12 files changed, 151 insertions, 30 deletions

diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index d6c7e71ea..73ca6ba9f 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -1268,7 +1268,6 @@ impl LifetimeParam {
     }
 }
 
-// FIXME: rename from `ImplDef` to `Impl`
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct Impl {
     pub(crate) id: ImplId,
diff --git a/crates/hir_def/src/generics.rs b/crates/hir_def/src/generics.rs
index 41134d23b..bb8fca009 100644
--- a/crates/hir_def/src/generics.rs
+++ b/crates/hir_def/src/generics.rs
@@ -62,6 +62,7 @@ pub struct GenericParams {
 pub enum WherePredicate {
     TypeBound { target: WherePredicateTypeTarget, bound: TypeBound },
     Lifetime { target: LifetimeRef, bound: LifetimeRef },
+    ForLifetime { lifetimes: Box<[Name]>, target: WherePredicateTypeTarget, bound: TypeBound },
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]
@@ -69,7 +70,6 @@ pub enum WherePredicateTypeTarget {
     TypeRef(TypeRef),
     /// For desugared where predicates that can directly refer to a type param.
     TypeParam(LocalTypeParamId),
-    // FIXME: ForLifetime(Vec<LifetimeParamId>, TypeRef)
 }
 
 #[derive(Default)]
@@ -234,7 +234,7 @@ impl GenericParams {
         for bound in
             node.type_bound_list().iter().flat_map(|type_bound_list| type_bound_list.bounds())
         {
-            self.add_where_predicate_from_bound(lower_ctx, bound, target.clone());
+            self.add_where_predicate_from_bound(lower_ctx, bound, None, target.clone());
         }
     }
 
@@ -279,8 +279,25 @@ impl GenericParams {
             } else {
                 continue;
             };
+
+            let lifetimes: Option<Box<_>> = pred.generic_param_list().map(|param_list| {
+                // Higher-Ranked Trait Bounds
+                param_list
+                    .lifetime_params()
+                    .map(|lifetime_param| {
+                        lifetime_param
+                            .lifetime()
+                            .map_or_else(Name::missing, |lt| Name::new_lifetime(&lt))
+                    })
+                    .collect()
+            });
             for bound in pred.type_bound_list().iter().flat_map(|l| l.bounds()) {
-                self.add_where_predicate_from_bound(lower_ctx, bound, target.clone());
+                self.add_where_predicate_from_bound(
+                    lower_ctx,
+                    bound,
+                    lifetimes.as_ref(),
+                    target.clone(),
+                );
             }
         }
     }
@@ -289,6 +306,7 @@ impl GenericParams {
         &mut self,
         lower_ctx: &LowerCtx,
         bound: ast::TypeBound,
+        hrtb_lifetimes: Option<&Box<[Name]>>,
         target: Either<TypeRef, LifetimeRef>,
     ) {
         if bound.question_mark_token().is_some() {
@@ -297,9 +315,16 @@ impl GenericParams {
         }
         let bound = TypeBound::from_ast(lower_ctx, bound);
         let predicate = match (target, bound) {
-            (Either::Left(type_ref), bound) => WherePredicate::TypeBound {
-                target: WherePredicateTypeTarget::TypeRef(type_ref),
-                bound,
+            (Either::Left(type_ref), bound) => match hrtb_lifetimes {
+                Some(hrtb_lifetimes) => WherePredicate::ForLifetime {
+                    lifetimes: hrtb_lifetimes.clone(),
+                    target: WherePredicateTypeTarget::TypeRef(type_ref),
+                    bound,
+                },
+                None => WherePredicate::TypeBound {
+                    target: WherePredicateTypeTarget::TypeRef(type_ref),
+                    bound,
+                },
             },
             (Either::Right(lifetime), TypeBound::Lifetime(bound)) => {
                 WherePredicate::Lifetime { target: lifetime, bound }
diff --git a/crates/hir_ty/src/lower.rs b/crates/hir_ty/src/lower.rs
index 8392cb770..8da56cd11 100644
--- a/crates/hir_ty/src/lower.rs
+++ b/crates/hir_ty/src/lower.rs
@@ -675,7 +675,8 @@ impl GenericPredicate {
         where_predicate: &'a WherePredicate,
     ) -> impl Iterator<Item = GenericPredicate> + 'a {
         match where_predicate {
-            WherePredicate::TypeBound { target, bound } => {
+            WherePredicate::ForLifetime { target, bound, .. }
+            | WherePredicate::TypeBound { target, bound } => {
                 let self_ty = match target {
                     WherePredicateTypeTarget::TypeRef(type_ref) => Ty::from_hir(ctx, type_ref),
                     WherePredicateTypeTarget::TypeParam(param_id) => {
@@ -888,14 +889,13 @@ pub(crate) fn generic_predicates_for_param_query(
         .where_predicates_in_scope()
         // we have to filter out all other predicates *first*, before attempting to lower them
         .filter(|pred| match pred {
-            WherePredicate::TypeBound {
-                target: WherePredicateTypeTarget::TypeRef(type_ref),
-                ..
-            } => Ty::from_hir_only_param(&ctx, type_ref) == Some(param_id),
-            WherePredicate::TypeBound {
-                target: WherePredicateTypeTarget::TypeParam(local_id),
-                ..
-            } => *local_id == param_id.local_id,
+            WherePredicate::ForLifetime { target, .. }
+            | WherePredicate::TypeBound { target, .. } => match target {
+                WherePredicateTypeTarget::TypeRef(type_ref) => {
+                    Ty::from_hir_only_param(&ctx, type_ref) == Some(param_id)
+                }
+                WherePredicateTypeTarget::TypeParam(local_id) => *local_id == param_id.local_id,
+            },
             WherePredicate::Lifetime { .. } => false,
         })
         .flat_map(|pred| {
diff --git a/crates/hir_ty/src/utils.rs b/crates/hir_ty/src/utils.rs
index af880c065..65b79df0d 100644
--- a/crates/hir_ty/src/utils.rs
+++ b/crates/hir_ty/src/utils.rs
@@ -5,7 +5,9 @@ use std::sync::Arc;
 use hir_def::{
     adt::VariantData,
     db::DefDatabase,
-    generics::{GenericParams, TypeParamData, TypeParamProvenance, WherePredicateTypeTarget},
+    generics::{
+        GenericParams, TypeParamData, TypeParamProvenance, WherePredicate, WherePredicateTypeTarget,
+    },
     path::Path,
     resolver::{HasResolver, TypeNs},
     type_ref::TypeRef,
@@ -27,7 +29,8 @@ fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec<TraitId> {
         .where_predicates
         .iter()
         .filter_map(|pred| match pred {
-            hir_def::generics::WherePredicate::TypeBound { target, bound } => match target {
+            WherePredicate::ForLifetime { target, bound, .. }
+            | WherePredicate::TypeBound { target, bound } => match target {
                 WherePredicateTypeTarget::TypeRef(TypeRef::Path(p))
                     if p == &Path::from(name![Self]) =>
                 {
@@ -38,7 +41,7 @@ fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec<TraitId> {
                 }
                 _ => None,
             },
-            hir_def::generics::WherePredicate::Lifetime { .. } => None,
+            WherePredicate::Lifetime { .. } => None,
         })
         .filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path.mod_path()) {
             Some(TypeNs::TraitId(t)) => Some(t),
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index 7a12e9965..431da5d9c 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -1077,4 +1077,32 @@ fn foo<'foobar>(_: &'foobar ()) {
 }"#,
         )
     }
+
+    #[test]
+    #[ignore] // requires the HIR to somehow track these hrtb lifetimes
+    fn goto_lifetime_hrtb() {
+        check(
+            r#"trait Foo<T> {}
+fn foo<T>() where for<'a> T: Foo<&'a<|> (u8, u16)>, {}
+                    //^^
+"#,
+        );
+        check(
+            r#"trait Foo<T> {}
+fn foo<T>() where for<'a<|>> T: Foo<&'a (u8, u16)>, {}
+                    //^^
+"#,
+        );
+    }
+
+    #[test]
+    #[ignore] // requires ForTypes to be implemented
+    fn goto_lifetime_hrtb_for_type() {
+        check(
+            r#"trait Foo<T> {}
+fn foo<T>() where T: for<'a> Foo<&'a<|> (u8, u16)>, {}
+                       //^^
+"#,
+        );
+    }
 }
diff --git a/crates/mbe/src/tests.rs b/crates/mbe/src/tests.rs
index f10e7a9b6..451fa1456 100644
--- a/crates/mbe/src/tests.rs
+++ b/crates/mbe/src/tests.rs
@@ -1004,6 +1004,18 @@ fn test_underscore() {
 }
 
 #[test]
+fn test_vertical_bar_with_pat() {
+    parse_macro(
+        r#"
+            macro_rules! foo {
+                 (| $pat:pat | ) => { 0 }
+            }
+    "#,
+    )
+    .assert_expand_items(r#"foo! { | x | }"#, r#"0"#);
+}
+
+#[test]
 fn test_lifetime() {
     parse_macro(
         r#"
diff --git a/crates/parser/src/grammar.rs b/crates/parser/src/grammar.rs
index 1a078f6b4..f08c8bab7 100644
--- a/crates/parser/src/grammar.rs
+++ b/crates/parser/src/grammar.rs
@@ -55,7 +55,7 @@ pub(crate) mod fragments {
     use super::*;
 
     pub(crate) use super::{
-        expressions::block_expr, paths::type_path as path, patterns::pattern, types::type_,
+        expressions::block_expr, paths::type_path as path, patterns::pattern_single, types::type_,
     };
 
     pub(crate) fn expr(p: &mut Parser) {
diff --git a/crates/parser/src/grammar/type_params.rs b/crates/parser/src/grammar/type_params.rs
index 9c3f7c28a..4aeccd193 100644
--- a/crates/parser/src/grammar/type_params.rs
+++ b/crates/parser/src/grammar/type_params.rs
@@ -113,7 +113,7 @@ fn type_bound(p: &mut Parser) -> bool {
     p.eat(T![?]);
     match p.current() {
         LIFETIME_IDENT => lifetime(p),
-        T![for] => types::for_type(p),
+        T![for] => types::for_type(p, false),
         _ if paths::is_use_path_start(p) => types::path_type_(p, false),
         _ => {
             m.abandon(p);
diff --git a/crates/parser/src/grammar/types.rs b/crates/parser/src/grammar/types.rs
index 36a15eace..94cbf7d85 100644
--- a/crates/parser/src/grammar/types.rs
+++ b/crates/parser/src/grammar/types.rs
@@ -44,7 +44,7 @@ fn type_with_bounds_cond(p: &mut Parser, allow_bounds: bool) {
         T![&] => ref_type(p),
         T![_] => infer_type(p),
         T![fn] | T![unsafe] | T![extern] => fn_ptr_type(p),
-        T![for] => for_type(p),
+        T![for] => for_type(p, allow_bounds),
         T![impl] => impl_trait_type(p),
         T![dyn] => dyn_trait_type(p),
         // Some path types are not allowed to have bounds (no plus)
@@ -227,7 +227,7 @@ pub(super) fn for_binder(p: &mut Parser) {
 // type A = for<'a> fn() -> ();
 // type B = for<'a> unsafe extern "C" fn(&'a ()) -> ();
 // type Obj = for<'a> PartialEq<&'a i32>;
-pub(super) fn for_type(p: &mut Parser) {
+pub(super) fn for_type(p: &mut Parser, allow_bounds: bool) {
     assert!(p.at(T![for]));
     let m = p.start();
     for_binder(p);
@@ -240,7 +240,13 @@ pub(super) fn for_type(p: &mut Parser) {
         }
     }
     type_no_bounds(p);
-    m.complete(p, FOR_TYPE);
+    let completed = m.complete(p, FOR_TYPE);
+
+    // test no_dyn_trait_leading_for
+    // type A = for<'a> Test<'a> + Send;
+    if allow_bounds {
+        opt_type_bounds_as_dyn_trait_type(p, completed);
+    }
 }
 
 // test impl_trait_type
@@ -290,7 +296,7 @@ fn path_or_macro_type_(p: &mut Parser, allow_bounds: bool) {
     let path = m.complete(p, kind);
 
     if allow_bounds {
-        opt_path_type_bounds_as_dyn_trait_type(p, path);
+        opt_type_bounds_as_dyn_trait_type(p, path);
     }
 }
 
@@ -304,19 +310,23 @@ pub(super) fn path_type_(p: &mut Parser, allow_bounds: bool) {
     // fn foo() -> Box<dyn T + 'f> {}
     let path = m.complete(p, PATH_TYPE);
     if allow_bounds {
-        opt_path_type_bounds_as_dyn_trait_type(p, path);
+        opt_type_bounds_as_dyn_trait_type(p, path);
     }
 }
 
-/// This turns a parsed PATH_TYPE optionally into a DYN_TRAIT_TYPE
+/// This turns a parsed PATH_TYPE or FOR_TYPE optionally into a DYN_TRAIT_TYPE
 /// with a TYPE_BOUND_LIST
-fn opt_path_type_bounds_as_dyn_trait_type(p: &mut Parser, path_type_marker: CompletedMarker) {
+fn opt_type_bounds_as_dyn_trait_type(p: &mut Parser, type_marker: CompletedMarker) {
+    assert!(matches!(
+        type_marker.kind(),
+        SyntaxKind::PATH_TYPE | SyntaxKind::FOR_TYPE | SyntaxKind::MACRO_CALL
+    ));
     if !p.at(T![+]) {
         return;
     }
 
     // First create a TYPE_BOUND from the completed PATH_TYPE
-    let m = path_type_marker.precede(p).complete(p, TYPE_BOUND);
+    let m = type_marker.precede(p).complete(p, TYPE_BOUND);
 
     // Next setup a marker for the TYPE_BOUND_LIST
     let m = m.precede(p);
diff --git a/crates/parser/src/lib.rs b/crates/parser/src/lib.rs
index ab8e4c70e..811e740f9 100644
--- a/crates/parser/src/lib.rs
+++ b/crates/parser/src/lib.rs
@@ -112,7 +112,7 @@ pub fn parse_fragment(
         FragmentKind::Path => grammar::fragments::path,
         FragmentKind::Expr => grammar::fragments::expr,
         FragmentKind::Type => grammar::fragments::type_,
-        FragmentKind::Pattern => grammar::fragments::pattern,
+        FragmentKind::Pattern => grammar::fragments::pattern_single,
         FragmentKind::Item => grammar::fragments::item,
         FragmentKind::Block => grammar::fragments::block_expr,
         FragmentKind::Visibility => grammar::fragments::opt_visibility,
diff --git a/crates/syntax/test_data/parser/inline/ok/0154_no_dyn_trait_leading_for.rast b/crates/syntax/test_data/parser/inline/ok/0154_no_dyn_trait_leading_for.rast
new file mode 100644
index 000000000..edfcb288c
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0154_no_dyn_trait_leading_for.rast
@@ -0,0 +1,43 @@
+[email protected]
+  [email protected]
+    [email protected] "type"
+    [email protected] " "
+    [email protected]
+      [email protected] "A"
+    [email protected] " "
+    [email protected] "="
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected] "for"
+            [email protected]
+              [email protected] "<"
+              [email protected]
+                [email protected]
+                  [email protected] "\'a"
+              [email protected] ">"
+            [email protected] " "
+            [email protected]
+              [email protected]
+                [email protected]
+                  [email protected]
+                    [email protected] "Test"
+                  [email protected]
+                    [email protected] "<"
+                    [email protected]
+                      [email protected]
+                        [email protected] "\'a"
+                    [email protected] ">"
+        [email protected] " "
+        [email protected] "+"
+        [email protected] " "
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected]
+                  [email protected] "Send"
+    [email protected] ";"
+  [email protected] "\n"
diff --git a/crates/syntax/test_data/parser/inline/ok/0154_no_dyn_trait_leading_for.rs b/crates/syntax/test_data/parser/inline/ok/0154_no_dyn_trait_leading_for.rs
new file mode 100644
index 000000000..47a71fd19
--- /dev/null
+++ b/crates/syntax/test_data/parser/inline/ok/0154_no_dyn_trait_leading_for.rs
@@ -0,0 +1 @@
+type A = for<'a> Test<'a> + Send;