Rollup merge of rust-lang#106978 - mejrs:mir_build3, r=davidtwco

Migrate mir_build's borrow conflicts

This also changes the error message slightly, for two reasons:

- I'm not a fan of saying "value borrowed, by `x`, here"
- it simplifies the error implementation significantly.

Author: matthiaskrgr

compiler/rustc_error_messages/locales/en-US/mir_build.ftl

@@ -299,10 +299,18 @@ mir_build_borrow_of_moved_value = borrow of moved value
     .suggestion = borrow this binding in the pattern to avoid moving the value
 
 mir_build_multiple_mut_borrows = cannot borrow value as mutable more than once at a time
-    .label = first mutable borrow, by `{$name}`, occurs here
-    .mutable_borrow = another mutable borrow, by `{$name_mut}`, occurs here
-    .immutable_borrow = also borrowed as immutable, by `{$name_immut}`, here
-    .moved = also moved into `{$name_moved}` here
+
+mir_build_already_borrowed = cannot borrow value as mutable because it is also borrowed as immutable
+
+mir_build_already_mut_borrowed = cannot borrow value as immutable because it is also borrowed as mutable
+
+mir_build_moved_while_borrowed = cannot move out of value because it is borrowed
+
+mir_build_mutable_borrow = value is mutably borrowed by `{$name}` here
+
+mir_build_borrow = value is borrowed by `{$name}` here
+
+mir_build_moved = value is moved into `{$name}` here
 
 mir_build_union_pattern = cannot use unions in constant patterns
 

compiler/rustc_mir_build/src/errors.rs

@@ -600,32 +600,56 @@ pub struct BorrowOfMovedValue<'tcx> {
 pub struct MultipleMutBorrows {
     #[primary_span]
     pub span: Span,
-    #[label]
-    pub binding_span: Span,
     #[subdiagnostic]
-    pub occurences: Vec<MultipleMutBorrowOccurence>,
-    pub name: Ident,
+    pub occurences: Vec<Conflict>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_already_borrowed)]
+pub struct AlreadyBorrowed {
+    #[primary_span]
+    pub span: Span,
+    #[subdiagnostic]
+    pub occurences: Vec<Conflict>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_already_mut_borrowed)]
+pub struct AlreadyMutBorrowed {
+    #[primary_span]
+    pub span: Span,
+    #[subdiagnostic]
+    pub occurences: Vec<Conflict>,
+}
+
+#[derive(Diagnostic)]
+#[diag(mir_build_moved_while_borrowed)]
+pub struct MovedWhileBorrowed {
+    #[primary_span]
+    pub span: Span,
+    #[subdiagnostic]
+    pub occurences: Vec<Conflict>,
 }
 
 #[derive(Subdiagnostic)]
-pub enum MultipleMutBorrowOccurence {
-    #[label(mutable_borrow)]
-    Mutable {
+pub enum Conflict {
+    #[label(mir_build_mutable_borrow)]
+    Mut {
         #[primary_span]
         span: Span,
-        name_mut: Ident,
+        name: Ident,
     },
-    #[label(immutable_borrow)]
-    Immutable {
+    #[label(mir_build_borrow)]
+    Ref {
         #[primary_span]
         span: Span,
-        name_immut: Ident,
+        name: Ident,
     },
-    #[label(moved)]
+    #[label(mir_build_moved)]
     Moved {
         #[primary_span]
         span: Span,
-        name_moved: Ident,
+        name: Ident,
     },
 }
 

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -926,58 +926,55 @@ fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pa
     sub.each_binding(|_, hir_id, span, name| {
         match typeck_results.extract_binding_mode(sess, hir_id, span) {
             Some(ty::BindByReference(mut_inner)) => match (mut_outer, mut_inner) {
-                (Mutability::Not, Mutability::Not) => {} // Both sides are `ref`.
-                (Mutability::Mut, Mutability::Mut) => conflicts_mut_mut.push((span, name)), // 2x `ref mut`.
-                _ => conflicts_mut_ref.push((span, name)), // `ref` + `ref mut` in either direction.
+                // Both sides are `ref`.
+                (Mutability::Not, Mutability::Not) => {}
+                // 2x `ref mut`.
+                (Mutability::Mut, Mutability::Mut) => {
+                    conflicts_mut_mut.push(Conflict::Mut { span, name })
+                }
+                (Mutability::Not, Mutability::Mut) => {
+                    conflicts_mut_ref.push(Conflict::Mut { span, name })
+                }
+                (Mutability::Mut, Mutability::Not) => {
+                    conflicts_mut_ref.push(Conflict::Ref { span, name })
+                }
             },
             Some(ty::BindByValue(_)) if is_binding_by_move(cx, hir_id) => {
-                conflicts_move.push((span, name)) // `ref mut?` + by-move conflict.
+                conflicts_move.push(Conflict::Moved { span, name }) // `ref mut?` + by-move conflict.
             }
             Some(ty::BindByValue(_)) | None => {} // `ref mut?` + by-copy is fine.
         }
     });
 
+    let report_mut_mut = !conflicts_mut_mut.is_empty();
+    let report_mut_ref = !conflicts_mut_ref.is_empty();
+    let report_move_conflict = !conflicts_move.is_empty();
+
+    let mut occurences = match mut_outer {
+        Mutability::Mut => vec![Conflict::Mut { span: binding_span, name }],
+        Mutability::Not => vec![Conflict::Ref { span: binding_span, name }],
+    };
+    occurences.extend(conflicts_mut_mut);
+    occurences.extend(conflicts_mut_ref);
+    occurences.extend(conflicts_move);
+
     // Report errors if any.
-    if !conflicts_mut_mut.is_empty() {
+    if report_mut_mut {
         // Report mutability conflicts for e.g. `ref mut x @ Some(ref mut y)`.
-        let mut occurences = vec![];
-
-        for (span, name_mut) in conflicts_mut_mut {
-            occurences.push(MultipleMutBorrowOccurence::Mutable { span, name_mut });
-        }
-        for (span, name_immut) in conflicts_mut_ref {
-            occurences.push(MultipleMutBorrowOccurence::Immutable { span, name_immut });
-        }
-        for (span, name_moved) in conflicts_move {
-            occurences.push(MultipleMutBorrowOccurence::Moved { span, name_moved });
-        }
-        sess.emit_err(MultipleMutBorrows { span: pat.span, binding_span, occurences, name });
-    } else if !conflicts_mut_ref.is_empty() {
+        sess.emit_err(MultipleMutBorrows { span: pat.span, occurences });
+    } else if report_mut_ref {
         // Report mutability conflicts for e.g. `ref x @ Some(ref mut y)` or the converse.
-        let (primary, also) = match mut_outer {
-            Mutability::Mut => ("mutable", "immutable"),
-            Mutability::Not => ("immutable", "mutable"),
+        match mut_outer {
+            Mutability::Mut => {
+                sess.emit_err(AlreadyMutBorrowed { span: pat.span, occurences });
+            }
+            Mutability::Not => {
+                sess.emit_err(AlreadyBorrowed { span: pat.span, occurences });
+            }
         };
-        let msg =
-            format!("cannot borrow value as {} because it is also borrowed as {}", also, primary);
-        let mut err = sess.struct_span_err(pat.span, &msg);
-        err.span_label(binding_span, format!("{} borrow, by `{}`, occurs here", primary, name));
-        for (span, name) in conflicts_mut_ref {
-            err.span_label(span, format!("{} borrow, by `{}`, occurs here", also, name));
-        }
-        for (span, name) in conflicts_move {
-            err.span_label(span, format!("also moved into `{}` here", name));
-        }
-        err.emit();
-    } else if !conflicts_move.is_empty() {
+    } else if report_move_conflict {
         // Report by-ref and by-move conflicts, e.g. `ref x @ y`.
-        let mut err =
-            sess.struct_span_err(pat.span, "cannot move out of value because it is borrowed");
-        err.span_label(binding_span, format!("value borrowed, by `{}`, here", name));
-        for (span, name) in conflicts_move {
-            err.span_label(span, format!("value moved into `{}` here", name));
-        }
-        err.emit();
+        sess.emit_err(MovedWhileBorrowed { span: pat.span, occurences });
     }
 }
 

tests/ui/borrowck/bindings-after-at-or-patterns-slice-patterns-box-patterns.stderr

@@ -4,17 +4,17 @@ error: cannot borrow value as mutable because it is also borrowed as immutable
 LL |         ref foo @ [.., ref mut bar] => (),
    |         -------^^^^^^^^-----------^
    |         |              |
-   |         |              mutable borrow, by `bar`, occurs here
-   |         immutable borrow, by `foo`, occurs here
+   |         |              value is mutably borrowed by `bar` here
+   |         value is borrowed by `foo` here
 
 error: cannot borrow value as mutable because it is also borrowed as immutable
   --> $DIR/bindings-after-at-or-patterns-slice-patterns-box-patterns.rs:120:9
    |
 LL |         ref foo @ Some(box ref mut s) => (),
    |         -------^^^^^^^^^^^^---------^
    |         |                  |
-   |         |                  mutable borrow, by `s`, occurs here
-   |         immutable borrow, by `foo`, occurs here
+   |         |                  value is mutably borrowed by `s` here
+   |         value is borrowed by `foo` here
 
 error[E0382]: borrow of moved value: `x`
   --> $DIR/bindings-after-at-or-patterns-slice-patterns-box-patterns.rs:18:5

tests/ui/pattern/bindings-after-at/bind-by-move-neither-can-live-while-the-other-survives-1.stderr

@@ -4,8 +4,8 @@ error: cannot move out of value because it is borrowed
 LL |         Some(ref _y @ _z) => {}
    |              ------^^^--
    |              |        |
-   |              |        value moved into `_z` here
-   |              value borrowed, by `_y`, here
+   |              |        value is moved into `_z` here
+   |              value is borrowed by `_y` here
 
 error: borrow of moved value
   --> $DIR/bind-by-move-neither-can-live-while-the-other-survives-1.rs:19:14
@@ -28,8 +28,8 @@ error: cannot move out of value because it is borrowed
 LL |         Some(ref mut _y @ _z) => {}
    |              ----------^^^--
    |              |            |
-   |              |            value moved into `_z` here
-   |              value borrowed, by `_y`, here
+   |              |            value is moved into `_z` here
+   |              value is mutably borrowed by `_y` here
 
 error: borrow of moved value
   --> $DIR/bind-by-move-neither-can-live-while-the-other-survives-1.rs:33:14

tests/ui/pattern/bindings-after-at/borrowck-pat-at-and-box.stderr

@@ -4,71 +4,71 @@ error: cannot move out of value because it is borrowed
 LL |     let ref a @ box b = Box::new(NC);
    |         -----^^^^^^^-
    |         |           |
-   |         |           value moved into `b` here
-   |         value borrowed, by `a`, here
+   |         |           value is moved into `b` here
+   |         value is borrowed by `a` here
 
 error: cannot borrow value as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-pat-at-and-box.rs:34:9
    |
 LL |     let ref a @ box ref mut b = Box::new(nc());
    |         -----^^^^^^^---------
    |         |           |
-   |         |           mutable borrow, by `b`, occurs here
-   |         immutable borrow, by `a`, occurs here
+   |         |           value is mutably borrowed by `b` here
+   |         value is borrowed by `a` here
 
 error: cannot borrow value as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-pat-at-and-box.rs:36:9
    |
 LL |     let ref a @ box ref mut b = Box::new(NC);
    |         -----^^^^^^^---------
    |         |           |
-   |         |           mutable borrow, by `b`, occurs here
-   |         immutable borrow, by `a`, occurs here
+   |         |           value is mutably borrowed by `b` here
+   |         value is borrowed by `a` here
 
 error: cannot borrow value as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-pat-at-and-box.rs:38:9
    |
 LL |     let ref a @ box ref mut b = Box::new(NC);
    |         -----^^^^^^^---------
    |         |           |
-   |         |           mutable borrow, by `b`, occurs here
-   |         immutable borrow, by `a`, occurs here
+   |         |           value is mutably borrowed by `b` here
+   |         value is borrowed by `a` here
 
 error: cannot borrow value as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-pat-at-and-box.rs:42:9
    |
 LL |     let ref a @ box ref mut b = Box::new(NC);
    |         -----^^^^^^^---------
    |         |           |
-   |         |           mutable borrow, by `b`, occurs here
-   |         immutable borrow, by `a`, occurs here
+   |         |           value is mutably borrowed by `b` here
+   |         value is borrowed by `a` here
 
 error: cannot borrow value as immutable because it is also borrowed as mutable
   --> $DIR/borrowck-pat-at-and-box.rs:48:9
    |
 LL |     let ref mut a @ box ref b = Box::new(NC);
    |         ---------^^^^^^^-----
    |         |               |
-   |         |               immutable borrow, by `b`, occurs here
-   |         mutable borrow, by `a`, occurs here
+   |         |               value is borrowed by `b` here
+   |         value is mutably borrowed by `a` here
 
 error: cannot borrow value as immutable because it is also borrowed as mutable
   --> $DIR/borrowck-pat-at-and-box.rs:62:9
    |
 LL |         ref mut a @ box ref b => {
    |         ---------^^^^^^^-----
    |         |               |
-   |         |               immutable borrow, by `b`, occurs here
-   |         mutable borrow, by `a`, occurs here
+   |         |               value is borrowed by `b` here
+   |         value is mutably borrowed by `a` here
 
 error: cannot borrow value as immutable because it is also borrowed as mutable
   --> $DIR/borrowck-pat-at-and-box.rs:54:11
    |
 LL |     fn f5(ref mut a @ box ref b: Box<NC>) {
    |           ---------^^^^^^^-----
    |           |               |
-   |           |               immutable borrow, by `b`, occurs here
-   |           mutable borrow, by `a`, occurs here
+   |           |               value is borrowed by `b` here
+   |           value is mutably borrowed by `a` here
 
 error[E0382]: borrow of moved value
   --> $DIR/borrowck-pat-at-and-box.rs:31:9