Rework "long type names" printing logic

Make it so more type-system types can be printed in a shortened version (like `Predicate`s).

Centralize printing the information about the "full type name path".

Make the "long type path" for the file where long types are written part of `Diag`, so that it becomes easier to keep track of it, and ensure it will always will be printed out last in the diagnostic by making its addition to the output implicit.

Tweak the shortening of types in "expected/found" labels.

Remove dead file `note.rs`.

compiler/rustc_borrowck/messages.ftl

@@ -92,9 +92,6 @@ borrowck_lifetime_constraints_error =
 borrowck_limitations_implies_static =
     due to current limitations in the borrow checker, this implies a `'static` lifetime
 
-borrowck_long_type_consider_verbose = consider using `--verbose` to print the full type name to the console
-borrowck_long_type_full_path = the full type name has been written to '{$path}'
-
 borrowck_move_closure_suggestion =
     consider adding 'move' keyword before the nested closure
 

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -289,8 +289,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 None => "value".to_owned(),
             };
             if needs_note {
-                let mut path = None;
-                let ty = self.infcx.tcx.short_ty_string(ty, &mut path);
+                let ty = self.infcx.tcx.short_string(ty, err.long_ty_path());
                 if let Some(local) = place.as_local() {
                     let span = self.body.local_decls[local].source_info.span;
                     err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
@@ -306,11 +305,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         place: &note_msg,
                     });
                 };
-                if let Some(path) = path {
-                    err.subdiagnostic(crate::session_diagnostics::LongTypePath {
-                        path: path.display().to_string(),
-                    });
-                }
             }
 
             if let UseSpans::FnSelfUse {

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -596,19 +596,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         self.suggest_cloning(err, place_ty, expr, None);
                     }
 
-                    let mut path = None;
-                    let ty = self.infcx.tcx.short_ty_string(place_ty, &mut path);
+                    let ty = self.infcx.tcx.short_string(place_ty, err.long_ty_path());
                     err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
                         is_partial_move: false,
                         ty,
                         place: &place_desc,
                         span,
                     });
-                    if let Some(path) = path {
-                        err.subdiagnostic(crate::session_diagnostics::LongTypePath {
-                            path: path.display().to_string(),
-                        });
-                    }
                 } else {
                     binds_to.sort();
                     binds_to.dedup();
@@ -635,19 +629,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     self.suggest_cloning(err, place_ty, expr, Some(use_spans));
                 }
 
-                let mut path = None;
-                let ty = self.infcx.tcx.short_ty_string(place_ty, &mut path);
+                let ty = self.infcx.tcx.short_string(place_ty, err.long_ty_path());
                 err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
                     is_partial_move: false,
                     ty,
                     place: &place_desc,
                     span: use_span,
                 });
-                if let Some(path) = path {
-                    err.subdiagnostic(crate::session_diagnostics::LongTypePath {
-                        path: path.display().to_string(),
-                    });
-                }
 
                 use_spans.args_subdiag(err, |args_span| {
                     crate::session_diagnostics::CaptureArgLabel::MoveOutPlace {
@@ -845,19 +833,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     self.suggest_cloning(err, bind_to.ty, expr, None);
                 }
 
-                let mut path = None;
-                let ty = self.infcx.tcx.short_ty_string(bind_to.ty, &mut path);
+                let ty = self.infcx.tcx.short_string(bind_to.ty, err.long_ty_path());
                 err.subdiagnostic(crate::session_diagnostics::TypeNoCopy::Label {
                     is_partial_move: false,
                     ty,
                     place: place_desc,
                     span: binding_span,
                 });
-                if let Some(path) = path {
-                    err.subdiagnostic(crate::session_diagnostics::LongTypePath {
-                        path: path.display().to_string(),
-                    });
-                }
             }
         }
 

compiler/rustc_borrowck/src/session_diagnostics.rs

@@ -458,13 +458,6 @@ pub(crate) enum OnClosureNote<'a> {
     },
 }
 
-#[derive(Subdiagnostic)]
-#[note(borrowck_long_type_full_path)]
-#[note(borrowck_long_type_consider_verbose)]
-pub(crate) struct LongTypePath {
-    pub(crate) path: String,
-}
-
 #[derive(Subdiagnostic)]
 pub(crate) enum TypeNoCopy<'a> {
     #[label(borrowck_ty_no_impl_copy)]

compiler/rustc_errors/src/diagnostic.rs

@@ -4,6 +4,7 @@ use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};
 use std::panic;
+use std::path::PathBuf;
 use std::thread::panicking;
 
 use rustc_data_structures::fx::FxIndexMap;
@@ -301,6 +302,7 @@ pub struct DiagInner {
 
     pub is_lint: Option<IsLint>,
 
+    pub long_ty_path: Option<PathBuf>,
     /// With `-Ztrack_diagnostics` enabled,
     /// we print where in rustc this error was emitted.
     pub(crate) emitted_at: DiagLocation,
@@ -324,6 +326,7 @@ impl DiagInner {
             args: Default::default(),
             sort_span: DUMMY_SP,
             is_lint: None,
+            long_ty_path: None,
             emitted_at: DiagLocation::caller(),
         }
     }
@@ -1293,9 +1296,37 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
     /// `cancel`, etc. Afterwards, `drop` is the only code that will be run on
     /// `self`.
     fn take_diag(&mut self) -> DiagInner {
+        if let Some(path) = &self.long_ty_path {
+            self.note(format!(
+                "the full name for the type has been written to '{}'",
+                path.display()
+            ));
+            self.note("consider using `--verbose` to print the full type name to the console");
+        }
         Box::into_inner(self.diag.take().unwrap())
     }
 
+    /// This method allows us to access the path of the file where "long types" are written to.
+    ///
+    /// When calling `Diag::emit`, as part of that we will check if a `long_ty_path` has been set,
+    /// and if it has been then we add a note mentioning the file where the "long types" were
+    /// written to.
+    ///
+    /// When calling `tcx.short_string()` after a `Diag` is constructed, the preferred way of doing
+    /// so is `tcx.short_string(ty, diag.long_ty_path())`. The diagnostic itself is the one that
+    /// keeps the existence of a "long type" anywhere in the diagnostic, so the note telling the
+    /// user where we wrote the file to is only printed once at most, *and* it makes it much harder
+    /// to forget to set it.
+    ///
+    /// If the diagnostic hasn't been created before a "short ty string" is created, then you should
+    /// ensure that this method is called to set it `*diag.long_ty_path() = path`.
+    ///
+    /// As a rule of thumb, if you see or add at least one `tcx.short_string()` call anywhere, in a
+    /// scope, `diag.long_ty_path()` should be called once somewhere close by.
+    pub fn long_ty_path(&mut self) -> &mut Option<PathBuf> {
+        &mut self.long_ty_path
+    }
+
     /// Most `emit_producing_guarantee` functions use this as a starting point.
     fn emit_producing_nothing(mut self) {
         let diag = self.take_diag();

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -5,6 +5,7 @@
 
 use core::ops::ControlFlow;
 use std::borrow::Cow;
+use std::path::PathBuf;
 
 use hir::Expr;
 use rustc_ast::ast::Mutability;
@@ -362,14 +363,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     fn suggest_missing_writer(&self, rcvr_ty: Ty<'tcx>, rcvr_expr: &hir::Expr<'tcx>) -> Diag<'_> {
         let mut file = None;
-        let ty_str = self.tcx.short_ty_string(rcvr_ty, &mut file);
         let mut err = struct_span_code_err!(
             self.dcx(),
             rcvr_expr.span,
             E0599,
             "cannot write into `{}`",
-            ty_str
+            self.tcx.short_string(rcvr_ty, &mut file),
         );
+        *err.long_ty_path() = file;
         err.span_note(
             rcvr_expr.span,
             "must implement `io::Write`, `fmt::Write`, or have a `write_fmt` method",
@@ -380,11 +381,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 "a writer is needed before this format string",
             );
         };
-        if let Some(file) = file {
-            err.note(format!("the full type name has been written to '{}'", file.display()));
-            err.note("consider using `--verbose` to print the full type name to the console");
-        }
-
         err
     }
 
@@ -595,7 +591,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 (predicates.to_string(), with_forced_trimmed_paths!(predicates.to_string()))
             } else {
                 (
-                    tcx.short_ty_string(rcvr_ty, &mut ty_file),
+                    tcx.short_string(rcvr_ty, &mut ty_file),
                     with_forced_trimmed_paths!(rcvr_ty.to_string()),
                 )
             };
@@ -624,6 +620,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             span,
             item_name,
             &short_ty_str,
+            &mut ty_file,
         ) {
             return guar;
         }
@@ -635,6 +632,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             item_kind,
             item_name,
             &short_ty_str,
+            &mut ty_file,
         ) {
             return guar;
         }
@@ -728,10 +726,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ty_str = short_ty_str;
         }
 
-        if let Some(file) = ty_file {
-            err.note(format!("the full type name has been written to '{}'", file.display(),));
-            err.note("consider using `--verbose` to print the full type name to the console");
-        }
         if rcvr_ty.references_error() {
             err.downgrade_to_delayed_bug();
         }
@@ -1314,7 +1308,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     bound_list.into_iter().map(|(_, path)| path).collect::<Vec<_>>().join("\n");
                 let actual_prefix = rcvr_ty.prefix_string(self.tcx);
                 info!("unimplemented_traits.len() == {}", unimplemented_traits.len());
-                let mut long_ty_file = None;
                 let (primary_message, label, notes) = if unimplemented_traits.len() == 1
                     && unimplemented_traits_only
                 {
@@ -1329,7 +1322,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             }
                             let OnUnimplementedNote { message, label, notes, .. } = self
                                 .err_ctxt()
-                                .on_unimplemented_note(trait_ref, &obligation, &mut long_ty_file);
+                                .on_unimplemented_note(trait_ref, &obligation, &mut ty_file);
                             (message, label, notes)
                         })
                         .unwrap()
@@ -1343,15 +1336,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     )
                 });
                 err.primary_message(primary_message);
-                if let Some(file) = long_ty_file {
-                    err.note(format!(
-                        "the full name for the type has been written to '{}'",
-                        file.display(),
-                    ));
-                    err.note(
-                        "consider using `--verbose` to print the full type name to the console",
-                    );
-                }
                 if let Some(label) = label {
                     custom_span_label = true;
                     err.span_label(span, label);
@@ -2403,6 +2387,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         span: Span,
         item_name: Ident,
         ty_str: &str,
+        long_ty_path: &mut Option<PathBuf>,
     ) -> Result<(), ErrorGuaranteed> {
         if let SelfSource::MethodCall(expr) = source {
             for (_, parent) in tcx.hir().parent_iter(expr.hir_id).take(5) {
@@ -2460,7 +2445,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     );
                     if pick.is_ok() {
                         let range_span = parent_expr.span.with_hi(expr.span.hi());
-                        return Err(self.dcx().emit_err(errors::MissingParenthesesInRange {
+                        let mut err = self.dcx().create_err(errors::MissingParenthesesInRange {
                             span,
                             ty_str: ty_str.to_string(),
                             method_name: item_name.as_str().to_string(),
@@ -2469,7 +2454,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 left: range_span.shrink_to_lo(),
                                 right: range_span.shrink_to_hi(),
                             }),
-                        }));
+                        });
+                        *err.long_ty_path() = long_ty_path.take();
+                        return Err(err.emit());
                     }
                 }
             }
@@ -2486,6 +2473,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         item_kind: &str,
         item_name: Ident,
         ty_str: &str,
+        long_ty_path: &mut Option<PathBuf>,
     ) -> Result<(), ErrorGuaranteed> {
         let found_candidate = all_traits(self.tcx)
             .into_iter()
@@ -2526,6 +2514,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 item_name,
                 ty_str
             );
+            *err.long_ty_path() = long_ty_path.take();
             let concrete_type = if actual.is_integral() { "i32" } else { "f32" };
             match expr.kind {
                 ExprKind::Lit(lit) => {