[PATCH] c++: wrong looser exception spec with deleted fn

[PATCH] c++: wrong looser exception spec with deleted fn

[Marek Polacek]

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

IMHO trivial enough to go ahead now seeing as it doesn't introduce
new errors.

-- >8 --
I noticed we don't implement the "unless the overriding function is
defined as deleted" wording added to [except.spec] via CWG 1351.

	DR 1351

gcc/cp/ChangeLog:

	* search.cc (maybe_check_overriding_exception_spec): Don't error about
	a looser exception specification if the overrider is deleted.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/noexcept82.C: New test.
---
 gcc/cp/search.cc                        | 11 +++++++++--
 gcc/testsuite/g++.dg/cpp0x/noexcept82.C | 14 ++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept82.C

diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index 2b4ed5d024e..c948839dc53 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -1949,7 +1949,11 @@ locate_field_accessor (tree basetype_path, tree field_decl, bool const_p)
 }
 
 /* Check throw specifier of OVERRIDER is at least as strict as
-   the one of BASEFN.  */
+   the one of BASEFN.  This is due to [except.spec]: "If a virtual function
+   has a non-throwing exception specification, all declarations, including
+   the definition, of any function that overrides that virtual function in
+   any derived class shall have a non-throwing exception specification,
+   unless the overriding function is defined as deleted."  */
 
 bool
 maybe_check_overriding_exception_spec (tree overrider, tree basefn)
@@ -1959,7 +1963,10 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
   tree base_throw = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (basefn));
   tree over_throw = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (overrider));
 
-  if (DECL_INVALID_OVERRIDER_P (overrider))
+  if (DECL_INVALID_OVERRIDER_P (overrider)
+      /* CWG 1351 added the "unless the overriding function is defined as
+	 deleted" wording.  */
+      || DECL_DELETED_FN (overrider))
     return true;
 
   /* Can't check this yet.  Pretend this is fine and let
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept82.C b/gcc/testsuite/g++.dg/cpp0x/noexcept82.C
new file mode 100644
index 00000000000..c996613139b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept82.C
@@ -0,0 +1,14 @@
+// DR 1351, Problems with implicitly-declared exception-specifications
+// { dg-do compile { target c++11 } }
+
+struct B {
+  virtual void f() noexcept;
+  virtual void g();
+  virtual void h() noexcept = delete;
+};
+
+struct D: B {
+  void f();                     // { dg-error "looser" }
+  void g() noexcept;            // OK
+  void h() = delete;            // OK
+};

base-commit: 0d5d1c75f5c68b6064640c3154ae5f4c0b464905
-- 
2.43.0

Re: [PATCH] c++: wrong looser exception spec with deleted fn

[Jason Merrill]

On 2/15/24 17:16, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> IMHO trivial enough to go ahead now seeing as it doesn't introduce
> new errors.

OK.

> -- >8 --
> I noticed we don't implement the "unless the overriding function is
> defined as deleted" wording added to [except.spec] via CWG 1351.
> 
> 	DR 1351
> 
> gcc/cp/ChangeLog:
> 
> 	* search.cc (maybe_check_overriding_exception_spec): Don't error about
> 	a looser exception specification if the overrider is deleted.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp0x/noexcept82.C: New test.
> ---
>   gcc/cp/search.cc                        | 11 +++++++++--
>   gcc/testsuite/g++.dg/cpp0x/noexcept82.C | 14 ++++++++++++++
>   2 files changed, 23 insertions(+), 2 deletions(-)
>   create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept82.C
> 
> diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> index 2b4ed5d024e..c948839dc53 100644
> --- a/gcc/cp/search.cc
> +++ b/gcc/cp/search.cc
> @@ -1949,7 +1949,11 @@ locate_field_accessor (tree basetype_path, tree field_decl, bool const_p)
>   }
>   
>   /* Check throw specifier of OVERRIDER is at least as strict as
> -   the one of BASEFN.  */
> +   the one of BASEFN.  This is due to [except.spec]: "If a virtual function
> +   has a non-throwing exception specification, all declarations, including
> +   the definition, of any function that overrides that virtual function in
> +   any derived class shall have a non-throwing exception specification,
> +   unless the overriding function is defined as deleted."  */
>   
>   bool
>   maybe_check_overriding_exception_spec (tree overrider, tree basefn)
> @@ -1959,7 +1963,10 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
>     tree base_throw = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (basefn));
>     tree over_throw = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (overrider));
>   
> -  if (DECL_INVALID_OVERRIDER_P (overrider))
> +  if (DECL_INVALID_OVERRIDER_P (overrider)
> +      /* CWG 1351 added the "unless the overriding function is defined as
> +	 deleted" wording.  */
> +      || DECL_DELETED_FN (overrider))
>       return true;
>   
>     /* Can't check this yet.  Pretend this is fine and let
> diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept82.C b/gcc/testsuite/g++.dg/cpp0x/noexcept82.C
> new file mode 100644
> index 00000000000..c996613139b
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept82.C
> @@ -0,0 +1,14 @@
> +// DR 1351, Problems with implicitly-declared exception-specifications
> +// { dg-do compile { target c++11 } }
> +
> +struct B {
> +  virtual void f() noexcept;
> +  virtual void g();
> +  virtual void h() noexcept = delete;
> +};
> +
> +struct D: B {
> +  void f();                     // { dg-error "looser" }
> +  void g() noexcept;            // OK
> +  void h() = delete;            // OK
> +};
> 
> base-commit: 0d5d1c75f5c68b6064640c3154ae5f4c0b464905