[pushed] c++: Add test for C++23 auto(x)

[Marek Polacek via Gcc-patches]

I was curious if our auto(x) works in contexts like bit-field width
and similar.  It appears that it does.  Might be worth adding a test
for it.

Tested x86_64-pc-linux-gnu, applying to trunk.

gcc/testsuite/ChangeLog:

        * g++.dg/cpp23/auto-fncast10.C: New test.
---
 gcc/testsuite/g++.dg/cpp23/auto-fncast10.C | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/cpp23/auto-fncast10.C

diff --git a/gcc/testsuite/g++.dg/cpp23/auto-fncast10.C 
b/gcc/testsuite/g++.dg/cpp23/auto-fncast10.C
new file mode 100644
index 00000000000..29c779b2cb4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/auto-fncast10.C
@@ -0,0 +1,18 @@
+// { dg-do compile { target c++23 } }
+
+struct S {
+  int i1 : auto(12);
+  int i2 : auto{12};
+  static constexpr auto x = auto(12);
+  static constexpr auto y = auto{12};
+};
+
+struct R {
+  int i;
+};
+
+static constexpr R r1 = { auto(23) };
+static constexpr R r2 = { auto{23} };
+enum E { X = auto(12), Y = auto{1u} };
+static_assert (auto(true));
+static_assert (auto{true});

base-commit: 982a2c9b7866558039df61b0596caad57c94c8c4
-- 
2.33.1