From 91def936bc0ecabd574eb312e376afa801f12dca Mon Sep 17 00:00:00 2001
From: Lukas Wirth <lukastw97@gmail.com>
Date: Sat, 20 Nov 2021 16:37:41 +0100
Subject: [PATCH] Replace Vec with Box in Path.generic_args field

---
 crates/hir_def/src/expr.rs       |  2 +-
 crates/hir_def/src/path.rs       | 16 ++++++++--------
 crates/hir_def/src/path/lower.rs | 17 ++++++-----------
 3 files changed, 15 insertions(+), 20 deletions(-)

diff --git a/crates/hir_def/src/expr.rs b/crates/hir_def/src/expr.rs
index e6518c3e2d78..6534f970ee6b 100644
--- a/crates/hir_def/src/expr.rs
+++ b/crates/hir_def/src/expr.rs
@@ -40,7 +40,7 @@ pub type LabelId = Idx<Label>;
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Literal {
-    String(String),
+    String(Box<str>),
     ByteString(Box<[u8]>),
     Char(char),
     Bool(bool),
diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs
index a54352439ca7..5bb8afa5cc99 100644
--- a/crates/hir_def/src/path.rs
+++ b/crates/hir_def/src/path.rs
@@ -22,7 +22,7 @@ pub struct ModPath {
     segments: Vec<Name>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum PathKind {
     Plain,
     /// `self::` is `Super(0)`
@@ -119,7 +119,7 @@ pub struct Path {
     type_anchor: Option<Interned<TypeRef>>,
     mod_path: Interned<ModPath>,
     /// Invariant: the same len as `self.mod_path.segments`
-    generic_args: Vec<Option<Interned<GenericArgs>>>,
+    generic_args: Box<[Option<Interned<GenericArgs>>]>,
 }
 
 /// Generic arguments to a path segment (e.g. the `i32` in `Option<i32>`). This
@@ -171,9 +171,9 @@ impl Path {
     /// Converts a known mod path to `Path`.
     pub fn from_known_path(
         path: ModPath,
-        generic_args: Vec<Option<Interned<GenericArgs>>>,
+        generic_args: impl Into<Box<[Option<Interned<GenericArgs>>]>>,
     ) -> Path {
-        Path { type_anchor: None, mod_path: Interned::new(path), generic_args }
+        Path { type_anchor: None, mod_path: Interned::new(path), generic_args: generic_args.into() }
     }
 
     pub fn kind(&self) -> &PathKind {
@@ -187,7 +187,7 @@ impl Path {
     pub fn segments(&self) -> PathSegments<'_> {
         PathSegments {
             segments: self.mod_path.segments.as_slice(),
-            generic_args: self.generic_args.as_slice(),
+            generic_args: &self.generic_args,
         }
     }
 
@@ -205,14 +205,14 @@ impl Path {
                 self.mod_path.kind.clone(),
                 self.mod_path.segments[..self.mod_path.segments.len() - 1].iter().cloned(),
             )),
-            generic_args: self.generic_args[..self.generic_args.len() - 1].to_vec(),
+            generic_args: self.generic_args[..self.generic_args.len() - 1].to_vec().into(),
         };
         Some(res)
     }
 
     pub fn is_self_type(&self) -> bool {
         self.type_anchor.is_none()
-            && self.generic_args == [None]
+            && *self.generic_args == [None]
             && self.mod_path.as_ident() == Some(&name!(Self))
     }
 }
@@ -286,7 +286,7 @@ impl From<Name> for Path {
         Path {
             type_anchor: None,
             mod_path: Interned::new(ModPath::from_segments(PathKind::Plain, iter::once(name))),
-            generic_args: vec![None],
+            generic_args: Box::new([None]),
         }
     }
 }
diff --git a/crates/hir_def/src/path/lower.rs b/crates/hir_def/src/path/lower.rs
index b08708bd28ac..c84cd50ce6e6 100644
--- a/crates/hir_def/src/path/lower.rs
+++ b/crates/hir_def/src/path/lower.rs
@@ -70,18 +70,13 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx) -> Option<Path> {
                     }
                     // <T as Trait<A>>::Foo desugars to Trait<Self=T, A>::Foo
                     Some(trait_ref) => {
-                        let path = Path::from_src(trait_ref.path()?, ctx)?;
-                        let mod_path = (*path.mod_path).clone();
-                        let num_segments = path.mod_path.segments.len();
+                        let Path { mod_path, generic_args: path_generic_args, .. } =
+                            Path::from_src(trait_ref.path()?, ctx)?;
+                        let num_segments = mod_path.segments.len();
                         kind = mod_path.kind;
 
-                        let mut prefix_segments = mod_path.segments;
-                        prefix_segments.reverse();
-                        segments.extend(prefix_segments);
-
-                        let mut prefix_args = path.generic_args;
-                        prefix_args.reverse();
-                        generic_args.extend(prefix_args);
+                        segments.extend(mod_path.segments.iter().cloned().rev());
+                        generic_args.extend(path_generic_args.iter().cloned().rev());
 
                         // Insert the type reference (T in the above example) as Self parameter for the trait
                         let last_segment =
@@ -139,7 +134,7 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx) -> Option<Path> {
     }
 
     let mod_path = Interned::new(ModPath::from_segments(kind, segments));
-    return Some(Path { type_anchor, mod_path, generic_args });
+    return Some(Path { type_anchor, mod_path, generic_args: generic_args.into() });
 
     fn qualifier(path: &ast::Path) -> Option<ast::Path> {
         if let Some(q) = path.qualifier() {