Add test for issue-71382

Author: JohnTitor

src/test/ui/const-generics/issues/issue-71382.rs

@@ -0,0 +1,24 @@
+#![feature(const_generics)]
+#![allow(incomplete_features)]
+
+struct Test();
+
+fn pass() {
+    println!("Hello, world!");
+}
+
+impl Test {
+    pub fn call_me(&self) {
+        self.test::<pass>();
+    }
+
+    fn test<const FN: fn()>(&self) {
+        //~^ ERROR: using function pointers as const generic parameters is forbidden
+        FN();
+    }
+}
+
+fn main() {
+    let x = Test();
+    x.call_me()
+}

src/test/ui/const-generics/issues/issue-71382.stderr

@@ -0,0 +1,8 @@
+error: using function pointers as const generic parameters is forbidden
+  --> $DIR/issue-71382.rs:15:23
+   |
+LL |     fn test<const FN: fn()>(&self) {
+   |                       ^^^^
+
+error: aborting due to previous error
+