Tweak short_ty_string to reduce number of files

When shortening types and writing them to disk, make `short_ty_string`
capable of reusing the same file, instead of writing a file per
shortened type.

Author: estebank

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -262,7 +262,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         rcvr_ty: Ty<'tcx>,
         rcvr_expr: &hir::Expr<'tcx>,
     ) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
-        let (ty_str, _ty_file) = self.tcx.short_ty_string(rcvr_ty);
+        let mut file = None;
+        let ty_str = self.tcx.short_ty_string(rcvr_ty, &mut file);
         let mut err = struct_span_err!(
             self.tcx.sess,
             rcvr_expr.span,
@@ -280,6 +281,9 @@ 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
     }
@@ -299,11 +303,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mode = no_match_data.mode;
         let tcx = self.tcx;
         let rcvr_ty = self.resolve_vars_if_possible(rcvr_ty);
-        let ((mut ty_str, ty_file), short_ty_str) =
+        let mut ty_file = None;
+        let (mut ty_str, short_ty_str) =
             if trait_missing_method && let ty::Dynamic(predicates, _, _) = rcvr_ty.kind() {
-                ((predicates.to_string(), None), with_forced_trimmed_paths!(predicates.to_string()))
+                (predicates.to_string(), with_forced_trimmed_paths!(predicates.to_string()))
             } else {
-                (tcx.short_ty_string(rcvr_ty), with_forced_trimmed_paths!(rcvr_ty.to_string()))
+                (
+                    tcx.short_ty_string(rcvr_ty, &mut ty_file),
+                    with_forced_trimmed_paths!(rcvr_ty.to_string()),
+                )
             };
         let is_method = mode == Mode::MethodCall;
         let unsatisfied_predicates = &no_match_data.unsatisfied_predicates;

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1735,7 +1735,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             }
         }
 
-        if let Some((expected, found, exp_p, found_p)) = expected_found {
+        if let Some((expected, found, path)) = expected_found {
             let (expected_label, found_label, exp_found) = match exp_found {
                 Mismatch::Variable(ef) => (
                     ef.expected.prefix_string(self.tcx),
@@ -1861,40 +1861,31 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 }
                 TypeError::Sorts(values) => {
                     let extra = expected == found;
-                    let sort_string = |ty: Ty<'tcx>, path: Option<PathBuf>| {
-                        let mut s = match (extra, ty.kind()) {
-                            (true, ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. })) => {
-                                let sm = self.tcx.sess.source_map();
-                                let pos = sm.lookup_char_pos(self.tcx.def_span(*def_id).lo());
-                                format!(
-                                    " (opaque type at <{}:{}:{}>)",
-                                    sm.filename_for_diagnostics(&pos.file.name),
-                                    pos.line,
-                                    pos.col.to_usize() + 1,
-                                )
-                            }
-                            (true, ty::Alias(ty::Projection, proj))
-                                if self.tcx.is_impl_trait_in_trait(proj.def_id) =>
-                            {
-                                let sm = self.tcx.sess.source_map();
-                                let pos = sm.lookup_char_pos(self.tcx.def_span(proj.def_id).lo());
-                                format!(
-                                    " (trait associated opaque type at <{}:{}:{}>)",
-                                    sm.filename_for_diagnostics(&pos.file.name),
-                                    pos.line,
-                                    pos.col.to_usize() + 1,
-                                )
-                            }
-                            (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
-                            (false, _) => "".to_string(),
-                        };
-                        if let Some(path) = path {
-                            s.push_str(&format!(
-                                "\nthe full type name has been written to '{}'",
-                                path.display(),
-                            ));
+                    let sort_string = |ty: Ty<'tcx>| match (extra, ty.kind()) {
+                        (true, ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. })) => {
+                            let sm = self.tcx.sess.source_map();
+                            let pos = sm.lookup_char_pos(self.tcx.def_span(*def_id).lo());
+                            format!(
+                                " (opaque type at <{}:{}:{}>)",
+                                sm.filename_for_diagnostics(&pos.file.name),
+                                pos.line,
+                                pos.col.to_usize() + 1,
+                            )
                         }
-                        s
+                        (true, ty::Alias(ty::Projection, proj))
+                            if self.tcx.is_impl_trait_in_trait(proj.def_id) =>
+                        {
+                            let sm = self.tcx.sess.source_map();
+                            let pos = sm.lookup_char_pos(self.tcx.def_span(proj.def_id).lo());
+                            format!(
+                                " (trait associated opaque type at <{}:{}:{}>)",
+                                sm.filename_for_diagnostics(&pos.file.name),
+                                pos.line,
+                                pos.col.to_usize() + 1,
+                            )
+                        }
+                        (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
+                        (false, _) => "".to_string(),
                     };
                     if !(values.expected.is_simple_text(self.tcx)
                         && values.found.is_simple_text(self.tcx))
@@ -1925,9 +1916,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                     expected,
                                     &found_label,
                                     found,
-                                    &sort_string(values.expected, exp_p),
-                                    &sort_string(values.found, found_p),
+                                    &sort_string(values.expected),
+                                    &sort_string(values.found),
                                 );
+                                if let Some(path) = path {
+                                    diag.note(format!(
+                                        "the full type name has been written to '{}'",
+                                        path.display(),
+                                    ));
+                                }
                             }
                         }
                     }
@@ -2093,7 +2090,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         if let &(MatchExpressionArm(box MatchExpressionArmCause { source, .. })
         | BlockTailExpression(.., source)) = code
             && let hir::MatchSource::TryDesugar(_) = source
-            && let Some((expected_ty, found_ty, _, _)) = self.values_str(trace.values)
+            && let Some((expected_ty, found_ty, _)) = self.values_str(trace.values)
         {
             suggestions.push(TypeErrorAdditionalDiags::TryCannotConvert {
                 found: found_ty.content(),
@@ -2211,8 +2208,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn values_str(
         &self,
         values: ValuePairs<'tcx>,
-    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>, Option<PathBuf>)>
-    {
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>)> {
         match values {
             infer::Regions(exp_found) => self.expected_found_str(exp_found),
             infer::Terms(exp_found) => self.expected_found_str_term(exp_found),
@@ -2225,7 +2221,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     found: exp_found.found.print_only_trait_path(),
                 };
                 match self.expected_found_str(pretty_exp_found) {
-                    Some((expected, found, _, _)) if expected == found => {
+                    Some((expected, found, _)) if expected == found => {
                         self.expected_found_str(exp_found)
                     }
                     ret => ret,
@@ -2237,7 +2233,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     found: exp_found.found.print_only_trait_path(),
                 };
                 match self.expected_found_str(pretty_exp_found) {
-                    Some((expected, found, _, _)) if expected == found => {
+                    Some((expected, found, _)) if expected == found => {
                         self.expected_found_str(exp_found)
                     }
                     ret => ret,
@@ -2249,16 +2245,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     return None;
                 }
                 let (exp, fnd) = self.cmp_fn_sig(&exp_found.expected, &exp_found.found);
-                Some((exp, fnd, None, None))
+                Some((exp, fnd, None))
             }
         }
     }
 
     fn expected_found_str_term(
         &self,
         exp_found: ty::error::ExpectedFound<ty::Term<'tcx>>,
-    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>, Option<PathBuf>)>
-    {
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>)> {
         let exp_found = self.resolve_vars_if_possible(exp_found);
         if exp_found.references_error() {
             return None;
@@ -2273,25 +2268,21 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 let len = self.tcx.sess().diagnostic_width() + 40;
                 let exp_s = exp.content();
                 let fnd_s = fnd.content();
-                let mut exp_p = None;
-                let mut fnd_p = None;
+                let mut path = None;
                 if exp_s.len() > len {
-                    let (exp_s, exp_path) = self.tcx.short_ty_string(expected);
+                    let exp_s = self.tcx.short_ty_string(expected, &mut path);
                     exp = DiagnosticStyledString::highlighted(exp_s);
-                    exp_p = exp_path;
                 }
                 if fnd_s.len() > len {
-                    let (fnd_s, fnd_path) = self.tcx.short_ty_string(found);
+                    let fnd_s = self.tcx.short_ty_string(found, &mut path);
                     fnd = DiagnosticStyledString::highlighted(fnd_s);
-                    fnd_p = fnd_path;
                 }
-                (exp, fnd, exp_p, fnd_p)
+                (exp, fnd, path)
             }
             _ => (
                 DiagnosticStyledString::highlighted(exp_found.expected.to_string()),
                 DiagnosticStyledString::highlighted(exp_found.found.to_string()),
                 None,
-                None,
             ),
         })
     }
@@ -2300,8 +2291,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn expected_found_str<T: fmt::Display + TypeFoldable<TyCtxt<'tcx>>>(
         &self,
         exp_found: ty::error::ExpectedFound<T>,
-    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>, Option<PathBuf>)>
-    {
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>)> {
         let exp_found = self.resolve_vars_if_possible(exp_found);
         if exp_found.references_error() {
             return None;
@@ -2311,7 +2301,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             DiagnosticStyledString::highlighted(exp_found.expected.to_string()),
             DiagnosticStyledString::highlighted(exp_found.found.to_string()),
             None,
-            None,
         ))
     }
 
@@ -2595,8 +2584,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
         if let infer::Subtype(ref sup_trace) = sup_origin
             && let infer::Subtype(ref sub_trace) = sub_origin
-            && let Some((sup_expected, sup_found, _, _)) = self.values_str(sup_trace.values)
-            && let Some((sub_expected, sub_found, _, _)) = self.values_str(sub_trace.values)
+            && let Some((sup_expected, sup_found, _)) = self.values_str(sup_trace.values)
+            && let Some((sub_expected, sub_found, _)) = self.values_str(sub_trace.values)
             && sub_expected == sup_expected
             && sub_found == sup_found
         {

compiler/rustc_infer/src/infer/error_reporting/note.rs

@@ -22,7 +22,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             infer::Subtype(ref trace) => RegionOriginNote::WithRequirement {
                 span: trace.cause.span,
                 requirement: ObligationCauseAsDiagArg(trace.cause.clone()),
-                expected_found: self.values_str(trace.values).map(|(e, f, _, _)| (e, f)),
+                expected_found: self.values_str(trace.values).map(|(e, f, _)| (e, f)),
             }
             .add_to_diagnostic(err),
             infer::Reborrow(span) => {

compiler/rustc_middle/src/ty/error.rs

@@ -345,33 +345,35 @@ impl<'tcx> TyCtxt<'tcx> {
         short
     }
 
-    pub fn short_ty_string(self, ty: Ty<'tcx>) -> (String, Option<PathBuf>) {
+    pub fn short_ty_string(self, ty: Ty<'tcx>, path: &mut Option<PathBuf>) -> String {
         let regular = FmtPrinter::print_string(self, hir::def::Namespace::TypeNS, |cx| {
             cx.pretty_print_type(ty)
         })
         .expect("could not write to `String`");
 
         if !self.sess.opts.unstable_opts.write_long_types_to_disk {
-            return (regular, None);
+            return regular;
         }
 
         let width = self.sess.diagnostic_width();
         let length_limit = width.saturating_sub(30);
         if regular.len() <= width {
-            return (regular, None);
+            return regular;
         }
         let short = self.ty_string_with_limit(ty, length_limit);
         if regular == short {
-            return (regular, None);
+            return regular;
         }
-        // Multiple types might be shortened in a single error, ensure we create a file for each.
+        // Ensure we create an unique file for the type passed in when we create a file.
         let mut s = DefaultHasher::new();
         ty.hash(&mut s);
         let hash = s.finish();
-        let path = self.output_filenames(()).temp_path_ext(&format!("long-type-{hash}.txt"), None);
-        match std::fs::write(&path, &regular) {
-            Ok(_) => (short, Some(path)),
-            Err(_) => (regular, None),
+        *path = Some(path.take().unwrap_or_else(|| {
+            self.output_filenames(()).temp_path_ext(&format!("long-type-{hash}.txt"), None)
+        }));
+        match std::fs::write(path.as_ref().unwrap(), &format!("{regular}\n")) {
+            Ok(_) => short,
+            Err(_) => regular,
         }
     }
 }