Reduce verbosity of capture analysis logs

Co-authored-by: Jenny Wills <[email protected]>

compiler/rustc_typeck/src/check/upvar.rs

@@ -39,23 +39,22 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_infer::infer::UpvarRegion;
-use rustc_middle::hir::place::{Place, PlaceBase, PlaceWithHirId};
+use rustc_middle::hir::place::{Place, PlaceBase, PlaceWithHirId, ProjectionKind};
 use rustc_middle::ty::{self, Ty, TyCtxt, UpvarSubsts};
 use rustc_span::sym;
 use rustc_span::{Span, Symbol};
 
 macro_rules! log_capture_analysis {
     ($fcx:expr, $closure_def_id:expr, $fmt:literal) => {
         if $fcx.should_log_capture_analysis($closure_def_id) {
-            print!("For closure={:?}: ", $closure_def_id);
-            println!($fmt);
+            eprint!("For closure={:?}: ", $closure_def_id);
+            eprintln!($fmt);
         }
     };
 
     ($fcx:expr, $closure_def_id:expr, $fmt:literal, $($args:expr),*) => {
         if $fcx.should_log_capture_analysis($closure_def_id) {
-            print!("For closure={:?}: ", $closure_def_id);
-            println!($fmt, $($args),*);
+            eprint!("For closure={:?}: ", $closure_def_id);
         }
     };
 }
@@ -92,6 +91,53 @@ impl<'a, 'tcx> Visitor<'tcx> for InferBorrowKindVisitor<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+    fn construct_capture_info_string(
+        &self,
+        place: &Place<'tcx>,
+        capture_info: &ty::CaptureInfo<'tcx>,
+    ) -> String {
+        let variable_name = match place.base {
+            PlaceBase::Upvar(upvar_id) => var_name(self.tcx, upvar_id.var_path.hir_id).to_string(),
+            _ => bug!("Capture_information should only contain upvars"),
+        };
+
+        let mut projections_str = String::new();
+        for (i, item) in place.projections.iter().enumerate() {
+            let proj = match item.kind {
+                ProjectionKind::Field(a, b) => format!("({:?}, {:?})", a, b),
+                ProjectionKind::Deref => String::from("Deref"),
+                ProjectionKind::Index => String::from("Index"),
+                ProjectionKind::Subslice => String::from("Subslice"),
+            };
+            if i != 0 {
+                projections_str.push_str(",");
+            }
+            projections_str.push_str(proj.as_str());
+        }
+
+        let capture_kind_str = match capture_info.capture_kind {
+            ty::UpvarCapture::ByValue(value) => format!("{:?}", value),
+            ty::UpvarCapture::ByRef(borrow) => format!("{:?}", borrow.kind),
+        };
+        format!("{}[{}] -> {}", variable_name, projections_str, capture_kind_str)
+    }
+
+    fn log_new_capture_analysis(
+        &self,
+        closure_def_id: rustc_hir::def_id::DefId,
+        capture_information: &FxIndexMap<Place<'tcx>, ty::CaptureInfo<'tcx>>,
+    ) {
+        if self.should_log_capture_analysis(closure_def_id) {
+            for (place, capture_info) in capture_information {
+                let capture_str = self.construct_capture_info_string(place, capture_info);
+                let output_str = format!("Capturing {}", capture_str);
+
+                let span = self.tcx.hir().span(capture_info.expr_id.unwrap());
+                self.tcx.sess.span_err(span, &output_str);
+            }
+        }
+    }
+
     /// Analysis starting point.
     fn analyze_closure(
         &self,
@@ -169,12 +215,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         )
         .consume_body(body);
 
-        log_capture_analysis!(
-            self,
-            closure_def_id,
-            "capture information: {:#?}",
-            delegate.capture_information
-        );
+        self.log_new_capture_analysis(closure_def_id, &delegate.capture_information);
 
         if let Some(closure_substs) = infer_kind {
             // Unify the (as yet unbound) type variable in the closure

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

@@ -16,6 +16,13 @@ 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 closure=DefId(0:4 ~ arrays_completely_captured[317d]::main::{closure#0}): Using new-style capture analysis
+error: Capturing m[] -> MutBorrow
+  --> $DIR/arrays-completely-captured.rs:12:9
+   |
+LL |         m[0] += 10;
+   |         ^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.

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

@@ -16,6 +16,13 @@ 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 closure=DefId(0:7 ~ capture_disjoint_field_struct[317d]::main::{closure#0}): Using new-style capture analysis
+error: Capturing p[(0, 0)] -> ImmBorrow
+  --> $DIR/capture-disjoint-field-struct.rs:18:24
+   |
+LL |         println!("{}", p.x);
+   |                        ^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.

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

@@ -16,6 +16,13 @@ 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 closure=DefId(0:4 ~ capture_disjoint_field_tuple[317d]::main::{closure#0}): Using new-style capture analysis
+error: Capturing t[(0, 0)] -> ImmBorrow
+  --> $DIR/capture-disjoint-field-tuple.rs:10:24
+   |
+LL |         println!("{}", t.0);
+   |                        ^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.

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

@@ -16,6 +16,13 @@ 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 closure=DefId(0:4 ~ feature_gate_capture_disjoint_fields[317d]::main::{closure#0}): Using new-style capture analysis
+error: Capturing s[] -> ImmBorrow
+  --> $DIR/feature-gate-capture_disjoint_fields.rs:11:69
+   |
+LL |         println!("This uses new capture analyysis to capture s={}", s);
+   |                                                                     ^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.

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

@@ -7,21 +7,12 @@ 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
+For closure=DefId(0:12 ~ filter_on_struct_member[317d]::{impl#1}::update::{closure#0}): Using new-style capture analysis
+error: Capturing self[Deref,(0, 0)] -> ImmBorrow
+  --> $DIR/filter-on-struct-member.rs:24:17
    |
-LL |           self.list.retain(
-   |           ^         ------ immutable borrow later used by call
-   |  _________|
-   | |
-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
+LL |             |v| self.filter.allowed(*v),
+   |                 ^^^^^^^^^^^
 
 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/multilevel-path-1.stderr

@@ -16,6 +16,13 @@ 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 closure=DefId(0:9 ~ multilevel_path_1[317d]::main::{closure#0}): Using new-style capture analysis
+error: Capturing w[(0, 0)] -> ImmBorrow
+  --> $DIR/multilevel-path-1.rs:25:19
+   |
+LL |         let wp = &w.p;
+   |                   ^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.

src/test/ui/closures/2229_closure_analysis/multilevel-path-2.stderr

@@ -16,6 +16,13 @@ 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 closure=DefId(0:9 ~ multilevel_path_2[317d]::main::{closure#0}): Using new-style capture analysis
+error: Capturing w[(0, 0),(0, 0)] -> ImmBorrow
+  --> $DIR/multilevel-path-2.rs:22:24
+   |
+LL |         println!("{}", w.p.x);
+   |                        ^^^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0658`.