Change default visibility of interface members and update docs. (#3381)

* Update behavior around interfaces and docs.

* Update toc

---------

Co-authored-by: Yong He <yhe@nvidia.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/diagnostics/internal-visibility/interface-default-visibility.slang b/tests/diagnostics/internal-visibility/interface-default-visibility.slang
new file mode 100644
index 000000000..79df14143
--- /dev/null
+++ b/tests/diagnostics/internal-visibility/interface-default-visibility.slang
@@ -0,0 +1,14 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+module m;
+
+public interface IFoo
+{
+    void foo(); // Should have public visibility by default.
+}
+
+public struct F : IFoo
+{
+    // CHECK:{{.*}}(13): error 30602:
+    void foo() {};
+}