The fail-fast predicate uses_deducible_template_parms used by
unify_one_argument is neglecting to look inside the noexcept-spec of a
function type, and this causes deduction to fail for the below testcase
since the noexcept-spec is the only part of the type which contains a
deducible template parameter.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
PR c++/80951
gcc/cp/ChangeLog:
* pt.cc (uses_deducible_template_parms): Consider the
noexcept-spec of a function type.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/noexcept-type25.C: New test.
---
gcc/cp/pt.cc | 5 +++++
gcc/testsuite/g++.dg/cpp1z/noexcept-type25.C | 13 +++++++++++++
2 files changed, 18 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/noexcept-type25.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index c7af4712d8b..97d247f6684 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -22398,6 +22398,11 @@ uses_deducible_template_parms (tree type)
for (; parm; parm = TREE_CHAIN (parm))
if (uses_deducible_template_parms (TREE_VALUE (parm)))
return true;
+ if (flag_noexcept_type
+ && TYPE_RAISES_EXCEPTIONS (type)
+ && TREE_PURPOSE (TYPE_RAISES_EXCEPTIONS (type))
+ && deducible_expression (TREE_PURPOSE (TYPE_RAISES_EXCEPTIONS
(type))))
+ return true;
}
return false;
diff --git a/gcc/testsuite/g++.dg/cpp1z/noexcept-type25.C
b/gcc/testsuite/g++.dg/cpp1z/noexcept-type25.C
new file mode 100644
index 00000000000..ef5c8265541
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/noexcept-type25.C
@@ -0,0 +1,13 @@
+// PR c++/80951
+// { dg-do compile { target c++17 } }
+
+void f() noexcept;
+void g();
+
+template<bool E>
+constexpr bool h(void (*)() noexcept(E)) {
+ return E;
+}
+
+static_assert(h(f));
+static_assert(!h(g));
--
2.35.1.46.g38062e73e0
