Regression test for issue 55492.

src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.ast.stderr

@@ -0,0 +1,55 @@
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:21:22
+   |
+LL |         let mut c1 = |y: &'static mut isize| x = y;
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow mutably
+help: consider removing the `&mut`, as it is an immutable binding to a mutable reference
+   |
+LL |         x
+   |
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:29:22
+   |
+LL |         let mut c1 = |z: &'static mut isize| {
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow mutably
+help: consider removing the `&mut`, as it is an immutable binding to a mutable reference
+   |
+LL |         x
+   |
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:40:9
+   |
+LL |     pub fn capture_assign_whole(x: (i32,)) {
+   |                                 - help: make this binding mutable: `mut x`
+LL |         || { x = (1,); };
+   |         ^^ cannot borrow mutably
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:43:9
+   |
+LL |     pub fn capture_assign_part(x: (i32,)) {
+   |                                - help: make this binding mutable: `mut x`
+LL |         || { x.0 = 1; };
+   |         ^^ cannot borrow mutably
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:46:9
+   |
+LL |     pub fn capture_reborrow_whole(x: (i32,)) {
+   |                                   - help: make this binding mutable: `mut x`
+LL |         || { &mut x; };
+   |         ^^ cannot borrow mutably
+
+error[E0595]: closure cannot assign to immutable argument `x`
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:49:9
+   |
+LL |     pub fn capture_reborrow_part(x: (i32,)) {
+   |                                  - help: make this binding mutable: `mut x`
+LL |         || { &mut x.0; };
+   |         ^^ cannot borrow mutably
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0595`.

src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.migrate.stderr

@@ -0,0 +1,54 @@
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:21:46
+   |
+LL |     pub fn e(x: &'static mut isize) {
+   |              - help: consider changing this to be mutable: `mut x`
+LL |         static mut Y: isize = 3;
+LL |         let mut c1 = |y: &'static mut isize| x = y;
+   |                                              ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:30:50
+   |
+LL |     pub fn ee(x: &'static mut isize) {
+   |               - help: consider changing this to be mutable: `mut x`
+...
+LL |             let mut c2 = |y: &'static mut isize| x = y;
+   |                                                  ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:40:14
+   |
+LL |     pub fn capture_assign_whole(x: (i32,)) {
+   |                                 - help: consider changing this to be mutable: `mut x`
+LL |         || { x = (1,); };
+   |              ^^^^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x.0`, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:43:14
+   |
+LL |     pub fn capture_assign_part(x: (i32,)) {
+   |                                - help: consider changing this to be mutable: `mut x`
+LL |         || { x.0 = 1; };
+   |              ^^^^^^^ cannot assign
+
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:46:14
+   |
+LL |     pub fn capture_reborrow_whole(x: (i32,)) {
+   |                                   - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x; };
+   |              ^^^^^^ cannot borrow as mutable
+
+error[E0596]: cannot borrow `x.0` as mutable, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:49:14
+   |
+LL |     pub fn capture_reborrow_part(x: (i32,)) {
+   |                                  - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x.0; };
+   |              ^^^^^^^^ cannot borrow as mutable
+
+error: aborting due to 6 previous errors
+
+Some errors occurred: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.

src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.nll.stderr

@@ -0,0 +1,54 @@
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:21:46
+   |
+LL |     pub fn e(x: &'static mut isize) {
+   |              - help: consider changing this to be mutable: `mut x`
+LL |         static mut Y: isize = 3;
+LL |         let mut c1 = |y: &'static mut isize| x = y;
+   |                                              ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:30:50
+   |
+LL |     pub fn ee(x: &'static mut isize) {
+   |               - help: consider changing this to be mutable: `mut x`
+...
+LL |             let mut c2 = |y: &'static mut isize| x = y;
+   |                                                  ^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x`, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:40:14
+   |
+LL |     pub fn capture_assign_whole(x: (i32,)) {
+   |                                 - help: consider changing this to be mutable: `mut x`
+LL |         || { x = (1,); };
+   |              ^^^^^^^^ cannot assign
+
+error[E0594]: cannot assign to `x.0`, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:43:14
+   |
+LL |     pub fn capture_assign_part(x: (i32,)) {
+   |                                - help: consider changing this to be mutable: `mut x`
+LL |         || { x.0 = 1; };
+   |              ^^^^^^^ cannot assign
+
+error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:46:14
+   |
+LL |     pub fn capture_reborrow_whole(x: (i32,)) {
+   |                                   - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x; };
+   |              ^^^^^^ cannot borrow as mutable
+
+error[E0596]: cannot borrow `x.0` as mutable, as `x` is not declared as mutable
+  --> $DIR/issue-55492-borrowck-migrate-scans-parents.rs:49:14
+   |
+LL |     pub fn capture_reborrow_part(x: (i32,)) {
+   |                                  - help: consider changing this to be mutable: `mut x`
+LL |         || { &mut x.0; };
+   |              ^^^^^^^^ cannot borrow as mutable
+
+error: aborting due to 6 previous errors
+
+Some errors occurred: E0594, E0596.
+For more information about an error, try `rustc --explain E0594`.

src/test/ui/borrowck/issue-55492-borrowck-migrate-scans-parents.rs

@@ -0,0 +1,61 @@
+// rust-lang/rust#55492: errors detected during MIR-borrowck's
+// analysis of a closure body may only be caught when AST-borrowck
+// looks at some parent.
+
+// revisions: ast migrate nll
+
+// Since we are testing nll (and migration) explicitly as a separate
+// revisions, don't worry about the --compare-mode=nll on this test.
+
+// ignore-compare-mode-nll
+
+//[ast]compile-flags: -Z borrowck=ast
+//[migrate]compile-flags: -Z borrowck=migrate -Z two-phase-borrows
+//[nll]compile-flags: -Z borrowck=mir -Z two-phase-borrows
+
+
+// transcribed from borrowck-closures-unique.rs
+mod borrowck_closures_unique {
+    pub fn e(x: &'static mut isize) {
+        static mut Y: isize = 3;
+        let mut c1 = |y: &'static mut isize| x = y;
+        unsafe { c1(&mut Y); }
+    }
+}
+
+mod borrowck_closures_unique_grandparent {
+    pub fn ee(x: &'static mut isize) {
+        static mut Z: isize = 3;
+        let mut c1 = |z: &'static mut isize| {
+            let mut c2 = |y: &'static mut isize| x = y;
+            c2(z);
+        };
+        unsafe { c1(&mut Z); }
+    }
+}
+
+// adapted from mutability_errors.rs
+mod mutability_errors {
+    pub fn capture_assign_whole(x: (i32,)) {
+        || { x = (1,); };
+    }
+    pub fn capture_assign_part(x: (i32,)) {
+        || { x.0 = 1; };
+    }
+    pub fn capture_reborrow_whole(x: (i32,)) {
+        || { &mut x; };
+    }
+    pub fn capture_reborrow_part(x: (i32,)) {
+        || { &mut x.0; };
+    }
+}
+
+fn main() {
+    static mut X: isize = 2;
+    unsafe { borrowck_closures_unique::e(&mut X); }
+
+    mutability_errors::capture_assign_whole((1000,));
+    mutability_errors::capture_assign_part((2000,));
+    mutability_errors::capture_reborrow_whole((3000,));
+    mutability_errors::capture_reborrow_part((4000,));
+}