gh-131927: Silence PEP 765 warnings in PyREPL

Lib/_pyrepl/console.py

@@ -217,8 +217,26 @@ def runsource(self, source, filename="<input>", symbol="single"):
             wrapper = ast.Interactive if stmt is last_stmt else ast.Module
             the_symbol = symbol if stmt is last_stmt else "exec"
             item = wrapper([stmt])
+            import warnings
             try:
-                code = self.compile.compiler(item, filename, the_symbol)
+                with warnings.catch_warnings(record=True) as caught_warnings:
+                    # Enable all warnings
+                    warnings.simplefilter("always")
+                    code = self.compile.compiler(item, filename, the_symbol)
+                for warning in caught_warnings:
+                    if issubclass(warning.category, SyntaxWarning) and "in a 'finally' block" in str(warning.message):
+                        # Ignore this warning as it would've alread been raised
+                        # when compiling the code above
+                        pass
+                    else:
+                        # Re-emit other warnings
+                        warnings.warn_explicit(
+                            message=warning.message,
+                            category=warning.category,
+                            filename=warning.filename,
+                            lineno=warning.lineno,
+                            source=warning.source
+                        )
                 linecache._register_code(code, source, filename)
             except SyntaxError as e:
                 if e.args[0] == "'await' outside function":

Lib/test/test_pyrepl/test_interact.py

@@ -1,5 +1,6 @@
 import contextlib
 import io
+import warnings
 import unittest
 from unittest.mock import patch
 from textwrap import dedent
@@ -273,3 +274,28 @@ def test_incomplete_statement(self):
         code = "if foo:"
         console = InteractiveColoredConsole(namespace, filename="<stdin>")
         self.assertTrue(_more_lines(console, code))
+
+
+class TestWarnings(unittest.TestCase):
+    def test_pep_765_warning(self):
+        """
+        Test that a SyntaxWarning emitted from the
+        AST optimizer is only shown once in the REPL.
+        """
+        # gh-131927
+        console = InteractiveColoredConsole()
+        code = dedent("""\
+        def f():
+            try:
+                return 1
+            finally:
+                return 2
+        """)
+
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter("always")
+            console.runsource(code)
+
+        count = sum("'return' in a 'finally' block" in str(w.message)
+                    for w in caught)
+        self.assertEqual(count, 1)

Misc/NEWS.d/next/Core_and_Builtins/2025-10-14-18-57-53.gh-issue-131927.LTxM-3.rst

@@ -0,0 +1,2 @@
+Silence duplicate syntax warnings for ``return``/``break``/``continue`` in
+``finally`` in the REPL.