9 files changed, 58 insertions, 39 deletions

diff --git a/crates/hir_def/src/find_path.rs b/crates/hir_def/src/find_path.rs
index 94a1d567d..aa2c6e04e 100644
--- a/crates/hir_def/src/find_path.rs
+++ b/crates/hir_def/src/find_path.rs
@@ -36,13 +36,13 @@ const MAX_PATH_LEN: usize = 15;
 
 impl ModPath {
     fn starts_with_std(&self) -> bool {
-        self.segments.first() == Some(&known::std)
+        self.segments().first() == Some(&known::std)
     }
 
     // When std library is present, paths starting with `std::`
     // should be preferred over paths starting with `core::` and `alloc::`
     fn can_start_with_std(&self) -> bool {
-        let first_segment = self.segments.first();
+        let first_segment = self.segments().first();
         first_segment == Some(&known::alloc) || first_segment == Some(&known::core)
     }
 }
@@ -157,7 +157,7 @@ fn find_path_inner(
     if let Some(ModuleDefId::EnumVariantId(variant)) = item.as_module_def_id() {
         if let Some(mut path) = find_path(db, ItemInNs::Types(variant.parent.into()), from) {
             let data = db.enum_data(variant.parent);
-            path.segments.push(data.variants[variant.local_id].name.clone());
+            path.push_segment(data.variants[variant.local_id].name.clone());
             return Some(path);
         }
         // If this doesn't work, it seems we have no way of referring to the
@@ -186,7 +186,7 @@ fn find_path_inner(
                 best_path_len - 1,
                 prefixed,
             ) {
-                path.segments.push(name);
+                path.push_segment(name);
 
                 let new_path = if let Some(best_path) = best_path {
                     select_best_path(best_path, path, prefer_no_std)
@@ -215,7 +215,7 @@ fn find_path_inner(
                     prefixed,
                 )?;
                 mark::hit!(partially_imported);
-                path.segments.push(info.path.segments.last().unwrap().clone());
+                path.push_segment(info.path.segments.last().unwrap().clone());
                 Some(path)
             })
         });
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index 401556931..3233b1957 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -240,7 +240,7 @@ impl ItemVisibilities {
     fn alloc(&mut self, vis: RawVisibility) -> RawVisibilityId {
         match &vis {
             RawVisibility::Public => RawVisibilityId::PUB,
-            RawVisibility::Module(path) if path.segments.is_empty() => match &path.kind {
+            RawVisibility::Module(path) if path.segments().is_empty() => match &path.kind {
                 PathKind::Super(0) => RawVisibilityId::PRIV,
                 PathKind::Crate => RawVisibilityId::PUB_CRATE,
                 _ => RawVisibilityId(self.arena.alloc(vis).into_raw().into()),
@@ -251,10 +251,8 @@ impl ItemVisibilities {
 }
 
 static VIS_PUB: RawVisibility = RawVisibility::Public;
-static VIS_PRIV: RawVisibility =
-    RawVisibility::Module(ModPath { kind: PathKind::Super(0), segments: Vec::new() });
-static VIS_PUB_CRATE: RawVisibility =
-    RawVisibility::Module(ModPath { kind: PathKind::Crate, segments: Vec::new() });
+static VIS_PRIV: RawVisibility = RawVisibility::Module(ModPath::from_kind(PathKind::Super(0)));
+static VIS_PUB_CRATE: RawVisibility = RawVisibility::Module(ModPath::from_kind(PathKind::Crate));
 
 #[derive(Default, Debug, Eq, PartialEq)]
 struct GenericParamsStorage {
diff --git a/crates/hir_def/src/item_tree/lower.rs b/crates/hir_def/src/item_tree/lower.rs
index 93cdca55d..8f2f0b340 100644
--- a/crates/hir_def/src/item_tree/lower.rs
+++ b/crates/hir_def/src/item_tree/lower.rs
@@ -750,7 +750,8 @@ impl Ctx {
 
 fn desugar_future_path(orig: TypeRef) -> Path {
     let path = path![core::future::Future];
-    let mut generic_args: Vec<_> = std::iter::repeat(None).take(path.segments.len() - 1).collect();
+    let mut generic_args: Vec<_> =
+        std::iter::repeat(None).take(path.segments().len() - 1).collect();
     let mut last = GenericArgs::empty();
     let binding =
         AssociatedTypeBinding { name: name![Output], type_ref: Some(orig), bounds: Vec::new() };
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index 5dd3705b0..b50923747 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -662,7 +662,7 @@ impl AsMacroCall for AstIdWithPath<ast::Item> {
             def.as_lazy_macro(
                 db.upcast(),
                 krate,
-                MacroCallKind::Attr(self.ast_id, self.path.segments.last()?.to_string()),
+                MacroCallKind::Attr(self.ast_id, self.path.segments().last()?.to_string()),
             )
             .into(),
         )
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index f904a97de..6bd41bc08 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -655,7 +655,7 @@ impl DefCollector<'_> {
                 }
             }
         } else {
-            match import.path.segments.last() {
+            match import.path.segments().last() {
                 Some(last_segment) => {
                     let name = match &import.alias {
                         Some(ImportAlias::Alias(name)) => Some(name.clone()),
@@ -956,7 +956,7 @@ impl DefCollector<'_> {
                 let item_tree = self.db.item_tree(import.file_id);
                 let import_data = &item_tree[import.value];
 
-                match (import_data.path.segments.first(), &import_data.path.kind) {
+                match (import_data.path.segments().first(), &import_data.path.kind) {
                     (Some(krate), PathKind::Plain) | (Some(krate), PathKind::Abs) => {
                         if diagnosed_extern_crates.contains(krate) {
                             continue;
diff --git a/crates/hir_def/src/nameres/path_resolution.rs b/crates/hir_def/src/nameres/path_resolution.rs
index 2a3ac5d7b..f2b59172d 100644
--- a/crates/hir_def/src/nameres/path_resolution.rs
+++ b/crates/hir_def/src/nameres/path_resolution.rs
@@ -149,7 +149,7 @@ impl DefMap {
         path: &ModPath,
         shadow: BuiltinShadowMode,
     ) -> ResolvePathResult {
-        let mut segments = path.segments.iter().enumerate();
+        let mut segments = path.segments().iter().enumerate();
         let mut curr_per_ns: PerNs = match path.kind {
             PathKind::DollarCrate(krate) => {
                 if krate == self.krate {
@@ -190,7 +190,7 @@ impl DefMap {
                 // BuiltinShadowMode wasn't Module, then we need to try
                 // resolving it as a builtin.
                 let prefer_module =
-                    if path.segments.len() == 1 { shadow } else { BuiltinShadowMode::Module };
+                    if path.segments().len() == 1 { shadow } else { BuiltinShadowMode::Module };
 
                 log::debug!("resolving {:?} in module", segment);
                 self.resolve_name_in_module(db, original_module, &segment, prefer_module)
@@ -203,10 +203,10 @@ impl DefMap {
                         None => match &self.block {
                             Some(block) => {
                                 // Look up remaining path in parent `DefMap`
-                                let new_path = ModPath {
-                                    kind: PathKind::Super(lvl - i),
-                                    segments: path.segments.clone(),
-                                };
+                                let new_path = ModPath::from_segments(
+                                    PathKind::Super(lvl - i),
+                                    path.segments().to_vec(),
+                                );
                                 log::debug!("`super` path: {} -> {} in parent map", path, new_path);
                                 return block.parent.def_map(db).resolve_path_fp_with_macro(
                                     db,
@@ -258,10 +258,10 @@ impl DefMap {
             curr_per_ns = match curr {
                 ModuleDefId::ModuleId(module) => {
                     if module.krate != self.krate {
-                        let path = ModPath {
-                            segments: path.segments[i..].to_vec(),
-                            kind: PathKind::Super(0),
-                        };
+                        let path = ModPath::from_segments(
+                            PathKind::Super(0),
+                            path.segments()[i..].iter().cloned(),
+                        );
                         log::debug!("resolving {:?} in other crate", path);
                         let defp_map = module.def_map(db);
                         let (def, s) = defp_map.resolve_path(db, module.local_id, &path, shadow);
diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs
index 84ea09b53..0caad53d3 100644
--- a/crates/hir_def/src/path.rs
+++ b/crates/hir_def/src/path.rs
@@ -20,7 +20,7 @@ use crate::{
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct ModPath {
     pub kind: PathKind,
-    pub segments: Vec<Name>,
+    segments: Vec<Name>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -53,6 +53,11 @@ impl ModPath {
         ModPath { kind, segments }
     }
 
+    /// Creates a `ModPath` from a `PathKind`, with no extra path segments.
+    pub const fn from_kind(kind: PathKind) -> ModPath {
+        ModPath { kind, segments: Vec::new() }
+    }
+
     /// Calls `cb` with all paths, represented by this use item.
     pub(crate) fn expand_use_item(
         item_src: InFile<ast::Use>,
@@ -64,6 +69,18 @@ impl ModPath {
         }
     }
 
+    pub fn segments(&self) -> &[Name] {
+        &self.segments
+    }
+
+    pub fn push_segment(&mut self, segment: Name) {
+        self.segments.push(segment);
+    }
+
+    pub fn pop_segment(&mut self) -> Option<Name> {
+        self.segments.pop()
+    }
+
     /// Returns the number of segments in the path (counting special segments like `$crate` and
     /// `super`).
     pub fn len(&self) -> usize {
@@ -78,7 +95,7 @@ impl ModPath {
     }
 
     pub fn is_ident(&self) -> bool {
-        self.kind == PathKind::Plain && self.segments.len() == 1
+        self.as_ident().is_some()
     }
 
     pub fn is_self(&self) -> bool {
@@ -87,10 +104,14 @@ impl ModPath {
 
     /// If this path is a single identifier, like `foo`, return its name.
     pub fn as_ident(&self) -> Option<&Name> {
-        if !self.is_ident() {
+        if self.kind != PathKind::Plain {
             return None;
         }
-        self.segments.first()
+
+        match &*self.segments {
+            [name] => Some(name),
+            _ => None,
+        }
     }
 }
 
diff --git a/crates/hir_def/src/resolver.rs b/crates/hir_def/src/resolver.rs
index 9021ea712..f9ad50301 100644
--- a/crates/hir_def/src/resolver.rs
+++ b/crates/hir_def/src/resolver.rs
@@ -164,7 +164,7 @@ impl Resolver {
         db: &dyn DefDatabase,
         path: &ModPath,
     ) -> Option<(TypeNs, Option<usize>)> {
-        let first_name = path.segments.first()?;
+        let first_name = path.segments().first()?;
         let skip_to_mod = path.kind != PathKind::Plain;
         for scope in self.scopes.iter().rev() {
             match scope {
@@ -179,7 +179,7 @@ impl Resolver {
 
                 Scope::GenericParams { params, def } => {
                     if let Some(local_id) = params.find_type_by_name(first_name) {
-                        let idx = if path.segments.len() == 1 { None } else { Some(1) };
+                        let idx = if path.segments().len() == 1 { None } else { Some(1) };
                         return Some((
                             TypeNs::GenericParam(TypeParamId { local_id, parent: *def }),
                             idx,
@@ -188,13 +188,13 @@ impl Resolver {
                 }
                 Scope::ImplDefScope(impl_) => {
                     if first_name == &name![Self] {
-                        let idx = if path.segments.len() == 1 { None } else { Some(1) };
+                        let idx = if path.segments().len() == 1 { None } else { Some(1) };
                         return Some((TypeNs::SelfType(*impl_), idx));
                     }
                 }
                 Scope::AdtScope(adt) => {
                     if first_name == &name![Self] {
-                        let idx = if path.segments.len() == 1 { None } else { Some(1) };
+                        let idx = if path.segments().len() == 1 { None } else { Some(1) };
                         return Some((TypeNs::AdtSelfType(*adt), idx));
                     }
                 }
@@ -270,9 +270,9 @@ impl Resolver {
         db: &dyn DefDatabase,
         path: &ModPath,
     ) -> Option<ResolveValueResult> {
-        let n_segments = path.segments.len();
+        let n_segments = path.segments().len();
         let tmp = name![self];
-        let first_name = if path.is_self() { &tmp } else { path.segments.first()? };
+        let first_name = if path.is_self() { &tmp } else { path.segments().first()? };
         let skip_to_mod = path.kind != PathKind::Plain && !path.is_self();
         for scope in self.scopes.iter().rev() {
             match scope {
diff --git a/crates/hir_def/src/visibility.rs b/crates/hir_def/src/visibility.rs
index e79a91102..38da3132b 100644
--- a/crates/hir_def/src/visibility.rs
+++ b/crates/hir_def/src/visibility.rs
@@ -22,8 +22,7 @@ pub enum RawVisibility {
 
 impl RawVisibility {
     pub(crate) const fn private() -> RawVisibility {
-        let path = ModPath { kind: PathKind::Super(0), segments: Vec::new() };
-        RawVisibility::Module(path)
+        RawVisibility::Module(ModPath::from_kind(PathKind::Super(0)))
     }
 
     pub(crate) fn from_ast(
@@ -59,15 +58,15 @@ impl RawVisibility {
                 RawVisibility::Module(path)
             }
             ast::VisibilityKind::PubCrate => {
-                let path = ModPath { kind: PathKind::Crate, segments: Vec::new() };
+                let path = ModPath::from_kind(PathKind::Crate);
                 RawVisibility::Module(path)
             }
             ast::VisibilityKind::PubSuper => {
-                let path = ModPath { kind: PathKind::Super(1), segments: Vec::new() };
+                let path = ModPath::from_kind(PathKind::Super(1));
                 RawVisibility::Module(path)
             }
             ast::VisibilityKind::PubSelf => {
-                let path = ModPath { kind: PathKind::Plain, segments: Vec::new() };
+                let path = ModPath::from_kind(PathKind::Plain);
                 RawVisibility::Module(path)
             }
             ast::VisibilityKind::Pub => RawVisibility::Public,