gh-121804: Always show error location for SyntaxError's in new repl (#121886)

Author: skirpichev

Lib/_pyrepl/console.py

@@ -161,6 +161,9 @@ def __init__(
         super().__init__(locals=locals, filename=filename, local_exit=local_exit)  # type: ignore[call-arg]
         self.can_colorize = _colorize.can_colorize()
 
+    def showsyntaxerror(self, filename=None, **kwargs):
+        super().showsyntaxerror(**kwargs)
+
     def _excepthook(self, typ, value, tb):
         import traceback
         lines = traceback.format_exception(
@@ -173,7 +176,7 @@ def runsource(self, source, filename="<input>", symbol="single"):
         try:
             tree = ast.parse(source)
         except (SyntaxError, OverflowError, ValueError):
-            self.showsyntaxerror(filename)
+            self.showsyntaxerror(filename, source=source)
             return False
         if tree.body:
             *_, last_stmt = tree.body
@@ -190,10 +193,10 @@ def runsource(self, source, filename="<input>", symbol="single"):
                         f"Try the asyncio REPL ({python} -m asyncio) to use"
                         f" top-level 'await' and run background asyncio tasks."
                     )
-                self.showsyntaxerror(filename)
+                self.showsyntaxerror(filename, source=source)
                 return False
             except (OverflowError, ValueError):
-                self.showsyntaxerror(filename)
+                self.showsyntaxerror(filename, source=source)
                 return False
 
             if code is None:

Lib/code.py

@@ -64,7 +64,7 @@ def runsource(self, source, filename="<input>", symbol="single"):
             code = self.compile(source, filename, symbol)
         except (OverflowError, SyntaxError, ValueError):
             # Case 1
-            self.showsyntaxerror(filename)
+            self.showsyntaxerror(filename, source=source)
             return False
 
         if code is None:
@@ -94,7 +94,7 @@ def runcode(self, code):
         except:
             self.showtraceback()
 
-    def showsyntaxerror(self, filename=None):
+    def showsyntaxerror(self, filename=None, **kwargs):
         """Display the syntax error that just occurred.
 
         This doesn't display a stack trace because there isn't one.
@@ -118,7 +118,8 @@ def showsyntaxerror(self, filename=None):
                 else:
                     # Stuff in the right filename
                     value = SyntaxError(msg, (filename, lineno, offset, line))
-            self._showtraceback(typ, value, None)
+            source = kwargs.pop('source', "")
+            self._showtraceback(typ, value, None, source)
         finally:
             typ = value = tb = None
 
@@ -132,14 +133,20 @@ def showtraceback(self):
         """
         try:
             typ, value, tb = sys.exc_info()
-            self._showtraceback(typ, value, tb.tb_next)
+            self._showtraceback(typ, value, tb.tb_next, "")
         finally:
             typ = value = tb = None
 
-    def _showtraceback(self, typ, value, tb):
+    def _showtraceback(self, typ, value, tb, source):
         sys.last_type = typ
         sys.last_traceback = tb
-        sys.last_exc = sys.last_value = value = value.with_traceback(tb)
+        value = value.with_traceback(tb)
+        # Set the line of text that the exception refers to
+        lines = source.splitlines()
+        if (source and typ is SyntaxError
+                and not value.text and len(lines) >= value.lineno):
+            value.text = lines[value.lineno - 1]
+        sys.last_exc = sys.last_value = value
         if sys.excepthook is sys.__excepthook__:
             self._excepthook(typ, value, tb)
         else:

Lib/idlelib/pyshell.py

@@ -706,7 +706,7 @@ def prepend_syspath(self, filename):
             del _filename, _sys, _dirname, _dir
             \n""".format(filename))
 
-    def showsyntaxerror(self, filename=None):
+    def showsyntaxerror(self, filename=None, **kwargs):
         """Override Interactive Interpreter method: Use Colorizing
 
         Color the offending position instead of printing it and pointing at it

Lib/test/test_pyrepl/test_interact.py

@@ -88,6 +88,20 @@ def test_runsource_returns_false_for_failed_compilation(self):
         self.assertFalse(result)
         self.assertIn('SyntaxError', f.getvalue())
 
+    @force_not_colorized
+    def test_runsource_show_syntax_error_location(self):
+        console = InteractiveColoredConsole()
+        source = "def f(x, x): ..."
+        f = io.StringIO()
+        with contextlib.redirect_stderr(f):
+            result = console.runsource(source)
+        self.assertFalse(result)
+        r = """
+    def f(x, x): ...
+             ^
+SyntaxError: duplicate argument 'x' in function definition"""
+        self.assertIn(r, f.getvalue())
+
     def test_runsource_shows_syntax_error_for_failed_compilation(self):
         console = InteractiveColoredConsole()
         source = "print('Hello, world!'"

Misc/NEWS.d/next/Library/2024-07-16-20-49-07.gh-issue-121804.gYN-In.rst

@@ -0,0 +1,2 @@
+Correctly show error locations, when :exc:`SyntaxError` raised in new repl.
+Patch by Sergey B Kirpichev.