Re: [PATCH v3 06/17] Replace delete_longjmp_breakpoint_cleanup with a forward_scope_exit type

Re: [PATCH v3 06/17] Replace delete_longjmp_breakpoint_cleanup with a forward_scope_exit type

[Pavel I. Kryukov]

The patch causes build errors on XCode:

$ clang --version
Apple LLVM version 10.0.0 (clang-1000.11.45.5)
Target: x86_64-apple-darwin17.7.0
Thread model: posix
InstalledDir: /Applications/Xcode10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin


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
      ^
/Applications/Xcode-10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:2220:7:
note: candidate constructor (the implicit move constructor) not
viable: no known conversion from '__bind<[...], int &>' to
'__bind<[...], int>' for 1st argument
/Applications/Xcode-10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:2240:16:
note: candidate template ignored: requirement 'is_constructible<_Fd,
__bind<void (*)(int), int &> >::value' was not satisfied [with _Gp =
std::__1::__bind<void (*)(int), int &>, _BA = <>]
      explicit __bind(_Gp&& __f, _BA&& ...__bound_args)
               ^
1 error generated.
make: *** [breakpoint.o] Error 1

Thanks,
--
Pavel

Re: [PATCH v3 06/17] Replace delete_longjmp_breakpoint_cleanup with a forward_scope_exit type

[Pedro Alves]

On 01/24/2019 11:23 AM, Pavel I. Kryukov wrote:
> The patch causes build errors on XCode:
> 
> $ clang --version
> Apple LLVM version 10.0.0 (clang-1000.11.45.5)
> Target: x86_64-apple-darwin17.7.0
> Thread model: posix
> InstalledDir: /Applications/Xcode10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

Thanks.

Hmm, I only have clang 5.0.2 handy, and I think it links with
libstdc++ instead of clang's own libc++.  Here it builds fine.
I had also made sure the patch builds fine with g++ 4.8.

> 
> 
> 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
>       ^

Hmm, references to the copy ctor.  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.  Does this work for you?

From b1caeb9c5334a59680af7b7717ab620e5a912bcf Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Thu, 24 Jan 2019 16:25:44 +0000
Subject: [PATCH] No copy ctor

---
 gdb/common/forward-scope-exit.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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.  */
   }
-- 
2.14.4

Re: [PATCH v3 06/17] Replace delete_longjmp_breakpoint_cleanup with a forward_scope_exit type

[John Baldwin]

On 1/24/19 9:09 AM, Pedro Alves wrote:
> On 01/24/2019 11:23 AM, Pavel I. Kryukov wrote:
>> The patch causes build errors on XCode:
>>
>> $ clang --version
>> Apple LLVM version 10.0.0 (clang-1000.11.45.5)
>> Target: x86_64-apple-darwin17.7.0
>> Thread model: posix
>> InstalledDir: /Applications/Xcode10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
> 
> Thanks.
> 
> Hmm, I only have clang 5.0.2 handy, and I think it links with
> libstdc++ instead of clang's own libc++.  Here it builds fine.
> I had also made sure the patch builds fine with g++ 4.8.
> 
>>
>>
>> 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
>>       ^
> 
> Hmm, references to the copy ctor.  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.  Does this work for you?
> 
> From b1caeb9c5334a59680af7b7717ab620e5a912bcf Mon Sep 17 00:00:00 2001
> From: Pedro Alves <palves@redhat.com>
> Date: Thu, 24 Jan 2019 16:25:44 +0000
> Subject: [PATCH] No copy ctor
> 
> ---
>  gdb/common/forward-scope-exit.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> 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.  */
>    }
> 

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

-- 
John Baldwin

                                                                            

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

[Pedro Alves]

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(-)

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.  */
   }
-- 
2.14.4