https://gcc.gnu.org/g:40f0f6ab75a391906bed40cbdc098b0df3a91af7
commit r15-6736-g40f0f6ab75a391906bed40cbdc098b0df3a91af7
Author: Patrick Palka <ppa...@redhat.com>
Date: Thu Jan 9 10:49:45 2025 -0500
c++: template-id dependence wrt local static arg [PR117792]
Here we end up ICEing at instantiation time for the call to
f<local_static> ultimately because we wrongly consider the call to be
non-dependent, and so we specialize f ahead of time and then get
confused when fully substituting this specialization.
The call is dependent due to [temp.dep.temp]/3 and we miss that because
function template-id arguments aren't coerced until overload resolution,
and so the local static template argument lacks an implicit cast to
reference type that value_dependent_expression_p looks for before
considering dependence of the address. Other kinds of template-ids aren't
affected since they're coerced ahead of time.
So when considering dependence of a function template-id, we need to
conservatively consider dependence of the address of each argument (if
applicable).
PR c++/117792
gcc/cp/ChangeLog:
* pt.cc (type_dependent_expression_p): Consider the dependence
of the address of each template argument of a function
template-id.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/nontype7.C: New test.
Reviewed-by: Jason Merrill <ja...@redhat.com>
Diff:
---
gcc/cp/pt.cc | 10 ++++++++--
gcc/testsuite/g++.dg/cpp1z/nontype7.C | 22 ++++++++++++++++++++++
2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index dfaa8906a2cf..081285ef7209 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -29034,9 +29034,15 @@ type_dependent_expression_p (tree expression)
if (TREE_CODE (expression) == TEMPLATE_ID_EXPR)
{
- if (any_dependent_template_arguments_p
- (TREE_OPERAND (expression, 1)))
+ tree args = TREE_OPERAND (expression, 1);
+ if (any_dependent_template_arguments_p (args))
return true;
+ /* Arguments of a function template-id aren't necessarily coerced
+ yet so we must conservatively assume that the address (and not
+ just value) of the argument matters as per [temp.dep.temp]/3. */
+ for (tree arg : tree_vec_range (args))
+ if (has_value_dependent_address (arg))
+ return true;
expression = TREE_OPERAND (expression, 0);
if (identifier_p (expression))
return true;
diff --git a/gcc/testsuite/g++.dg/cpp1z/nontype7.C
b/gcc/testsuite/g++.dg/cpp1z/nontype7.C
new file mode 100644
index 000000000000..f103d5a6888e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/nontype7.C
@@ -0,0 +1,22 @@
+// PR c++/117792
+// { dg-do compile { target c++17 } }
+
+template<const int& N, class T>
+void f(T) { }
+
+template<int N, class T>
+void f(...) = delete;
+
+template<const int& N> int v;
+
+template<const int& N> struct A { };
+
+template<class T>
+void g() {
+ static constexpr int local_static = 0;
+ auto x = v<local_static>; // OK
+ A<local_static> y; // OK
+ f<local_static>(0); // ICE
+}
+
+template void g<int>();
