PR: Add needs_local_scope to debug magic (#13960)

Fixes https://github.com/ipython/ipython/issues/13959

IPython/core/magics/execution.py

@@ -422,7 +422,8 class ExecutionMagics(Magics):
     )
     @no_var_expand
     @line_cell_magic
-    def debug(self, line='', cell=None):
+    @needs_local_scope
+    def debug(self, line="", cell=None, local_ns=None):
         """Activate the interactive debugger.
 
         This magic command support two ways of activating debugger.
@@ -453,7 +454,7 class ExecutionMagics(Magics):
             self._debug_post_mortem()
         elif not (args.breakpoint or cell):
             # If there is no breakpoints, the line is just code to execute
-            self._debug_exec(line, None)
+            self._debug_exec(line, None, local_ns)
         else:
             # Here we try to reconstruct the code from the output of
             # parse_argstring. This might not work if the code has spaces
@@ -461,18 +462,20 class ExecutionMagics(Magics):
             code = "\n".join(args.statement)
             if cell:
                 code += "\n" + cell
-            self._debug_exec(code, args.breakpoint)
+            self._debug_exec(code, args.breakpoint, local_ns)
 
     def _debug_post_mortem(self):
         self.shell.debugger(force=True)
 
-    def _debug_exec(self, code, breakpoint):
+    def _debug_exec(self, code, breakpoint, local_ns=None):
         if breakpoint:
             (filename, bp_line) = breakpoint.rsplit(':', 1)
             bp_line = int(bp_line)
         else:
             (filename, bp_line) = (None, None)
-        self._run_with_debugger(code, self.shell.user_ns, filename, bp_line)
+        self._run_with_debugger(
+            code, self.shell.user_ns, filename, bp_line, local_ns=local_ns
+        )
 
     @line_magic
     def tb(self, s):
@@ -867,8 +870,9 class ExecutionMagics(Magics):
 
         return stats
 
-    def _run_with_debugger(self, code, code_ns, filename=None,
-                           bp_line=None, bp_file=None):
+    def _run_with_debugger(
+        self, code, code_ns, filename=None, bp_line=None, bp_file=None, local_ns=None
+    ):
         """
         Run `code` in debugger with a break point.
 
@@ -885,6 +889,8 class ExecutionMagics(Magics):
         bp_file : str, optional
             Path to the file in which break point is specified.
             `filename` is used if not given.
+        local_ns : dict, optional
+            A local namespace in which `code` is executed.
 
         Raises
         ------
@@ -941,7 +947,7 class ExecutionMagics(Magics):
             while True:
                 try:
                     trace = sys.gettrace()
-                    deb.run(code, code_ns)
+                    deb.run(code, code_ns, local_ns)
                 except Restart:
                     print("Restarting")
                     if filename:

IPython/core/tests/test_magic.py

@@ -715,6 +715,7 def doctest_precision():
     Out[5]: '3.141593e+00'
     """
 
+
 def test_debug_magic():
     """Test debugging a small code with %debug
 
@@ -727,6 +728,22 def test_debug_magic():
     In [2]:
     """
 
+
+def test_debug_magic_locals():
+    """Test debugging a small code with %debug with locals
+
+    In [1]: with PdbTestInput(['c']):
+       ...:     def fun():
+       ...:         res = 1
+       ...:         %debug print(res)
+       ...:     fun()
+       ...:
+    ...
+    ipdb> c
+    1
+    In [2]:
+    """
+
 def test_psearch():
     with tt.AssertPrints("dict.fromkeys"):
         _ip.run_cell("dict.fr*?")