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* [PATCH] c++: wrong looser excep spec for dep noexcept [PR113158]
@ 2024-02-15 22:17 Marek Polacek
  2024-02-16 20:58 ` Jason Merrill
  0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2024-02-15 22:17 UTC (permalink / raw)
  To: Jason Merrill, GCC Patches

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

By the ??? below I mean that maybe_instantiate_noexcept could return
a tristate, and then maybe_check_overriding_exception_spec could check

  if (maybe_instantiate_noexcept ().is_unknown ())
    return true;

and we don't have to add any new checks to maybe_check_o_e_spec.

-- >8 --
Here we find ourselves in maybe_check_overriding_exception_spec in
a template context where we can't instantiate a dependent noexcept.
That's OK, but we have to defer the checking otherwise we give wrong
errors.

	PR c++/113158

gcc/cp/ChangeLog:

	* search.cc (maybe_check_overriding_exception_spec): Defer checking
	when a noexcept couldn't be instantiated.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/noexcept83.C: New test.
---
 gcc/cp/search.cc                        |  7 +++++
 gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C

diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index c948839dc53..73d254d6b84 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -1975,6 +1975,13 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
       || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
     return true;
 
+  /* We also have to defer checking when we're in a template and couldn't
+     instantiate the noexcept yet.
+     ??? maybe_instantiate_noexcept already checked these.  Use tristate?  */
+  if (type_dependent_expression_p (base_throw)
+      || type_dependent_expression_p (over_throw))
+    return true;
+
   if (!comp_except_specs (base_throw, over_throw, ce_derived))
     {
       auto_diagnostic_group d;
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
new file mode 100644
index 00000000000..47832bbb44d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
@@ -0,0 +1,37 @@
+// PR c++/113158
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct V {
+  static constexpr bool t = false;
+};
+struct base {
+    virtual int f() = 0;
+};
+
+template<typename T>
+struct derived : base {
+    int f() noexcept(V<T>::t) override;
+};
+
+struct base2 {
+    virtual int f() noexcept = 0;
+};
+
+template<bool B>
+struct W {
+  static constexpr bool t = B;
+};
+
+template<bool B>
+struct derived2 : base2 {
+    int f() noexcept(W<B>::t) override; // { dg-error "looser exception specification" }
+};
+
+void
+g ()
+{
+  derived<int> d1;
+  derived2<false> d2; // { dg-message "required from here" }
+  derived2<true> d3;
+}

base-commit: b3b3bd250f0a7c22b7d46d3522c8b94c6a35d22a
prerequisite-patch-id: 3beddc8cae6ef7f28cd7eac7240d5f4dad08e5f7
-- 
2.43.0


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] c++: wrong looser excep spec for dep noexcept [PR113158]
  2024-02-15 22:17 [PATCH] c++: wrong looser excep spec for dep noexcept [PR113158] Marek Polacek
@ 2024-02-16 20:58 ` Jason Merrill
  2024-02-16 21:33   ` [PATCH v2] " Marek Polacek
  0 siblings, 1 reply; 6+ messages in thread
From: Jason Merrill @ 2024-02-16 20:58 UTC (permalink / raw)
  To: Marek Polacek, GCC Patches

On 2/15/24 17:17, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> By the ??? below I mean that maybe_instantiate_noexcept could return
> a tristate, and then maybe_check_overriding_exception_spec could check
> 
>    if (maybe_instantiate_noexcept ().is_unknown ())
>      return true;
> 
> and we don't have to add any new checks to maybe_check_o_e_spec.
> 
> -- >8 --
> Here we find ourselves in maybe_check_overriding_exception_spec in
> a template context where we can't instantiate a dependent noexcept.
> That's OK, but we have to defer the checking otherwise we give wrong
> errors.
> 
> 	PR c++/113158
> 
> gcc/cp/ChangeLog:
> 
> 	* search.cc (maybe_check_overriding_exception_spec): Defer checking
> 	when a noexcept couldn't be instantiated.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp0x/noexcept83.C: New test.
> ---
>   gcc/cp/search.cc                        |  7 +++++
>   gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
>   2 files changed, 44 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> 
> diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> index c948839dc53..73d254d6b84 100644
> --- a/gcc/cp/search.cc
> +++ b/gcc/cp/search.cc
> @@ -1975,6 +1975,13 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
>         || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
>       return true;
>   
> +  /* We also have to defer checking when we're in a template and couldn't
> +     instantiate the noexcept yet.
> +     ??? maybe_instantiate_noexcept already checked these.  Use tristate?  */
> +  if (type_dependent_expression_p (base_throw)
> +      || type_dependent_expression_p (over_throw))

I think we also want to avoid comparing value-dependent expressions, but 
actually checking either one seems like more work than needed here; I'd 
think we want to defer in a template if the specifiers aren't both 
exactly true or false.

> +    return true;
> +
>     if (!comp_except_specs (base_throw, over_throw, ce_derived))
>       {
>         auto_diagnostic_group d;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> new file mode 100644
> index 00000000000..47832bbb44d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> @@ -0,0 +1,37 @@
> +// PR c++/113158
> +// { dg-do compile { target c++11 } }
> +
> +template<typename T>
> +struct V {
> +  static constexpr bool t = false;
> +};
> +struct base {
> +    virtual int f() = 0;
> +};
> +
> +template<typename T>
> +struct derived : base {
> +    int f() noexcept(V<T>::t) override;
> +};
> +
> +struct base2 {
> +    virtual int f() noexcept = 0;
> +};
> +
> +template<bool B>
> +struct W {
> +  static constexpr bool t = B;
> +};
> +
> +template<bool B>
> +struct derived2 : base2 {
> +    int f() noexcept(W<B>::t) override; // { dg-error "looser exception specification" }
> +};
> +
> +void
> +g ()
> +{
> +  derived<int> d1;
> +  derived2<false> d2; // { dg-message "required from here" }
> +  derived2<true> d3;
> +}
> 
> base-commit: b3b3bd250f0a7c22b7d46d3522c8b94c6a35d22a
> prerequisite-patch-id: 3beddc8cae6ef7f28cd7eac7240d5f4dad08e5f7


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH v2] c++: wrong looser excep spec for dep noexcept [PR113158]
  2024-02-16 20:58 ` Jason Merrill
@ 2024-02-16 21:33   ` Marek Polacek
  2024-02-16 21:39     ` Patrick Palka
  0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2024-02-16 21:33 UTC (permalink / raw)
  To: Jason Merrill; +Cc: GCC Patches

On Fri, Feb 16, 2024 at 03:58:02PM -0500, Jason Merrill wrote:
> On 2/15/24 17:17, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > 
> > By the ??? below I mean that maybe_instantiate_noexcept could return
> > a tristate, and then maybe_check_overriding_exception_spec could check
> > 
> >    if (maybe_instantiate_noexcept ().is_unknown ())
> >      return true;
> > 
> > and we don't have to add any new checks to maybe_check_o_e_spec.
> > 
> > -- >8 --
> > Here we find ourselves in maybe_check_overriding_exception_spec in
> > a template context where we can't instantiate a dependent noexcept.
> > That's OK, but we have to defer the checking otherwise we give wrong
> > errors.
> > 
> > 	PR c++/113158
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	* search.cc (maybe_check_overriding_exception_spec): Defer checking
> > 	when a noexcept couldn't be instantiated.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > 	* g++.dg/cpp0x/noexcept83.C: New test.
> > ---
> >   gcc/cp/search.cc                        |  7 +++++
> >   gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
> >   2 files changed, 44 insertions(+)
> >   create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> > 
> > diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> > index c948839dc53..73d254d6b84 100644
> > --- a/gcc/cp/search.cc
> > +++ b/gcc/cp/search.cc
> > @@ -1975,6 +1975,13 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
> >         || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
> >       return true;
> > +  /* We also have to defer checking when we're in a template and couldn't
> > +     instantiate the noexcept yet.
> > +     ??? maybe_instantiate_noexcept already checked these.  Use tristate?  */
> > +  if (type_dependent_expression_p (base_throw)
> > +      || type_dependent_expression_p (over_throw))
> 
> I think we also want to avoid comparing value-dependent expressions, but
> actually checking either one seems like more work than needed here; I'd
> think we want to defer in a template if the specifiers aren't both exactly
> true or false.

Yeah, that'll work too.  So like this?

Bootstrap/regtest running; dg.exp passed.  FWIW, the new check only
triggered on the new test.

Thanks,

-- >8 --
Here we find ourselves in maybe_check_overriding_exception_spec in
a template context where we can't instantiate a dependent noexcept.
That's OK, but we have to defer the checking otherwise we give wrong
errors.

	PR c++/113158

gcc/cp/ChangeLog:

	* search.cc (maybe_check_overriding_exception_spec): Defer checking
	when a noexcept couldn't be instantiated & evaluated to false/true.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/noexcept83.C: New test.
---
 gcc/cp/search.cc                        | 11 ++++++++
 gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C

diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index c948839dc53..554ba71f4a7 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -1975,6 +1975,17 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
       || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
     return true;
 
+  /* We also have to defer checking when we're in a template and couldn't
+     instantiate & evaluate the noexcept to true/false.  */
+  if (processing_template_decl)
+    if ((base_throw
+	 && (base_throw != noexcept_true_spec
+	     || base_throw != noexcept_false_spec))
+	|| (over_throw
+	    && (over_throw != noexcept_true_spec
+		|| over_throw != noexcept_false_spec)))
+      return true;
+
   if (!comp_except_specs (base_throw, over_throw, ce_derived))
     {
       auto_diagnostic_group d;
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
new file mode 100644
index 00000000000..47832bbb44d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
@@ -0,0 +1,37 @@
+// PR c++/113158
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct V {
+  static constexpr bool t = false;
+};
+struct base {
+    virtual int f() = 0;
+};
+
+template<typename T>
+struct derived : base {
+    int f() noexcept(V<T>::t) override;
+};
+
+struct base2 {
+    virtual int f() noexcept = 0;
+};
+
+template<bool B>
+struct W {
+  static constexpr bool t = B;
+};
+
+template<bool B>
+struct derived2 : base2 {
+    int f() noexcept(W<B>::t) override; // { dg-error "looser exception specification" }
+};
+
+void
+g ()
+{
+  derived<int> d1;
+  derived2<false> d2; // { dg-message "required from here" }
+  derived2<true> d3;
+}

base-commit: 40b8d7b73ad2ce498758c1d9bd38ebdbc26b918b
-- 
2.43.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH v2] c++: wrong looser excep spec for dep noexcept [PR113158]
  2024-02-16 21:33   ` [PATCH v2] " Marek Polacek
@ 2024-02-16 21:39     ` Patrick Palka
  2024-02-16 22:06       ` [PATCH v3] " Marek Polacek
  0 siblings, 1 reply; 6+ messages in thread
From: Patrick Palka @ 2024-02-16 21:39 UTC (permalink / raw)
  To: Marek Polacek; +Cc: Jason Merrill, GCC Patches

On Fri, 16 Feb 2024, Marek Polacek wrote:

> On Fri, Feb 16, 2024 at 03:58:02PM -0500, Jason Merrill wrote:
> > On 2/15/24 17:17, Marek Polacek wrote:
> > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > > 
> > > By the ??? below I mean that maybe_instantiate_noexcept could return
> > > a tristate, and then maybe_check_overriding_exception_spec could check
> > > 
> > >    if (maybe_instantiate_noexcept ().is_unknown ())
> > >      return true;
> > > 
> > > and we don't have to add any new checks to maybe_check_o_e_spec.
> > > 
> > > -- >8 --
> > > Here we find ourselves in maybe_check_overriding_exception_spec in
> > > a template context where we can't instantiate a dependent noexcept.
> > > That's OK, but we have to defer the checking otherwise we give wrong
> > > errors.
> > > 
> > > 	PR c++/113158
> > > 
> > > gcc/cp/ChangeLog:
> > > 
> > > 	* search.cc (maybe_check_overriding_exception_spec): Defer checking
> > > 	when a noexcept couldn't be instantiated.
> > > 
> > > gcc/testsuite/ChangeLog:
> > > 
> > > 	* g++.dg/cpp0x/noexcept83.C: New test.
> > > ---
> > >   gcc/cp/search.cc                        |  7 +++++
> > >   gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
> > >   2 files changed, 44 insertions(+)
> > >   create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> > > 
> > > diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> > > index c948839dc53..73d254d6b84 100644
> > > --- a/gcc/cp/search.cc
> > > +++ b/gcc/cp/search.cc
> > > @@ -1975,6 +1975,13 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
> > >         || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
> > >       return true;
> > > +  /* We also have to defer checking when we're in a template and couldn't
> > > +     instantiate the noexcept yet.
> > > +     ??? maybe_instantiate_noexcept already checked these.  Use tristate?  */
> > > +  if (type_dependent_expression_p (base_throw)
> > > +      || type_dependent_expression_p (over_throw))
> > 
> > I think we also want to avoid comparing value-dependent expressions, but
> > actually checking either one seems like more work than needed here; I'd
> > think we want to defer in a template if the specifiers aren't both exactly
> > true or false.
> 
> Yeah, that'll work too.  So like this?
> 
> Bootstrap/regtest running; dg.exp passed.  FWIW, the new check only
> triggered on the new test.
> 
> Thanks,
> 
> -- >8 --
> Here we find ourselves in maybe_check_overriding_exception_spec in
> a template context where we can't instantiate a dependent noexcept.
> That's OK, but we have to defer the checking otherwise we give wrong
> errors.
> 
> 	PR c++/113158
> 
> gcc/cp/ChangeLog:
> 
> 	* search.cc (maybe_check_overriding_exception_spec): Defer checking
> 	when a noexcept couldn't be instantiated & evaluated to false/true.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp0x/noexcept83.C: New test.
> ---
>  gcc/cp/search.cc                        | 11 ++++++++
>  gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
>  2 files changed, 48 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> 
> diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> index c948839dc53..554ba71f4a7 100644
> --- a/gcc/cp/search.cc
> +++ b/gcc/cp/search.cc
> @@ -1975,6 +1975,17 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
>        || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
>      return true;
>  
> +  /* We also have to defer checking when we're in a template and couldn't
> +     instantiate & evaluate the noexcept to true/false.  */
> +  if (processing_template_decl)
> +    if ((base_throw
> +	 && (base_throw != noexcept_true_spec
> +	     || base_throw != noexcept_false_spec))

Shouldn't these innermost || be &&?

> +	|| (over_throw
> +	    && (over_throw != noexcept_true_spec
> +		|| over_throw != noexcept_false_spec)))

> +      return true;
> +
>    if (!comp_except_specs (base_throw, over_throw, ce_derived))
>      {
>        auto_diagnostic_group d;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> new file mode 100644
> index 00000000000..47832bbb44d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> @@ -0,0 +1,37 @@
> +// PR c++/113158
> +// { dg-do compile { target c++11 } }
> +
> +template<typename T>
> +struct V {
> +  static constexpr bool t = false;
> +};
> +struct base {
> +    virtual int f() = 0;
> +};
> +
> +template<typename T>
> +struct derived : base {
> +    int f() noexcept(V<T>::t) override;
> +};
> +
> +struct base2 {
> +    virtual int f() noexcept = 0;
> +};
> +
> +template<bool B>
> +struct W {
> +  static constexpr bool t = B;
> +};
> +
> +template<bool B>
> +struct derived2 : base2 {
> +    int f() noexcept(W<B>::t) override; // { dg-error "looser exception specification" }
> +};
> +
> +void
> +g ()
> +{
> +  derived<int> d1;
> +  derived2<false> d2; // { dg-message "required from here" }
> +  derived2<true> d3;
> +}
> 
> base-commit: 40b8d7b73ad2ce498758c1d9bd38ebdbc26b918b
> -- 
> 2.43.2
> 
> 


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH v3] c++: wrong looser excep spec for dep noexcept [PR113158]
  2024-02-16 21:39     ` Patrick Palka
@ 2024-02-16 22:06       ` Marek Polacek
  2024-02-17 10:07         ` Jason Merrill
  0 siblings, 1 reply; 6+ messages in thread
From: Marek Polacek @ 2024-02-16 22:06 UTC (permalink / raw)
  To: Patrick Palka; +Cc: Jason Merrill, GCC Patches

On Fri, Feb 16, 2024 at 04:39:47PM -0500, Patrick Palka wrote:
> On Fri, 16 Feb 2024, Marek Polacek wrote:
> > +  /* We also have to defer checking when we're in a template and couldn't
> > +     instantiate & evaluate the noexcept to true/false.  */
> > +  if (processing_template_decl)
> > +    if ((base_throw
> > +	 && (base_throw != noexcept_true_spec
> > +	     || base_throw != noexcept_false_spec))
> 
> Shouldn't these innermost || be &&?

D'oh, yes, what a dumb mistake.  But that shows that we could also just
always return true in a template ;).

Fixed.  dg.exp passed so far.

-- >8 --
Here we find ourselves in maybe_check_overriding_exception_spec in
a template context where we can't instantiate a dependent noexcept.
That's OK, but we have to defer the checking otherwise we give wrong
errors.

	PR c++/113158

gcc/cp/ChangeLog:

	* search.cc (maybe_check_overriding_exception_spec): Defer checking
	when a noexcept couldn't be instantiated & evaluated to false/true.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/noexcept83.C: New test.
---
 gcc/cp/search.cc                        | 11 ++++++++
 gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C

diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
index c948839dc53..827f48e8604 100644
--- a/gcc/cp/search.cc
+++ b/gcc/cp/search.cc
@@ -1975,6 +1975,17 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
       || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
     return true;
 
+  /* We also have to defer checking when we're in a template and couldn't
+     instantiate & evaluate the noexcept to true/false.  */
+  if (processing_template_decl)
+    if ((base_throw
+	 && base_throw != noexcept_true_spec
+	 && base_throw != noexcept_false_spec)
+	|| (over_throw
+	    && over_throw != noexcept_true_spec
+	    && over_throw != noexcept_false_spec))
+      return true;
+
   if (!comp_except_specs (base_throw, over_throw, ce_derived))
     {
       auto_diagnostic_group d;
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
new file mode 100644
index 00000000000..47832bbb44d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
@@ -0,0 +1,37 @@
+// PR c++/113158
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct V {
+  static constexpr bool t = false;
+};
+struct base {
+    virtual int f() = 0;
+};
+
+template<typename T>
+struct derived : base {
+    int f() noexcept(V<T>::t) override;
+};
+
+struct base2 {
+    virtual int f() noexcept = 0;
+};
+
+template<bool B>
+struct W {
+  static constexpr bool t = B;
+};
+
+template<bool B>
+struct derived2 : base2 {
+    int f() noexcept(W<B>::t) override; // { dg-error "looser exception specification" }
+};
+
+void
+g ()
+{
+  derived<int> d1;
+  derived2<false> d2; // { dg-message "required from here" }
+  derived2<true> d3;
+}

base-commit: cd503b0616462445381a8232fb753239d319af76
-- 
2.43.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH v3] c++: wrong looser excep spec for dep noexcept [PR113158]
  2024-02-16 22:06       ` [PATCH v3] " Marek Polacek
@ 2024-02-17 10:07         ` Jason Merrill
  0 siblings, 0 replies; 6+ messages in thread
From: Jason Merrill @ 2024-02-17 10:07 UTC (permalink / raw)
  To: Marek Polacek, Patrick Palka; +Cc: GCC Patches

On 2/16/24 17:06, Marek Polacek wrote:
> On Fri, Feb 16, 2024 at 04:39:47PM -0500, Patrick Palka wrote:
>> On Fri, 16 Feb 2024, Marek Polacek wrote:
>>> +  /* We also have to defer checking when we're in a template and couldn't
>>> +     instantiate & evaluate the noexcept to true/false.  */
>>> +  if (processing_template_decl)
>>> +    if ((base_throw
>>> +	 && (base_throw != noexcept_true_spec
>>> +	     || base_throw != noexcept_false_spec))
>>
>> Shouldn't these innermost || be &&?
> 
> D'oh, yes, what a dumb mistake.  But that shows that we could also just
> always return true in a template ;).
> 
> Fixed.  dg.exp passed so far.

OK.

> -- >8 --
> Here we find ourselves in maybe_check_overriding_exception_spec in
> a template context where we can't instantiate a dependent noexcept.
> That's OK, but we have to defer the checking otherwise we give wrong
> errors.
> 
> 	PR c++/113158
> 
> gcc/cp/ChangeLog:
> 
> 	* search.cc (maybe_check_overriding_exception_spec): Defer checking
> 	when a noexcept couldn't be instantiated & evaluated to false/true.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp0x/noexcept83.C: New test.
> ---
>   gcc/cp/search.cc                        | 11 ++++++++
>   gcc/testsuite/g++.dg/cpp0x/noexcept83.C | 37 +++++++++++++++++++++++++
>   2 files changed, 48 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> 
> diff --git a/gcc/cp/search.cc b/gcc/cp/search.cc
> index c948839dc53..827f48e8604 100644
> --- a/gcc/cp/search.cc
> +++ b/gcc/cp/search.cc
> @@ -1975,6 +1975,17 @@ maybe_check_overriding_exception_spec (tree overrider, tree basefn)
>         || UNPARSED_NOEXCEPT_SPEC_P (over_throw))
>       return true;
>   
> +  /* We also have to defer checking when we're in a template and couldn't
> +     instantiate & evaluate the noexcept to true/false.  */
> +  if (processing_template_decl)
> +    if ((base_throw
> +	 && base_throw != noexcept_true_spec
> +	 && base_throw != noexcept_false_spec)
> +	|| (over_throw
> +	    && over_throw != noexcept_true_spec
> +	    && over_throw != noexcept_false_spec))
> +      return true;
> +
>     if (!comp_except_specs (base_throw, over_throw, ce_derived))
>       {
>         auto_diagnostic_group d;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept83.C b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> new file mode 100644
> index 00000000000..47832bbb44d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/noexcept83.C
> @@ -0,0 +1,37 @@
> +// PR c++/113158
> +// { dg-do compile { target c++11 } }
> +
> +template<typename T>
> +struct V {
> +  static constexpr bool t = false;
> +};
> +struct base {
> +    virtual int f() = 0;
> +};
> +
> +template<typename T>
> +struct derived : base {
> +    int f() noexcept(V<T>::t) override;
> +};
> +
> +struct base2 {
> +    virtual int f() noexcept = 0;
> +};
> +
> +template<bool B>
> +struct W {
> +  static constexpr bool t = B;
> +};
> +
> +template<bool B>
> +struct derived2 : base2 {
> +    int f() noexcept(W<B>::t) override; // { dg-error "looser exception specification" }
> +};
> +
> +void
> +g ()
> +{
> +  derived<int> d1;
> +  derived2<false> d2; // { dg-message "required from here" }
> +  derived2<true> d3;
> +}
> 
> base-commit: cd503b0616462445381a8232fb753239d319af76


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2024-02-17 10:07 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-02-15 22:17 [PATCH] c++: wrong looser excep spec for dep noexcept [PR113158] Marek Polacek
2024-02-16 20:58 ` Jason Merrill
2024-02-16 21:33   ` [PATCH v2] " Marek Polacek
2024-02-16 21:39     ` Patrick Palka
2024-02-16 22:06       ` [PATCH v3] " Marek Polacek
2024-02-17 10:07         ` Jason Merrill

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