9 files changed, 557 insertions, 51 deletions

diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 228d706db..c64b78445 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -23,7 +23,7 @@ use crate::{
 };
 
 /// Holds documentation
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Documentation(String);
 
 impl Documentation {
@@ -32,9 +32,9 @@ impl Documentation {
     }
 }
 
-impl Into<String> for Documentation {
-    fn into(self) -> String {
-        self.0
+impl From<Documentation> for String {
+    fn from(Documentation(string): Documentation) -> Self {
+        string
     }
 }
 
diff --git a/crates/hir_def/src/builtin_attr.rs b/crates/hir_def/src/builtin_attr.rs
new file mode 100644
index 000000000..2e989c504
--- /dev/null
+++ b/crates/hir_def/src/builtin_attr.rs
@@ -0,0 +1,430 @@
+//! Builtin attributes resolved by nameres.
+//!
+//! The actual definitions were copied from rustc's `compiler/rustc_feature/src/builtin_attrs.rs`.
+//!
+//! It was last synchronized with upstream commit 2225ee1b62ff089917434aefd9b2bf509cfa087f.
+//!
+//! The macros were adjusted to only expand to the attribute name, since that is all we need to do
+//! name resolution, and `BUILTIN_ATTRIBUTES` is almost entirely unchanged from the original, to
+//! ease updating.
+
+/// Ignored attribute namespaces used by tools.
+pub const TOOL_MODULES: &[&str] = &["rustfmt", "clippy"];
+
+type BuiltinAttribute = &'static str;
+
+macro_rules! ungated {
+    ($attr:ident, $typ:expr, $tpl:expr $(,)?) => {
+        stringify!($attr)
+    };
+}
+
+macro_rules! gated {
+    ($attr:ident $($rest:tt)*) => {
+        stringify!($attr)
+    };
+}
+
+macro_rules! rustc_attr {
+    (TEST, $attr:ident $($rest:tt)*) => {
+        stringify!($attr)
+    };
+    ($attr:ident $($rest:tt)*) => {
+        stringify!($attr)
+    };
+}
+
+/// Attributes that have a special meaning to rustc or rustdoc.
+#[rustfmt::skip]
+pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
+    // ==========================================================================
+    // Stable attributes:
+    // ==========================================================================
+
+    // Conditional compilation:
+    ungated!(cfg, Normal, template!(List: "predicate")),
+    ungated!(cfg_attr, Normal, template!(List: "predicate, attr1, attr2, ...")),
+
+    // Testing:
+    ungated!(ignore, Normal, template!(Word, NameValueStr: "reason")),
+    ungated!(
+        should_panic, Normal,
+        template!(Word, List: r#"expected = "reason"#, NameValueStr: "reason"),
+    ),
+    // FIXME(Centril): This can be used on stable but shouldn't.
+    ungated!(reexport_test_harness_main, Normal, template!(NameValueStr: "name")),
+
+    // Macros:
+    ungated!(derive, Normal, template!(List: "Trait1, Trait2, ...")),
+    ungated!(automatically_derived, Normal, template!(Word)),
+    // FIXME(#14407)
+    ungated!(macro_use, Normal, template!(Word, List: "name1, name2, ...")),
+    ungated!(macro_escape, Normal, template!(Word)), // Deprecated synonym for `macro_use`.
+    ungated!(macro_export, Normal, template!(Word, List: "local_inner_macros")),
+    ungated!(proc_macro, Normal, template!(Word)),
+    ungated!(
+        proc_macro_derive, Normal,
+        template!(List: "TraitName, /*opt*/ attributes(name1, name2, ...)"),
+    ),
+    ungated!(proc_macro_attribute, Normal, template!(Word)),
+
+    // Lints:
+    ungated!(warn, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(allow, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
+    ungated!(must_use, AssumedUsed, template!(Word, NameValueStr: "reason")),
+    // FIXME(#14407)
+    ungated!(
+        deprecated, Normal,
+        template!(
+            Word,
+            List: r#"/*opt*/ since = "version", /*opt*/ note = "reason""#,
+            NameValueStr: "reason"
+        ),
+    ),
+
+    // Crate properties:
+    ungated!(crate_name, CrateLevel, template!(NameValueStr: "name")),
+    ungated!(crate_type, CrateLevel, template!(NameValueStr: "bin|lib|...")),
+    ungated!(crate_id, CrateLevel, template!(NameValueStr: "ignored")),
+
+    // ABI, linking, symbols, and FFI
+    ungated!(
+        link, AssumedUsed,
+        template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#),
+    ),
+    ungated!(link_name, AssumedUsed, template!(NameValueStr: "name")),
+    ungated!(no_link, Normal, template!(Word)),
+    ungated!(repr, Normal, template!(List: "C")),
+    ungated!(export_name, AssumedUsed, template!(NameValueStr: "name")),
+    ungated!(link_section, AssumedUsed, template!(NameValueStr: "name")),
+    ungated!(no_mangle, AssumedUsed, template!(Word)),
+    ungated!(used, AssumedUsed, template!(Word)),
+
+    // Limits:
+    ungated!(recursion_limit, CrateLevel, template!(NameValueStr: "N")),
+    ungated!(type_length_limit, CrateLevel, template!(NameValueStr: "N")),
+    gated!(
+        const_eval_limit, CrateLevel, template!(NameValueStr: "N"), const_eval_limit,
+        experimental!(const_eval_limit)
+    ),
+
+    // Entry point:
+    ungated!(main, Normal, template!(Word)),
+    ungated!(start, Normal, template!(Word)),
+    ungated!(no_start, CrateLevel, template!(Word)),
+    ungated!(no_main, CrateLevel, template!(Word)),
+
+    // Modules, prelude, and resolution:
+    ungated!(path, Normal, template!(NameValueStr: "file")),
+    ungated!(no_std, CrateLevel, template!(Word)),
+    ungated!(no_implicit_prelude, Normal, template!(Word)),
+    ungated!(non_exhaustive, AssumedUsed, template!(Word)),
+
+    // Runtime
+    ungated!(windows_subsystem, AssumedUsed, template!(NameValueStr: "windows|console")),
+    ungated!(panic_handler, Normal, template!(Word)), // RFC 2070
+
+    // Code generation:
+    ungated!(inline, AssumedUsed, template!(Word, List: "always|never")),
+    ungated!(cold, AssumedUsed, template!(Word)),
+    ungated!(no_builtins, AssumedUsed, template!(Word)),
+    ungated!(target_feature, AssumedUsed, template!(List: r#"enable = "name""#)),
+    ungated!(track_caller, AssumedUsed, template!(Word)),
+    gated!(
+        no_sanitize, AssumedUsed,
+        template!(List: "address, memory, thread"),
+        experimental!(no_sanitize)
+    ),
+
+    // FIXME: #14408 assume docs are used since rustdoc looks at them.
+    ungated!(doc, AssumedUsed, template!(List: "hidden|inline|...", NameValueStr: "string")),
+
+    // ==========================================================================
+    // Unstable attributes:
+    // ==========================================================================
+
+    // Linking:
+    gated!(naked, AssumedUsed, template!(Word), naked_functions, experimental!(naked)),
+    gated!(
+        link_args, Normal, template!(NameValueStr: "args"),
+        "the `link_args` attribute is experimental and not portable across platforms, \
+        it is recommended to use `#[link(name = \"foo\")] instead",
+    ),
+    gated!(
+        link_ordinal, AssumedUsed, template!(List: "ordinal"), raw_dylib,
+        experimental!(link_ordinal)
+    ),
+
+    // Plugins:
+    // XXX Modified for use in rust-analyzer
+    gated!(plugin_registrar),
+    gated!(plugin),
+
+    // Testing:
+    gated!(allow_fail, Normal, template!(Word), experimental!(allow_fail)),
+    gated!(
+        test_runner, CrateLevel, template!(List: "path"), custom_test_frameworks,
+        "custom test frameworks are an unstable feature",
+    ),
+    // RFC #1268
+    gated!(marker, Normal, template!(Word), marker_trait_attr, experimental!(marker)),
+    gated!(
+        thread_local, AssumedUsed, template!(Word),
+        "`#[thread_local]` is an experimental feature, and does not currently handle destructors",
+    ),
+    gated!(no_core, CrateLevel, template!(Word), experimental!(no_core)),
+    // RFC 2412
+    gated!(
+        optimize, AssumedUsed, template!(List: "size|speed"), optimize_attribute,
+        experimental!(optimize),
+    ),
+    // RFC 2867
+    gated!(instruction_set, AssumedUsed, template!(List: "set"), isa_attribute, experimental!(instruction_set)),
+
+    gated!(ffi_returns_twice, AssumedUsed, template!(Word), experimental!(ffi_returns_twice)),
+    gated!(ffi_pure, AssumedUsed, template!(Word), experimental!(ffi_pure)),
+    gated!(ffi_const, AssumedUsed, template!(Word), experimental!(ffi_const)),
+    gated!(
+        register_attr, CrateLevel, template!(List: "attr1, attr2, ..."),
+        experimental!(register_attr),
+    ),
+    gated!(
+        register_tool, CrateLevel, template!(List: "tool1, tool2, ..."),
+        experimental!(register_tool),
+    ),
+
+    gated!(cmse_nonsecure_entry, AssumedUsed, template!(Word), experimental!(cmse_nonsecure_entry)),
+
+    // ==========================================================================
+    // Internal attributes: Stability, deprecation, and unsafe:
+    // ==========================================================================
+
+    ungated!(feature, CrateLevel, template!(List: "name1, name1, ...")),
+    // FIXME(#14407) -- only looked at on-demand so we can't
+    // guarantee they'll have already been checked.
+    ungated!(
+        rustc_deprecated, AssumedUsed,
+        template!(List: r#"since = "version", reason = "...""#)
+    ),
+    // FIXME(#14407)
+    ungated!(stable, AssumedUsed, template!(List: r#"feature = "name", since = "version""#)),
+    // FIXME(#14407)
+    ungated!(
+        unstable, AssumedUsed,
+        template!(List: r#"feature = "name", reason = "...", issue = "N""#),
+    ),
+    // FIXME(#14407)
+    ungated!(rustc_const_unstable, AssumedUsed, template!(List: r#"feature = "name""#)),
+    // FIXME(#14407)
+    ungated!(rustc_const_stable, AssumedUsed, template!(List: r#"feature = "name""#)),
+    gated!(
+        allow_internal_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
+        "allow_internal_unstable side-steps feature gating and stability checks",
+    ),
+    gated!(
+        rustc_allow_const_fn_unstable, AssumedUsed, template!(Word, List: "feat1, feat2, ..."),
+        "rustc_allow_const_fn_unstable side-steps feature gating and stability checks"
+    ),
+    gated!(
+        allow_internal_unsafe, Normal, template!(Word),
+        "allow_internal_unsafe side-steps the unsafe_code lint",
+    ),
+
+    // ==========================================================================
+    // Internal attributes: Type system related:
+    // ==========================================================================
+
+    gated!(fundamental, AssumedUsed, template!(Word), experimental!(fundamental)),
+    gated!(
+        may_dangle, Normal, template!(Word), dropck_eyepatch,
+        "`may_dangle` has unstable semantics and may be removed in the future",
+    ),
+
+    // ==========================================================================
+    // Internal attributes: Runtime related:
+    // ==========================================================================
+
+    rustc_attr!(rustc_allocator, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_allocator_nounwind, AssumedUsed, template!(Word), IMPL_DETAIL),
+    gated!(alloc_error_handler, Normal, template!(Word), experimental!(alloc_error_handler)),
+    gated!(
+        default_lib_allocator, AssumedUsed, template!(Word), allocator_internals,
+        experimental!(default_lib_allocator),
+    ),
+    gated!(
+        needs_allocator, Normal, template!(Word), allocator_internals,
+        experimental!(needs_allocator),
+    ),
+    gated!(panic_runtime, AssumedUsed, template!(Word), experimental!(panic_runtime)),
+    gated!(needs_panic_runtime, AssumedUsed, template!(Word), experimental!(needs_panic_runtime)),
+    gated!(
+        unwind, AssumedUsed, template!(List: "allowed|aborts"), unwind_attributes,
+        experimental!(unwind),
+    ),
+    gated!(
+        compiler_builtins, AssumedUsed, template!(Word),
+        "the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate \
+        which contains compiler-rt intrinsics and will never be stable",
+    ),
+    gated!(
+        profiler_runtime, AssumedUsed, template!(Word),
+        "the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate \
+        which contains the profiler runtime and will never be stable",
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Linkage:
+    // ==========================================================================
+
+    gated!(
+        linkage, AssumedUsed, template!(NameValueStr: "external|internal|..."),
+        "the `linkage` attribute is experimental and not portable across platforms",
+    ),
+    rustc_attr!(rustc_std_internal_symbol, AssumedUsed, template!(Word), INTERNAL_UNSTABLE),
+
+    // ==========================================================================
+    // Internal attributes, Macro related:
+    // ==========================================================================
+
+    rustc_attr!(rustc_builtin_macro, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_proc_macro_decls, Normal, template!(Word), INTERNAL_UNSTABLE),
+    rustc_attr!(
+        rustc_macro_transparency, AssumedUsed,
+        template!(NameValueStr: "transparent|semitransparent|opaque"),
+        "used internally for testing macro hygiene",
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Diagnostics related:
+    // ==========================================================================
+
+    rustc_attr!(
+        rustc_on_unimplemented, AssumedUsed,
+        template!(
+            List: r#"/*opt*/ message = "...", /*opt*/ label = "...", /*opt*/ note = "...""#,
+            NameValueStr: "message"
+        ),
+        INTERNAL_UNSTABLE
+    ),
+    // Enumerates "identity-like" conversion methods to suggest on type mismatch.
+    rustc_attr!(rustc_conversion_suggestion, AssumedUsed, template!(Word), INTERNAL_UNSTABLE),
+
+    // ==========================================================================
+    // Internal attributes, Const related:
+    // ==========================================================================
+
+    rustc_attr!(rustc_promotable, AssumedUsed, template!(Word), IMPL_DETAIL),
+    rustc_attr!(rustc_args_required_const, AssumedUsed, template!(List: "N"), INTERNAL_UNSTABLE),
+
+    // ==========================================================================
+    // Internal attributes, Layout related:
+    // ==========================================================================
+
+    rustc_attr!(
+        rustc_layout_scalar_valid_range_start, AssumedUsed, template!(List: "value"),
+        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
+        niche optimizations in libcore and will never be stable",
+    ),
+    rustc_attr!(
+        rustc_layout_scalar_valid_range_end, AssumedUsed, template!(List: "value"),
+        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
+        niche optimizations in libcore and will never be stable",
+    ),
+    rustc_attr!(
+        rustc_nonnull_optimization_guaranteed, AssumedUsed, template!(Word),
+        "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \
+        niche optimizations in libcore and will never be stable",
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Misc:
+    // ==========================================================================
+    gated!(
+        lang, Normal, template!(NameValueStr: "name"), lang_items,
+        "language items are subject to change",
+    ),
+    gated!(rustc_diagnostic_item), // XXX modified in rust-analyzer
+    gated!(
+        // Used in resolve:
+        prelude_import, AssumedUsed, template!(Word),
+        "`#[prelude_import]` is for use by rustc only",
+    ),
+    gated!(
+        rustc_paren_sugar, Normal, template!(Word), unboxed_closures,
+        "unboxed_closures are still evolving",
+    ),
+    rustc_attr!(
+        rustc_inherit_overflow_checks, AssumedUsed, template!(Word),
+        "the `#[rustc_inherit_overflow_checks]` attribute is just used to control \
+        overflow checking behavior of several libcore functions that are inlined \
+        across crates and will never be stable",
+    ),
+    rustc_attr!(rustc_reservation_impl, Normal, template!(NameValueStr: "reservation message"),
+                "the `#[rustc_reservation_impl]` attribute is internally used \
+                 for reserving for `for<T> From<!> for T` impl"
+    ),
+    rustc_attr!(
+        rustc_test_marker, Normal, template!(Word),
+        "the `#[rustc_test_marker]` attribute is used internally to track tests",
+    ),
+    rustc_attr!(
+        rustc_unsafe_specialization_marker, Normal, template!(Word),
+        "the `#[rustc_unsafe_specialization_marker]` attribute is used to check specializations"
+    ),
+    rustc_attr!(
+        rustc_specialization_trait, Normal, template!(Word),
+        "the `#[rustc_specialization_trait]` attribute is used to check specializations"
+    ),
+
+    // ==========================================================================
+    // Internal attributes, Testing:
+    // ==========================================================================
+
+    rustc_attr!(TEST, rustc_outlives, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_capture_analysis, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_variance, Normal, template!(Word)),
+    rustc_attr!(TEST, rustc_layout, Normal, template!(List: "field1, field2, ...")),
+    rustc_attr!(TEST, rustc_regions, Normal, template!(Word)),
+    rustc_attr!(
+        TEST, rustc_error, AssumedUsed,
+        template!(Word, List: "delay_span_bug_from_inside_query")
+    ),
+    rustc_attr!(TEST, rustc_dump_user_substs, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_if_this_changed, AssumedUsed, template!(Word, List: "DepNode")),
+    rustc_attr!(TEST, rustc_then_this_would_need, AssumedUsed, template!(List: "DepNode")),
+    rustc_attr!(
+        TEST, rustc_dirty, AssumedUsed,
+        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_clean, AssumedUsed,
+        template!(List: r#"cfg = "...", /*opt*/ label = "...", /*opt*/ except = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_partition_reused, AssumedUsed,
+        template!(List: r#"cfg = "...", module = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_partition_codegened, AssumedUsed,
+        template!(List: r#"cfg = "...", module = "...""#),
+    ),
+    rustc_attr!(
+        TEST, rustc_expected_cgu_reuse, AssumedUsed,
+        template!(List: r#"cfg = "...", module = "...", kind = "...""#),
+    ),
+    rustc_attr!(TEST, rustc_synthetic, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_symbol_name, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_polymorphize_error, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_def_path, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_mir, AssumedUsed, template!(List: "arg1, arg2, ...")),
+    rustc_attr!(TEST, rustc_dump_program_clauses, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_dump_env_program_clauses, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_object_lifetime_default, AssumedUsed, template!(Word)),
+    rustc_attr!(TEST, rustc_dummy, Normal, template!(Word /* doesn't matter*/)),
+    gated!(
+        omit_gdb_pretty_printer_section, AssumedUsed, template!(Word),
+        "the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite",
+    ),
+];
diff --git a/crates/hir_def/src/generics.rs b/crates/hir_def/src/generics.rs
index 835fe3fbd..5189c7e9f 100644
--- a/crates/hir_def/src/generics.rs
+++ b/crates/hir_def/src/generics.rs
@@ -21,7 +21,7 @@ use crate::{
     keys,
     src::HasChildSource,
     src::HasSource,
-    type_ref::{TypeBound, TypeRef},
+    type_ref::{LifetimeRef, TypeBound, TypeRef},
     AdtId, GenericDefId, LocalTypeParamId, Lookup, TypeParamId,
 };
 
@@ -33,6 +33,12 @@ pub struct TypeParamData {
     pub provenance: TypeParamProvenance,
 }
 
+/// Data about a generic parameter (to a function, struct, impl, ...).
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct LifetimeParamData {
+    pub name: Name,
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum TypeParamProvenance {
     TypeParamList,
@@ -44,7 +50,7 @@ pub enum TypeParamProvenance {
 #[derive(Clone, PartialEq, Eq, Debug, Default)]
 pub struct GenericParams {
     pub types: Arena<TypeParamData>,
-    // lifetimes: Arena<LocalLifetimeParamId, LifetimeParamData>,
+    pub lifetimes: Arena<LifetimeParamData>,
     pub where_predicates: Vec<WherePredicate>,
 }
 
@@ -53,16 +59,17 @@ pub struct GenericParams {
 /// It might still result in multiple actual predicates though, because of
 /// associated type bindings like `Iterator<Item = u32>`.
 #[derive(Clone, PartialEq, Eq, Debug)]
-pub struct WherePredicate {
-    pub target: WherePredicateTarget,
-    pub bound: TypeBound,
+pub enum WherePredicate {
+    TypeBound { target: WherePredicateTypeTarget, bound: TypeBound },
+    Lifetime { target: LifetimeRef, bound: LifetimeRef },
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]
-pub enum WherePredicateTarget {
+pub enum WherePredicateTypeTarget {
     TypeRef(TypeRef),
     /// For desugared where predicates that can directly refer to a type param.
     TypeParam(LocalTypeParamId),
+    // FIXME: ForLifetime(Vec<LifetimeParamId>, TypeRef)
 }
 
 type SourceMap = ArenaMap<LocalTypeParamId, Either<ast::Trait, ast::TypeParam>>;
@@ -123,7 +130,7 @@ impl GenericParams {
     }
 
     fn new(db: &dyn DefDatabase, def: GenericDefId) -> (GenericParams, InFile<SourceMap>) {
-        let mut generics = GenericParams { types: Arena::default(), where_predicates: Vec::new() };
+        let mut generics = GenericParams::default();
         let mut sm = ArenaMap::default();
 
         // FIXME: add `: Sized` bound for everything except for `Self` in traits
@@ -171,7 +178,7 @@ impl GenericParams {
                 // add super traits as bounds on Self
                 // i.e., trait Foo: Bar is equivalent to trait Foo where Self: Bar
                 let self_param = TypeRef::Path(name![Self].into());
-                generics.fill_bounds(&lower_ctx, &src.value, self_param);
+                generics.fill_bounds(&lower_ctx, &src.value, Either::Left(self_param));
 
                 generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
@@ -218,12 +225,12 @@ impl GenericParams {
         &mut self,
         lower_ctx: &LowerCtx,
         node: &dyn ast::TypeBoundsOwner,
-        type_ref: TypeRef,
+        target: Either<TypeRef, LifetimeRef>,
     ) {
         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, type_ref.clone());
+            self.add_where_predicate_from_bound(lower_ctx, bound, target.clone());
         }
     }
 
@@ -246,19 +253,30 @@ impl GenericParams {
             sm.insert(param_id, Either::Right(type_param.clone()));
 
             let type_ref = TypeRef::Path(name.into());
-            self.fill_bounds(&lower_ctx, &type_param, type_ref);
+            self.fill_bounds(&lower_ctx, &type_param, Either::Left(type_ref));
+        }
+        for lifetime_param in params.lifetime_params() {
+            let name = lifetime_param
+                .lifetime_token()
+                .map_or_else(Name::missing, |tok| Name::new_lifetime(&tok));
+            let param = LifetimeParamData { name: name.clone() };
+            let _param_id = self.lifetimes.alloc(param);
+            let lifetime_ref = LifetimeRef::new_name(name);
+            self.fill_bounds(&lower_ctx, &lifetime_param, Either::Right(lifetime_ref));
         }
     }
 
     fn fill_where_predicates(&mut self, lower_ctx: &LowerCtx, where_clause: ast::WhereClause) {
         for pred in where_clause.predicates() {
-            let type_ref = match pred.ty() {
-                Some(type_ref) => type_ref,
-                None => continue,
+            let target = if let Some(type_ref) = pred.ty() {
+                Either::Left(TypeRef::from_ast(lower_ctx, type_ref))
+            } else if let Some(lifetime_tok) = pred.lifetime_token() {
+                Either::Right(LifetimeRef::from_token(lifetime_tok))
+            } else {
+                continue;
             };
-            let type_ref = TypeRef::from_ast(lower_ctx, type_ref);
             for bound in pred.type_bound_list().iter().flat_map(|l| l.bounds()) {
-                self.add_where_predicate_from_bound(lower_ctx, bound, type_ref.clone());
+                self.add_where_predicate_from_bound(lower_ctx, bound, target.clone());
             }
         }
     }
@@ -267,15 +285,24 @@ impl GenericParams {
         &mut self,
         lower_ctx: &LowerCtx,
         bound: ast::TypeBound,
-        type_ref: TypeRef,
+        target: Either<TypeRef, LifetimeRef>,
     ) {
         if bound.question_mark_token().is_some() {
             // FIXME: remove this bound
             return;
         }
         let bound = TypeBound::from_ast(lower_ctx, bound);
-        self.where_predicates
-            .push(WherePredicate { target: WherePredicateTarget::TypeRef(type_ref), bound });
+        let predicate = match (target, bound) {
+            (Either::Left(type_ref), bound) => WherePredicate::TypeBound {
+                target: WherePredicateTypeTarget::TypeRef(type_ref),
+                bound,
+            },
+            (Either::Right(lifetime), TypeBound::Lifetime(bound)) => {
+                WherePredicate::Lifetime { target: lifetime, bound }
+            }
+            _ => return,
+        };
+        self.where_predicates.push(predicate);
     }
 
     pub(crate) fn fill_implicit_impl_trait_args(&mut self, type_ref: &TypeRef) {
@@ -288,8 +315,8 @@ impl GenericParams {
                 };
                 let param_id = self.types.alloc(param);
                 for bound in bounds {
-                    self.where_predicates.push(WherePredicate {
-                        target: WherePredicateTarget::TypeParam(param_id),
+                    self.where_predicates.push(WherePredicate::TypeBound {
+                        target: WherePredicateTypeTarget::TypeParam(param_id),
                         bound: bound.clone(),
                     });
                 }
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index c017b352d..b08167281 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -246,7 +246,10 @@ struct GenericParamsStorage {
 
 impl GenericParamsStorage {
     fn alloc(&mut self, params: GenericParams) -> GenericParamsId {
-        if params.types.is_empty() && params.where_predicates.is_empty() {
+        if params.types.is_empty()
+            && params.lifetimes.is_empty()
+            && params.where_predicates.is_empty()
+        {
             return GenericParamsId::EMPTY;
         }
 
@@ -255,7 +258,7 @@ impl GenericParamsStorage {
 }
 
 static EMPTY_GENERICS: GenericParams =
-    GenericParams { types: Arena::new(), where_predicates: Vec::new() };
+    GenericParams { types: Arena::new(), lifetimes: Arena::new(), where_predicates: Vec::new() };
 
 #[derive(Default, Debug, Eq, PartialEq)]
 struct ItemTreeData {
diff --git a/crates/hir_def/src/item_tree/lower.rs b/crates/hir_def/src/item_tree/lower.rs
index 63b2826f8..f7ce2e26d 100644
--- a/crates/hir_def/src/item_tree/lower.rs
+++ b/crates/hir_def/src/item_tree/lower.rs
@@ -13,6 +13,7 @@ use syntax::{
 use crate::{
     attr::Attrs,
     generics::{GenericParams, TypeParamData, TypeParamProvenance},
+    type_ref::LifetimeRef,
 };
 
 use super::*;
@@ -292,12 +293,16 @@ impl Ctx {
                         let self_type = TypeRef::Path(name![Self].into());
                         match self_param.kind() {
                             ast::SelfParamKind::Owned => self_type,
-                            ast::SelfParamKind::Ref => {
-                                TypeRef::Reference(Box::new(self_type), Mutability::Shared)
-                            }
-                            ast::SelfParamKind::MutRef => {
-                                TypeRef::Reference(Box::new(self_type), Mutability::Mut)
-                            }
+                            ast::SelfParamKind::Ref => TypeRef::Reference(
+                                Box::new(self_type),
+                                self_param.lifetime_token().map(LifetimeRef::from_token),
+                                Mutability::Shared,
+                            ),
+                            ast::SelfParamKind::MutRef => TypeRef::Reference(
+                                Box::new(self_type),
+                                self_param.lifetime_token().map(LifetimeRef::from_token),
+                                Mutability::Mut,
+                            ),
                         }
                     }
                 };
@@ -629,8 +634,7 @@ impl Ctx {
                 // add super traits as bounds on Self
                 // i.e., trait Foo: Bar is equivalent to trait Foo where Self: Bar
                 let self_param = TypeRef::Path(name![Self].into());
-                generics.fill_bounds(&self.body_ctx, trait_def, self_param);
-
+                generics.fill_bounds(&self.body_ctx, trait_def, Either::Left(self_param));
                 generics.fill(&self.body_ctx, &mut sm, node);
             }
             GenericsOwner::Impl => {
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index 02ed30e4d..7e2199a9c 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -18,6 +18,7 @@ pub mod attr;
 pub mod path;
 pub mod type_ref;
 pub mod builtin_type;
+pub mod builtin_attr;
 pub mod diagnostics;
 pub mod per_ns;
 pub mod item_scope;
@@ -224,6 +225,13 @@ pub struct TypeParamId {
 pub type LocalTypeParamId = Idx<generics::TypeParamData>;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct LifetimeParamId {
+    pub parent: GenericDefId,
+    pub local_id: LocalLifetimeParamId,
+}
+pub type LocalLifetimeParamId = Idx<generics::LifetimeParamData>;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum ContainerId {
     ModuleId(ModuleId),
     DefWithBodyId(DefWithBodyId),
diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs
index 5b8c1e449..00a69a8a6 100644
--- a/crates/hir_def/src/path.rs
+++ b/crates/hir_def/src/path.rs
@@ -7,7 +7,7 @@ use std::{
     sync::Arc,
 };
 
-use crate::body::LowerCtx;
+use crate::{body::LowerCtx, type_ref::LifetimeRef};
 use base_db::CrateId;
 use hir_expand::{
     hygiene::Hygiene,
@@ -145,7 +145,7 @@ pub struct AssociatedTypeBinding {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum GenericArg {
     Type(TypeRef),
-    // or lifetime...
+    Lifetime(LifetimeRef),
 }
 
 impl Path {
diff --git a/crates/hir_def/src/path/lower.rs b/crates/hir_def/src/path/lower.rs
index 07b9723ce..60fa7646b 100644
--- a/crates/hir_def/src/path/lower.rs
+++ b/crates/hir_def/src/path/lower.rs
@@ -15,7 +15,7 @@ use super::AssociatedTypeBinding;
 use crate::{
     body::LowerCtx,
     path::{GenericArg, GenericArgs, ModPath, Path, PathKind},
-    type_ref::{TypeBound, TypeRef},
+    type_ref::{LifetimeRef, TypeBound, TypeRef},
 };
 
 pub(super) use lower_use::lower_use_tree;
@@ -170,8 +170,14 @@ pub(super) fn lower_generic_args(
                     bindings.push(AssociatedTypeBinding { name, type_ref, bounds });
                 }
             }
-            // Lifetimes and constants are ignored for now.
-            ast::GenericArg::LifetimeArg(_) | ast::GenericArg::ConstArg(_) => (),
+            ast::GenericArg::LifetimeArg(lifetime_arg) => {
+                if let Some(lifetime) = lifetime_arg.lifetime_token() {
+                    let lifetime_ref = LifetimeRef::from_token(lifetime);
+                    args.push(GenericArg::Lifetime(lifetime_ref))
+                }
+            }
+            // constants are ignored for now.
+            ast::GenericArg::ConstArg(_) => (),
         }
     }
 
diff --git a/crates/hir_def/src/type_ref.rs b/crates/hir_def/src/type_ref.rs
index 1a78c1444..347ceabb9 100644
--- a/crates/hir_def/src/type_ref.rs
+++ b/crates/hir_def/src/type_ref.rs
@@ -1,6 +1,7 @@
 //! HIR for references to types. Paths in these are not yet resolved. They can
 //! be directly created from an ast::TypeRef, without further queries.
-use syntax::ast::{self};
+use hir_expand::name::Name;
+use syntax::{ast, SyntaxToken};
 
 use crate::{body::LowerCtx, path::Path};
 
@@ -58,7 +59,7 @@ pub enum TypeRef {
     Tuple(Vec<TypeRef>),
     Path(Path),
     RawPtr(Box<TypeRef>, Mutability),
-    Reference(Box<TypeRef>, Mutability),
+    Reference(Box<TypeRef>, Option<LifetimeRef>, Mutability),
     Array(Box<TypeRef> /*, Expr*/),
     Slice(Box<TypeRef>),
     /// A fn pointer. Last element of the vector is the return type.
@@ -70,10 +71,29 @@ pub enum TypeRef {
 }
 
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
+pub struct LifetimeRef {
+    pub name: Name,
+}
+
+impl LifetimeRef {
+    pub(crate) fn new_name(name: Name) -> Self {
+        LifetimeRef { name }
+    }
+
+    pub(crate) fn from_token(token: SyntaxToken) -> Self {
+        LifetimeRef { name: Name::new_lifetime(&token) }
+    }
+
+    pub fn missing() -> LifetimeRef {
+        LifetimeRef { name: Name::missing() }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub enum TypeBound {
     Path(Path),
-    // also for<> bounds
-    // also Lifetimes
+    // ForLifetime(Vec<LifetimeRef>, Path), FIXME ForLifetime
+    Lifetime(LifetimeRef),
     Error,
 }
 
@@ -107,8 +127,9 @@ impl TypeRef {
             }
             ast::Type::RefType(inner) => {
                 let inner_ty = TypeRef::from_ast_opt(&ctx, inner.ty());
+                let lifetime = inner.lifetime_token().map(|t| LifetimeRef::from_token(t));
                 let mutability = Mutability::from_mutable(inner.mut_token().is_some());
-                TypeRef::Reference(Box::new(inner_ty), mutability)
+                TypeRef::Reference(Box::new(inner_ty), lifetime, mutability)
             }
             ast::Type::InferType(_inner) => TypeRef::Placeholder,
             ast::Type::FnPtrType(inner) => {
@@ -163,14 +184,14 @@ impl TypeRef {
                     types.iter().for_each(|t| go(t, f))
                 }
                 TypeRef::RawPtr(type_ref, _)
-                | TypeRef::Reference(type_ref, _)
+                | TypeRef::Reference(type_ref, ..)
                 | TypeRef::Array(type_ref)
                 | TypeRef::Slice(type_ref) => go(&type_ref, f),
                 TypeRef::ImplTrait(bounds) | TypeRef::DynTrait(bounds) => {
                     for bound in bounds {
                         match bound {
                             TypeBound::Path(path) => go_path(path, f),
-                            TypeBound::Error => (),
+                            TypeBound::Lifetime(_) | TypeBound::Error => (),
                         }
                     }
                 }
@@ -186,8 +207,12 @@ impl TypeRef {
             for segment in path.segments().iter() {
                 if let Some(args_and_bindings) = segment.args_and_bindings {
                     for arg in &args_and_bindings.args {
-                        let crate::path::GenericArg::Type(type_ref) = arg;
-                        go(type_ref, f);
+                        match arg {
+                            crate::path::GenericArg::Type(type_ref) => {
+                                go(type_ref, f);
+                            }
+                            crate::path::GenericArg::Lifetime(_) => {}
+                        }
                     }
                     for binding in &args_and_bindings.bindings {
                         if let Some(type_ref) = &binding.type_ref {
@@ -196,7 +221,7 @@ impl TypeRef {
                         for bound in &binding.bounds {
                             match bound {
                                 TypeBound::Path(path) => go_path(path, f),
-                                TypeBound::Error => (),
+                                TypeBound::Lifetime(_) | TypeBound::Error => (),
                             }
                         }
                     }
@@ -232,7 +257,10 @@ impl TypeBound {
                 };
                 TypeBound::Path(path)
             }
-            ast::TypeBoundKind::ForType(_) | ast::TypeBoundKind::Lifetime(_) => TypeBound::Error,
+            ast::TypeBoundKind::ForType(_) => TypeBound::Error, // FIXME ForType
+            ast::TypeBoundKind::Lifetime(lifetime) => {
+                TypeBound::Lifetime(LifetimeRef::from_token(lifetime))
+            }
         }
     }