Fixes for gdb stubs (python#13169)

* gdb: Clarify a comment
* gdb: Fix gdb.unwinder.Unwinder.__call__ argument. It takes a gdb.PendingFrame, not a gdb.Frame.
* gdb: Unwinders may implement a proto without subclassing gdb.unwinder.Unwinder
* gdb: Fix Breakpoint.__init__

 1. `line` should be `int|str`, not just `int` (IDK what a string means,
    but that it can be a string is clear if you read
    py-breakpoint.c:bppy_init().
 2. `type` argument should be able to be passed to the "location" form,
    not just the "spec" form, even if
    https://sourceware.org/gdb/current/onlinedocs/gdb.html/Breakpoints-In-Python.html
    neglects to mention it (don't worry, I'll be submitting a patch to fix
    the doc soon).
 3. Fix the positional argument order (based on GDB's sources, it isn't
    really documented)
 4. Use more `@overloads` to enforce that at least 1 of `function`,
    `label`, or `line` are given in the location form.

stubs/gdb/METADATA.toml

@@ -1,5 +1,5 @@
 version = "15.0.*"
-# This is the official web portal for GDB,
+# This is the official web portal for the GDB Git repo,
 # see https://sourceware.org/gdb/current/ for other ways of obtaining the source code.
 upstream_repository = "https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=tree"
 extra_description = """\

stubs/gdb/gdb/__init__.pyi

@@ -7,12 +7,11 @@ import threading
 from _typeshed import Incomplete
 from collections.abc import Callable, Iterator, Mapping, Sequence
 from contextlib import AbstractContextManager
-from typing import Any, Final, Generic, Literal, Protocol, TypeVar, final, overload
+from typing import Any, Final, Generic, Literal, Protocol, TypeVar, final, overload, type_check_only
 from typing_extensions import TypeAlias, deprecated
 
 import gdb.FrameDecorator
 import gdb.types
-import gdb.unwinder
 import gdb.xmethod
 
 # The following submodules are automatically imported
@@ -289,7 +288,15 @@ class PendingFrame:
 class UnwindInfo:
     def add_saved_register(self, reg: str | RegisterDescriptor | int, value: Value, /) -> None: ...
 
-frame_unwinders: list[gdb.unwinder.Unwinder]
+@type_check_only
+class _Unwinder(Protocol):
+    @property
+    def name(self) -> str: ...
+    enabled: bool
+
+    def __call__(self, pending_frame: PendingFrame) -> UnwindInfo | None: ...
+
+frame_unwinders: list[_Unwinder]
 
 # Inferiors
 
@@ -468,7 +475,7 @@ class Progspace:
     pretty_printers: list[_PrettyPrinterLookupFunction]
     type_printers: list[gdb.types._TypePrinter]
     frame_filters: dict[str, _FrameFilter]
-    frame_unwinders: list[gdb.unwinder.Unwinder]
+    frame_unwinders: list[_Unwinder]
     missing_debug_handlers: Incomplete
 
     def block_for_pc(self, pc: int, /) -> Block | None: ...
@@ -493,7 +500,7 @@ class Objfile:
     pretty_printers: list[_PrettyPrinterLookupFunction]
     type_printers: list[gdb.types._TypePrinter]
     frame_filters: dict[str, _FrameFilter]
-    frame_unwinders: list[gdb.unwinder.Unwinder]
+    frame_unwinders: list[_Unwinder]
     is_file: bool
 
     def is_valid(self) -> bool: ...
@@ -664,21 +671,131 @@ class LineTable:
 # Breakpoints
 
 class Breakpoint:
+
+    # The where="spec" form of __init__().  See py-breakpoints.c:bppy_init():keywords for the positional order.
+    @overload
+    def __init__(
+        self,
+        # where
+        spec: str,
+        # options
+        type: int = ...,
+        wp_class: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
+    ) -> None: ...
+
+    # The where="location" form of __init__().  A watchpoint (`type=BP_WATCHPOINT`) cannot be created with this form.
+    #
+    # We exclude the `wp_class` (watchpoint class) option here, even though py-breakpoints.c accepts it.  It doesn't make sense
+    # unless type==BP_WATCHPOINT, and is silently ignored in those cases; allowing it in those cases is likely an oversight, not
+    # an intentional allowance.
+    #
+    # We repeat this 7 times because the type system doesn't have simple a way for us to say "at least one of `function`, `label`,
+    # or `line`", so we must repeat it for each combination of the 3.
+    #
+    # The len=3 combination.
+    @overload
+    def __init__(
+        self,
+        *,
+        # where
+        source: str = ...,
+        function: str,
+        label: str,
+        line: int | str,
+        # options
+        type: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
+    ) -> None: ...
+    # The 3 len=2 combinations.
+    @overload
+    def __init__(
+        self,
+        *,
+        source: str = ...,
+        # where
+        label: str,
+        line: int | str,
+        # options
+        type: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
+    ) -> None: ...
+    @overload
+    def __init__(
+        self,
+        *,
+        source: str = ...,
+        # where
+        function: str,
+        line: int | str,
+        # options
+        type: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
+    ) -> None: ...
     @overload
     def __init__(
-        self, spec: str, type: int = ..., wp_class: int = ..., internal: bool = ..., temporary: bool = ..., qualified: bool = ...
+        self,
+        *,
+        source: str = ...,
+        # where
+        function: str,
+        label: str,
+        # options
+        type: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
     ) -> None: ...
+    # The 3 len=1 combinations.
     @overload
     def __init__(
         self,
+        *,
         source: str = ...,
-        function: str = ...,
-        label: str = ...,
-        line: int = ...,
+        # where
+        function: str,
+        # options
+        type: int = ...,
         internal: bool = ...,
         temporary: bool = ...,
         qualified: bool = ...,
     ) -> None: ...
+    @overload
+    def __init__(
+        self,
+        *,
+        source: str = ...,
+        # where
+        label: str,
+        # options
+        type: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
+    ) -> None: ...
+    @overload
+    def __init__(
+        self,
+        *,
+        source: str = ...,
+        # where
+        line: int | str,
+        # options
+        type: int = ...,
+        internal: bool = ...,
+        temporary: bool = ...,
+        qualified: bool = ...,
+    ) -> None: ...
+
+    # Methods.
     def stop(self) -> bool: ...
     def is_valid(self) -> bool: ...
     def delete(self) -> None: ...

stubs/gdb/gdb/unwinder.pyi

@@ -1,5 +1,4 @@
 import gdb
-from gdb import Frame, UnwindInfo
 
 class FrameId:
     def __init__(self, sp: gdb.Value | int, pc: gdb.Value | int, special: gdb.Value | int | None = None) -> None: ...
@@ -16,6 +15,6 @@ class Unwinder:
     enabled: bool
 
     def __init__(self, name: str) -> None: ...
-    def __call__(self, pending_frame: Frame) -> UnwindInfo | None: ...
+    def __call__(self, pending_frame: gdb.PendingFrame) -> gdb.UnwindInfo | None: ...
 
-def register_unwinder(locus: gdb.Objfile | gdb.Progspace | None, unwinder: Unwinder, replace: bool = ...) -> None: ...
+def register_unwinder(locus: gdb.Objfile | gdb.Progspace | None, unwinder: gdb._Unwinder, replace: bool = ...) -> None: ...