* [PATCH] Fix building gdb with gcc-4.x
@ 2021-01-04 20:57 Bernd Edlinger
2021-01-04 21:16 ` Luis Machado
2021-01-04 21:30 ` Simon Marchi
0 siblings, 2 replies; 6+ messages in thread
From: Bernd Edlinger @ 2021-01-04 20:57 UTC (permalink / raw)
To: gdb-patches, Luis Machado, Simon Marchi
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Hi,
with Luis' commit of today the trunk is no longer able to
be compiled with gcc-4.x.
The problem is std::is_trivially_default_constructible is
not defined before gcc-5 although the compiler supports C++11
I am not sure about what's the best approach for conditionally
enabling the code, especially for compilers other than g++.
This fixes the build for me.
Is it OK for trunk?
Thanks
Bernd.
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From 0879e2cff0ea732769aa80b89fa6fbba70c84260 Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 4 Jan 2021 21:40:41 +0100
Subject: [PATCH] Fix building gdb with gcc-4.x
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Since is_trivially_default_constructible was not implemented before gcc-5
it cannot be used with gcc-4.x.
../../binutils-gdb/gdb/trad-frame.c: In function ‘trad_frame_saved_reg* trad_frame_alloc_saved_regs(gdbarch*)’:
../../binutils-gdb/gdb/trad-frame.c:64:22: error: ‘is_trivially_default_constructible’ is not a member of ‘std’
gdb_static_assert (std::is_trivially_default_constructible<trad_frame_saved_reg>::value);
Fix build by using conditional compilation around that line.
Fixes: 098caef485a ("Refactor struct trad_frame_saved_regs")
gdb:
2021-01-04 Bernd Edlinger <bernd.edlinger@hotmail.de>
* trad-frame.c (trad_frame_alloc_saved_regs): Avoid compile-error
because is_trivially_default_constructible was first implemented with
gcc-5.
---
gdb/trad-frame.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/gdb/trad-frame.c b/gdb/trad-frame.c
index 17375e8..de1acc1 100644
--- a/gdb/trad-frame.c
+++ b/gdb/trad-frame.c
@@ -60,7 +60,9 @@ struct trad_frame_cache *
trad_frame_saved_reg *
trad_frame_alloc_saved_regs (struct gdbarch *gdbarch)
{
+#if defined(__GNUC__) && __GNUC__ >= 5
gdb_static_assert (std::is_trivially_default_constructible<trad_frame_saved_reg>::value);
+#endif
int numregs = gdbarch_num_cooked_regs (gdbarch);
trad_frame_saved_reg *this_saved_regs
--
1.9.1
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] Fix building gdb with gcc-4.x
2021-01-04 20:57 [PATCH] Fix building gdb with gcc-4.x Bernd Edlinger
@ 2021-01-04 21:16 ` Luis Machado
2021-01-04 21:34 ` Luis Machado
2021-01-04 21:30 ` Simon Marchi
1 sibling, 1 reply; 6+ messages in thread
From: Luis Machado @ 2021-01-04 21:16 UTC (permalink / raw)
To: Bernd Edlinger, gdb-patches, Simon Marchi
Hi Bernd,
On 1/4/21 5:57 PM, Bernd Edlinger wrote:
> Hi,
>
> with Luis' commit of today the trunk is no longer able to
> be compiled with gcc-4.x.
>
> The problem is std::is_trivially_default_constructible is
> not defined before gcc-5 although the compiler supports C++11
>
Sorry for the breakage. It looks like GCC 4.x does not fully support
C++11, although it used to be able to build GDB.
> I am not sure about what's the best approach for conditionally
> enabling the code, especially for compilers other than g++.
Right now it looks like GDB's requirement is a compiler that (fully?)
supports C++ 11. It doesn't seem to name specific minimum versions of
compilers.
With that said, I wouldn't mind a conditional in the code to support
builds with GCC 4.x, if that is deemed important. But as we start using
more and more C++ 11 constructs, breakages may happen again in the future.
>
>
> This fixes the build for me.
> Is it OK for trunk?
>
>
> Thanks
> Bernd.
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Fix building gdb with gcc-4.x
2021-01-04 21:16 ` Luis Machado
@ 2021-01-04 21:34 ` Luis Machado
0 siblings, 0 replies; 6+ messages in thread
From: Luis Machado @ 2021-01-04 21:34 UTC (permalink / raw)
To: Bernd Edlinger, gdb-patches, Simon Marchi
On 1/4/21 6:16 PM, Luis Machado wrote:
> Hi Bernd,
>
> On 1/4/21 5:57 PM, Bernd Edlinger wrote:
>> Hi,
>>
>> with Luis' commit of today the trunk is no longer able to
>> be compiled with gcc-4.x.
>>
>> The problem is std::is_trivially_default_constructible is
>> not defined before gcc-5 although the compiler supports C++11
>>
>
> Sorry for the breakage. It looks like GCC 4.x does not fully support
> C++11, although it used to be able to build GDB.
>
>> I am not sure about what's the best approach for conditionally
>> enabling the code, especially for compilers other than g++.
>
> Right now it looks like GDB's requirement is a compiler that (fully?)
> supports C++ 11. It doesn't seem to name specific minimum versions of
> compilers.
>
> With that said, I wouldn't mind a conditional in the code to support
> builds with GCC 4.x, if that is deemed important. But as we start using
> more and more C++ 11 constructs, breakages may happen again in the future.
>
>>
>>
>> This fixes the build for me.
>> Is it OK for trunk?
It's worth mentioning that I'll be changing this code again in the
future, and that static assertion will likely go away when I do.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Fix building gdb with gcc-4.x
2021-01-04 20:57 [PATCH] Fix building gdb with gcc-4.x Bernd Edlinger
2021-01-04 21:16 ` Luis Machado
@ 2021-01-04 21:30 ` Simon Marchi
2021-01-14 6:36 ` Bernd Edlinger
1 sibling, 1 reply; 6+ messages in thread
From: Simon Marchi @ 2021-01-04 21:30 UTC (permalink / raw)
To: Bernd Edlinger, gdb-patches, Luis Machado
On 2021-01-04 3:57 p.m., Bernd Edlinger wrote:
> Hi,
>
> with Luis' commit of today the trunk is no longer able to
> be compiled with gcc-4.x.
>
> The problem is std::is_trivially_default_constructible is
> not defined before gcc-5 although the compiler supports C++11
>
> I am not sure about what's the best approach for conditionally
> enabling the code, especially for compilers other than g++.
>
>
> This fixes the build for me.
> Is it OK for trunk?
>
>
> Thanks
> Bernd.
>
We have other instances of this, I'd suggest inspiring yourself from:
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/unittests/enum-flags-selftests.c;h=e3b6cf81d07f1eaefec72bce131d1c75ce00ef82;hb=HEAD#l66
These defines are defined here:
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdbsupport/traits.h;h=f545edbb0d93e95f65e954fbf54cbc8843e5239a;hb=HEAD#l28
As you see, we already have a HAVE_IS_TRIVIALLY_CONSTRUCTIBLE, we could
use it. The code in trad-frame.c could be changed to use
std::is_trivially_constructible instead of
std::is_trivially_default_constructible, I believe it's the same when
passing no Args... to is_trivially_constructible. See "Possible
implementation" in:
https://en.cppreference.com/w/cpp/types/is_default_constructible
Simon
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Fix building gdb with gcc-4.x
2021-01-04 21:30 ` Simon Marchi
@ 2021-01-14 6:36 ` Bernd Edlinger
2021-01-14 15:56 ` Simon Marchi
0 siblings, 1 reply; 6+ messages in thread
From: Bernd Edlinger @ 2021-01-14 6:36 UTC (permalink / raw)
To: Simon Marchi, gdb-patches, Luis Machado
[-- Attachment #1: Type: text/plain, Size: 1478 bytes --]
On 1/4/21 10:30 PM, Simon Marchi wrote:
> On 2021-01-04 3:57 p.m., Bernd Edlinger wrote:
>> Hi,
>>
>> with Luis' commit of today the trunk is no longer able to
>> be compiled with gcc-4.x.
>>
>> The problem is std::is_trivially_default_constructible is
>> not defined before gcc-5 although the compiler supports C++11
>>
>> I am not sure about what's the best approach for conditionally
>> enabling the code, especially for compilers other than g++.
>>
>>
>> This fixes the build for me.
>> Is it OK for trunk?
>>
>>
>> Thanks
>> Bernd.
>>
>
> We have other instances of this, I'd suggest inspiring yourself from:
>
> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/unittests/enum-flags-selftests.c;h=e3b6cf81d07f1eaefec72bce131d1c75ce00ef82;hb=HEAD#l66
>
> These defines are defined here:
>
> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdbsupport/traits.h;h=f545edbb0d93e95f65e954fbf54cbc8843e5239a;hb=HEAD#l28
>
> As you see, we already have a HAVE_IS_TRIVIALLY_CONSTRUCTIBLE, we could
> use it. The code in trad-frame.c could be changed to use
> std::is_trivially_constructible instead of
> std::is_trivially_default_constructible, I believe it's the same when
> passing no Args... to is_trivially_constructible. See "Possible
> implementation" in:
>
> https://en.cppreference.com/w/cpp/types/is_default_constructible
>
> Simon
>
Okay, good point.
I updated the patch following your suggestion.
Is the updated patch OK?
Thanks
Bernd.
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-Fix-building-gdb-with-gcc-4.x.patch --]
[-- Type: text/x-patch; name="0001-Fix-building-gdb-with-gcc-4.x.patch", Size: 2005 bytes --]
From 588e7a57056e8aabdd6906993dd3d27354cc70fc Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 4 Jan 2021 21:40:41 +0100
Subject: [PATCH] Fix building gdb with gcc-4.x
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Since is_trivially_default_constructible was not implemented before gcc-5
it cannot be used with gcc-4.x.
../../binutils-gdb/gdb/trad-frame.c: In function ‘trad_frame_saved_reg* trad_frame_alloc_saved_regs(gdbarch*)’:
../../binutils-gdb/gdb/trad-frame.c:64:22: error: ‘is_trivially_default_constructible’ is not a member of ‘std’
gdb_static_assert (std::is_trivially_default_constructible<trad_frame_saved_reg>::value);
Fix the build by using conditional compilation around that line.
Use the equivalent is_trivially_constructible<T> instead, since
we already have HAVE_IS_TRIVIALLY_CONSTRUCTIBLE for that purpose.
Fixes: 098caef485a ("Refactor struct trad_frame_saved_regs")
gdb:
2021-01-14 Bernd Edlinger <bernd.edlinger@hotmail.de>
* trad-frame.c (trad_frame_alloc_saved_regs): Avoid compile-error
because is_trivially_default_constructible was first implemented with
gcc-5.
---
gdb/trad-frame.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/gdb/trad-frame.c b/gdb/trad-frame.c
index 17375e8..3284c45 100644
--- a/gdb/trad-frame.c
+++ b/gdb/trad-frame.c
@@ -25,6 +25,7 @@
#include "target.h"
#include "value.h"
#include "gdbarch.h"
+#include "gdbsupport/traits.h"
struct trad_frame_cache
{
@@ -60,7 +61,9 @@ struct trad_frame_cache *
trad_frame_saved_reg *
trad_frame_alloc_saved_regs (struct gdbarch *gdbarch)
{
- gdb_static_assert (std::is_trivially_default_constructible<trad_frame_saved_reg>::value);
+#ifdef HAVE_IS_TRIVIALLY_CONSTRUCTIBLE
+ gdb_static_assert (std::is_trivially_constructible<trad_frame_saved_reg>::value);
+#endif
int numregs = gdbarch_num_cooked_regs (gdbarch);
trad_frame_saved_reg *this_saved_regs
--
1.9.1
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] Fix building gdb with gcc-4.x
2021-01-14 6:36 ` Bernd Edlinger
@ 2021-01-14 15:56 ` Simon Marchi
0 siblings, 0 replies; 6+ messages in thread
From: Simon Marchi @ 2021-01-14 15:56 UTC (permalink / raw)
To: Bernd Edlinger, gdb-patches, Luis Machado
On 2021-01-14 1:36 a.m., Bernd Edlinger wrote:
> On 1/4/21 10:30 PM, Simon Marchi wrote:
>> On 2021-01-04 3:57 p.m., Bernd Edlinger wrote:
>>> Hi,
>>>
>>> with Luis' commit of today the trunk is no longer able to
>>> be compiled with gcc-4.x.
>>>
>>> The problem is std::is_trivially_default_constructible is
>>> not defined before gcc-5 although the compiler supports C++11
>>>
>>> I am not sure about what's the best approach for conditionally
>>> enabling the code, especially for compilers other than g++.
>>>
>>>
>>> This fixes the build for me.
>>> Is it OK for trunk?
>>>
>>>
>>> Thanks
>>> Bernd.
>>>
>>
>> We have other instances of this, I'd suggest inspiring yourself from:
>>
>> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/unittests/enum-flags-selftests.c;h=e3b6cf81d07f1eaefec72bce131d1c75ce00ef82;hb=HEAD#l66
>>
>> These defines are defined here:
>>
>> https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdbsupport/traits.h;h=f545edbb0d93e95f65e954fbf54cbc8843e5239a;hb=HEAD#l28
>>
>> As you see, we already have a HAVE_IS_TRIVIALLY_CONSTRUCTIBLE, we could
>> use it. The code in trad-frame.c could be changed to use
>> std::is_trivially_constructible instead of
>> std::is_trivially_default_constructible, I believe it's the same when
>> passing no Args... to is_trivially_constructible. See "Possible
>> implementation" in:
>>
>> https://en.cppreference.com/w/cpp/types/is_default_constructible
>>
>> Simon
>>
>
> Okay, good point.
>
> I updated the patch following your suggestion.
>
> Is the updated patch OK?
>
>
> Thanks
> Bernd.
>
Yep, LGTM, thanks.
Simon
^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-01-04 20:57 [PATCH] Fix building gdb with gcc-4.x Bernd Edlinger
2021-01-04 21:16 ` Luis Machado
2021-01-04 21:34 ` Luis Machado
2021-01-04 21:30 ` Simon Marchi
2021-01-14 6:36 ` Bernd Edlinger
2021-01-14 15:56 ` Simon Marchi
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