Fix index out of bounds issues in rustdoc

Author: chenyukang

src/librustdoc/clean/types.rs

@@ -1740,7 +1740,7 @@ impl Type {
     fn inner_def_id(&self, cache: Option<&Cache>) -> Option<DefId> {
         let t: PrimitiveType = match *self {
             Type::Path { ref path } => return Some(path.def_id()),
-            DynTrait(ref bounds, _) => return Some(bounds[0].trait_.def_id()),
+            DynTrait(ref bounds, _) => return bounds.get(0).map(|b| b.trait_.def_id()),
             Primitive(p) => return cache.and_then(|c| c.primitive_locations.get(&p).cloned()),
             BorrowedRef { type_: box Generic(..), .. } => PrimitiveType::Reference,
             BorrowedRef { ref type_, .. } => return type_.inner_def_id(cache),

src/librustdoc/html/render/search_index.rs

@@ -322,8 +322,7 @@ fn get_index_type_id(clean_type: &clean::Type) -> Option<RenderTypeId> {
     match *clean_type {
         clean::Type::Path { ref path, .. } => Some(RenderTypeId::DefId(path.def_id())),
         clean::DynTrait(ref bounds, _) => {
-            let path = &bounds[0].trait_;
-            Some(RenderTypeId::DefId(path.def_id()))
+            bounds.get(0).map(|b| RenderTypeId::DefId(b.trait_.def_id()))
         }
         clean::Primitive(p) => Some(RenderTypeId::Primitive(p)),
         clean::BorrowedRef { ref type_, .. } | clean::RawPointer(_, ref type_) => {

src/test/rustdoc-ui/issue-106213.rs

@@ -0,0 +1,7 @@
+// compile-flags: --document-private-items
+// edition:2021
+
+fn use_avx() -> dyn  {
+    //~^ ERROR at least one trait is required for an object type
+    !( ident_error )
+}

src/test/rustdoc-ui/issue-106213.stderr

@@ -0,0 +1,9 @@
+error[E0224]: at least one trait is required for an object type
+  --> $DIR/issue-106213.rs:4:17
+   |
+LL | fn use_avx() -> dyn  {
+   |                 ^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0224`.