Make disjoint_capture_migration an edition lint.

compiler/rustc_lint_defs/src/builtin.rs

@@ -3001,8 +3001,7 @@ declare_lint! {
 
 declare_lint! {
     /// The `disjoint_capture_migration` lint detects variables that aren't completely
-    /// captured when the feature `capture_disjoint_fields` is enabled and it affects the Drop
-    /// order of at least one path starting at this variable.
+    /// captured in Rust 2021 and affect the Drop order of at least one path starting at this variable.
     /// It can also detect when a variable implements a trait, but one of its field does not and
     /// the field is captured by a closure and used with the assumption that said field implements
     /// the same trait as the root variable.
@@ -3039,16 +3038,16 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// In the above example `p.y` will be dropped at the end of `f` instead of with `c` if
-    /// the feature `capture_disjoint_fields` is enabled.
+    /// In the above example, `p.y` will be dropped at the end of `f` instead of
+    /// with `c` in Rust 2021.
     ///
     /// ### Example of auto-trait
     ///
     /// ```rust,compile_fail
     /// #![deny(disjoint_capture_migration)]
     /// use std::thread;
     ///
-    /// struct Pointer (*mut i32);
+    /// struct Pointer(*mut i32);
     /// unsafe impl Send for Pointer {}
     ///
     /// fn main() {
@@ -3064,12 +3063,16 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// In the above example `fptr.0` is captured when feature `capture_disjoint_fields` is enabled.
+    /// In the above example, only `fptr.0` is captured in Rust 2021.
     /// The field is of type *mut i32 which doesn't implement Send, making the code invalid as the
     /// field cannot be sent between thread safely.
     pub DISJOINT_CAPTURE_MIGRATION,
     Allow,
-    "Drop reorder and auto traits error because of `capture_disjoint_fields`"
+    "detects closures affected by Rust 2021 changes",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::EditionSemanticsChange(Edition::Edition2021),
+        explain_reason: false,
+    };
 }
 
 declare_lint_pass!(UnusedDocComment => [UNUSED_DOC_COMMENTS]);

compiler/rustc_lint_defs/src/lib.rs

@@ -145,6 +145,11 @@ pub struct FutureIncompatibleInfo {
     /// The reason for the lint used by diagnostics to provide
     /// the right help message
     pub reason: FutureIncompatibilityReason,
+    /// Whether to explain the reason to the user.
+    ///
+    /// Set to false for lints that already include a more detailed
+    /// explanation.
+    pub explain_reason: bool,
     /// Information about a future breakage, which will
     /// be emitted in JSON messages to be displayed by Cargo
     /// for upstream deps
@@ -185,6 +190,7 @@ impl FutureIncompatibleInfo {
         FutureIncompatibleInfo {
             reference: "",
             reason: FutureIncompatibilityReason::FutureReleaseError,
+            explain_reason: true,
             future_breakage: None,
         }
     }

compiler/rustc_middle/src/lint.rs

@@ -398,9 +398,14 @@ pub fn struct_lint_level<'s, 'd>(
                  it will become a hard error in a future release!"
                     .to_owned()
             };
-            let citation = format!("for more information, see {}", future_incompatible.reference);
-            err.warn(&explanation);
-            err.note(&citation);
+            if future_incompatible.explain_reason {
+                err.warn(&explanation);
+            }
+            if !future_incompatible.reference.is_empty() {
+                let citation =
+                    format!("for more information, see {}", future_incompatible.reference);
+                err.note(&citation);
+            }
         }
 
         // Finally, run `decorate`. This function is also responsible for emitting the diagnostic.

compiler/rustc_typeck/src/check/upvar.rs

@@ -494,11 +494,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 |lint| {
                     let mut diagnostics_builder = lint.build(
                         format!(
-                            "{} affected for closure because of `capture_disjoint_fields`",
+                            "{} will change in Rust 2021",
                             reasons
                         )
                         .as_str(),
                     );
+                    diagnostics_builder.note("for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>");
                     let closure_body_span = self.tcx.hir().span(body_id.hir_id);
                     let (sugg, app) =
                         match self.tcx.sess.source_map().span_to_snippet(closure_body_span) {

src/test/ui/closures/2229_closure_analysis/migrations/auto_traits.fixed

@@ -11,7 +11,7 @@ fn test_send_trait() {
     let mut f = 10;
     let fptr = SendPointer(&mut f as *mut i32);
     thread::spawn(move || { let _ = &fptr; unsafe {
-        //~^ ERROR: `Send` trait implementation affected for closure because of `capture_disjoint_fields`
+        //~^ ERROR: `Send` trait implementation
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
         *fptr.0 = 20;
     } });
@@ -28,7 +28,7 @@ fn test_sync_trait() {
     let f = CustomInt(&mut f as *mut i32);
     let fptr = SyncPointer(f);
     thread::spawn(move || { let _ = &fptr; unsafe {
-        //~^ ERROR: `Sync`, `Send` trait implementation affected for closure because of `capture_disjoint_fields`
+        //~^ ERROR: `Sync`, `Send` trait implementation
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
         *fptr.0.0 = 20;
     } });
@@ -49,7 +49,7 @@ impl Clone for U {
 fn test_clone_trait() {
     let f = U(S(String::from("Hello World")), T(0));
     let c = || { let _ = &f; 
-        //~^ ERROR: `Clone` trait implementation, and drop order affected for closure because of `capture_disjoint_fields`
+        //~^ ERROR: `Clone` trait implementation, and drop order
         //~| HELP: add a dummy let to cause `f` to be fully captured
         let f_1 = f.1;
         println!("{:?}", f_1.0);

src/test/ui/closures/2229_closure_analysis/migrations/auto_traits.rs

@@ -11,7 +11,7 @@ fn test_send_trait() {
     let mut f = 10;
     let fptr = SendPointer(&mut f as *mut i32);
     thread::spawn(move || unsafe {
-        //~^ ERROR: `Send` trait implementation affected for closure because of `capture_disjoint_fields`
+        //~^ ERROR: `Send` trait implementation
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
         *fptr.0 = 20;
     });
@@ -28,7 +28,7 @@ fn test_sync_trait() {
     let f = CustomInt(&mut f as *mut i32);
     let fptr = SyncPointer(f);
     thread::spawn(move || unsafe {
-        //~^ ERROR: `Sync`, `Send` trait implementation affected for closure because of `capture_disjoint_fields`
+        //~^ ERROR: `Sync`, `Send` trait implementation
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
         *fptr.0.0 = 20;
     });
@@ -49,7 +49,7 @@ impl Clone for U {
 fn test_clone_trait() {
     let f = U(S(String::from("Hello World")), T(0));
     let c = || {
-        //~^ ERROR: `Clone` trait implementation, and drop order affected for closure because of `capture_disjoint_fields`
+        //~^ ERROR: `Clone` trait implementation, and drop order
         //~| HELP: add a dummy let to cause `f` to be fully captured
         let f_1 = f.1;
         println!("{:?}", f_1.0);

src/test/ui/closures/2229_closure_analysis/migrations/auto_traits.stderr

@@ -1,4 +1,4 @@
-error: `Send` trait implementation affected for closure because of `capture_disjoint_fields`
+error: `Send` trait implementation will change in Rust 2021
   --> $DIR/auto_traits.rs:13:19
    |
 LL |       thread::spawn(move || unsafe {
@@ -14,6 +14,7 @@ note: the lint level is defined here
    |
 LL | #![deny(disjoint_capture_migration)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>
 help: add a dummy let to cause `fptr` to be fully captured
    |
 LL |     thread::spawn(move || { let _ = &fptr; unsafe {
@@ -23,7 +24,7 @@ LL |         *fptr.0 = 20;
 LL |     } });
    |
 
-error: `Sync`, `Send` trait implementation affected for closure because of `capture_disjoint_fields`
+error: `Sync`, `Send` trait implementation will change in Rust 2021
   --> $DIR/auto_traits.rs:30:19
    |
 LL |       thread::spawn(move || unsafe {
@@ -34,6 +35,7 @@ LL | |         *fptr.0.0 = 20;
 LL | |     });
    | |_____^
    |
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>
 help: add a dummy let to cause `fptr` to be fully captured
    |
 LL |     thread::spawn(move || { let _ = &fptr; unsafe {
@@ -43,7 +45,7 @@ LL |         *fptr.0.0 = 20;
 LL |     } });
    |
 
-error: `Clone` trait implementation, and drop order affected for closure because of `capture_disjoint_fields`
+error: `Clone` trait implementation, and drop order will change in Rust 2021
   --> $DIR/auto_traits.rs:51:13
    |
 LL |       let c = || {
@@ -55,6 +57,7 @@ LL | |         println!("{:?}", f_1.0);
 LL | |     };
    | |_____^
    |
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/disjoint-capture-in-closures.html>
 help: add a dummy let to cause `f` to be fully captured
    |
 LL |     let c = || { let _ = &f; 

src/test/ui/closures/2229_closure_analysis/migrations/insignificant_drop.fixed

@@ -13,7 +13,8 @@ fn test1_all_need_migration() {
     let t2 = (String::new(), String::new());
 
     let c = || { let _ = (&t, &t1, &t2); 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t`, `t1`, `t2` to be fully captured
 
         let _t = t.0;
@@ -32,7 +33,8 @@ fn test2_only_precise_paths_need_migration() {
     let t2 = (String::new(), String::new());
 
     let c = || { let _ = (&t, &t1); 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t`, `t1` to be fully captured
         let _t = t.0;
         let _t1 = t1.0;
@@ -48,7 +50,8 @@ fn test3_only_by_value_need_migration() {
     let t = (String::new(), String::new());
     let t1 = (String::new(), String::new());
     let c = || { let _ = &t; 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
         println!("{}", t1.1);
@@ -66,7 +69,8 @@ fn test4_only_non_copy_types_need_migration() {
     let t1 = (0i32, 0i32);
 
     let c = || { let _ = &t; 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
         let _t1 = t1.0;
@@ -84,7 +88,8 @@ fn test5_only_drop_types_need_migration() {
     let s = S(0i32, 0i32);
 
     let c = || { let _ = &t; 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
         let _s = s.0;
@@ -99,7 +104,8 @@ fn test6_move_closures_non_copy_types_might_need_migration() {
     let t = (String::new(), String::new());
     let t1 = (String::new(), String::new());
     let c = move || { let _ = (&t1, &t); 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t1`, `t` to be fully captured
         println!("{} {}", t1.1, t.1);
     };
@@ -114,7 +120,8 @@ fn test7_drop_non_drop_aggregate_need_migration() {
     let t = (String::new(), String::new(), 0i32);
 
     let c = || { let _ = &t; 
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
     };

src/test/ui/closures/2229_closure_analysis/migrations/insignificant_drop.rs

@@ -13,7 +13,8 @@ fn test1_all_need_migration() {
     let t2 = (String::new(), String::new());
 
     let c = || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t`, `t1`, `t2` to be fully captured
 
         let _t = t.0;
@@ -32,7 +33,8 @@ fn test2_only_precise_paths_need_migration() {
     let t2 = (String::new(), String::new());
 
     let c = || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t`, `t1` to be fully captured
         let _t = t.0;
         let _t1 = t1.0;
@@ -48,7 +50,8 @@ fn test3_only_by_value_need_migration() {
     let t = (String::new(), String::new());
     let t1 = (String::new(), String::new());
     let c = || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
         println!("{}", t1.1);
@@ -66,7 +69,8 @@ fn test4_only_non_copy_types_need_migration() {
     let t1 = (0i32, 0i32);
 
     let c = || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
         let _t1 = t1.0;
@@ -84,7 +88,8 @@ fn test5_only_drop_types_need_migration() {
     let s = S(0i32, 0i32);
 
     let c = || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
         let _s = s.0;
@@ -99,7 +104,8 @@ fn test6_move_closures_non_copy_types_might_need_migration() {
     let t = (String::new(), String::new());
     let t1 = (String::new(), String::new());
     let c = move || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t1`, `t` to be fully captured
         println!("{} {}", t1.1, t.1);
     };
@@ -114,7 +120,8 @@ fn test7_drop_non_drop_aggregate_need_migration() {
     let t = (String::new(), String::new(), 0i32);
 
     let c = || {
-    //~^ ERROR: drop order affected for closure because of `capture_disjoint_fields`
+    //~^ ERROR: drop order
+    //~| NOTE: for more information, see
     //~| HELP: add a dummy let to cause `t` to be fully captured
         let _t = t.0;
     };