Auto merge of #58788 - matthewjasper:compare-children, r=pnkfelix

Make migrate mode work at item level granularity

Migrate mode now works entirely at the item level rather than the body level,
ensuring that we don't lose any errors in contained closures.

Closes #58776

r? @pnkfelix

4 files changed, 100 insertions, 0 deletions

diff --git a/src/test/ui/borrowck/issue-58776-borrowck-scans-children.ast.stderr b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.ast.stderr
new file mode 100644
index 00000000000..9e0b0aac1e3
--- /dev/null
+++ b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.ast.stderr
@@ -0,0 +1,15 @@
+error[E0597]: `**greeting` does not live long enough
+  --> $DIR/issue-58776-borrowck-scans-children.rs:10:24
+   |
+LL |     let res = (|| (|| &greeting)())();
+   |                    --  ^^^^^^^^     - borrowed value only lives until here
+   |                    |   |
+   |                    |   borrowed value does not live long enough
+   |                    capture occurs here
+...
+LL | }
+   | - borrowed value needs to live until here
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0597`.
diff --git a/src/test/ui/borrowck/issue-58776-borrowck-scans-children.migrate.stderr b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.migrate.stderr
new file mode 100644
index 00000000000..bd8f2286f17
--- /dev/null
+++ b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.migrate.stderr
@@ -0,0 +1,32 @@
+error[E0506]: cannot assign to `greeting` because it is borrowed
+  --> $DIR/issue-58776-borrowck-scans-children.rs:13:5
+   |
+LL |     let res = (|| (|| &greeting)())();
+   |                --      -------- borrow occurs due to use in closure
+   |                |
+   |                borrow of `greeting` occurs here
+...
+LL |     greeting = "DEALLOCATED".to_string();
+   |     ^^^^^^^^ assignment to borrowed `greeting` occurs here
+...
+LL |     println!("thread result: {:?}", res);
+   |                                     --- borrow later used here
+
+error[E0505]: cannot move out of `greeting` because it is borrowed
+  --> $DIR/issue-58776-borrowck-scans-children.rs:16:10
+   |
+LL |     let res = (|| (|| &greeting)())();
+   |                --      -------- borrow occurs due to use in closure
+   |                |
+   |                borrow of `greeting` occurs here
+...
+LL |     drop(greeting);
+   |          ^^^^^^^^ move out of `greeting` occurs here
+...
+LL |     println!("thread result: {:?}", res);
+   |                                     --- borrow later used here
+
+error: aborting due to 2 previous errors
+
+Some errors occurred: E0505, E0506.
+For more information about an error, try `rustc --explain E0505`.
diff --git a/src/test/ui/borrowck/issue-58776-borrowck-scans-children.nll.stderr b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.nll.stderr
new file mode 100644
index 00000000000..bd8f2286f17
--- /dev/null
+++ b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.nll.stderr
@@ -0,0 +1,32 @@
+error[E0506]: cannot assign to `greeting` because it is borrowed
+  --> $DIR/issue-58776-borrowck-scans-children.rs:13:5
+   |
+LL |     let res = (|| (|| &greeting)())();
+   |                --      -------- borrow occurs due to use in closure
+   |                |
+   |                borrow of `greeting` occurs here
+...
+LL |     greeting = "DEALLOCATED".to_string();
+   |     ^^^^^^^^ assignment to borrowed `greeting` occurs here
+...
+LL |     println!("thread result: {:?}", res);
+   |                                     --- borrow later used here
+
+error[E0505]: cannot move out of `greeting` because it is borrowed
+  --> $DIR/issue-58776-borrowck-scans-children.rs:16:10
+   |
+LL |     let res = (|| (|| &greeting)())();
+   |                --      -------- borrow occurs due to use in closure
+   |                |
+   |                borrow of `greeting` occurs here
+...
+LL |     drop(greeting);
+   |          ^^^^^^^^ move out of `greeting` occurs here
+...
+LL |     println!("thread result: {:?}", res);
+   |                                     --- borrow later used here
+
+error: aborting due to 2 previous errors
+
+Some errors occurred: E0505, E0506.
+For more information about an error, try `rustc --explain E0505`.
diff --git a/src/test/ui/borrowck/issue-58776-borrowck-scans-children.rs b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.rs
new file mode 100644
index 00000000000..378969f9a18
--- /dev/null
+++ b/src/test/ui/borrowck/issue-58776-borrowck-scans-children.rs
@@ -0,0 +1,21 @@
+// ignore-compare-mode-nll
+
+// revisions: ast migrate nll
+
+//[migrate]compile-flags: -Z borrowck=migrate
+#![cfg_attr(nll, feature(nll))]
+
+fn main() {
+    let mut greeting = "Hello world!".to_string();
+    let res = (|| (|| &greeting)())();
+    //[ast]~^ ERROR does not live long enough
+
+    greeting = "DEALLOCATED".to_string();
+    //[migrate]~^ ERROR cannot assign
+    //[nll]~^^ ERROR cannot assign
+    drop(greeting);
+    //[migrate]~^ ERROR cannot move
+    //[nll]~^^ ERROR cannot move
+
+    println!("thread result: {:?}", res);
+}