Rollup merge of #132816 - compiler-errors:2024-apit, r=jieyouxu

Dont suggest `use<impl Trait>` when we have an edition-2024-related borrowck issue

#131186 implements some machinery to detect in borrowck when we may have RPIT overcaptures due to edition 2024, and suggests adding `+ use<'a, T>` to go back to the edition 2021 capture rules. However, we weren't filtering out cases when there are APITs in scope.

This PR implements a more sophisticated diagnostic where we will suggest turning any APITs in scope into type parameters, and applies this to both the borrowck error note, and to the `impl_trait_overcaptures` migration lint.

cc #132809

5 files changed, 126 insertions, 13 deletions

diff --git a/tests/ui/impl-trait/precise-capturing/migration-note.rs b/tests/ui/impl-trait/precise-capturing/migration-note.rs
index a5bade4ddc5..1d98750f6dd 100644
--- a/tests/ui/impl-trait/precise-capturing/migration-note.rs
+++ b/tests/ui/impl-trait/precise-capturing/migration-note.rs
@@ -187,4 +187,19 @@ fn returned() -> impl Sized {
 }
 //~^ NOTE `x` dropped here while still borrowed
 
+fn capture_apit(x: &impl Sized) -> impl Sized {}
+//~^ NOTE you could use a `use<...>` bound to explicitly specify captures, but
+
+fn test_apit() {
+    let x = String::new();
+    //~^ NOTE binding `x` declared here
+    let y = capture_apit(&x);
+    //~^ NOTE borrow of `x` occurs here
+    //~| NOTE this call may capture more lifetimes than intended
+    drop(x);
+    //~^ ERROR cannot move out of `x` because it is borrowed
+    //~| NOTE move out of `x` occurs here
+}
+//~^ NOTE borrow might be used here, when `y` is dropped
+
 fn main() {}
diff --git a/tests/ui/impl-trait/precise-capturing/migration-note.stderr b/tests/ui/impl-trait/precise-capturing/migration-note.stderr
index 3ac47ed1bcd..a859a114dbc 100644
--- a/tests/ui/impl-trait/precise-capturing/migration-note.stderr
+++ b/tests/ui/impl-trait/precise-capturing/migration-note.stderr
@@ -30,7 +30,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_len(&x);
    |             ^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len<T>(x: &Vec<T>) -> impl Display + use<T> {
    |                                               ++++++++
@@ -55,7 +55,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_len(&x);
    |             ^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len<T>(x: &Vec<T>) -> impl Display + use<T> {
    |                                               ++++++++
@@ -80,7 +80,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_len(&x);
    |             ^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len<T>(x: &Vec<T>) -> impl Display + use<T> {
    |                                               ++++++++
@@ -106,7 +106,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_len_mut(&mut x);
    |             ^^^^^^^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len_mut<T>(x: &mut Vec<T>) -> impl Display + use<T> {
    |                                                       ++++++++
@@ -131,7 +131,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_len_mut(&mut x);
    |             ^^^^^^^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len_mut<T>(x: &mut Vec<T>) -> impl Display + use<T> {
    |                                                       ++++++++
@@ -156,7 +156,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_len_mut(&mut x);
    |             ^^^^^^^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len_mut<T>(x: &mut Vec<T>) -> impl Display + use<T> {
    |                                                       ++++++++
@@ -182,7 +182,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_field(&s.f);
    |             ^^^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_field<T: Copy + Display>(t: &T) -> impl Display + use<T> {
    |                                                            ++++++++
@@ -204,7 +204,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_field(&mut s.f);
    |             ^^^^^^^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_field<T: Copy + Display>(t: &T) -> impl Display + use<T> {
    |                                                            ++++++++
@@ -226,7 +226,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |     let a = display_field(&mut s.f);
    |             ^^^^^^^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_field<T: Copy + Display>(t: &T) -> impl Display + use<T> {
    |                                                            ++++++++
@@ -252,7 +252,7 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
    |
 LL |         x = display_len(&z.f);
    |             ^^^^^^^^^^^^^^^^^
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len<T>(x: &Vec<T>) -> impl Display + use<T> {
    |                                               ++++++++
@@ -273,12 +273,46 @@ note: this call may capture more lifetimes than intended, because Rust 2024 has
 LL |     let x = { let x = display_len(&mut vec![0]); x };
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
-help: add a precise capturing bound to avoid overcapturing
+help: use the precise capturing `use<...>` syntax to make the captures explicit
    |
 LL | fn display_len<T>(x: &Vec<T>) -> impl Display + use<T> {
    |                                               ++++++++
 
-error: aborting due to 12 previous errors
+error[E0505]: cannot move out of `x` because it is borrowed
+  --> $DIR/migration-note.rs:199:10
+   |
+LL |     let x = String::new();
+   |         - binding `x` declared here
+LL |
+LL |     let y = capture_apit(&x);
+   |                          -- borrow of `x` occurs here
+...
+LL |     drop(x);
+   |          ^ move out of `x` occurs here
+...
+LL | }
+   | - borrow might be used here, when `y` is dropped and runs the destructor for type `impl Sized`
+   |
+note: this call may capture more lifetimes than intended, because Rust 2024 has adjusted the `impl Trait` lifetime capture rules
+  --> $DIR/migration-note.rs:196:13
+   |
+LL |     let y = capture_apit(&x);
+   |             ^^^^^^^^^^^^^^^^
+note: you could use a `use<...>` bound to explicitly specify captures, but argument-position `impl Trait`s are not nameable
+  --> $DIR/migration-note.rs:190:21
+   |
+LL | fn capture_apit(x: &impl Sized) -> impl Sized {}
+   |                     ^^^^^^^^^^
+help: use the precise capturing `use<...>` syntax to make the captures explicit
+   |
+LL | fn capture_apit<T: Sized>(x: &T) -> impl Sized + use<T> {}
+   |                ++++++++++     ~                ++++++++
+help: consider cloning the value if the performance cost is acceptable
+   |
+LL |     let y = capture_apit(&x.clone());
+   |                            ++++++++
+
+error: aborting due to 13 previous errors
 
 Some errors have detailed explanations: E0499, E0502, E0503, E0505, E0506, E0597, E0716.
 For more information about an error, try `rustc --explain E0499`.
diff --git a/tests/ui/impl-trait/precise-capturing/overcaptures-2024.fixed b/tests/ui/impl-trait/precise-capturing/overcaptures-2024.fixed
index 89a3f3136c8..6a9d72d028c 100644
--- a/tests/ui/impl-trait/precise-capturing/overcaptures-2024.fixed
+++ b/tests/ui/impl-trait/precise-capturing/overcaptures-2024.fixed
@@ -29,4 +29,12 @@ fn hrtb() -> impl for<'a> Higher<'a, Output = impl Sized + use<>> {}
 //~^ ERROR `impl Sized` will capture more lifetimes than possibly intended in edition 2024
 //~| WARN this changes meaning in Rust 2024
 
+fn apit<T: Sized>(_: &T) -> impl Sized + use<T> {}
+//~^ ERROR `impl Sized` will capture more lifetimes than possibly intended in edition 2024
+//~| WARN this changes meaning in Rust 2024
+
+fn apit2<U, T: Sized>(_: &T, _: U) -> impl Sized + use<U, T> {}
+//~^ ERROR `impl Sized` will capture more lifetimes than possibly intended in edition 2024
+//~| WARN this changes meaning in Rust 2024
+
 fn main() {}
diff --git a/tests/ui/impl-trait/precise-capturing/overcaptures-2024.rs b/tests/ui/impl-trait/precise-capturing/overcaptures-2024.rs
index 18c04f9f799..3a4f5ebb7fb 100644
--- a/tests/ui/impl-trait/precise-capturing/overcaptures-2024.rs
+++ b/tests/ui/impl-trait/precise-capturing/overcaptures-2024.rs
@@ -29,4 +29,12 @@ fn hrtb() -> impl for<'a> Higher<'a, Output = impl Sized> {}
 //~^ ERROR `impl Sized` will capture more lifetimes than possibly intended in edition 2024
 //~| WARN this changes meaning in Rust 2024
 
+fn apit(_: &impl Sized) -> impl Sized {}
+//~^ ERROR `impl Sized` will capture more lifetimes than possibly intended in edition 2024
+//~| WARN this changes meaning in Rust 2024
+
+fn apit2<U>(_: &impl Sized, _: U) -> impl Sized {}
+//~^ ERROR `impl Sized` will capture more lifetimes than possibly intended in edition 2024
+//~| WARN this changes meaning in Rust 2024
+
 fn main() {}
diff --git a/tests/ui/impl-trait/precise-capturing/overcaptures-2024.stderr b/tests/ui/impl-trait/precise-capturing/overcaptures-2024.stderr
index 94dafb04d64..c101b980c71 100644
--- a/tests/ui/impl-trait/precise-capturing/overcaptures-2024.stderr
+++ b/tests/ui/impl-trait/precise-capturing/overcaptures-2024.stderr
@@ -79,5 +79,53 @@ help: use the precise capturing `use<...>` syntax to make the captures explicit
 LL | fn hrtb() -> impl for<'a> Higher<'a, Output = impl Sized + use<>> {}
    |                                                          +++++++
 
-error: aborting due to 4 previous errors
+error: `impl Sized` will capture more lifetimes than possibly intended in edition 2024
+  --> $DIR/overcaptures-2024.rs:32:28
+   |
+LL | fn apit(_: &impl Sized) -> impl Sized {}
+   |                            ^^^^^^^^^^
+   |
+   = warning: this changes meaning in Rust 2024
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/rpit-lifetime-capture.html>
+note: specifically, this lifetime is in scope but not mentioned in the type's bounds
+  --> $DIR/overcaptures-2024.rs:32:12
+   |
+LL | fn apit(_: &impl Sized) -> impl Sized {}
+   |            ^
+   = note: all lifetimes in scope will be captured by `impl Trait`s in edition 2024
+note: you could use a `use<...>` bound to explicitly specify captures, but argument-position `impl Trait`s are not nameable
+  --> $DIR/overcaptures-2024.rs:32:13
+   |
+LL | fn apit(_: &impl Sized) -> impl Sized {}
+   |             ^^^^^^^^^^
+help: use the precise capturing `use<...>` syntax to make the captures explicit
+   |
+LL | fn apit<T: Sized>(_: &T) -> impl Sized + use<T> {}
+   |        ++++++++++     ~                ++++++++
+
+error: `impl Sized` will capture more lifetimes than possibly intended in edition 2024
+  --> $DIR/overcaptures-2024.rs:36:38
+   |
+LL | fn apit2<U>(_: &impl Sized, _: U) -> impl Sized {}
+   |                                      ^^^^^^^^^^
+   |
+   = warning: this changes meaning in Rust 2024
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/rpit-lifetime-capture.html>
+note: specifically, this lifetime is in scope but not mentioned in the type's bounds
+  --> $DIR/overcaptures-2024.rs:36:16
+   |
+LL | fn apit2<U>(_: &impl Sized, _: U) -> impl Sized {}
+   |                ^
+   = note: all lifetimes in scope will be captured by `impl Trait`s in edition 2024
+note: you could use a `use<...>` bound to explicitly specify captures, but argument-position `impl Trait`s are not nameable
+  --> $DIR/overcaptures-2024.rs:36:17
+   |
+LL | fn apit2<U>(_: &impl Sized, _: U) -> impl Sized {}
+   |                 ^^^^^^^^^^
+help: use the precise capturing `use<...>` syntax to make the captures explicit
+   |
+LL | fn apit2<U, T: Sized>(_: &T, _: U) -> impl Sized + use<U, T> {}
+   |           ++++++++++      ~                      +++++++++++
+
+error: aborting due to 6 previous errors