From e2fce3a8e77d33d52d47b567964ddebd6984a097 Mon Sep 17 00:00:00 2001
From: Brandt Bucher <brandtbucher@microsoft.com>
Date: Wed, 20 Jul 2022 15:01:42 -0700
Subject: [PATCH] [3.11] GH-91409: Don't overwrite valid locations with NOP
 locations (GH-95067) (GH-95068)

(cherry picked from commit 742d4614e1a645d765dbf76c19bd9a818239b1cb)
---
 Lib/test/test_compile.py                      | 38 +++++++++++++++++++
 ...2-07-20-13-46-01.gh-issue-91409.dhL8Zo.rst |  2 +
 Python/compile.c                              |  5 ++-
 3 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2022-07-20-13-46-01.gh-issue-91409.dhL8Zo.rst

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index 80b32dee066..e22696499e2 100644
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -1166,6 +1166,44 @@ def test_multiline_assert_rewritten_as_method_call(self):
         tree.body[0] = new_node
         compile(tree, "<test>", "exec")
 
+    def test_push_null_load_global_positions(self):
+        source_template = """
+        import abc, dis
+        import ast as art
+
+        abc = None
+        dix = dis
+        ast = art
+
+        def f():
+        {}
+        """
+        for body in [
+            "    abc.a()",
+            "    art.a()",
+            "    ast.a()",
+            "    dis.a()",
+            "    dix.a()",
+            "    abc[...]()",
+            "    art()()",
+            "   (ast or ...)()",
+            "   [dis]()",
+            "   (dix + ...)()",
+        ]:
+            with self.subTest(body):
+                namespace = {}
+                source = textwrap.dedent(source_template.format(body))
+                exec(source, namespace)
+                code = namespace["f"].__code__
+                self.assertOpcodeSourcePositionIs(
+                    code,
+                    "LOAD_GLOBAL",
+                    line=10,
+                    end_line=10,
+                    column=4,
+                    end_column=7,
+                )
+
 
 class TestExpressionStackSize(unittest.TestCase):
     # These tests check that the computed stack size for a code object
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-07-20-13-46-01.gh-issue-91409.dhL8Zo.rst b/Misc/NEWS.d/next/Core and Builtins/2022-07-20-13-46-01.gh-issue-91409.dhL8Zo.rst
new file mode 100644
index 00000000000..2bc0d8224c6
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-07-20-13-46-01.gh-issue-91409.dhL8Zo.rst	
@@ -0,0 +1,2 @@
+Fix incorrect source location info caused by certain optimizations in the
+bytecode compiler.
diff --git a/Python/compile.c b/Python/compile.c
index 3fe0930e7ae..e8acd859777 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -9045,7 +9045,10 @@ clean_basic_block(basicblock *bb) {
             /* or, if the next instruction has same line number or no line number */
             if (src < bb->b_iused - 1) {
                 int next_lineno = bb->b_instr[src+1].i_lineno;
-                if (next_lineno < 0 || next_lineno == lineno) {
+                if (next_lineno == lineno) {
+                    continue;
+                }
+                if (next_lineno < 0) {
                     COPY_INSTR_LOC(bb->b_instr[src], bb->b_instr[src+1]);
                     continue;
                 }
-- 
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