Properly stop at line 1 in frame eval mode. Fixes #995

Author: fabioz

src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_cython.c

@@ -1002,7 +1002,7 @@ cdef class PyDBFrame:
                     new_frame = frame
                     stop_reason = CMD_SET_FUNCTION_BREAK
 
-                elif not is_return and info.pydev_state != 2 and breakpoints_for_file is not None and line in breakpoints_for_file:
+                elif is_line and info.pydev_state != 2 and breakpoints_for_file is not None and line in breakpoints_for_file:
                     breakpoint = breakpoints_for_file[line]
                     new_frame = frame
                     stop = True

src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_cython.pyx

@@ -869,7 +869,7 @@ def trace_dispatch(self, frame, event, arg):
                     new_frame = frame
                     stop_reason = CMD_SET_FUNCTION_BREAK
 
-                elif not is_return and info.pydev_state != STATE_SUSPEND and breakpoints_for_file is not None and line in breakpoints_for_file:
+                elif is_line and info.pydev_state != STATE_SUSPEND and breakpoints_for_file is not None and line in breakpoints_for_file:
                     breakpoint = breakpoints_for_file[line]
                     new_frame = frame
                     stop = True

src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_frame.py

@@ -87,6 +87,12 @@ def get_instructions_to_add(
     '''
     # Good reference to how things work regarding line numbers and jumps:
     # https://github.com/python/cpython/blob/3.6/Objects/lnotab_notes.txt
+
+    # Usually use a stop line -1, but if that'd be 0, using line +1 is ok too.
+    spurious_line = stop_at_line - 1
+    if spurious_line <= 0:
+        spurious_line = stop_at_line + 1
+
     label = Label()
     return [
         # -- if _pydev_needs_stop_at_break():
@@ -99,10 +105,10 @@ def get_instructions_to_add(
         #
         # Note that this has line numbers -1 so that when the NOP just below
         # is executed we have a spurious line event.
-        Instr("LOAD_CONST", _pydev_stop_at_break, lineno=stop_at_line - 1),
-        Instr("LOAD_CONST", stop_at_line, lineno=stop_at_line - 1),
-        Instr("CALL_FUNCTION", 1, lineno=stop_at_line - 1),
-        Instr("POP_TOP", lineno=stop_at_line - 1),
+        Instr("LOAD_CONST", _pydev_stop_at_break, lineno=spurious_line),
+        Instr("LOAD_CONST", stop_at_line, lineno=spurious_line),
+        Instr("CALL_FUNCTION", 1, lineno=spurious_line),
+        Instr("POP_TOP", lineno=spurious_line),
 
         # Reason for the NOP: Python will give us a 'line' trace event whenever we forward jump to
         # the first instruction of a line, so, in the case where we haven't added a programmatic
@@ -259,6 +265,12 @@ def insert_pydevd_breaks(
     # if code_to_modify.co_firstlineno in breakpoint_lines:
     #     return False, code_to_modify
 
+    for line in breakpoint_lines:
+        if line <= 0:
+            # The first line is line 1, so, a break at line 0 is not valid.
+            pydev_log.info('Trying to add breakpoint in invalid line: %s', line)
+            return False, code_to_modify
+
     try:
         b = bytecode.Bytecode.from_code(code_to_modify)
 

src/debugpy/_vendored/pydevd/_pydevd_frame_eval/pydevd_modify_bytecode.py

@@ -1995,6 +1995,9 @@ def do_wait_suspend(self, thread, frame, event, arg, exception_type=None):  # @U
         thread_id = get_current_thread_id(thread)
 
         # print('do_wait_suspend %s %s %s %s %s %s (%s)' % (frame.f_lineno, frame.f_code.co_name, frame.f_code.co_filename, event, arg, constant_to_str(thread.additional_info.pydev_step_cmd), constant_to_str(thread.additional_info.pydev_original_step_cmd)))
+        # print('--- stack ---')
+        # print(traceback.print_stack(file=sys.stdout))
+        # print('--- end stack ---')
 
         # Send the suspend message
         message = thread.additional_info.pydev_message

src/debugpy/_vendored/pydevd/pydevd.py

@@ -8,6 +8,7 @@ def breaknow():
 
 
 if '--fork-in-subprocess' in sys.argv:
+    popen = None
     if sys.platform == 'win32':
         popen = subprocess.Popen([sys.executable, __file__, '--forked'])
         pid = popen.pid
@@ -20,6 +21,16 @@ def breaknow():
     print('currently in pid: %s, ppid: %s' % (os.getpid(), ppid))
     print('os.fork returned', pid)
     breaknow()
+    # i.e.: wait so that we check for the retcode so that we don't get a traceback such as the one
+    # below (as that code in __del__ will only be called if returncode is None).
+    # Traceback (most recent call last):
+    # File "C:\hostedtoolcache\windows\Python\3.9.13\x64\lib\subprocess.py", line 1055, in __del__
+    # self._internal_poll(_deadstate=_maxsize)
+    # File "C:\hostedtoolcache\windows\Python\3.9.13\x64\lib\subprocess.py", line 1457, in _internal_poll
+    # if _WaitForSingleObject(self._handle, 0) == _WAIT_OBJECT_0:
+    # OSError: [WinError 6] The handle is invalid
+    if popen is not None:
+        popen.wait(20)
 
 elif '--forked' in sys.argv:
     try:

src/debugpy/_vendored/pydevd/tests_python/resources/_debugger_case_subprocess_and_fork.py

@@ -2274,9 +2274,9 @@ def test_case_method_single_line(case_setup):
         writer.write_add_breakpoint(writer.get_line_index_with_content('Break here'), 'None')
         writer.write_make_initial_run()
 
-        for _ in range(5):
-            # We'll hit the same breakpoint 5 times (method creation,
-            # (enter method, exit method) * 2.
+        for _ in range(3):
+            # We'll hit the same breakpoint 3 times (method creation,
+            # method line for each call).
             hit = writer.wait_for_breakpoint_hit()
 
             writer.write_run_thread(hit.thread_id)

src/debugpy/_vendored/pydevd/tests_python/test_debugger.py

@@ -262,3 +262,17 @@ def test_generator_code_cache(case_setup_force_frame_eval):
         writer.write_run_thread(hit.thread_id)
 
         writer.finished_ok = True
+
+
+def test_break_line_1(case_setup_force_frame_eval):
+    with case_setup_force_frame_eval.test_file('_debugger_case_yield_from.py') as writer:
+        break1_line = 1
+        break1_id = writer.write_add_breakpoint(break1_line, 'None')
+        writer.write_make_initial_run()
+
+        hit = writer.wait_for_breakpoint_hit(line=break1_line)
+        assert hit.suspend_type == "frame_eval"
+
+        writer.write_run_thread(hit.thread_id)
+
+        writer.finished_ok = True