add test for rust-lang#83993

Fixes rust-lang#83993

Author: matthiaskrgr

tests/ui/const-generics/adt_const_params/index-oob-ice-83993.rs

@@ -0,0 +1,20 @@
+// issue: rust-lang/rust/#83993
+
+#![feature(adt_const_params)]
+//~^ WARN the feature `adt_const_params` is incomplete and may not be safe to use and/or cause compiler crashes
+fn bug<'a>()
+where
+    for<'b> [(); {
+        let x: &'b ();
+        //~^ ERROR generic parameters may not be used in const operations
+        //~| WARN unused variable: `x`
+        0
+    }]:
+{}
+
+fn bad() where for<'b> [();{let _:&'b (); 0}]: Sized { }
+//~^ ERROR generic parameters may not be used in const operations
+fn good() where for<'b> [();{0}]: Sized { }
+//~^ WARN unnecessary braces around const expression
+
+pub fn main() {}