Add initial set of testcases for RFC 2229

Co-authored-by: Dhruv Jauhar <[email protected]>

compiler/rustc_typeck/src/check/upvar.rs

@@ -169,6 +169,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         )
         .consume_body(body);
 
+        log_capture_analysis!(
+            self,
+            closure_def_id,
+            "capture information: {:#?}",
+            delegate.capture_information
+        );
+
         if let Some(closure_substs) = infer_kind {
             // Unify the (as yet unbound) type variable in the closure
             // substs with the kind we inferred.

src/test/ui/closures/2229_closure_analysis/arrays-completely-captured.rs

@@ -0,0 +1,17 @@
+#![feature(capture_disjoint_fields)]
+//~^ WARNING the feature `capture_disjoint_fields` is incomplete
+#![feature(rustc_attrs)]
+
+// Ensure that capture analysis results in arrays being completely captured.
+fn main() {
+    let mut m = [1, 2, 3, 4, 5];
+
+    let mut c = #[rustc_capture_analysis]
+    //~^ ERROR: attributes on expressions are experimental
+    || {
+        m[0] += 10;
+        m[1] += 40;
+    };
+
+    c();
+}

src/test/ui/closures/2229_closure_analysis/arrays-completely-captured.stderr

@@ -0,0 +1,21 @@
+error[E0658]: attributes on expressions are experimental
+  --> $DIR/arrays-completely-captured.rs:9:17
+   |
+LL |     let mut c = #[rustc_capture_analysis]
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
+   = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
+
+warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/arrays-completely-captured.rs:1:12
+   |
+LL | #![feature(capture_disjoint_fields)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/closures/2229_closure_analysis/arrays-completely-captured.stdout

@@ -0,0 +1,20 @@
+For closure=DefId(0:4 ~ arrays_completely_captured[317d]::main::{closure#0}): Using new-style capture analysis
+For closure=DefId(0:4 ~ arrays_completely_captured[317d]::main::{closure#0}): capture information: {
+    Place {
+        base_ty: [i32; 5],
+        base: Upvar(
+            UpvarId(HirId { owner: DefId(0:3 ~ arrays_completely_captured[317d]::main), local_id: 1 };`m`;DefId(0:4 ~ arrays_completely_captured[317d]::main::{closure#0})),
+        ),
+        projections: [],
+    }: CaptureInfo {
+        expr_id: Some(
+            HirId {
+                owner: DefId(0:3 ~ arrays_completely_captured[317d]::main),
+                local_id: 12,
+            },
+        ),
+        capture_kind: ByRef(
+            UpvarBorrow(MutBorrow, '_#6r),
+        ),
+    },
+}

src/test/ui/closures/2229_closure_analysis/capture-disjoint-field-struct.rs

@@ -0,0 +1,26 @@
+// FIXME(arora-aman) add run-pass once 2229 is implemented
+
+#![feature(capture_disjoint_fields)]
+//~^ WARNING the feature `capture_disjoint_fields` is incomplete
+#![feature(rustc_attrs)]
+
+struct Point {
+    x: i32,
+    y: i32,
+}
+
+fn main() {
+    let mut p = Point { x: 10, y: 10 };
+
+    let c = #[rustc_capture_analysis]
+    //~^ ERROR: attributes on expressions are experimental
+    || {
+        println!("{}", p.x);
+    };
+
+    // `c` should only capture `p.x`, therefore mutating `p.y` is allowed.
+    let py = &mut p.y;
+
+    c();
+    *py = 20;
+}

src/test/ui/closures/2229_closure_analysis/capture-disjoint-field-struct.stderr

@@ -0,0 +1,21 @@
+error[E0658]: attributes on expressions are experimental
+  --> $DIR/capture-disjoint-field-struct.rs:15:13
+   |
+LL |     let c = #[rustc_capture_analysis]
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
+   = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
+
+warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/capture-disjoint-field-struct.rs:3:12
+   |
+LL | #![feature(capture_disjoint_fields)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/closures/2229_closure_analysis/capture-disjoint-field-struct.stdout

@@ -0,0 +1,28 @@
+For closure=DefId(0:7 ~ capture_disjoint_field_struct[317d]::main::{closure#0}): Using new-style capture analysis
+For closure=DefId(0:7 ~ capture_disjoint_field_struct[317d]::main::{closure#0}): capture information: {
+    Place {
+        base_ty: Point,
+        base: Upvar(
+            UpvarId(HirId { owner: DefId(0:6 ~ capture_disjoint_field_struct[317d]::main), local_id: 1 };`p`;DefId(0:7 ~ capture_disjoint_field_struct[317d]::main::{closure#0})),
+        ),
+        projections: [
+            Projection {
+                ty: i32,
+                kind: Field(
+                    0,
+                    0,
+                ),
+            },
+        ],
+    }: CaptureInfo {
+        expr_id: Some(
+            HirId {
+                owner: DefId(0:6 ~ capture_disjoint_field_struct[317d]::main),
+                local_id: 31,
+            },
+        ),
+        capture_kind: ByRef(
+            UpvarBorrow(ImmBorrow, '_#35r),
+        ),
+    },
+}

src/test/ui/closures/2229_closure_analysis/capture-disjoint-field-tuple.rs

@@ -0,0 +1,21 @@
+// FIXME(arora-aman) add run-pass once 2229 is implemented
+
+#![feature(capture_disjoint_fields)]
+//~^ WARNING the feature `capture_disjoint_fields` is incomplete
+#![feature(rustc_attrs)]
+
+fn main() {
+    let mut t = (10, 10);
+
+    let c = #[rustc_capture_analysis]
+    //~^ ERROR: attributes on expressions are experimental
+    || {
+        println!("{}", t.0);
+    };
+
+    // `c` only captures t.0, therefore mutating t.1 is allowed.
+    let t1 = &mut t.1;
+
+    c();
+    *t1 = 20;
+}

src/test/ui/closures/2229_closure_analysis/capture-disjoint-field-tuple.stderr

@@ -0,0 +1,21 @@
+error[E0658]: attributes on expressions are experimental
+  --> $DIR/capture-disjoint-field-tuple.rs:8:13
+   |
+LL |     let c = #[rustc_capture_analysis]
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
+   = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
+
+warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/capture-disjoint-field-tuple.rs:1:12
+   |
+LL | #![feature(capture_disjoint_fields)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/closures/2229_closure_analysis/capture-disjoint-field-tuple.stdout

@@ -0,0 +1,28 @@
+For closure=DefId(0:4 ~ capture_disjoint_field_tuple[317d]::main::{closure#0}): Using new-style capture analysis
+For closure=DefId(0:4 ~ capture_disjoint_field_tuple[317d]::main::{closure#0}): capture information: {
+    Place {
+        base_ty: (i32, i32),
+        base: Upvar(
+            UpvarId(HirId { owner: DefId(0:3 ~ capture_disjoint_field_tuple[317d]::main), local_id: 1 };`t`;DefId(0:4 ~ capture_disjoint_field_tuple[317d]::main::{closure#0})),
+        ),
+        projections: [
+            Projection {
+                ty: i32,
+                kind: Field(
+                    0,
+                    0,
+                ),
+            },
+        ],
+    }: CaptureInfo {
+        expr_id: Some(
+            HirId {
+                owner: DefId(0:3 ~ capture_disjoint_field_tuple[317d]::main),
+                local_id: 28,
+            },
+        ),
+        capture_kind: ByRef(
+            UpvarBorrow(ImmBorrow, '_#35r),
+        ),
+    },
+}

src/test/ui/closures/2229_closure_analysis/feature-gate-capture_disjoint_fields.rs

@@ -5,8 +5,9 @@
 fn main() {
     let s = format!("s");
 
-    let c = #[rustc_capture_analysis] || {
+    let c = #[rustc_capture_analysis]
     //~^ ERROR: attributes on expressions are experimental
+    || {
         println!("This uses new capture analyysis to capture s={}", s);
     };
 }

src/test/ui/closures/2229_closure_analysis/feature-gate-capture_disjoint_fields.stderr

@@ -1,7 +1,7 @@
 error[E0658]: attributes on expressions are experimental
   --> $DIR/feature-gate-capture_disjoint_fields.rs:8:13
    |
-LL |     let c = #[rustc_capture_analysis] || {
+LL |     let c = #[rustc_capture_analysis]
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information

src/test/ui/closures/2229_closure_analysis/feature-gate-capture_disjoint_fields.stdout

@@ -1 +1,20 @@
 For closure=DefId(0:4 ~ feature_gate_capture_disjoint_fields[317d]::main::{closure#0}): Using new-style capture analysis
+For closure=DefId(0:4 ~ feature_gate_capture_disjoint_fields[317d]::main::{closure#0}): capture information: {
+    Place {
+        base_ty: std::string::String,
+        base: Upvar(
+            UpvarId(HirId { owner: DefId(0:3 ~ feature_gate_capture_disjoint_fields[317d]::main), local_id: 1 };`s`;DefId(0:4 ~ feature_gate_capture_disjoint_fields[317d]::main::{closure#0})),
+        ),
+        projections: [],
+    }: CaptureInfo {
+        expr_id: Some(
+            HirId {
+                owner: DefId(0:3 ~ feature_gate_capture_disjoint_fields[317d]::main),
+                local_id: 52,
+            },
+        ),
+        capture_kind: ByRef(
+            UpvarBorrow(ImmBorrow, '_#50r),
+        ),
+    },
+}

src/test/ui/closures/2229_closure_analysis/filter-on-struct-member.rs

@@ -0,0 +1,40 @@
+// FIXME(arora-aman) add run-pass once 2229 is implemented
+
+#![feature(capture_disjoint_fields)]
+//~^ warning the feature `capture_disjoint_fields` is incomplete
+#![feature(rustc_attrs)]
+
+struct Filter {
+    div: i32,
+}
+impl Filter {
+    fn allowed(&self, x: i32) -> bool {
+        x % self.div == 1
+    }
+}
+
+struct Data {
+    filter: Filter,
+    list: Vec<i32>,
+}
+impl Data {
+    fn update(&mut self) {
+        // The closure passed to filter only captures self.filter,
+        // therefore mutating self.list is allowed.
+        self.list.retain(
+        //~^ cannot borrow `self.list` as mutable because it is also borrowed as immutable
+            #[rustc_capture_analysis]
+            |v| self.filter.allowed(*v),
+        );
+    }
+}
+
+fn main() {
+    let mut d = Data { filter: Filter { div: 3 }, list: Vec::new() };
+
+    for i in 1..10 {
+        d.list.push(i);
+    }
+
+    d.update();
+}

src/test/ui/closures/2229_closure_analysis/filter-on-struct-member.stderr

@@ -0,0 +1,28 @@
+warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/filter-on-struct-member.rs:1:12
+   |
+LL | #![feature(capture_disjoint_fields)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
+
+error[E0502]: cannot borrow `self.list` as mutable because it is also borrowed as immutable
+  --> $DIR/filter-on-struct-member.rs:22:9
+   |
+LL |           self.list.retain(
+   |           ^         ------ immutable borrow later used by call
+   |  _________|
+   | |
+LL | |
+LL | |             #[rustc_capture_analysis]
+LL | |             |v| self.filter.allowed(*v),
+   | |             --- ---- first borrow occurs due to use of `self` in closure
+   | |             |
+   | |             immutable borrow occurs here
+LL | |         );
+   | |_________^ mutable borrow occurs here
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0502`.

src/test/ui/closures/2229_closure_analysis/filter-on-struct-member.stdout

@@ -0,0 +1,32 @@
+For closure=DefId(0:12 ~ filter_on_struct_member[317d]::{impl#1}::update::{closure#0}): Using new-style capture analysis
+For closure=DefId(0:12 ~ filter_on_struct_member[317d]::{impl#1}::update::{closure#0}): capture information: {
+    Place {
+        base_ty: &mut Data,
+        base: Upvar(
+            UpvarId(HirId { owner: DefId(0:11 ~ filter_on_struct_member[317d]::{impl#1}::update), local_id: 1 };`self`;DefId(0:12 ~ filter_on_struct_member[317d]::{impl#1}::update::{closure#0})),
+        ),
+        projections: [
+            Projection {
+                ty: Data,
+                kind: Deref,
+            },
+            Projection {
+                ty: Filter,
+                kind: Field(
+                    0,
+                    0,
+                ),
+            },
+        ],
+    }: CaptureInfo {
+        expr_id: Some(
+            HirId {
+                owner: DefId(0:11 ~ filter_on_struct_member[317d]::{impl#1}::update),
+                local_id: 13,
+            },
+        ),
+        capture_kind: ByRef(
+            UpvarBorrow(ImmBorrow, '_#7r),
+        ),
+    },
+}