Patchwork [pushed] Fix clang/libc++ build (Re: [PATCH v3 06/17] Replace delete_longjmp_breakpoint_cleanup with a forward_scope_exit type)

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Submitter Pedro Alves
Date Jan. 24, 2019, 6:09 p.m.
Message ID <e4b455cd-c5b3-328c-491e-36251f188d2e@redhat.com>
Download mbox | patch
Permalink /patch/31206/
State New
Headers show

Comments

Pedro Alves - Jan. 24, 2019, 6:09 p.m.
On 01/24/2019 05:33 PM, John Baldwin wrote:

> I got the same failure on FreeBSD (also uses libc++) and this patch fixed
> the build for me.

In that case, I've merged the patch in, as below.

Thanks,
Pedro Alves

From 3046d67a0e29686ec18abd719660969c97973063 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Thu, 24 Jan 2019 18:01:49 +0000
Subject: [PATCH] Fix clang/libc++ build

This fixes the following build error with clang/libc++, reported at
<https://sourceware.org/ml/gdb-patches/2019-01/msg00537.html>:

  (...)
  In file included from breakpoint.c:34:
  In file included from ./inferior.h:54:
  ./common/forward-scope-exit.h:98:7: error: no matching constructor for
  initialization of 'decltype(std::bind(&delete_longjmp_breakpoint,
  std::declval<int>()))' (aka '__bind<void (*)(int), int>')
      : m_bind_function (std::bind (function, args...))
	^                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ./common/gdb_optional.h:155:19: note: in instantiation of member
  function 'detail::forward_scope_exit<void (int),
  &delete_longjmp_breakpoint, void (int)>::forward_scope_exit' requested
  here
      new (&m_item) T (std::forward<Args>(args)...);
		    ^
  breakpoint.c:11127:18: note: in instantiation of function template
  specialization 'gdb::optional<detail::forward_scope_exit<void (int),
  &delete_longjmp_breakpoint, void (int)> >::emplace<int &>' requested
  here
	lj_deleter.emplace (thread);
		   ^
  /Applications/Xcode-10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:2220:7:
  note: candidate constructor (the implicit copy constructor) not
  viable: no known conversion from '__bind<[...], int &>' to 'const
  __bind<[...], int>' for 1st argument
  class __bind
	^
  (...)

I don't really know why I ended up with a copy here.  We can just pass
the arguments directly to the being-constructed bind.

gdb/ChangeLog:
2019-01-24  Pedro Alves  <palves@redhat.com>

	* common/forward-scope-exit.h
	(forward_scope_exit::forward_scope_exit): Pass arguments to
	m_bind_function directly, instead of creating a std::bind and
	copying that.
---
 gdb/ChangeLog                   | 7 +++++++
 gdb/common/forward-scope-exit.h | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

Patch

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 453677e599..e8e01288d9 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@ 
+2019-01-24  Pedro Alves  <palves@redhat.com>
+
+	* common/forward-scope-exit.h
+	(forward_scope_exit::forward_scope_exit): Pass arguments to
+	m_bind_function directly, instead of creating a std::bind and
+	copying that.
+
 2019-01-24  Alan Hayward  <alan.hayward@arm.com>
 
 	* aarch64-tdep.c (aapcs_is_vfp_call_or_return_candidate_1): Check
diff --git a/gdb/common/forward-scope-exit.h b/gdb/common/forward-scope-exit.h
index 8d639151a4..bffc6e683b 100644
--- a/gdb/common/forward-scope-exit.h
+++ b/gdb/common/forward-scope-exit.h
@@ -95,7 +95,7 @@  class forward_scope_exit<Function, function, Res (Args...)>
 
 public:
   explicit forward_scope_exit (Args ...args)
-    : m_bind_function (std::bind (function, args...))
+    : m_bind_function (function, args...)
   {
     /* Nothing.  */
   }