From bc7d958ab2768d022a3ed6af96a222543b13e1a3 Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume.gomez@huawei.com>
Date: Tue, 11 Jul 2023 11:38:31 +0200
Subject: [PATCH] Remove needs for transmute

---
 src/librustdoc/clean/mod.rs   | 37 ++++++++++++++++-------------------
 src/librustdoc/clean/types.rs | 11 +++++++++++
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index b5c257d8d3d..9aaef40aa6b 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1500,13 +1500,11 @@ fn param_eq_arg(param: &GenericParamDef, arg: &GenericArg) -> bool {
 /// or `doc(hidden)`). If it's not possible, it'll return the "end type".
 ///
 /// If the path is not a re-export or is public, it'll return `None`.
-fn first_non_private(
-    cx: &mut DocContext<'_>,
+fn first_non_private<'tcx>(
+    cx: &mut DocContext<'tcx>,
     hir_id: hir::HirId,
-    path: &hir::Path<'_>,
+    path: &hir::Path<'tcx>,
 ) -> Option<Path> {
-    use std::mem::transmute;
-
     let (parent_def_id, mut ident) = match &path.segments[..] {
         [] => return None,
         // Relative paths are available in the same scope as the owner.
@@ -1577,26 +1575,25 @@ fn first_non_private(
                 // 1. We found a public reexport.
                 // 2. We didn't find a public reexport so it's the "end type" path.
                 if let Some((new_path, _)) = last_path_res {
+                    let new_hir_path = hir::Path {
+                        segments: new_path.segments,
+                        res: path.res,
+                        span: new_path.span,
+                    };
+                    let mut new_clean_path = clean_path(&new_hir_path, cx);
                     // In here we need to play with the path data one last time to provide it the
                     // missing `args` and `res` of the final `Path` we get, which, since it comes
                     // from a re-export, doesn't have the generics that were originally there, so
                     // we add them by hand.
-                    let mut segments = new_path.segments.to_vec();
-                    if let Some(last) = segments.last_mut() {
-                        // `transmute` is needed because we are using a wrong lifetime. Since
-                        // `segments` will be dropped at the end of this block, it's fine.
-                        last.args = unsafe {
-                            transmute(
-                                path.segments.last().as_ref().unwrap().args.clone(),
-                            )
-                        };
-                        last.res = path.res;
+                    if let Some(path_last) = path.segments.last().as_ref()
+                        && let Some(new_path_last) = new_clean_path.segments[..].last_mut()
+                        && let Some(path_last_args) = path_last.args.as_ref()
+                        && path_last.args.is_some()
+                    {
+                        assert!(new_path_last.args.is_empty());
+                        new_path_last.args = clean_generic_args(path_last_args, cx);
                     }
-                    // `transmute` is needed because we are using a wrong lifetime. Since
-                    // `segments` will be dropped at the end of this block, it's fine.
-                    let segments = unsafe { transmute(segments.as_slice()) };
-                    let new_path = hir::Path { segments, res: path.res, span: new_path.span };
-                    return Some(clean_path(&new_path, cx));
+                    return Some(new_clean_path);
                 }
                 // If `last_path_res` is `None`, it can mean two things:
                 //
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index ddef165a054..60e316decf9 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -2203,6 +2203,17 @@ pub(crate) enum GenericArgs {
     Parenthesized { inputs: Box<[Type]>, output: Option<Box<Type>> },
 }
 
+impl GenericArgs {
+    pub(crate) fn is_empty(&self) -> bool {
+        match self {
+            GenericArgs::AngleBracketed { args, bindings } => {
+                args.is_empty() && bindings.is_empty()
+            }
+            GenericArgs::Parenthesized { inputs, output } => inputs.is_empty() && output.is_none(),
+        }
+    }
+}
+
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub(crate) struct PathSegment {
     pub(crate) name: Symbol,