also lint against fn ptr and raw ptr nested inside the const

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -239,19 +239,15 @@ impl<'tcx> ConstToPat<'tcx> {
  }
  }
  } else if !self.saw_const_match_lint.get() {
- match cv.ty().kind() {
- ty::RawPtr(..) if have_valtree => {
- // This is a good raw pointer, it was accepted by valtree construction.
- }
- ty::FnPtr(..) | ty::RawPtr(..) => {
- self.tcx().emit_spanned_lint(
- lint::builtin::POINTER_STRUCTURAL_MATCH,
- self.id,
- self.span,
- PointerPattern,
- );
- }
- _ => {}
+ if !have_valtree {
+ // The only way valtree construction can fail without the structural match
+ // checker finding a violation is if there is a pointer somewhere.
+ self.tcx().emit_spanned_lint(
+ lint::builtin::POINTER_STRUCTURAL_MATCH,
+ self.id,
+ self.span,
+ PointerPattern,
+ );
  }
  }
 

tests/ui/consts/const_in_pattern/issue-34784-match-on-non-int-raw-ptr.rs

@@ -1,6 +1,9 @@
 #![deny(pointer_structural_match)]
 #![allow(dead_code)]
+
 const C: *const u8 = &0;
+// Make sure we also find pointers nested in other types.
+const C_INNER: (*const u8, u8) = (C, 0);
 
 fn foo(x: *const u8) {
  match x {
@@ -10,6 +13,14 @@ fn foo(x: *const u8) {
  }
 }
 
+fn foo2(x: *const u8) {
+ match (x, 1) {
+ C_INNER => {} //~ERROR: behave unpredictably
+ //~| previously accepted
+ _ => {}
+ }
+}
+
 const D: *const [u8; 4] = b"abcd";
 
 fn main() {

tests/ui/consts/const_in_pattern/issue-34784-match-on-non-int-raw-ptr.stderr

@@ -1,5 +1,5 @@
 error: 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/issue-34784-match-on-non-int-raw-ptr.rs:7:9
+ --> $DIR/issue-34784-match-on-non-int-raw-ptr.rs:10:9
  |
 LL | C => {}
  | ^
@@ -13,13 +13,22 @@ LL | #![deny(pointer_structural_match)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: 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/issue-34784-match-on-non-int-raw-ptr.rs:17:9
+ --> $DIR/issue-34784-match-on-non-int-raw-ptr.rs:18:9
+ |
+LL | C_INNER => {}
+ | ^^^^^^^
+ |
+ = 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 #62411 <https://github.com/rust-lang/rust/issues/70861>
+
+error: 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/issue-34784-match-on-non-int-raw-ptr.rs:28:9
  |
 LL | D => {}
  | ^
  |
  = 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 #62411 <https://github.com/rust-lang/rust/issues/70861>
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 

tests/ui/rfcs/rfc-1445-restrict-constants-in-patterns/issue-63479-match-fnptr.rs

@@ -26,15 +26,22 @@ fn my_fn(_args: &[A]) {
 }
 
 const TEST: Fn = my_fn;
+const TEST2: (Fn, u8) = (TEST, 0);
 
 struct B(Fn);
 
 fn main() {
  let s = B(my_fn);
  match s {
  B(TEST) => println!("matched"),
-  //~^ WARN behave unpredictably
+ //~^ WARN behave unpredictably
  //~| WARN this was previously accepted by the compiler but is being phased out
  _ => panic!("didn't match")
  };
+ match (s.0, 0) {
+ TEST2 => println!("matched"),
+ //~^ WARN behave unpredictably
+ //~| WARN this was previously accepted by the compiler but is being phased out
+ _ => panic!("didn't match")
+ }
 }

tests/ui/rfcs/rfc-1445-restrict-constants-in-patterns/issue-63479-match-fnptr.stderr

@@ -1,5 +1,5 @@
 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/issue-63479-match-fnptr.rs:35:7
+ --> $DIR/issue-63479-match-fnptr.rs:36:7
  |
 LL | B(TEST) => println!("matched"),
  | ^^^^
@@ -12,5 +12,14 @@ note: the lint level is defined here
 LL | #![warn(pointer_structural_match)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^
 
-warning: 1 warning emitted
+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/issue-63479-match-fnptr.rs:42:5
+ |
+LL | TEST2 => println!("matched"),
+ | ^^^^^
+ |
+ = 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 #62411 <https://github.com/rust-lang/rust/issues/70861>
+
+warning: 2 warnings emitted