From 1065ee0d94af7a72572d91f698307b7be065b4bc Mon Sep 17 00:00:00 2001
From: Andrew Burgess <aburgess@redhat.com>
Date: Tue, 9 Dec 2025 10:34:11 +0000
Subject: [PATCH] gdb: fix build error after forward_scope_exit changes

After commit:

  commit 43db8f70d86b2492b79f59342187b919fd58b3dd
  Date:   Thu Oct 23 16:34:20 2025 +0100

      gdbsupport: remove undefined behaviour from (forward_)scope_exit

A build failure was reported[1] when using clang++.  The failure looks
like this:

    CXX    aarch64-fbsd-tdep.o
  In file included from /tmp/src/binutils-gdb/gdb/aarch64-fbsd-tdep.c:22:
  In file included from /tmp/src/binutils-gdb/gdb/gdbarch.h:28:
  In file included from /tmp/src/binutils-gdb/gdb/infrun.h:21:
  In file included from /tmp/src/binutils-gdb/gdb/gdbthread.h:35:
  /tmp/src/binutils-gdb/gdb/../gdbsupport/forward-scope-exit.h:112:20: error: too many template arguments
  for class template 'forward_scope_exit_policy'
    112 |         = scope_exit_base<forward_scope_exit_policy<Function,
        |                           ^
    113 |                                                     function, Res, Args...>>;
        |                                                                    ~~~~~~~~
  /tmp/src/binutils-gdb/gdb/../gdbsupport/forward-scope-exit.h:82:8: note: template is declared here
     81 | template<typename Function, Function *function, typename Signature>
        | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     82 | struct forward_scope_exit_policy;
        |        ^

The problem is that the forward_scope_exit_policy class expects 3
template arguments, but in forward-scope-exit.h we say:

  template<typename Function, Function *function,
  	 typename Res, typename... Args>
  using forward_scope_exit
  	= scope_exit_base<forward_scope_exit_policy<Function,
  						    function, Res, Args...>>;

Which passes 4 template arguments.  Fix this by changing the above
'using' like too:

  template<typename Function, Function *function, typename Signature>
  using forward_scope_exit
  	= scope_exit_base<forward_scope_exit_policy<Function, function,
  						    Signature>>;

This now compiles with clang++.
---
 gdbsupport/forward-scope-exit.h | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/gdbsupport/forward-scope-exit.h b/gdbsupport/forward-scope-exit.h
index fd93374afc9..35ef521de62 100644
--- a/gdbsupport/forward-scope-exit.h
+++ b/gdbsupport/forward-scope-exit.h
@@ -106,11 +106,10 @@ private:
     m_bind_function;
 };
 
-template<typename Function, Function *function,
-	 typename Res, typename... Args>
+template<typename Function, Function *function, typename Signature>
 using forward_scope_exit
-	= scope_exit_base<forward_scope_exit_policy<Function,
-						    function, Res, Args...>>;
+	= scope_exit_base<forward_scope_exit_policy<Function, function,
+						    Signature>>;
 
 } /* namespace detail */
 
-- 
2.47.3