Warn for variables that are no longer captured

src/test/ui/closures/2229_closure_analysis/issue-90465.fixed

@@ -0,0 +1,35 @@
+// run-rustfix
+
+#![deny(rust_2021_incompatible_closure_captures)]
+//~^ NOTE lint level is defined here
+
+fn main() {
+    struct Foo(u32);
+    impl Drop for Foo {
+        fn drop(&mut self) {
+            println!("dropped {}", self.0);
+        }
+    }
+
+    let f0 = Foo(0);
+    let f1 = Foo(1);
+
+    let c0 = move || {
+        let _ = &f0;
+        //~^ ERROR changes to closure capture in Rust 2021 will affect drop order
+        //~| NOTE for more information
+        let _ = f0;
+        //~^ NOTE in Rust 2018, this causes the closure to capture `f0`, but in Rust 2021, it has no effect
+    };
+
+    let c1 = move || {
+        let _ = &f1;
+    };
+
+    println!("dropping 0");
+    drop(c0);
+    println!("dropping 1");
+    drop(c1);
+    println!("dropped all");
+}
+//~^ NOTE in Rust 2018, `f0` is dropped here along with the closure, but in Rust 2021 `f0` is not part of the closure

src/test/ui/closures/2229_closure_analysis/issue-90465.rs

@@ -0,0 +1,34 @@
+// run-rustfix
+
+#![deny(rust_2021_incompatible_closure_captures)]
+//~^ NOTE lint level is defined here
+
+fn main() {
+    struct Foo(u32);
+    impl Drop for Foo {
+        fn drop(&mut self) {
+            println!("dropped {}", self.0);
+        }
+    }
+
+    let f0 = Foo(0);
+    let f1 = Foo(1);
+
+    let c0 = move || {
+        //~^ ERROR changes to closure capture in Rust 2021 will affect drop order
+        //~| NOTE for more information
+        let _ = f0;
+        //~^ NOTE in Rust 2018, this causes the closure to capture `f0`, but in Rust 2021, it has no effect
+    };
+
+    let c1 = move || {
+        let _ = &f1;
+    };
+
+    println!("dropping 0");
+    drop(c0);
+    println!("dropping 1");
+    drop(c1);
+    println!("dropped all");
+}
+//~^ NOTE in Rust 2018, `f0` is dropped here along with the closure, but in Rust 2021 `f0` is not part of the closure

src/test/ui/closures/2229_closure_analysis/issue-90465.stderr

@@ -0,0 +1,26 @@
+error: changes to closure capture in Rust 2021 will affect drop order
+  --> $DIR/issue-90465.rs:17:14
+   |
+LL |     let c0 = move || {
+   |              ^^^^^^^
+...
+LL |         let _ = f0;
+   |                 -- in Rust 2018, this causes the closure to capture `f0`, but in Rust 2021, it has no effect
+...
+LL | }
+   | - in Rust 2018, `f0` is dropped here along with the closure, but in Rust 2021 `f0` is not part of the closure
+   |
+note: the lint level is defined here
+  --> $DIR/issue-90465.rs:3:9
+   |
+LL | #![deny(rust_2021_incompatible_closure_captures)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = 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 `f0` to be fully captured
+   |
+LL ~     let c0 = move || {
+LL +         let _ = &f0;
+   |
+
+error: aborting due to previous error
+

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

@@ -20,7 +20,7 @@ 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 for closure
+        //~^ ERROR: changes to closure capture
         //~| NOTE: in Rust 2018, this closure implements `Send` as `fptr` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr.0` does not implement `Send`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
@@ -40,8 +40,9 @@ 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 for closure
-        //~| NOTE: in Rust 2018, this closure implements `Sync`, `Send` as `fptr` implements `Sync`, `Send`, but in Rust 2021, this closure will no longer implement `Sync`, `Send` as `fptr.0.0` does not implement `Sync`, `Send`
+        //~^ ERROR: changes to closure capture
+        //~| NOTE: in Rust 2018, this closure implements `Sync` as `fptr` implements `Sync`, but in Rust 2021, this closure will no longer implement `Sync` as `fptr.0.0` does not implement `Sync`
+        //~| NOTE: in Rust 2018, this closure implements `Send` as `fptr` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr.0.0` does not implement `Send`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
         *fptr.0.0 = 20;
@@ -65,7 +66,7 @@ fn test_clone_trait() {
     let f = U(S(Foo(0)), T(0));
     let c = || {
         let _ = &f;
-        //~^ ERROR: `Clone` trait implementation for closure and drop order
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect drop order and which traits the closure implements
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f.1` does not implement `Clone`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f` to be fully captured

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

@@ -20,7 +20,7 @@ fn test_send_trait() {
     let mut f = 10;
     let fptr = SendPointer(&mut f as *mut i32);
     thread::spawn(move || unsafe {
-        //~^ ERROR: `Send` trait implementation for closure
+        //~^ ERROR: changes to closure capture
         //~| NOTE: in Rust 2018, this closure implements `Send` as `fptr` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr.0` does not implement `Send`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
@@ -40,8 +40,9 @@ 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 for closure
-        //~| NOTE: in Rust 2018, this closure implements `Sync`, `Send` as `fptr` implements `Sync`, `Send`, but in Rust 2021, this closure will no longer implement `Sync`, `Send` as `fptr.0.0` does not implement `Sync`, `Send`
+        //~^ ERROR: changes to closure capture
+        //~| NOTE: in Rust 2018, this closure implements `Sync` as `fptr` implements `Sync`, but in Rust 2021, this closure will no longer implement `Sync` as `fptr.0.0` does not implement `Sync`
+        //~| NOTE: in Rust 2018, this closure implements `Send` as `fptr` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr.0.0` does not implement `Send`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `fptr` to be fully captured
         *fptr.0.0 = 20;
@@ -64,7 +65,7 @@ impl Clone for U {
 fn test_clone_trait() {
     let f = U(S(Foo(0)), T(0));
     let c = || {
-        //~^ ERROR: `Clone` trait implementation for closure and drop order
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect drop order and which traits the closure implements
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f.1` does not implement `Clone`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f` to be fully captured

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

@@ -1,4 +1,4 @@
-error: changes to closure capture in Rust 2021 will affect `Send` trait implementation for closure
+error: changes to closure capture in Rust 2021 will affect which traits the closure implements
   --> $DIR/auto_traits.rs:22:19
    |
 LL |     thread::spawn(move || unsafe {
@@ -23,11 +23,14 @@ LL |
 LL |         *fptr.0 = 20;
  ...
 
-error: changes to closure capture in Rust 2021 will affect `Sync`, `Send` trait implementation for closure
+error: changes to closure capture in Rust 2021 will affect which traits the closure implements
   --> $DIR/auto_traits.rs:42:19
    |
 LL |     thread::spawn(move || unsafe {
-   |                   ^^^^^^^^^^^^^^ in Rust 2018, this closure implements `Sync`, `Send` as `fptr` implements `Sync`, `Send`, but in Rust 2021, this closure will no longer implement `Sync`, `Send` as `fptr.0.0` does not implement `Sync`, `Send`
+   |                   ^^^^^^^^^^^^^^
+   |                   |
+   |                   in Rust 2018, this closure implements `Sync` as `fptr` implements `Sync`, but in Rust 2021, this closure will no longer implement `Sync` as `fptr.0.0` does not implement `Sync`
+   |                   in Rust 2018, this closure implements `Send` as `fptr` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr.0.0` does not implement `Send`
 ...
 LL |         *fptr.0.0 = 20;
    |         --------- in Rust 2018, this closure captures all of `fptr`, but in Rust 2021, it will only capture `fptr.0.0`
@@ -40,11 +43,11 @@ LL |
 LL |
 LL |
 LL |
-LL |         *fptr.0.0 = 20;
+LL |
  ...
 
-error: changes to closure capture in Rust 2021 will affect `Clone` trait implementation for closure and drop order
-  --> $DIR/auto_traits.rs:66:13
+error: changes to closure capture in Rust 2021 will affect drop order and which traits the closure implements
+  --> $DIR/auto_traits.rs:67:13
    |
 LL |     let c = || {
    |             ^^ in Rust 2018, this closure implements `Clone` as `f` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f.1` does not implement `Clone`

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

@@ -19,8 +19,9 @@ where
     let f = panic::AssertUnwindSafe(f);
     let result = panic::catch_unwind(move || {
         let _ = &f;
-        //~^ ERROR: `UnwindSafe`, `RefUnwindSafe` trait implementation for closure
-        //~| NOTE: in Rust 2018, this closure implements `UnwindSafe`, `RefUnwindSafe` as `f` implements `UnwindSafe`, `RefUnwindSafe`, but in Rust 2021, this closure will no longer implement `UnwindSafe`, `RefUnwindSafe` as `f.0` does not implement `UnwindSafe`, `RefUnwindSafe`
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect which traits the closure implements [rust_2021_incompatible_closure_captures]
+        //~| NOTE: in Rust 2018, this closure implements `UnwindSafe` as `f` implements `UnwindSafe`, but in Rust 2021, this closure will no longer implement `UnwindSafe` as `f.0` does not implement `UnwindSafe`
+        //~| NOTE: in Rust 2018, this closure implements `RefUnwindSafe` as `f` implements `RefUnwindSafe`, but in Rust 2021, this closure will no longer implement `RefUnwindSafe` as `f.0` does not implement `RefUnwindSafe`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f` to be fully captured
         f.0()

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

@@ -18,8 +18,9 @@ where
 {
     let f = panic::AssertUnwindSafe(f);
     let result = panic::catch_unwind(move || {
-        //~^ ERROR: `UnwindSafe`, `RefUnwindSafe` trait implementation for closure
-        //~| NOTE: in Rust 2018, this closure implements `UnwindSafe`, `RefUnwindSafe` as `f` implements `UnwindSafe`, `RefUnwindSafe`, but in Rust 2021, this closure will no longer implement `UnwindSafe`, `RefUnwindSafe` as `f.0` does not implement `UnwindSafe`, `RefUnwindSafe`
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect which traits the closure implements [rust_2021_incompatible_closure_captures]
+        //~| NOTE: in Rust 2018, this closure implements `UnwindSafe` as `f` implements `UnwindSafe`, but in Rust 2021, this closure will no longer implement `UnwindSafe` as `f.0` does not implement `UnwindSafe`
+        //~| NOTE: in Rust 2018, this closure implements `RefUnwindSafe` as `f` implements `RefUnwindSafe`, but in Rust 2021, this closure will no longer implement `RefUnwindSafe` as `f.0` does not implement `RefUnwindSafe`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f` to be fully captured
         f.0()

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

@@ -1,8 +1,11 @@
-error: changes to closure capture in Rust 2021 will affect `UnwindSafe`, `RefUnwindSafe` trait implementation for closure
+error: changes to closure capture in Rust 2021 will affect which traits the closure implements
   --> $DIR/mir_calls_to_shims.rs:20:38
    |
 LL |     let result = panic::catch_unwind(move || {
-   |                                      ^^^^^^^ in Rust 2018, this closure implements `UnwindSafe`, `RefUnwindSafe` as `f` implements `UnwindSafe`, `RefUnwindSafe`, but in Rust 2021, this closure will no longer implement `UnwindSafe`, `RefUnwindSafe` as `f.0` does not implement `UnwindSafe`, `RefUnwindSafe`
+   |                                      ^^^^^^^
+   |                                      |
+   |                                      in Rust 2018, this closure implements `UnwindSafe` as `f` implements `UnwindSafe`, but in Rust 2021, this closure will no longer implement `UnwindSafe` as `f.0` does not implement `UnwindSafe`
+   |                                      in Rust 2018, this closure implements `RefUnwindSafe` as `f` implements `RefUnwindSafe`, but in Rust 2021, this closure will no longer implement `RefUnwindSafe` as `f.0` does not implement `RefUnwindSafe`
 ...
 LL |         f.0()
    |         --- in Rust 2018, this closure captures all of `f`, but in Rust 2021, it will only capture `f.0`

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

@@ -18,7 +18,6 @@ impl Foo {
     }
 }
 
-
 struct S(Foo);
 
 #[derive(Clone)]
@@ -37,7 +36,7 @@ fn test_multi_issues() {
     let f2 = U(S(Foo::from("bar")), T(0));
     let c = || {
         let _ = (&f1, &f2);
-        //~^ ERROR: `Clone` trait implementation for closure and drop order
+        //~^ ERROR: changes to closure capture in Rust 2021
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f1` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f1.0` does not implement `Clone`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f1`, `f2` to be fully captured
@@ -57,7 +56,7 @@ fn test_capturing_all_disjoint_fields_individually() {
     let f1 = U(S(Foo::from("foo")), T(0));
     let c = || {
         let _ = &f1;
-        //~^ ERROR: `Clone` trait implementation for closure
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect which traits the closure implements [rust_2021_incompatible_closure_captures]
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f1` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f1.0` does not implement `Clone`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f1` to be fully captured
@@ -83,7 +82,7 @@ fn test_capturing_several_disjoint_fields_individually_1() {
     let f1 = U1(S(Foo::from("foo")), T(0), S(Foo::from("bar")));
     let c = || {
         let _ = &f1;
-        //~^ ERROR: `Clone` trait implementation for closure
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect which traits the closure implements [rust_2021_incompatible_closure_captures]
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f1` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f1.0` does not implement `Clone`
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f1` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f1.2` does not implement `Clone`
         //~| NOTE: for more information, see
@@ -103,7 +102,7 @@ fn test_capturing_several_disjoint_fields_individually_2() {
     let f1 = U1(S(Foo::from("foo")), T(0), S(Foo::from("bar")));
     let c = || {
         let _ = &f1;
-        //~^ ERROR: `Clone` trait implementation for closure and drop order
+        //~^ ERROR: changes to closure capture in Rust 2021 will affect drop order and which traits the closure implements
         //~| NOTE: in Rust 2018, this closure implements `Clone` as `f1` implements `Clone`, but in Rust 2021, this closure will no longer implement `Clone` as `f1.0` does not implement `Clone`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `f1` to be fully captured
@@ -136,8 +135,9 @@ fn test_multi_traits_issues() {
     let mut f2 = 10;
     let fptr2 = SendPointer(&mut f2 as *mut i32);
     thread::spawn(move || { let _ = (&fptr1, &fptr2); unsafe {
-        //~^ ERROR: `Sync`, `Send` trait implementation for closure
-        //~| NOTE: in Rust 2018, this closure implements `Sync`, `Send` as `fptr1` implements `Sync`, `Send`, but in Rust 2021, this closure will no longer implement `Sync`, `Send` as `fptr1.0.0` does not implement `Sync`, `Send`
+        //~^ ERROR: changes to closure capture in Rust 2021
+        //~| NOTE: in Rust 2018, this closure implements `Sync` as `fptr1` implements `Sync`, but in Rust 2021, this closure will no longer implement `Sync` as `fptr1.0.0` does not implement `Sync`
+        //~| NOTE: in Rust 2018, this closure implements `Send` as `fptr1` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr1.0.0` does not implement `Send`
         //~| NOTE: in Rust 2018, this closure implements `Send` as `fptr2` implements `Send`, but in Rust 2021, this closure will no longer implement `Send` as `fptr2.0` does not implement `Send`
         //~| NOTE: for more information, see
         //~| HELP: add a dummy let to cause `fptr1`, `fptr2` to be fully captured