From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Sat, 6 Jun 2020 08:24:45 +0000 (-0700)
Subject: bpo-40807: Show warnings once from codeop._maybe_compile (GH-20486)
X-Git-Tag: v3.8.4rc1~65
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c067183605cf84bb1a246635f52827251d0476f8;p=thirdparty%2FPython%2Fcpython.git

bpo-40807: Show warnings once from codeop._maybe_compile (GH-20486)


* bpo-40807: Show warnings once from codeop._maybe_compile

* Move catch_warnings

* news

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
(cherry picked from commit 052d3fc0907be253cfd64b2c737a0b0aca586011)

Co-authored-by: Cheryl Sabella <cheryl.sabella@gmail.com>
---

diff --git a/Lib/codeop.py b/Lib/codeop.py
index 3c37f35eb025..3c2bb6083561 100644
--- a/Lib/codeop.py
+++ b/Lib/codeop.py
@@ -57,6 +57,7 @@ Compile():
 """
 
 import __future__
+import warnings
 
 _features = [getattr(__future__, fname)
              for fname in __future__.all_feature_names]
@@ -83,15 +84,18 @@ def _maybe_compile(compiler, source, filename, symbol):
     except SyntaxError as err:
         pass
 
-    try:
-        code1 = compiler(source + "\n", filename, symbol)
-    except SyntaxError as e:
-        err1 = e
-
-    try:
-        code2 = compiler(source + "\n\n", filename, symbol)
-    except SyntaxError as e:
-        err2 = e
+    # Suppress warnings after the first compile to avoid duplication.
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore")
+        try:
+            code1 = compiler(source + "\n", filename, symbol)
+        except SyntaxError as e:
+            err1 = e
+
+        try:
+            code2 = compiler(source + "\n\n", filename, symbol)
+        except SyntaxError as e:
+            err2 = e
 
     try:
         if code:
diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py
index 4d52d15fa0fb..1e57ab9d51e2 100644
--- a/Lib/test/test_codeop.py
+++ b/Lib/test/test_codeop.py
@@ -294,6 +294,11 @@ class CodeopTests(unittest.TestCase):
         self.assertNotEqual(compile_command("a = 1\n", "abc").co_filename,
                             compile("a = 1\n", "def", 'single').co_filename)
 
+    def test_warning(self):
+        # Test that the warning is only returned once.
+        with support.check_warnings((".*literal", SyntaxWarning)) as w:
+            compile_command("0 is 0")
+            self.assertEqual(len(w.warnings), 1)
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2020-06-04-16-25-15.bpo-40807.yYyLWx.rst b/Misc/NEWS.d/next/Library/2020-06-04-16-25-15.bpo-40807.yYyLWx.rst
new file mode 100644
index 000000000000..532b809b77ee
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-06-04-16-25-15.bpo-40807.yYyLWx.rst
@@ -0,0 +1,2 @@
+Stop codeop._maybe_compile, used by code.InteractiveInterpreter (and IDLE).
+from from emitting each warning three times.