Re: [PATCH] c++: direct enum init from type-dep elt [PR112515]

[Jason Merrill]

On 11/14/23 11:35, Patrick Palka wrote:

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
OK for trunk?

OK.

-- >8 --

The NON_DEPENDENT_EXPR removal exposed that is_direct_enum_init may end
up checking convertibility of a type-dependent argument.

        PR c++/112515

gcc/cp/ChangeLog:

        * decl.cc (is_direct_enum_init): Return false if the single
        element is type-dependent.

gcc/testsuite/ChangeLog:

        * g++.dg/template/non-dependent30.C: New test.
---
  gcc/cp/decl.cc                                  | 1 +
  gcc/testsuite/g++.dg/template/non-dependent30.C | 9 +++++++++
  2 files changed, 10 insertions(+)
  create mode 100644 gcc/testsuite/g++.dg/template/non-dependent30.C

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 4a07c7e879b..4be4847810a 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -6614,6 +6614,7 @@ is_direct_enum_init (tree type, tree init)
        && CONSTRUCTOR_NELTS (init) == 1
        /* DR 2374: The single element needs to be implicitly
         convertible to the underlying type of the enum.  */
+      && !type_dependent_expression_p (CONSTRUCTOR_ELT (init, 0)->value)
        && can_convert_arg (ENUM_UNDERLYING_TYPE (type),
                          TREE_TYPE (CONSTRUCTOR_ELT (init, 0)->value),
                          CONSTRUCTOR_ELT (init, 0)->value,
diff --git a/gcc/testsuite/g++.dg/template/non-dependent30.C 
b/gcc/testsuite/g++.dg/template/non-dependent30.C
new file mode 100644
index 00000000000..32d48e44c09
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent30.C
@@ -0,0 +1,9 @@
+// PR c++/112515
+// { dg-do compile { target c++11 } }
+
+enum E : int { };
+
+template<class T>
+E f(T t) {
+  return E{t.e};
+}