[v3] c++: wrong looser excep spec for dep noexcept [PR113158]
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Commit Message
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
base-commit: cd503b0616462445381a8232fb753239d319af76
Comments
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
@@ -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;
new file mode 100644
@@ -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;
+}