Make pointer_structural_match normal and warn

compiler/rustc_lint_defs/src/builtin.rs

@@ -2277,19 +2277,16 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// Previous versions of Rust allowed function pointers and wide raw pointers in patterns.
-    /// While these work in many cases as expected by users, it is possible that due to
-    /// optimizations pointers are "not equal to themselves" or pointers to different functions
-    /// compare as equal during runtime. This is because LLVM optimizations can deduplicate
-    /// functions if their bodies are the same, thus also making pointers to these functions point
-    /// to the same location. Additionally functions may get duplicated if they are instantiated
+    /// Use of function pointers and wide raw pointers in patterns works in many cases as
+    /// expected by users. However, it is possible that due to optimizations pointers are "not equal
+    /// to themselves" or pointers to different functions compare as equal during runtime.
+    /// This is because LLVM optimizations can deduplicate functions if their bodies are the same,
+    /// thus also making pointers to these functions point to the same location.
+    /// Additionally, functions and vtables may get duplicated if they are instantiated
     /// in different crates and not deduplicated again via LTO.
     pub POINTER_STRUCTURAL_MATCH,
-    Allow,
-    "pointers are not structural-match",
-    @future_incompatible = FutureIncompatibleInfo {
-        reference: "issue #62411 <https://github.com/rust-lang/rust/issues/70861>",
-    };
+    Warn,
+    "pointers are not structural-match"
 }
 
 declare_lint! {

library/core/src/marker.rs

@@ -243,6 +243,7 @@ pub trait StructuralPartialEq {
 ///
 /// const CFN: Wrap<fn(&())> = Wrap(higher_order);
 ///
+/// # #[allow(pointer_structural_match)]
 /// fn main() {
 ///     match CFN {
 ///         CFN => {}

tests/ui/consts/const_in_pattern/issue-44333.rs

@@ -1,7 +1,5 @@
 // run-pass
 
-#![warn(pointer_structural_match)]
-
 type Func = fn(usize, usize) -> usize;
 
 fn foo(a: usize, b: usize) -> usize { a + b }
@@ -17,9 +15,7 @@ const BAR: Func = bar;
 fn main() {
     match test(std::env::consts::ARCH.len()) {
         FOO => println!("foo"), //~ WARN pointers in patterns behave unpredictably
-        //~^ WARN will become a hard error
         BAR => println!("bar"), //~ WARN pointers in patterns behave unpredictably
-        //~^ WARN will become a hard error
         _ => unreachable!(),
     }
 }

tests/ui/consts/const_in_pattern/issue-44333.stderr

@@ -1,25 +1,16 @@
 warning: function pointers and unsized pointers in patterns behave unpredictably and should not be relied upon. See https://github.com/rust-lang/rust/issues/70861 for details.
-  --> $DIR/issue-44333.rs:19:9
+  --> $DIR/issue-44333.rs:17:9
    |
 LL |         FOO => println!("foo"),
    |         ^^^
    |
-   = 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>
-note: the lint level is defined here
-  --> $DIR/issue-44333.rs:3:9
-   |
-LL | #![warn(pointer_structural_match)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: `#[warn(pointer_structural_match)]` on by default
 
 warning: function pointers and unsized pointers in patterns behave unpredictably and should not be relied upon. See https://github.com/rust-lang/rust/issues/70861 for details.
-  --> $DIR/issue-44333.rs:21:9
+  --> $DIR/issue-44333.rs:18:9
    |
 LL |         BAR => println!("bar"),
    |         ^^^
-   |
-   = 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
 

tests/ui/consts/issue-34784.rs

@@ -1,6 +1,6 @@
 // run-pass
 
-#![warn(pointer_structural_match)]
+
 #![allow(dead_code)]
 const C: *const u8 = &0;
 

tests/ui/pattern/usefulness/consts-opaque.rs

@@ -2,7 +2,7 @@
 // unnecessary warnings because const_to_pat.rs converts a constant pattern to a wildcard when the
 // constant is not allowed as a pattern. This is an edge case so we may not care to fix it.
 // See also https://github.com/rust-lang/rust/issues/78057
-
+#![allow(pointer_structural_match)]
 #![deny(unreachable_patterns)]
 
 #[derive(PartialEq)]

tests/ui/rfc-1445-restrict-constants-in-patterns/allow-hide-behind-direct-unsafe-ptr-embedded.rs

@@ -3,7 +3,7 @@
 
 // run-pass
 
-#![warn(pointer_structural_match)]
+#![deny(pointer_structural_match)]
 
 struct NoDerive(#[allow(unused_tuple_struct_fields)] i32);
 

tests/ui/rfc-1445-restrict-constants-in-patterns/allow-hide-behind-direct-unsafe-ptr-param.rs

@@ -3,7 +3,7 @@
 
 // run-pass
 
-#![warn(pointer_structural_match)]
+#![deny(pointer_structural_match)]
 
 struct NoDerive(#[allow(unused_tuple_struct_fields)] i32);
 

tests/ui/rfc-1445-restrict-constants-in-patterns/allow-hide-behind-indirect-unsafe-ptr-embedded.rs

@@ -3,7 +3,7 @@
 
 // run-pass
 
-#![warn(pointer_structural_match)]
+#![deny(pointer_structural_match)]
 
 struct NoDerive(#[allow(unused_tuple_struct_fields)] i32);
 

tests/ui/rfc-1445-restrict-constants-in-patterns/allow-hide-behind-indirect-unsafe-ptr-param.rs

@@ -3,7 +3,7 @@
 
 // run-pass
 
-#![warn(pointer_structural_match)]
+#![deny(pointer_structural_match)]
 
 struct NoDerive(#[allow(unused_tuple_struct_fields)] i32);
 

tests/ui/rfc-1445-restrict-constants-in-patterns/fn-ptr-is-structurally-matchable.rs

@@ -3,6 +3,8 @@
 // This file checks that fn ptrs are considered structurally matchable.
 // See also rust-lang/rust#63479.
 
+#![allow(pointer_structural_match)]
+
 fn main() {
     let mut count = 0;
 

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

@@ -5,8 +5,6 @@
 // cover the case this hit; I've since expanded it accordingly, but the
 // experience left me wary of leaving this regression test out.)
 
-#![warn(pointer_structural_match)]
-
 #[derive(Eq)]
 struct A {
   a: i64
@@ -34,7 +32,6 @@ fn main() {
   match s {
     B(TEST) => println!("matched"),
      //~^ WARN pointers in patterns behave unpredictably
-    //~| WARN this was previously accepted by the compiler but is being phased out
     _ => panic!("didn't match")
   };
 }

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

@@ -1,16 +1,10 @@
 warning: function pointers and unsized pointers 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:33:7
    |
 LL |     B(TEST) => 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>
-note: the lint level is defined here
-  --> $DIR/issue-63479-match-fnptr.rs:8:9
-   |
-LL | #![warn(pointer_structural_match)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: `#[warn(pointer_structural_match)]` on by default
 
 warning: 1 warning emitted