Rollup merge of #84358 - sexxi-goose:print_captures_borrowck_rebased, r=nikomatsakis

Update closure capture error logging for disjoint captures for disjoint captures

Improved error logging when `#![feature(capture_disjoint_fields)]` is used.

Closes rust-lang/project-rfc-2229#8
Closes rust-lang/project-rfc-2229#36
Closes rust-lang/project-rfc-2229#39
Closes #76005

Author: Dylan-DPC

compiler/rustc_middle/src/mir/mod.rs

@@ -683,6 +683,15 @@ impl BorrowKind {
             BorrowKind::Mut { allow_two_phase_borrow } => allow_two_phase_borrow,
         }
     }
+
+    pub fn describe_mutability(&self) -> String {
+        match *self {
+            BorrowKind::Shared | BorrowKind::Shallow | BorrowKind::Unique => {
+                "immutable".to_string()
+            }
+            BorrowKind::Mut { .. } => "mutable".to_string(),
+        }
+    }
 }
 
 ///////////////////////////////////////////////////////////////////////////
@@ -2369,6 +2378,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                             };
                             let mut struct_fmt = fmt.debug_struct(&name);
 
+                            // FIXME(project-rfc-2229#48): This should be a list of capture names/places
                             if let Some(upvars) = tcx.upvars_mentioned(def_id) {
                                 for (&var_id, place) in iter::zip(upvars.keys(), places) {
                                     let var_name = tcx.hir().name(var_id);
@@ -2388,6 +2398,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                             let name = format!("[generator@{:?}]", tcx.hir().span(hir_id));
                             let mut struct_fmt = fmt.debug_struct(&name);
 
+                            // FIXME(project-rfc-2229#48): This should be a list of capture names/places
                             if let Some(upvars) = tcx.upvars_mentioned(def_id) {
                                 for (&var_id, place) in iter::zip(upvars.keys(), places) {
                                     let var_name = tcx.hir().name(var_id);

compiler/rustc_middle/src/ty/closure.rs

@@ -151,6 +151,10 @@ pub struct CapturedPlace<'tcx> {
 }
 
 impl CapturedPlace<'tcx> {
+    pub fn to_string(&self, tcx: TyCtxt<'tcx>) -> String {
+        place_to_string_for_capture(tcx, &self.place)
+    }
+
     /// Returns the hir-id of the root variable for the captured place.
     /// e.g., if `a.b.c` was captured, would return the hir-id for `a`.
     pub fn get_root_variable(&self) -> hir::HirId {
@@ -168,6 +172,22 @@ impl CapturedPlace<'tcx> {
         }
     }
 
+    /// Return span pointing to use that resulted in selecting the captured path
+    pub fn get_path_span(&self, tcx: TyCtxt<'tcx>) -> Span {
+        if let Some(path_expr_id) = self.info.path_expr_id {
+            tcx.hir().span(path_expr_id)
+        } else if let Some(capture_kind_expr_id) = self.info.capture_kind_expr_id {
+            tcx.hir().span(capture_kind_expr_id)
+        } else {
+            // Fallback on upvars mentioned if neither path or capture expr id is captured
+
+            // Safe to unwrap since we know this place is captured by the closure, therefore the closure must have upvars.
+            tcx.upvars_mentioned(self.get_closure_local_def_id()).unwrap()
+                [&self.get_root_variable()]
+                .span
+        }
+    }
+
     /// Return span pointing to use that resulted in selecting the current capture kind
     pub fn get_capture_kind_span(&self, tcx: TyCtxt<'tcx>) -> Span {
         if let Some(capture_kind_expr_id) = self.info.capture_kind_expr_id {