From e90f129adfebc7edce61b9f6ec573fc09f712ab3 Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Wed, 29 Jan 2025 15:14:10 -0700
Subject: [PATCH] rustdoc: use ThinVec for generic arg parts

This reduces the size of both these args, and of path segments,
so should measurably help with memory use.
---
 src/librustdoc/clean/types.rs              | 10 +++++-----
 src/librustdoc/html/render/search_index.rs |  2 +-
 src/librustdoc/json/conversions.rs         |  4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 6e817af0d6e0..4b01eed40418 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -2254,8 +2254,8 @@ impl GenericArg {
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub(crate) enum GenericArgs {
-    AngleBracketed { args: Box<[GenericArg]>, constraints: ThinVec<AssocItemConstraint> },
-    Parenthesized { inputs: Box<[Type]>, output: Option<Box<Type>> },
+    AngleBracketed { args: ThinVec<GenericArg>, constraints: ThinVec<AssocItemConstraint> },
+    Parenthesized { inputs: ThinVec<Type>, output: Option<Box<Type>> },
 }
 
 impl GenericArgs {
@@ -2279,7 +2279,7 @@ impl GenericArgs {
                         assoc: PathSegment {
                             name: sym::Output,
                             args: GenericArgs::AngleBracketed {
-                                args: Vec::new().into_boxed_slice(),
+                                args: ThinVec::new(),
                                 constraints: ThinVec::new(),
                             },
                         },
@@ -2596,12 +2596,12 @@ mod size_asserts {
     static_assert_size!(Crate, 56); // frequently moved by-value
     static_assert_size!(DocFragment, 32);
     static_assert_size!(GenericArg, 32);
-    static_assert_size!(GenericArgs, 32);
+    static_assert_size!(GenericArgs, 24);
     static_assert_size!(GenericParamDef, 40);
     static_assert_size!(Generics, 16);
     static_assert_size!(Item, 48);
     static_assert_size!(ItemKind, 48);
-    static_assert_size!(PathSegment, 40);
+    static_assert_size!(PathSegment, 32);
     static_assert_size!(Type, 32);
     // tidy-alphabetical-end
 }
diff --git a/src/librustdoc/html/render/search_index.rs b/src/librustdoc/html/render/search_index.rs
index e4a9a2b512e5..8ac8b3a1f843 100644
--- a/src/librustdoc/html/render/search_index.rs
+++ b/src/librustdoc/html/render/search_index.rs
@@ -821,7 +821,7 @@ pub(crate) fn get_function_type_for_search(
                     .map(|name| clean::PathSegment {
                         name: *name,
                         args: clean::GenericArgs::AngleBracketed {
-                            args: Vec::new().into_boxed_slice(),
+                            args: ThinVec::new(),
                             constraints: ThinVec::new(),
                         },
                     })
diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index afe81937495d..fcee29609797 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -231,11 +231,11 @@ impl FromClean<clean::GenericArgs> for GenericArgs {
         use clean::GenericArgs::*;
         match args {
             AngleBracketed { args, constraints } => GenericArgs::AngleBracketed {
-                args: args.into_vec().into_json(renderer),
+                args: args.into_json(renderer),
                 constraints: constraints.into_json(renderer),
             },
             Parenthesized { inputs, output } => GenericArgs::Parenthesized {
-                inputs: inputs.into_vec().into_json(renderer),
+                inputs: inputs.into_json(renderer),
                 output: output.map(|a| (*a).into_json(renderer)),
             },
         }