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

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