Render more lifetimes

Author: Veykril

Diff for: crates/hir-ty/src/display.rs

@@ -91,11 +91,26 @@ pub struct HirFormatter<'a> {
     show_container_bounds: bool,
     omit_verbose_types: bool,
     closure_style: ClosureStyle,
+    display_lifetimes: DisplayLifetime,
     display_kind: DisplayKind,
     display_target: DisplayTarget,
     bounds_formatting_ctx: BoundsFormattingCtx,
 }
 
+// FIXME: To consider, ref and dyn trait lifetimes can be omitted if they are `'_`, path args should
+// not be when in signatures
+// So this enum does not encode this well enough
+// Also 'static can be omitted for ref and dyn trait lifetimes in static/const item types
+// FIXME: Also named lifetimes may be rendered in places where their name is not in scope?
+#[derive(Copy, Clone)]
+pub enum DisplayLifetime {
+    Always,
+    OnlyStatic,
+    OnlyNamed,
+    OnlyNamedOrStatic,
+    Never,
+}
+
 #[derive(Default)]
 enum BoundsFormattingCtx {
     Entered {
@@ -156,6 +171,21 @@ impl HirFormatter<'_> {
             }
         }
     }
+
+    fn render_lifetime(&self, lifetime: &Lifetime) -> bool {
+        match self.display_lifetimes {
+            DisplayLifetime::Always => true,
+            DisplayLifetime::OnlyStatic => matches!(***lifetime.interned(), LifetimeData::Static),
+            DisplayLifetime::OnlyNamed => {
+                matches!(***lifetime.interned(), LifetimeData::Placeholder(_))
+            }
+            DisplayLifetime::OnlyNamedOrStatic => matches!(
+                ***lifetime.interned(),
+                LifetimeData::Static | LifetimeData::Placeholder(_)
+            ),
+            DisplayLifetime::Never => false,
+        }
+    }
 }
 
 pub trait HirDisplay {
@@ -190,6 +220,7 @@ pub trait HirDisplay {
             display_kind,
             closure_style,
             show_container_bounds,
+            display_lifetimes: DisplayLifetime::OnlyNamedOrStatic,
         }
     }
 
@@ -213,6 +244,7 @@ pub trait HirDisplay {
             display_target,
             display_kind: DisplayKind::Diagnostics,
             show_container_bounds: false,
+            display_lifetimes: DisplayLifetime::OnlyNamedOrStatic,
         }
     }
 
@@ -237,6 +269,7 @@ pub trait HirDisplay {
             display_target,
             display_kind: DisplayKind::Diagnostics,
             show_container_bounds: false,
+            display_lifetimes: DisplayLifetime::OnlyNamedOrStatic,
         }
     }
 
@@ -261,6 +294,7 @@ pub trait HirDisplay {
             display_target,
             display_kind: DisplayKind::Diagnostics,
             show_container_bounds: false,
+            display_lifetimes: DisplayLifetime::OnlyNamedOrStatic,
         }
     }
 
@@ -285,6 +319,7 @@ pub trait HirDisplay {
             display_target: DisplayTarget::from_crate(db, module_id.krate()),
             display_kind: DisplayKind::SourceCode { target_module_id: module_id, allow_opaque },
             show_container_bounds: false,
+            display_lifetimes: DisplayLifetime::OnlyNamedOrStatic,
             bounds_formatting_ctx: Default::default(),
         }) {
             Ok(()) => {}
@@ -313,6 +348,7 @@ pub trait HirDisplay {
             display_target,
             display_kind: DisplayKind::Test,
             show_container_bounds: false,
+            display_lifetimes: DisplayLifetime::Always,
         }
     }
 
@@ -337,6 +373,7 @@ pub trait HirDisplay {
             display_target,
             display_kind: DisplayKind::Diagnostics,
             show_container_bounds,
+            display_lifetimes: DisplayLifetime::OnlyNamedOrStatic,
         }
     }
 }
@@ -481,6 +518,7 @@ pub struct HirDisplayWrapper<'a, T> {
     display_kind: DisplayKind,
     display_target: DisplayTarget,
     show_container_bounds: bool,
+    display_lifetimes: DisplayLifetime,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -503,7 +541,7 @@ impl<T: HirDisplay> HirDisplayWrapper<'_, T> {
         self.t.hir_fmt(&mut HirFormatter {
             db: self.db,
             fmt: f,
-            buf: String::with_capacity(20),
+            buf: String::with_capacity(self.max_size.unwrap_or(20)),
             curr_size: 0,
             max_size: self.max_size,
             entity_limit: self.limited_size,
@@ -512,6 +550,7 @@ impl<T: HirDisplay> HirDisplayWrapper<'_, T> {
             display_target: self.display_target,
             closure_style: self.closure_style,
             show_container_bounds: self.show_container_bounds,
+            display_lifetimes: self.display_lifetimes,
             bounds_formatting_ctx: Default::default(),
         })
     }
@@ -520,6 +559,11 @@ impl<T: HirDisplay> HirDisplayWrapper<'_, T> {
         self.closure_style = c;
         self
     }
+
+    pub fn with_lifetime_display(mut self, l: DisplayLifetime) -> Self {
+        self.display_lifetimes = l;
+        self
+    }
 }
 
 impl<T> fmt::Display for HirDisplayWrapper<'_, T>
@@ -1024,9 +1068,7 @@ impl HirDisplay for Ty {
             kind @ (TyKind::Raw(m, t) | TyKind::Ref(m, _, t)) => {
                 if let TyKind::Ref(_, l, _) = kind {
                     f.write_char('&')?;
-                    if cfg!(test) {
-                        // rendering these unconditionally is probably too much (at least for inlay
-                        // hints) so we gate it to testing only for the time being
+                    if f.render_lifetime(l) {
                         l.hir_fmt(f)?;
                         f.write_char(' ')?;
                     }
@@ -1057,9 +1099,10 @@ impl HirDisplay for Ty {
                     })
                 };
                 let (preds_to_print, has_impl_fn_pred) = match t.kind(Interner) {
-                    TyKind::Dyn(dyn_ty) if dyn_ty.bounds.skip_binders().interned().len() > 1 => {
+                    TyKind::Dyn(dyn_ty) => {
                         let bounds = dyn_ty.bounds.skip_binders().interned();
-                        (bounds.len(), contains_impl_fn(bounds))
+                        let render_lifetime = f.render_lifetime(&dyn_ty.lifetime);
+                        (bounds.len() + render_lifetime as usize, contains_impl_fn(bounds))
                     }
                     TyKind::Alias(AliasTy::Opaque(OpaqueTy {
                         opaque_ty_id,
@@ -1479,7 +1522,7 @@ impl HirDisplay for Ty {
             TyKind::BoundVar(idx) => idx.hir_fmt(f)?,
             TyKind::Dyn(dyn_ty) => {
                 // Reorder bounds to satisfy `write_bounds_like_dyn_trait()`'s expectation.
-                // FIXME: `Iterator::partition_in_place()` or `Vec::drain_filter()` may make it
+                // FIXME: `Iterator::partition_in_place()` or `Vec::extract_if()` may make it
                 // more efficient when either of them hits stable.
                 let mut bounds: SmallVec<[_; 4]> =
                     dyn_ty.bounds.skip_binders().iter(Interner).cloned().collect();
@@ -1488,6 +1531,17 @@ impl HirDisplay for Ty {
                 bounds.extend(others);
                 bounds.extend(auto_traits);
 
+                if f.render_lifetime(&dyn_ty.lifetime) {
+                    // we skip the binders in `write_bounds_like_dyn_trait_with_prefix`
+                    bounds.push(Binders::empty(
+                        Interner,
+                        chalk_ir::WhereClause::TypeOutlives(chalk_ir::TypeOutlives {
+                            ty: self.clone(),
+                            lifetime: dyn_ty.lifetime.clone(),
+                        }),
+                    ));
+                }
+
                 write_bounds_like_dyn_trait_with_prefix(
                     f,
                     "dyn",
@@ -1991,7 +2045,6 @@ impl HirDisplay for LifetimeData {
                 write!(f, "{}", param_data.name.display(f.db, f.edition()))?;
                 Ok(())
             }
-            _ if f.display_kind.is_source_code() => write!(f, "'_"),
             LifetimeData::BoundVar(idx) => idx.hir_fmt(f),
             LifetimeData::InferenceVar(_) => write!(f, "_"),
             LifetimeData::Static => write!(f, "'static"),

Diff for: crates/hir-ty/src/tests/coercion.rs

@@ -561,7 +561,7 @@ trait Foo {}
 fn test(f: impl Foo, g: &(impl Foo + ?Sized)) {
     let _: &dyn Foo = &f;
     let _: &dyn Foo = g;
-                    //^ expected &'? dyn Foo, got &'? impl Foo + ?Sized
+                    //^ expected &'? (dyn Foo + 'static), got &'? impl Foo + ?Sized
 }
         "#,
     );
@@ -827,11 +827,11 @@ struct V<T> { t: T }
 fn main() {
     let a: V<&dyn Tr>;
     (a,) = V { t: &S };
-  //^^^^expected V<&'? S>, got (V<&'? dyn Tr>,)
+  //^^^^expected V<&'? S>, got (V<&'? (dyn Tr + '?)>,)
 
     let mut a: V<&dyn Tr> = V { t: &S };
     (a,) = V { t: &S };
-  //^^^^expected V<&'? S>, got (V<&'? dyn Tr>,)
+  //^^^^expected V<&'? S>, got (V<&'? (dyn Tr + '?)>,)
 }
         "#,
     );

Diff for: crates/hir-ty/src/tests/display_source_code.rs

@@ -65,13 +65,13 @@ trait A {
 }
 trait B: A {}
 
-fn test(
+fn test<'a>(
     _: &(dyn A<Assoc = ()> + Send),
-  //^ &'_ (dyn A<Assoc = ()> + Send)
-    _: &(dyn Send + A<Assoc = ()>),
-  //^ &'_ (dyn A<Assoc = ()> + Send)
+  //^ &(dyn A<Assoc = ()> + Send + '_)
+    _: &'a (dyn Send + A<Assoc = ()>),
+  //^ &'a (dyn A<Assoc = ()> + Send + '_)
     _: &dyn B<Assoc = ()>,
-  //^ &'_ (dyn B<Assoc = ()>)
+  //^ &(dyn B<Assoc = ()> + '_)
 ) {}
         "#,
     );
@@ -85,7 +85,7 @@ fn render_dyn_for_ty() {
 trait Foo<'a> {}
 
 fn foo(foo: &dyn for<'a> Foo<'a>) {}
-    // ^^^ &'_ dyn Foo<'_>
+    // ^^^ &(dyn Foo<'_> + '_)
 "#,
     );
 }
@@ -111,11 +111,11 @@ fn test(
     b;
   //^ impl Foo
     c;
-  //^ &'_ impl Foo + ?Sized
+  //^ &impl Foo + ?Sized
     d;
   //^ S<impl Foo>
     ref_any;
-  //^^^^^^^ &'_ impl ?Sized
+  //^^^^^^^ &impl ?Sized
     empty;
 } //^^^^^ impl Sized
 "#,
@@ -192,7 +192,7 @@ fn test(
     b;
   //^ fn(impl Foo) -> impl Foo
     c;
-} //^ fn(&'_ impl Foo + ?Sized) -> &'_ impl Foo + ?Sized
+} //^ fn(&impl Foo + ?Sized) -> &impl Foo + ?Sized
 "#,
     );
 }

Diff for: crates/hir-ty/src/tests/method_resolution.rs

@@ -1153,9 +1153,9 @@ fn dyn_trait_super_trait_not_in_scope() {
             51..55 'self': &'? Self
             64..69 '{ 0 }': u32
             66..67 '0': u32
-            176..177 'd': &'? dyn Trait
+            176..177 'd': &'? (dyn Trait + 'static)
             191..207 '{     ...o(); }': ()
-            197..198 'd': &'? dyn Trait
+            197..198 'd': &'? (dyn Trait + 'static)
             197..204 'd.foo()': u32
         "#]],
     );
@@ -2019,10 +2019,10 @@ impl dyn Error + Send {
     /// Attempts to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error + Send>> {
         let err: Box<dyn Error> = self;
-                               // ^^^^ expected Box<dyn Error>, got Box<dyn Error + Send>
+                               // ^^^^ expected Box<dyn Error + 'static>, got Box<dyn Error + Send + 'static>
                                // FIXME, type mismatch should not occur
         <dyn Error>::downcast(err).map_err(|_| loop {})
-      //^^^^^^^^^^^^^^^^^^^^^ type: fn downcast<{unknown}>(Box<dyn Error>) -> Result<Box<{unknown}>, Box<dyn Error>>
+      //^^^^^^^^^^^^^^^^^^^^^ type: fn downcast<{unknown}>(Box<dyn Error + 'static>) -> Result<Box<{unknown}>, Box<dyn Error + 'static>>
     }
 }
 "#,

Diff for: crates/hir-ty/src/tests/regression.rs

@@ -629,7 +629,7 @@ fn issue_4053_diesel_where_clauses() {
             488..522 '{     ...     }': ()
             498..502 'self': SelectStatement<F, S, D, W, O, LOf, {unknown}, {unknown}>
             498..508 'self.order': O
-            498..515 'self.o...into()': dyn QueryFragment<DB>
+            498..515 'self.o...into()': dyn QueryFragment<DB> + 'static
         "#]],
     );
 }
@@ -773,7 +773,7 @@ fn issue_4800() {
         "#,
         expect![[r#"
             379..383 'self': &'? mut PeerSet<D>
-            401..424 '{     ...     }': dyn Future<Output = ()>
+            401..424 '{     ...     }': dyn Future<Output = ()> + 'static
             411..418 'loop {}': !
             416..418 '{}': ()
             575..579 'self': &'? mut Self

Diff for: crates/hir-ty/src/tests/simple.rs

@@ -2741,11 +2741,11 @@ impl B for Astruct {}
             715..744 '#[rust...1i32])': Box<[i32; 1], Global>
             737..743 '[1i32]': [i32; 1]
             738..742 '1i32': i32
-            755..756 'v': Vec<Box<dyn B, Global>, Global>
-            776..793 '<[_]> ...to_vec': fn into_vec<Box<dyn B, Global>, Global>(Box<[Box<dyn B, Global>], Global>) -> Vec<Box<dyn B, Global>, Global>
-            776..850 '<[_]> ...ct)]))': Vec<Box<dyn B, Global>, Global>
-            794..849 '#[rust...uct)])': Box<[Box<dyn B, Global>; 1], Global>
-            816..848 '[#[rus...ruct)]': [Box<dyn B, Global>; 1]
+            755..756 'v': Vec<Box<dyn B + 'static, Global>, Global>
+            776..793 '<[_]> ...to_vec': fn into_vec<Box<dyn B + 'static, Global>, Global>(Box<[Box<dyn B + 'static, Global>], Global>) -> Vec<Box<dyn B + 'static, Global>, Global>
+            776..850 '<[_]> ...ct)]))': Vec<Box<dyn B + 'static, Global>, Global>
+            794..849 '#[rust...uct)])': Box<[Box<dyn B + 'static, Global>; 1], Global>
+            816..848 '[#[rus...ruct)]': [Box<dyn B + 'static, Global>; 1]
             817..847 '#[rust...truct)': Box<Astruct, Global>
             839..846 'Astruct': Astruct
         "#]],