add test for ICE "raw ptr comparison should already be caught in the trait system" #105047

Fixes #105047

Author: matthiaskrgr

tests/ui/raw-ref-op/const-eval-compare-ice-105047.rs

@@ -0,0 +1,15 @@
+// issue: rust-lang/rust#105047
+// ICE raw ptr comparison should already be caught in the trait systems
+
+#![feature(raw_ref_op)]
+
+const RCZ: *const i32 = &raw const *&0;
+
+const fn f() {
+    if let RCZ = &raw const *&0 { }
+    //~^ WARN function pointers and raw pointers not derived from integers in patterns
+    //~^^ ERROR pointers cannot be reliably compared during const eval
+    //~^^^ WARN this was previously accepted by the compiler but is being phased out
+}
+
+fn main() {}

tests/ui/raw-ref-op/const-eval-compare-ice-105047.stderr

@@ -0,0 +1,31 @@
+warning: function pointers and raw pointers not derived from integers in patterns behave unpredictably and should not be relied upon. See https://github.com/rust-lang/rust/issues/70861 for details.
+  --> $DIR/const-eval-compare-ice-105047.rs:9:12
+   |
+LL |     if let RCZ = &raw const *&0 { }
+   |            ^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #120362 <https://github.com/rust-lang/rust/issues/120362>
+   = note: `#[warn(pointer_structural_match)]` on by default
+
+error: pointers cannot be reliably compared during const eval
+  --> $DIR/const-eval-compare-ice-105047.rs:9:12
+   |
+LL |     if let RCZ = &raw const *&0 { }
+   |            ^^^
+   |
+   = note: see issue #53020 <https://github.com/rust-lang/rust/issues/53020> for more information
+
+error: aborting due to 1 previous error; 1 warning emitted
+
+Future incompatibility report: Future breakage diagnostic:
+warning: function pointers and raw pointers not derived from integers in patterns behave unpredictably and should not be relied upon. See https://github.com/rust-lang/rust/issues/70861 for details.
+  --> $DIR/const-eval-compare-ice-105047.rs:9:12
+   |
+LL |     if let RCZ = &raw const *&0 { }
+   |            ^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #120362 <https://github.com/rust-lang/rust/issues/120362>
+   = note: `#[warn(pointer_structural_match)]` on by default
+