[PATCH] gcc: Add deleted assignment operators to non-copyable types

[PATCH] gcc: Add deleted assignment operators to non-copyable types

[Jonathan Wakely]

Bootstrapped and regtested on powerpc64le-linux.

OK for trunk?

It's safe to do now rather than waiting for Stage 1, because if we were
actually relying on copy-assigning these types it would have failed to
compile with this change. So it has no functional change, but will help
prevent any future misuse of these types.

-- >8 --

The auto_timevar and auto_cond_timevar classes are supposed to be
non-copyable, but they have implicit assignment operators. Define their
assignment operators as deleted.

The auto_bitmap declares private copy/move constructors/assignments,
which can be replced with deleted copies to get the same effect but
using more idiomatic C++11 style.

gcc/ChangeLog:

	* bitmap.h (class auto_bitmap): Replace private-and-undefined
	copy and move special member functions with deleted copies.
	* timevar.h (class auto_timevar): Delete assignment operator.
	(class auto_cond_timevar): Likewise.
---
 gcc/bitmap.h  | 11 ++++-------
 gcc/timevar.h |  6 ++++--
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/gcc/bitmap.h b/gcc/bitmap.h
index 43337d2e9d9..ccb484651ab 100644
--- a/gcc/bitmap.h
+++ b/gcc/bitmap.h
@@ -945,7 +945,7 @@ bmp_iter_and_compl (bitmap_iterator *bi, unsigned *bit_no)
 /* A class that ties the lifetime of a bitmap to its scope.  */
 class auto_bitmap
 {
- public:
+public:
   auto_bitmap (ALONE_CXX_MEM_STAT_INFO)
     { bitmap_initialize (&m_bits, &bitmap_default_obstack PASS_MEM_STAT); }
   explicit auto_bitmap (bitmap_obstack *o CXX_MEM_STAT_INFO)
@@ -954,12 +954,9 @@ class auto_bitmap
   // Allow calling bitmap functions on our bitmap.
   operator bitmap () { return &m_bits; }
 
- private:
-  // Prevent making a copy that references our bitmap.
-  auto_bitmap (const auto_bitmap &);
-  auto_bitmap &operator = (const auto_bitmap &);
-  auto_bitmap (auto_bitmap &&);
-  auto_bitmap &operator = (auto_bitmap &&);
+  // Prevent shallow copies.
+  auto_bitmap (const auto_bitmap &) = delete;
+  auto_bitmap &operator = (const auto_bitmap &) = delete;
 
   bitmap_head m_bits;
 };
diff --git a/gcc/timevar.h b/gcc/timevar.h
index ad465731609..b2d13d44190 100644
--- a/gcc/timevar.h
+++ b/gcc/timevar.h
@@ -247,8 +247,9 @@ class auto_timevar
       m_timer->pop (m_tv);
   }
 
-  // Disallow copies.
+  // Prevent shallow copies.
   auto_timevar (const auto_timevar &) = delete;
+  auto_timevar &operator= (const auto_timevar &) = delete;
 
  private:
   timer *m_timer;
@@ -279,8 +280,9 @@ class auto_cond_timevar
       m_timer->cond_stop (m_tv);
   }
 
-  // Disallow copies.
+  // Prevent shallow copies.
   auto_cond_timevar (const auto_cond_timevar &) = delete;
+  auto_cond_timevar &operator= (const auto_cond_timevar &) = delete;
 
  private:
   void start()
-- 
2.39.2

Re: [PATCH] gcc: Add deleted assignment operators to non-copyable types

[Richard Biener]

> Am 10.03.2023 um 16:36 schrieb Jonathan Wakely via Gcc-patches <gcc-patches@gcc.gnu.org>:
> 
> Bootstrapped and regtested on powerpc64le-linux.
> 
> OK for trunk?

Ok.

Thanks,
Richard 

> It's safe to do now rather than waiting for Stage 1, because if we were
> actually relying on copy-assigning these types it would have failed to
> compile with this change. So it has no functional change, but will help
> prevent any future misuse of these types.
> 
> -- >8 --
> 
> The auto_timevar and auto_cond_timevar classes are supposed to be
> non-copyable, but they have implicit assignment operators. Define their
> assignment operators as deleted.
> 
> The auto_bitmap declares private copy/move constructors/assignments,
> which can be replced with deleted copies to get the same effect but
> using more idiomatic C++11 style.
> 
> gcc/ChangeLog:
> 
>    * bitmap.h (class auto_bitmap): Replace private-and-undefined
>    copy and move special member functions with deleted copies.
>    * timevar.h (class auto_timevar): Delete assignment operator.
>    (class auto_cond_timevar): Likewise.
> ---
> gcc/bitmap.h  | 11 ++++-------
> gcc/timevar.h |  6 ++++--
> 2 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/gcc/bitmap.h b/gcc/bitmap.h
> index 43337d2e9d9..ccb484651ab 100644
> --- a/gcc/bitmap.h
> +++ b/gcc/bitmap.h
> @@ -945,7 +945,7 @@ bmp_iter_and_compl (bitmap_iterator *bi, unsigned *bit_no)
> /* A class that ties the lifetime of a bitmap to its scope.  */
> class auto_bitmap
> {
> - public:
> +public:
>   auto_bitmap (ALONE_CXX_MEM_STAT_INFO)
>     { bitmap_initialize (&m_bits, &bitmap_default_obstack PASS_MEM_STAT); }
>   explicit auto_bitmap (bitmap_obstack *o CXX_MEM_STAT_INFO)
> @@ -954,12 +954,9 @@ class auto_bitmap
>   // Allow calling bitmap functions on our bitmap.
>   operator bitmap () { return &m_bits; }
> 
> - private:
> -  // Prevent making a copy that references our bitmap.
> -  auto_bitmap (const auto_bitmap &);
> -  auto_bitmap &operator = (const auto_bitmap &);
> -  auto_bitmap (auto_bitmap &&);
> -  auto_bitmap &operator = (auto_bitmap &&);
> +  // Prevent shallow copies.
> +  auto_bitmap (const auto_bitmap &) = delete;
> +  auto_bitmap &operator = (const auto_bitmap &) = delete;
> 
>   bitmap_head m_bits;
> };
> diff --git a/gcc/timevar.h b/gcc/timevar.h
> index ad465731609..b2d13d44190 100644
> --- a/gcc/timevar.h
> +++ b/gcc/timevar.h
> @@ -247,8 +247,9 @@ class auto_timevar
>       m_timer->pop (m_tv);
>   }
> 
> -  // Disallow copies.
> +  // Prevent shallow copies.
>   auto_timevar (const auto_timevar &) = delete;
> +  auto_timevar &operator= (const auto_timevar &) = delete;
> 
>  private:
>   timer *m_timer;
> @@ -279,8 +280,9 @@ class auto_cond_timevar
>       m_timer->cond_stop (m_tv);
>   }
> 
> -  // Disallow copies.
> +  // Prevent shallow copies.
>   auto_cond_timevar (const auto_cond_timevar &) = delete;
> +  auto_cond_timevar &operator= (const auto_cond_timevar &) = delete;
> 
>  private:
>   void start()
> -- 
> 2.39.2
>