code), all_lines, strict=True
+                    )
+                    if instruction.opname == opname
+                ]
+                with self.subTest(source):
+                    self.assertEqual(actual_lines, expected_lines)
+
 
 class TestExpressionStackSize(unittest.TestCase):
     # These tests check that the computed stack size for a code object

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.

Python/compile.c

@@ -2691,6 +2691,7 @@ compiler_jump_if(struct compiler *c, expr_ty e, basicblock *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)) {