[PATCH] gdb: add constructor to gdb_user_regs

[PATCH] gdb: add constructor to gdb_user_regs

[Enze Li via Gdb-patches]

When building gdb with clang 14 and -std=gnu++11, I ran into:

  CXX    user-regs.o
user-regs.c:83:29: error: no matching constructor for initialization of 'struct gdb_user_regs'
static struct gdb_user_regs builtin_user_regs = {
                            ^                   ~
user-regs.c:58:8: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 2 were provided
struct gdb_user_regs
       ^
user-regs.c:58:8: note: candidate constructor (the implicit move constructor) not viable: requires 1 argument, but 2 were provided
user-regs.c:58:8: note: candidate constructor (the implicit default constructor) not viable: requires 0 arguments, but 2 were provided
1 error generated.

The fundamental reason is that C++11 does not support this approach.
This patch adds a constructor to gdb_user_regs to avoid the build
failure.

Tested by rebuilding on x86_64-linux with clang 14 and gcc 12, with and
without -std=gnu++11.
---
 gdb/user-regs.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/gdb/user-regs.c b/gdb/user-regs.c
index 4bc4685387f..a2012b84534 100644
--- a/gdb/user-regs.c
+++ b/gdb/user-regs.c
@@ -57,8 +57,16 @@ struct user_reg
 
 struct gdb_user_regs
 {
-  struct user_reg *first = nullptr;
-  struct user_reg **last = nullptr;
+  gdb_user_regs (struct user_reg *mfirst, struct user_reg **mlast)
+    : first (mfirst),
+      last (mlast)
+  {
+  }
+
+  gdb_user_regs () = default;
+
+  struct user_reg *first;
+  struct user_reg **last;
 };
 
 static void
-- 
2.37.1

Re: [PATCH] gdb: add constructor to gdb_user_regs

[Tom de Vries via Gdb-patches]

On 8/6/22 07:14, Enze Li via Gdb-patches wrote:
> When building gdb with clang 14 and -std=gnu++11, I ran into:
> 
>    CXX    user-regs.o
> user-regs.c:83:29: error: no matching constructor for initialization of 'struct gdb_user_regs'
> static struct gdb_user_regs builtin_user_regs = {
>                              ^                   ~
> user-regs.c:58:8: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 2 were provided
> struct gdb_user_regs
>         ^
> user-regs.c:58:8: note: candidate constructor (the implicit move constructor) not viable: requires 1 argument, but 2 were provided
> user-regs.c:58:8: note: candidate constructor (the implicit default constructor) not viable: requires 0 arguments, but 2 were provided
> 1 error generated.
> 
> The fundamental reason is that C++11 does not support this approach.
> This patch adds a constructor to gdb_user_regs to avoid the build
> failure.
> 

Hi,

I ran into a similar problem with gcc 4.8 (I noticed a build failure 
with centos @ builder.sourceware.org) and fixed it here ( 
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=411c7e044fa99089d3030f2c61525c4d415f7b45 
).

My apologies that I didn't notice your patch.

Anyway, I hope that this fixes the problem for you as well.  I've 
managed to do a build using clang-13.0.0 (with --disable-werror) up to 
the point of an AFAICT unrelated linker failure.

Thanks,
- Tom

> Tested by rebuilding on x86_64-linux with clang 14 and gcc 12, with and
> without -std=gnu++11.
> ---
>   gdb/user-regs.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/user-regs.c b/gdb/user-regs.c
> index 4bc4685387f..a2012b84534 100644
> --- a/gdb/user-regs.c
> +++ b/gdb/user-regs.c
> @@ -57,8 +57,16 @@ struct user_reg
>   
>   struct gdb_user_regs
>   {
> -  struct user_reg *first = nullptr;
> -  struct user_reg **last = nullptr;
> +  gdb_user_regs (struct user_reg *mfirst, struct user_reg **mlast)
> +    : first (mfirst),
> +      last (mlast)
> +  {
> +  }
> +
> +  gdb_user_regs () = default;
> +
> +  struct user_reg *first;
> +  struct user_reg **last;
>   };
>   
>   static void

Re: [PATCH] gdb: add constructor to gdb_user_regs

[Enze Li via Gdb-patches]

Hi Tom,

On Mon, 2022-08-08 at 10:03 +0200, Tom de Vries wrote:
> > On 8/6/22 07:14, Enze Li via Gdb-patches wrote:
> > > > When building gdb with clang 14 and -std=gnu++11, I ran into:
> > > > 
> > > >    CXX    user-regs.o
> > > > user-regs.c:83:29: error: no matching constructor for> >
> > initialization of 'struct gdb_user_regs'
> > > > static struct gdb_user_regs builtin_user_regs = {
> > > >                              ^                   ~
> > > > user-regs.c:58:8: note: candidate constructor (the implicit
> > > > copy> >
> > constructor) not viable: requires 1 argument, but 2 were provided
> > > > struct gdb_user_regs
> > > >         ^
> > > > user-regs.c:58:8: note: candidate constructor (the implicit
> > > > move> >
> > constructor) not viable: requires 1 argument, but 2 were provided
> > > > user-regs.c:58:8: note: candidate constructor (the implicit
> > default> > constructor) not viable: requires 0 arguments, but 2
> > were
> > provided
> > > > 1 error generated.
> > > > 
> > > > The fundamental reason is that C++11 does not support this> >
> > approach.
> > > > This patch adds a constructor to gdb_user_regs to avoid the
> > > > build
> > > > failure.
> > > > 
> > 
> > Hi,
> > 
> > I ran into a similar problem with gcc 4.8 (I noticed a build
> > failure 
> > with centos @ builder.sourceware.org) and fixed it here ( 
> > https://sourceware.org/git/?p=binutils-
> gdb.git;a=commit;h=411c7e044fa99089d3030f2c61525c4d415f7b45 
> > ).
> > 
> > My apologies that I didn't notice your patch.

It's okay, mine is just a proposed one.
 
> > 
> > Anyway, I hope that this fixes the problem for you as well.  I've 
> > managed to do a build using clang-13.0.0 (with --disable-werror)
> > up>
> to 
> > the point of an AFAICT unrelated linker failure.
> > 
> > Thanks,
> > - Tom

With your patch applied, I have tested with clang 13, 14 and 15, and
they all built successfully.  Thanks for doing this.

Thanks,
Enze

> > 
> > > > Tested by rebuilding on x86_64-linux with clang 14 and gcc 12,
> > with> > and
> > > > without -std=gnu++11.
> > > > ---
> > > >   gdb/user-regs.c | 12 ++++++++++--
> > > >   1 file changed, 10 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/gdb/user-regs.c b/gdb/user-regs.c
> > > > index 4bc4685387f..a2012b84534 100644
> > > > --- a/gdb/user-regs.c
> > > > +++ b/gdb/user-regs.c
> > > > @@ -57,8 +57,16 @@ struct user_reg
> > > >   
> > > >   struct gdb_user_regs
> > > >   {
> > > > -  struct user_reg *first = nullptr;
> > > > -  struct user_reg **last = nullptr;
> > > > +  gdb_user_regs (struct user_reg *mfirst, struct user_reg
> > > > **mlast)
> > > > +    : first (mfirst),
> > > > +      last (mlast)
> > > > +  {
> > > > +  }
> > > > +
> > > > +  gdb_user_regs () = default;
> > > > +
> > > > +  struct user_reg *first;
> > > > +  struct user_reg **last;
> > > >   };
> > > >   
> > > >   static void