review comments

Author: estebank

src/librustc_resolve/diagnostics.rs

@@ -19,7 +19,7 @@ use syntax::ast::{self, Ident, Path};
 use syntax::util::lev_distance::find_best_match_for_name;
 
 use crate::imports::{ImportDirective, ImportDirectiveSubclass, ImportResolver};
-use crate::lifetimes::{ElisionFailureInfo, ForLifetimeSpanType, MissingLifetimeSpot};
+use crate::lifetimes::{ElisionFailureInfo, MissingLifetimeSpot};
 use crate::path_names_to_string;
 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
 use crate::{BindingError, CrateLint, HasGenericParams, LegacyScope, Module, ModuleOrUniformRoot};
@@ -1502,30 +1502,17 @@ crate fn add_missing_lifetime_specifiers_label(
                             [param, ..] => (param.span.shrink_to_lo(), "'a, ".to_string()),
                         }
                     }
-                    MissingLifetimeSpot::HRLT { span, span_type } => {
+                    MissingLifetimeSpot::HigherRanked { span, span_type } => {
                         msg = format!(
                             "consider making the {} lifetime-generic with a new `'a` lifetime",
-                            match span_type {
-                                ForLifetimeSpanType::BoundEmpty
-                                | ForLifetimeSpanType::BoundTail => "bound",
-                                ForLifetimeSpanType::TypeEmpty | ForLifetimeSpanType::TypeTail =>
-                                    "type",
-                            }
+                            span_type.descr(),
                         );
                         should_break = false;
                         err.note(
                             "for more information on higher-ranked polymorphism, visit \
                              https://doc.rust-lang.org/nomicon/hrtb.html",
                         );
-                        let suggestion = match span_type {
-                            ForLifetimeSpanType::BoundEmpty | ForLifetimeSpanType::TypeEmpty => {
-                                "for<'a> "
-                            }
-                            ForLifetimeSpanType::BoundTail | ForLifetimeSpanType::TypeTail => {
-                                ", 'a"
-                            }
-                        };
-                        (*span, suggestion.to_string())
+                        (*span, span_type.suggestion("'a"))
                     }
                 });
                 for param in params {

src/librustc_resolve/lifetimes.rs

@@ -155,7 +155,7 @@ struct NamedRegionMap {
 
 crate enum MissingLifetimeSpot<'tcx> {
     Generics(&'tcx hir::Generics<'tcx>),
-    HRLT { span: Span, span_type: ForLifetimeSpanType },
+    HigherRanked { span: Span, span_type: ForLifetimeSpanType },
 }
 
 crate enum ForLifetimeSpanType {
@@ -165,6 +165,22 @@ crate enum ForLifetimeSpanType {
     TypeTail,
 }
 
+impl ForLifetimeSpanType {
+    crate fn descr(&self) -> &'static str {
+        match self {
+            Self::BoundEmpty | Self::BoundTail => "bound",
+            Self::TypeEmpty | Self::TypeTail => "type",
+        }
+    }
+
+    crate fn suggestion(&self, sugg: &str) -> String {
+        match self {
+            Self::BoundEmpty | Self::TypeEmpty => format!("for<{}> ", sugg),
+            Self::BoundTail | Self::TypeTail => format!(", {}", sugg),
+        }
+    }
+}
+
 impl<'tcx> Into<MissingLifetimeSpot<'tcx>> for &'tcx hir::Generics<'tcx> {
     fn into(self) -> MissingLifetimeSpot<'tcx> {
         MissingLifetimeSpot::Generics(self)
@@ -525,7 +541,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
                     (ty.span.shrink_to_lo(), ForLifetimeSpanType::TypeEmpty)
                 };
                 self.missing_named_lifetime_spots
-                    .push(MissingLifetimeSpot::HRLT { span, span_type });
+                    .push(MissingLifetimeSpot::HigherRanked { span, span_type });
                 let scope = Scope::Binder {
                     lifetimes: c
                         .generic_params
@@ -1887,29 +1903,15 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                             Applicability::MaybeIncorrect,
                         );
                     }
-                    MissingLifetimeSpot::HRLT { span, span_type } => {
+                    MissingLifetimeSpot::HigherRanked { span, span_type } => {
                         err.span_suggestion(
                             *span,
                             &format!(
                                 "consider making the {} lifetime-generic with a new `{}` lifetime",
-                                match span_type {
-                                    ForLifetimeSpanType::BoundEmpty
-                                    | ForLifetimeSpanType::BoundTail => "bound",
-                                    ForLifetimeSpanType::TypeEmpty
-                                    | ForLifetimeSpanType::TypeTail => "type",
-                                },
+                                span_type.descr(),
                                 lifetime_ref
                             ),
-                            match span_type {
-                                ForLifetimeSpanType::TypeEmpty
-                                | ForLifetimeSpanType::BoundEmpty => {
-                                    format!("for<{}> ", lifetime_ref)
-                                }
-                                ForLifetimeSpanType::TypeTail | ForLifetimeSpanType::BoundTail => {
-                                    format!(", {}", lifetime_ref)
-                                }
-                            }
-                            .to_string(),
+                            span_type.suggestion(&lifetime_ref.to_string()),
                             Applicability::MaybeIncorrect,
                         );
                         err.note(
@@ -2840,7 +2842,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                     [.., bound] => (bound.span.shrink_to_hi(), ForLifetimeSpanType::BoundTail),
                 };
                 self.missing_named_lifetime_spots
-                    .push(MissingLifetimeSpot::HRLT { span, span_type });
+                    .push(MissingLifetimeSpot::HigherRanked { span, span_type });
                 return true;
             }
         };