Add static lifetime

rust-lang · Oct 3, 2020 · b276130 · b276130
1 parent c74da51
commit b276130
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Showing 15 changed files with 164 additions and 72 deletions.
diff --git a/chalk-engine/src/slg/aggregate.rs b/chalk-engine/src/slg/aggregate.rs
@@ -422,23 +422,14 @@ impl<I: Interner> AntiUnifier<'_, '_, I> {
     fn aggregate_lifetimes(&mut self, l1: &Lifetime<I>, l2: &Lifetime<I>) -> Lifetime<I> {
         let interner = self.interner;
         match (l1.data(interner), l2.data(interner)) {
-            (LifetimeData::InferenceVar(_), _) | (_, LifetimeData::InferenceVar(_)) => {
-                self.new_lifetime_variable()
-            }
-
-            (LifetimeData::BoundVar(_), _) | (_, LifetimeData::BoundVar(_)) => {
-                self.new_lifetime_variable()
-            }
-
-            (LifetimeData::Placeholder(_), LifetimeData::Placeholder(_)) => {
+            (LifetimeData::Phantom(..), _) | (_, LifetimeData::Phantom(..)) => unreachable!(),
+            _ => {
                 if l1 == l2 {
                     l1.clone()
                 } else {
                     self.new_lifetime_variable()
                 }
             }
-
-            (LifetimeData::Phantom(..), _) | (_, LifetimeData::Phantom(..)) => unreachable!(),
         }
     }
 

diff --git a/chalk-engine/src/slg/resolvent.rs b/chalk-engine/src/slg/resolvent.rs
@@ -445,7 +445,8 @@ impl<'i, I: Interner> Zipper<'i, I> for AnswerSubstitutor<'i, I> {
                 self.assert_matching_vars(*answer_depth, *pending_depth)
             }
 
-            (LifetimeData::Placeholder(_), LifetimeData::Placeholder(_)) => {
+            (LifetimeData::Static, LifetimeData::Static)
+            | (LifetimeData::Placeholder(_), LifetimeData::Placeholder(_)) => {
                 assert_eq!(answer, pending);
                 Ok(())
             }
@@ -455,7 +456,9 @@ impl<'i, I: Interner> Zipper<'i, I> for AnswerSubstitutor<'i, I> {
                 answer, pending,
             ),
 
-            (LifetimeData::BoundVar(_), _) | (LifetimeData::Placeholder(_), _) => panic!(
+            (LifetimeData::Static, _)
+            | (LifetimeData::BoundVar(_), _)
+            | (LifetimeData::Placeholder(_), _) => panic!(
                 "structural mismatch between answer `{:?}` and pending goal `{:?}`",
                 answer, pending,
             ),

diff --git a/chalk-integration/src/lowering.rs b/chalk-integration/src/lowering.rs
@@ -910,6 +910,10 @@ impl LowerWithEnv for Lifetime {
                     }
                 })
             }
+            Lifetime::Static => Ok(chalk_ir::Lifetime::new(
+                interner,
+                chalk_ir::LifetimeData::Static,
+            )),
         }
     }
 }

diff --git a/chalk-ir/src/debug.rs b/chalk-ir/src/debug.rs
@@ -285,6 +285,7 @@ impl<I: Interner> Debug for LifetimeData<I> {
             LifetimeData::BoundVar(db) => write!(fmt, "'{:?}", db),
             LifetimeData::InferenceVar(var) => write!(fmt, "'{:?}", var),
             LifetimeData::Placeholder(index) => write!(fmt, "'{:?}", index),
+            LifetimeData::Static => write!(fmt, "'static"),
             LifetimeData::Phantom(..) => unreachable!(),
         }
     }

diff --git a/chalk-ir/src/fold.rs b/chalk-ir/src/fold.rs
@@ -489,6 +489,7 @@ where
             LifetimeData::Placeholder(universe) => {
                 folder.fold_free_placeholder_lifetime(*universe, outer_binder)
             }
+            LifetimeData::Static => Ok(LifetimeData::<TI>::Static.intern(folder.target_interner())),
             LifetimeData::Phantom(..) => unreachable!(),
         }
     }

diff --git a/chalk-ir/src/lib.rs b/chalk-ir/src/lib.rs
@@ -1064,6 +1064,7 @@ impl<I: Interner> Lifetime<I> {
             LifetimeData::BoundVar(_) => true,
             LifetimeData::InferenceVar(_) => false,
             LifetimeData::Placeholder(_) => false,
+            LifetimeData::Static => false,
             LifetimeData::Phantom(..) => unreachable!(),
         }
     }
@@ -1078,6 +1079,8 @@ pub enum LifetimeData<I: Interner> {
     InferenceVar(InferenceVar),
     /// Lifetime on some yet-unknown placeholder.
     Placeholder(PlaceholderIndex),
+    /// Static lifetime
+    Static,
     /// Lifetime on phantom data.
     Phantom(Void, PhantomData<I>),
 }

diff --git a/chalk-ir/src/visit.rs b/chalk-ir/src/visit.rs
@@ -325,6 +325,7 @@ impl<I: Interner> SuperVisit<I> for Lifetime<I> {
             LifetimeData::Placeholder(universe) => {
                 visitor.visit_free_placeholder(*universe, outer_binder)
             }
+            LifetimeData::Static => R::new(),
             LifetimeData::Phantom(..) => unreachable!(),
         }
     }

diff --git a/chalk-parse/src/ast.rs b/chalk-parse/src/ast.rs
@@ -369,6 +369,7 @@ impl Default for Safety {
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub enum Lifetime {
     Id { name: Identifier },
+    Static,
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]

diff --git a/chalk-parse/src/parser.lalrpop b/chalk-parse/src/parser.lalrpop
@@ -431,6 +431,7 @@ RawMutability: Mutability = {
 
 Lifetime: Lifetime = {
     <n:LifetimeId> => Lifetime::Id { name: n },
+    "'static" => Lifetime::Static,
 };
 
 ConstWithoutId: Const = {

diff --git a/chalk-solve/src/display/ty.rs b/chalk-solve/src/display/ty.rs
@@ -274,6 +274,7 @@ impl<I: Interner> RenderAsRust<I> for LifetimeData<I> {
             LifetimeData::Placeholder(ix) => {
                 write!(f, "'_placeholder_{}_{}", ix.ui.counter, ix.idx)
             }
+            LifetimeData::Static => write!(f, "'static"),
             // Matching the void ensures at compile time that this code is
             // unreachable
             LifetimeData::Phantom(void, _) => match *void {},

diff --git a/chalk-solve/src/infer/unify.rs b/chalk-solve/src/infer/unify.rs
@@ -333,7 +333,19 @@ impl<'t, I: Interner> Unifier<'t, I> {
                 self.unify_lifetime_var(a, b, b_var, a, a_idx.ui)
             }
 
-            (&LifetimeData::Placeholder(_), &LifetimeData::Placeholder(_)) => {
+            (&LifetimeData::InferenceVar(a_var), &LifetimeData::Static) => {
+                self.unify_lifetime_var(a, b, a_var, b, UniverseIndex::root())
+            }
+
+            (&LifetimeData::Static, &LifetimeData::InferenceVar(b_var)) => {
+                self.unify_lifetime_var(a, b, b_var, a, UniverseIndex::root())
+            }
+
+            (&LifetimeData::Static, &LifetimeData::Static) => Ok(()),
+
+            (&LifetimeData::Static, &LifetimeData::Placeholder(_)) 
+            | (&LifetimeData::Placeholder(_), &LifetimeData::Static)
+            | (&LifetimeData::Placeholder(_), &LifetimeData::Placeholder(_)) => {
                 if a != b {
                     Ok(self.push_lifetime_eq_goals(a.clone(), b.clone()))
                 } else {
-Original file line number
+Diff line change
@@ Expand Up / @@ -910,6 +910,10 @@ impl LowerWithEnv for Lifetime { @@
                         }
                     })
                 }
+                Lifetime::Static => Ok(chalk_ir::Lifetime::new(
+                    interner,
+                    chalk_ir::LifetimeData::Static,
+                )),
             }
         }
     }
@@ Expand Down @@