diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index 9ad945359b6b3..a29cdade02343 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -444,6 +444,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                             "aborted execution: attempted to leave type `{}` uninitialized, which is invalid",
                             ty
                         ),
+                        ValidityRequirement::Uninit => bug!("assert_uninit_valid doesn't exist"),
                     };
 
                     M::abort(self, msg)?;
diff --git a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
index dcd15b919f4e3..23fcd22c52b8e 100644
--- a/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
+++ b/compiler/rustc_const_eval/src/util/check_validity_requirement.rs
@@ -30,7 +30,7 @@ pub fn check_validity_requirement<'tcx>(
         return Ok(!layout.abi.is_uninhabited());
     }
 
-    if tcx.sess.opts.unstable_opts.strict_init_checks {
+    if kind == ValidityRequirement::Uninit || tcx.sess.opts.unstable_opts.strict_init_checks {
         might_permit_raw_init_strict(layout, tcx, kind)
     } else {
         let layout_cx = LayoutCx { tcx, param_env: param_env_and_ty.param_env };
@@ -99,6 +99,9 @@ fn might_permit_raw_init_lax<'tcx>(
                 }
                 s.valid_range(cx).contains(val)
             }
+            ValidityRequirement::Uninit => {
+                bug!("ValidityRequirement::Uninit should have been handled above")
+            }
         }
     };
 
diff --git a/compiler/rustc_expand/locales/en-US.ftl b/compiler/rustc_expand/locales/en-US.ftl
index b475d285f6b7e..cfae781bdee5f 100644
--- a/compiler/rustc_expand/locales/en-US.ftl
+++ b/compiler/rustc_expand/locales/en-US.ftl
@@ -133,3 +133,6 @@ expand_trace_macro = trace_macro
 expand_proc_macro_panicked =
     proc macro panicked
     .help = message: {$message}
+
+expand_proc_macro_derive_tokens =
+    proc-macro derive produced unparseable tokens
diff --git a/compiler/rustc_expand/src/errors.rs b/compiler/rustc_expand/src/errors.rs
index 70ab222b48470..e5102a952e741 100644
--- a/compiler/rustc_expand/src/errors.rs
+++ b/compiler/rustc_expand/src/errors.rs
@@ -390,3 +390,10 @@ pub(crate) struct ProcMacroPanicked {
 pub(crate) struct ProcMacroPanickedHelp {
     pub message: String,
 }
+
+#[derive(Diagnostic)]
+#[diag(expand_proc_macro_derive_tokens)]
+pub struct ProcMacroDeriveTokens {
+    #[primary_span]
+    pub span: Span,
+}
diff --git a/compiler/rustc_expand/src/proc_macro.rs b/compiler/rustc_expand/src/proc_macro.rs
index cef64a1047902..ddba14417195b 100644
--- a/compiler/rustc_expand/src/proc_macro.rs
+++ b/compiler/rustc_expand/src/proc_macro.rs
@@ -176,7 +176,7 @@ impl MultiItemModifier for DeriveProcMacro {
 
         // fail if there have been errors emitted
         if ecx.sess.parse_sess.span_diagnostic.err_count() > error_count_before {
-            ecx.struct_span_err(span, "proc-macro derive produced unparseable tokens").emit();
+            ecx.sess.emit_err(errors::ProcMacroDeriveTokens { span });
         }
 
         ExpandResult::Ready(items)
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index e9e121f9c9b04..d9af2fd74cee5 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -794,8 +794,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     pub fn consider_optimizing<T: Fn() -> String>(self, msg: T) -> bool {
-        let cname = self.crate_name(LOCAL_CRATE);
-        self.sess.consider_optimizing(cname.as_str(), msg)
+        self.sess.consider_optimizing(|| self.crate_name(LOCAL_CRATE), msg)
     }
 
     /// Obtain all lang items of this crate and all dependencies (recursively)
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 9a517d2d2b425..254ffc33c96f0 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -170,13 +170,17 @@ pub const FAT_PTR_EXTRA: usize = 1;
 /// * Cranelift stores the base-2 log of the lane count in a 4 bit integer.
 pub const MAX_SIMD_LANES: u64 = 1 << 0xF;
 
-/// Used in `might_permit_raw_init` to indicate the kind of initialisation
+/// Used in `check_validity_requirement` to indicate the kind of initialization
 /// that is checked to be valid
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
 pub enum ValidityRequirement {
     Inhabited,
     Zero,
+    /// The return value of mem::uninitialized, 0x01
+    /// (unless -Zstrict-init-checks is on, in which case it's the same as Uninit).
     UninitMitigated0x01Fill,
+    /// True uninitialized memory.
+    Uninit,
 }
 
 impl ValidityRequirement {
@@ -196,6 +200,7 @@ impl fmt::Display for ValidityRequirement {
             Self::Inhabited => f.write_str("is inhabited"),
             Self::Zero => f.write_str("allows being left zeroed"),
             Self::UninitMitigated0x01Fill => f.write_str("allows being filled with 0x01"),
+            Self::Uninit => f.write_str("allows being left uninitialized"),
         }
     }
 }
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index b2951e7a1847d..95a7ca80d5d73 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1210,8 +1210,13 @@ impl<'a> Parser<'a> {
                         // `Enum::Foo { a: 3, b: 4 }` or `Enum::Foo(3, 4)`.
                         self.restore_snapshot(snapshot);
                         let close_paren = self.prev_token.span;
-                        let span = lo.to(self.prev_token.span);
-                        if !fields.is_empty() {
+                        let span = lo.to(close_paren);
+                        if !fields.is_empty() &&
+                            // `token.kind` should not be compared here.
+                            // This is because the `snapshot.token.kind` is treated as the same as
+                            // that of the open delim in `TokenTreesReader::parse_token_tree`, even if they are different.
+                            self.span_to_snippet(close_paren).map_or(false, |snippet| snippet == ")")
+                        {
                             let mut replacement_err = errors::ParenthesesWithStructFields {
                                 span,
                                 r#type: path,
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 446ba63ed1c86..12634f67185fd 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -882,10 +882,14 @@ impl Session {
 
     /// We want to know if we're allowed to do an optimization for crate foo from -z fuel=foo=n.
     /// This expends fuel if applicable, and records fuel if applicable.
-    pub fn consider_optimizing<T: Fn() -> String>(&self, crate_name: &str, msg: T) -> bool {
+    pub fn consider_optimizing(
+        &self,
+        get_crate_name: impl Fn() -> Symbol,
+        msg: impl Fn() -> String,
+    ) -> bool {
         let mut ret = true;
         if let Some((ref c, _)) = self.opts.unstable_opts.fuel {
-            if c == crate_name {
+            if c == get_crate_name().as_str() {
                 assert_eq!(self.threads(), 1);
                 let mut fuel = self.optimization_fuel.lock();
                 ret = fuel.remaining != 0;
@@ -903,7 +907,7 @@ impl Session {
             }
         }
         if let Some(ref c) = self.opts.unstable_opts.print_fuel {
-            if c == crate_name {
+            if c == get_crate_name().as_str() {
                 assert_eq!(self.threads(), 1);
                 self.print_fuel.fetch_add(1, SeqCst);
             }
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 2b843647dd510..c7e7ed3e95e02 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -2213,10 +2213,6 @@ impl PartialEq for String {
     fn eq(&self, other: &String) -> bool {
         PartialEq::eq(&self[..], &other[..])
     }
-    #[inline]
-    fn ne(&self, other: &String) -> bool {
-        PartialEq::ne(&self[..], &other[..])
-    }
 }
 
 macro_rules! impl_eq {
diff --git a/library/core/src/str/traits.rs b/library/core/src/str/traits.rs
index d3ed811b1575b..68f62ce8be5f6 100644
--- a/library/core/src/str/traits.rs
+++ b/library/core/src/str/traits.rs
@@ -28,10 +28,6 @@ impl PartialEq for str {
     fn eq(&self, other: &str) -> bool {
         self.as_bytes() == other.as_bytes()
     }
-    #[inline]
-    fn ne(&self, other: &str) -> bool {
-        !(*self).eq(other)
-    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/src/librustdoc/html/static/js/search.js b/src/librustdoc/html/static/js/search.js
index 5a46729156d19..b98bced41261c 100644
--- a/src/librustdoc/html/static/js/search.js
+++ b/src/librustdoc/html/static/js/search.js
@@ -469,6 +469,15 @@ function initSearch(rawSearchIndex) {
             }
             const posBefore = parserState.pos;
             getNextElem(query, parserState, elems, endChar === ">");
+            if (endChar !== "") {
+                if (parserState.pos >= parserState.length) {
+                    throw ["Unclosed ", "<"];
+                }
+                const c2 = parserState.userQuery[parserState.pos];
+                if (!isSeparatorCharacter(c2) && c2 !== endChar) {
+                    throw ["Expected ", endChar, ", found ", c2];
+                }
+            }
             // This case can be encountered if `getNextElem` encountered a "stop character" right
             // from the start. For example if you have `,,` or `<>`. In this case, we simply move up
             // the current position to continue the parsing.
@@ -477,7 +486,10 @@ function initSearch(rawSearchIndex) {
             }
             foundStopChar = false;
         }
-        // We are either at the end of the string or on the `endChar`` character, let's move forward
+        if (parserState.pos >= parserState.length && endChar !== "") {
+            throw ["Unclosed ", "<"];
+        }
+        // We are either at the end of the string or on the `endChar` character, let's move forward
         // in any case.
         parserState.pos += 1;
     }
diff --git a/tests/rustdoc-js-std/parser-errors.js b/tests/rustdoc-js-std/parser-errors.js
index 6c5a777028335..98c6f27ca61b8 100644
--- a/tests/rustdoc-js-std/parser-errors.js
+++ b/tests/rustdoc-js-std/parser-errors.js
@@ -39,6 +39,7 @@ const QUERY = [
     "a!!",
     "mod:a!",
     "a!::a",
+    "a<",
 ];
 
 const PARSED = [
@@ -402,4 +403,13 @@ const PARSED = [
         userQuery: "a!::a",
         error: 'Cannot have associated items in macros',
     },
+    {
+        elems: [],
+        foundElems: 0,
+        original: "a<",
+        returned: [],
+        typeFilter: -1,
+        userQuery: "a<",
+        error: "Unclosed `<`",
+    },
 ];
diff --git a/tests/ui/parser/issue-107705.rs b/tests/ui/parser/issue-107705.rs
new file mode 100644
index 0000000000000..b80984fcdb026
--- /dev/null
+++ b/tests/ui/parser/issue-107705.rs
@@ -0,0 +1,3 @@
+// compile-flags: -C debug-assertions
+
+fn f() {a(b:&, //~ ERROR this file contains an unclosed delimiter
diff --git a/tests/ui/parser/issue-107705.stderr b/tests/ui/parser/issue-107705.stderr
new file mode 100644
index 0000000000000..d2d6134611863
--- /dev/null
+++ b/tests/ui/parser/issue-107705.stderr
@@ -0,0 +1,10 @@
+error: this file contains an unclosed delimiter
+  --> $DIR/issue-107705.rs:3:67
+   |
+LL | fn f() {a(b:&,
+   |        - - unclosed delimiter                                     ^
+   |        |
+   |        unclosed delimiter
+
+error: aborting due to previous error
+