Check bytecode before accepting a breakpoint in pdb

Author: aisk

Lib/bdb.py

@@ -177,6 +177,17 @@ def _get_lineno(self, code, offset):
         return last_lineno
 
 
+def _get_executable_linenos(code):
+    linenos = set()
+    for _, _, lineno in code.co_lines():
+        if lineno is not None:
+            linenos.add(lineno)
+    for const in code.co_consts:
+        if hasattr(const, 'co_lines'):
+            linenos |= _get_executable_linenos(const)
+    return linenos
+
+
 class Bdb:
     """Generic Python debugger base class.
 
@@ -671,6 +682,15 @@ def set_break(self, filename, lineno, temporary=False, cond=None,
         line = linecache.getline(filename, lineno)
         if not line:
             return 'Line %s:%d does not exist' % (filename, lineno)
+        source = ''.join(linecache.getlines(filename))
+        if source:
+            try:
+                code = compile(source, filename, 'exec')
+                executable_lines = _get_executable_linenos(code)
+                if executable_lines and lineno not in executable_lines:
+                    return 'Line %d has no code associated with it' % lineno
+            except SyntaxError:
+                pass
         self._add_to_breaks(filename, lineno)
         bp = Breakpoint(filename, lineno, temporary, cond, funcname)
         # After we set a new breakpoint, we need to search through all frames

Lib/test/test_pdb.py

@@ -4188,6 +4188,22 @@ def test_breakpoint(self):
         self.assertTrue(any("Breakpoint 1 at" in l for l in stdout.splitlines()), stdout)
         self.assertTrue(all("SUCCESS" not in l for l in stdout.splitlines()), stdout)
 
+    def test_breakpoint_on_no_bytecode_line(self):
+        script = """
+            x = 1
+            def f():
+                global x  # line 4: no bytecode
+                x = 2
+            f()
+        """
+        commands = """
+            b 4
+            c
+            quit
+        """
+        stdout, _ = self.run_pdb_module(script, commands)
+        self.assertIn('no code', '\n'.join(stdout.splitlines()))
+
     def test_run_pdb_with_pdb(self):
         commands = """
             c