Auto merge of #102704 - Dylan-DPC:rollup-66ff8sm, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #100986 (Stop suggesting adding generic args for turbofish)
 - #101061 (panic-on-uninit: adjust checks to 0x01-filling)
 - #102440 (Only export `__tls_*` on wasm32-unknown-unknown.)
 - #102496 (Suggest `.into()` when all other coercion suggestions fail)
 - #102699 (Fix hamburger button color)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

28 files changed, 666 insertions, 342 deletions

diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index f59a753a5ce..2cd746ccb6a 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -1180,16 +1180,19 @@ impl<'a> WasmLd<'a> {
         //   sharing memory and instantiating the module multiple times. As a
         //   result if it were exported then we'd just have no sharing.
         //
-        // * `--export=*tls*` - when `#[thread_local]` symbols are used these
-        //   symbols are how the TLS segments are initialized and configured.
+        // On wasm32-unknown-unknown, we also export symbols for glue code to use:
+        //    * `--export=*tls*` - when `#[thread_local]` symbols are used these
+        //      symbols are how the TLS segments are initialized and configured.
         if sess.target_features.contains(&sym::atomics) {
             cmd.arg("--shared-memory");
             cmd.arg("--max-memory=1073741824");
             cmd.arg("--import-memory");
-            cmd.arg("--export=__wasm_init_tls");
-            cmd.arg("--export=__tls_size");
-            cmd.arg("--export=__tls_align");
-            cmd.arg("--export=__tls_base");
+            if sess.target.os == "unknown" {
+                cmd.arg("--export=__wasm_init_tls");
+                cmd.arg("--export=__tls_size");
+                cmd.arg("--export=__tls_align");
+                cmd.arg("--export=__tls_base");
+            }
         }
         WasmLd { cmd, sess }
     }
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index ebdaf61e439..230f841cf4d 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -32,7 +32,6 @@ extern crate rustc_middle;
 pub mod const_eval;
 mod errors;
 pub mod interpret;
-mod might_permit_raw_init;
 pub mod transform;
 pub mod util;
 
@@ -61,7 +60,6 @@ pub fn provide(providers: &mut Providers) {
         const_eval::deref_mir_constant(tcx, param_env, value)
     };
     providers.permits_uninit_init =
-        |tcx, ty| might_permit_raw_init::might_permit_raw_init(tcx, ty, InitKind::Uninit);
-    providers.permits_zero_init =
-        |tcx, ty| might_permit_raw_init::might_permit_raw_init(tcx, ty, InitKind::Zero);
+        |tcx, ty| util::might_permit_raw_init(tcx, ty, InitKind::UninitMitigated0x01Fill);
+    providers.permits_zero_init = |tcx, ty| util::might_permit_raw_init(tcx, ty, InitKind::Zero);
 }
diff --git a/compiler/rustc_const_eval/src/might_permit_raw_init.rs b/compiler/rustc_const_eval/src/might_permit_raw_init.rs
deleted file mode 100644
index 37ffa19ccd6..00000000000
--- a/compiler/rustc_const_eval/src/might_permit_raw_init.rs
+++ /dev/null
@@ -1,44 +0,0 @@
-use crate::const_eval::CompileTimeInterpreter;
-use crate::interpret::{InterpCx, MemoryKind, OpTy};
-use rustc_middle::ty::layout::LayoutCx;
-use rustc_middle::ty::{layout::TyAndLayout, ParamEnv, TyCtxt};
-use rustc_session::Limit;
-use rustc_target::abi::InitKind;
-
-pub fn might_permit_raw_init<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    ty: TyAndLayout<'tcx>,
-    kind: InitKind,
-) -> bool {
-    let strict = tcx.sess.opts.unstable_opts.strict_init_checks;
-
-    if strict {
-        let machine = CompileTimeInterpreter::new(
-            Limit::new(0),
-            /*can_access_statics:*/ false,
-            /*check_alignment:*/ true,
-        );
-
-        let mut cx = InterpCx::new(tcx, rustc_span::DUMMY_SP, ParamEnv::reveal_all(), machine);
-
-        let allocated = cx
-            .allocate(ty, MemoryKind::Machine(crate::const_eval::MemoryKind::Heap))
-            .expect("OOM: failed to allocate for uninit check");
-
-        if kind == InitKind::Zero {
-            cx.write_bytes_ptr(
-                allocated.ptr,
-                std::iter::repeat(0_u8).take(ty.layout.size().bytes_usize()),
-            )
-            .expect("failed to write bytes for zero valid check");
-        }
-
-        let ot: OpTy<'_, _> = allocated.into();
-
-        // Assume that if it failed, it's a validation failure.
-        cx.validate_operand(&ot).is_ok()
-    } else {
-        let layout_cx = LayoutCx { tcx, param_env: ParamEnv::reveal_all() };
-        ty.might_permit_raw_init(&layout_cx, kind)
-    }
-}
diff --git a/compiler/rustc_const_eval/src/util/might_permit_raw_init.rs b/compiler/rustc_const_eval/src/util/might_permit_raw_init.rs
new file mode 100644
index 00000000000..6ca71223391
--- /dev/null
+++ b/compiler/rustc_const_eval/src/util/might_permit_raw_init.rs
@@ -0,0 +1,151 @@
+use rustc_middle::ty::layout::{LayoutCx, LayoutOf, TyAndLayout};
+use rustc_middle::ty::{ParamEnv, TyCtxt};
+use rustc_session::Limit;
+use rustc_target::abi::{Abi, FieldsShape, InitKind, Scalar, Variants};
+
+use crate::const_eval::CompileTimeInterpreter;
+use crate::interpret::{InterpCx, MemoryKind, OpTy};
+
+/// Determines if this type permits "raw" initialization by just transmuting some memory into an
+/// instance of `T`.
+///
+/// `init_kind` indicates if the memory is zero-initialized or left uninitialized. We assume
+/// uninitialized memory is mitigated by filling it with 0x01, which reduces the chance of causing
+/// LLVM UB.
+///
+/// By default we check whether that operation would cause *LLVM UB*, i.e., whether the LLVM IR we
+/// generate has UB or not. This is a mitigation strategy, which is why we are okay with accepting
+/// Rust UB as long as there is no risk of miscompilations. The `strict_init_checks` can be set to
+/// do a full check against Rust UB instead (in which case we will also ignore the 0x01-filling and
+/// to the full uninit check).
+pub fn might_permit_raw_init<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    ty: TyAndLayout<'tcx>,
+    kind: InitKind,
+) -> bool {
+    if tcx.sess.opts.unstable_opts.strict_init_checks {
+        might_permit_raw_init_strict(ty, tcx, kind)
+    } else {
+        let layout_cx = LayoutCx { tcx, param_env: ParamEnv::reveal_all() };
+        might_permit_raw_init_lax(ty, &layout_cx, kind)
+    }
+}
+
+/// Implements the 'strict' version of the `might_permit_raw_init` checks; see that function for
+/// details.
+fn might_permit_raw_init_strict<'tcx>(
+    ty: TyAndLayout<'tcx>,
+    tcx: TyCtxt<'tcx>,
+    kind: InitKind,
+) -> bool {
+    let machine = CompileTimeInterpreter::new(
+        Limit::new(0),
+        /*can_access_statics:*/ false,
+        /*check_alignment:*/ true,
+    );
+
+    let mut cx = InterpCx::new(tcx, rustc_span::DUMMY_SP, ParamEnv::reveal_all(), machine);
+
+    let allocated = cx
+        .allocate(ty, MemoryKind::Machine(crate::const_eval::MemoryKind::Heap))
+        .expect("OOM: failed to allocate for uninit check");
+
+    if kind == InitKind::Zero {
+        cx.write_bytes_ptr(
+            allocated.ptr,
+            std::iter::repeat(0_u8).take(ty.layout.size().bytes_usize()),
+        )
+        .expect("failed to write bytes for zero valid check");
+    }
+
+    let ot: OpTy<'_, _> = allocated.into();
+
+    // Assume that if it failed, it's a validation failure.
+    // This does *not* actually check that references are dereferenceable, but since all types that
+    // require dereferenceability also require non-null, we don't actually get any false negatives
+    // due to this.
+    cx.validate_operand(&ot).is_ok()
+}
+
+/// Implements the 'lax' (default) version of the `might_permit_raw_init` checks; see that function for
+/// details.
+fn might_permit_raw_init_lax<'tcx>(
+    this: TyAndLayout<'tcx>,
+    cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
+    init_kind: InitKind,
+) -> bool {
+    let scalar_allows_raw_init = move |s: Scalar| -> bool {
+        match init_kind {
+            InitKind::Zero => {
+                // The range must contain 0.
+                s.valid_range(cx).contains(0)
+            }
+            InitKind::UninitMitigated0x01Fill => {
+                // The range must include an 0x01-filled buffer.
+                let mut val: u128 = 0x01;
+                for _ in 1..s.size(cx).bytes() {
+                    // For sizes >1, repeat the 0x01.
+                    val = (val << 8) | 0x01;
+                }
+                s.valid_range(cx).contains(val)
+            }
+        }
+    };
+
+    // Check the ABI.
+    let valid = match this.abi {
+        Abi::Uninhabited => false, // definitely UB
+        Abi::Scalar(s) => scalar_allows_raw_init(s),
+        Abi::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
+        Abi::Vector { element: s, count } => count == 0 || scalar_allows_raw_init(s),
+        Abi::Aggregate { .. } => true, // Fields are checked below.
+    };
+    if !valid {
+        // This is definitely not okay.
+        return false;
+    }
+
+    // Special magic check for references and boxes (i.e., special pointer types).
+    if let Some(pointee) = this.ty.builtin_deref(false) {
+        let pointee = cx.layout_of(pointee.ty).expect("need to be able to compute layouts");
+        // We need to ensure that the LLVM attributes `aligned` and `dereferenceable(size)` are satisfied.
+        if pointee.align.abi.bytes() > 1 {
+            // 0x01-filling is not aligned.
+            return false;
+        }
+        if pointee.size.bytes() > 0 {
+            // A 'fake' integer pointer is not sufficiently dereferenceable.
+            return false;
+        }
+    }
+
+    // If we have not found an error yet, we need to recursively descend into fields.
+    match &this.fields {
+        FieldsShape::Primitive | FieldsShape::Union { .. } => {}
+        FieldsShape::Array { .. } => {
+            // Arrays never have scalar layout in LLVM, so if the array is not actually
+            // accessed, there is no LLVM UB -- therefore we can skip this.
+        }
+        FieldsShape::Arbitrary { offsets, .. } => {
+            for idx in 0..offsets.len() {
+                if !might_permit_raw_init_lax(this.field(cx, idx), cx, init_kind) {
+                    // We found a field that is unhappy with this kind of initialization.
+                    return false;
+                }
+            }
+        }
+    }
+
+    match &this.variants {
+        Variants::Single { .. } => {
+            // All fields of this single variant have already been checked above, there is nothing
+            // else to do.
+        }
+        Variants::Multiple { .. } => {
+            // We cannot tell LLVM anything about the details of this multi-variant layout, so
+            // invalid values "hidden" inside the variant cannot cause LLVM trouble.
+        }
+    }
+
+    true
+}
diff --git a/compiler/rustc_const_eval/src/util/mod.rs b/compiler/rustc_const_eval/src/util/mod.rs
index a1876bed83e..7a05cfd235f 100644
--- a/compiler/rustc_const_eval/src/util/mod.rs
+++ b/compiler/rustc_const_eval/src/util/mod.rs
@@ -3,8 +3,10 @@ mod alignment;
 mod call_kind;
 pub mod collect_writes;
 mod find_self_call;
+mod might_permit_raw_init;
 
 pub use self::aggregate::expand_aggregate;
 pub use self::alignment::is_disaligned;
 pub use self::call_kind::{call_kind, CallDesugaringKind, CallKind};
 pub use self::find_self_call::find_self_call;
+pub use self::might_permit_raw_init::might_permit_raw_init;
diff --git a/compiler/rustc_hir_analysis/src/check/demand.rs b/compiler/rustc_hir_analysis/src/check/demand.rs
index 264df8b914b..d396c801c09 100644
--- a/compiler/rustc_hir_analysis/src/check/demand.rs
+++ b/compiler/rustc_hir_analysis/src/check/demand.rs
@@ -32,17 +32,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         error: Option<TypeError<'tcx>>,
     ) {
         self.annotate_expected_due_to_let_ty(err, expr, error);
-        self.suggest_deref_ref_or_into(err, expr, expected, expr_ty, expected_ty_expr);
-        self.suggest_compatible_variants(err, expr, expected, expr_ty);
-        self.suggest_non_zero_new_unwrap(err, expr, expected, expr_ty);
-        if self.suggest_calling_boxed_future_when_appropriate(err, expr, expected, expr_ty) {
-            return;
-        }
-        self.suggest_no_capture_closure(err, expected, expr_ty);
-        self.suggest_boxing_when_appropriate(err, expr, expected, expr_ty);
-        self.suggest_missing_parentheses(err, expr);
-        self.suggest_block_to_brackets_peeling_refs(err, expr, expr_ty, expected);
-        self.suggest_copied_or_cloned(err, expr, expr_ty, expected);
+
+        // Use `||` to give these suggestions a precedence
+        let _ = self.suggest_missing_parentheses(err, expr)
+            || self.suggest_deref_ref_or_into(err, expr, expected, expr_ty, expected_ty_expr)
+            || self.suggest_compatible_variants(err, expr, expected, expr_ty)
+            || self.suggest_non_zero_new_unwrap(err, expr, expected, expr_ty)
+            || self.suggest_calling_boxed_future_when_appropriate(err, expr, expected, expr_ty)
+            || self.suggest_no_capture_closure(err, expected, expr_ty)
+            || self.suggest_boxing_when_appropriate(err, expr, expected, expr_ty)
+            || self.suggest_block_to_brackets_peeling_refs(err, expr, expr_ty, expected)
+            || self.suggest_copied_or_cloned(err, expr, expr_ty, expected)
+            || self.suggest_into(err, expr, expr_ty, expected);
+
         self.note_type_is_not_clone(err, expected, expr_ty, expr);
         self.note_need_for_fn_pointer(err, expected, expr_ty);
         self.note_internal_mutation_in_method(err, expr, expected, expr_ty);
@@ -286,7 +288,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &hir::Expr<'_>,
         expected: Ty<'tcx>,
         expr_ty: Ty<'tcx>,
-    ) {
+    ) -> bool {
         if let ty::Adt(expected_adt, substs) = expected.kind() {
             if let hir::ExprKind::Field(base, ident) = expr.kind {
                 let base_ty = self.typeck_results.borrow().expr_ty(base);
@@ -299,7 +301,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         "",
                         Applicability::MaybeIncorrect,
                     );
-                    return
+                    return true;
                 }
             }
 
@@ -338,7 +340,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             } else if self.tcx.is_diagnostic_item(sym::Option, expected_adt.did()) {
                                 vec!["None", "Some(())"]
                             } else {
-                                return;
+                                return false;
                             };
                             if let Some(indent) =
                                 self.tcx.sess.source_map().indentation_before(span.shrink_to_lo())
@@ -358,7 +360,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                     Applicability::MaybeIncorrect,
                                 );
                             }
-                            return;
+                            return true;
                         }
                     }
                 }
@@ -445,6 +447,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         suggestions_for(&**variant, *ctor_kind, *field_name),
                         Applicability::MaybeIncorrect,
                     );
+                    return true;
                 }
                 _ => {
                     // More than one matching variant.
@@ -460,9 +463,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         ),
                         Applicability::MaybeIncorrect,
                     );
+                    return true;
                 }
             }
         }
+
+        false
     }
 
     fn suggest_non_zero_new_unwrap(
@@ -471,19 +477,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &hir::Expr<'_>,
         expected: Ty<'tcx>,
         expr_ty: Ty<'tcx>,
-    ) {
+    ) -> bool {
         let tcx = self.tcx;
         let (adt, unwrap) = match expected.kind() {
             // In case Option<NonZero*> is wanted, but * is provided, suggest calling new
             ty::Adt(adt, substs) if tcx.is_diagnostic_item(sym::Option, adt.did()) => {
                 // Unwrap option
-                let ty::Adt(adt, _) = substs.type_at(0).kind() else { return };
+                let ty::Adt(adt, _) = substs.type_at(0).kind() else { return false; };
 
                 (adt, "")
             }
             // In case NonZero* is wanted, but * is provided also add `.unwrap()` to satisfy types
             ty::Adt(adt, _) => (adt, ".unwrap()"),
-            _ => return,
+            _ => return false,
         };
 
         let map = [
@@ -502,7 +508,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let Some((s, _)) = map
             .iter()
             .find(|&&(s, t)| self.tcx.is_diagnostic_item(s, adt.did()) && self.can_coerce(expr_ty, t))
-            else { return };
+            else { return false; };
 
         let path = self.tcx.def_path_str(adt.non_enum_variant().def_id);
 
@@ -514,6 +520,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ],
             Applicability::MaybeIncorrect,
         );
+
+        true
     }
 
     pub fn get_conversion_methods(
diff --git a/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs b/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs
index 3618cfba533..09890c55cd3 100644
--- a/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_hir_analysis/src/check/fn_ctxt/suggestions.rs
@@ -3,7 +3,7 @@ use crate::astconv::AstConv;
 use crate::errors::{AddReturnTypeSuggestion, ExpectedReturnTypeLabel};
 
 use hir::def_id::DefId;
-use rustc_ast::util::parser::ExprPrecedence;
+use rustc_ast::util::parser::{ExprPrecedence, PREC_POSTFIX};
 use rustc_errors::{Applicability, Diagnostic, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind};
@@ -327,7 +327,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         found: Ty<'tcx>,
         expected_ty_expr: Option<&'tcx hir::Expr<'tcx>>,
-    ) {
+    ) -> bool {
         let expr = expr.peel_blocks();
         if let Some((sp, msg, suggestion, applicability, verbose)) =
             self.check_ref(expr, found, expected)
@@ -337,14 +337,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             } else {
                 err.span_suggestion(sp, &msg, suggestion, applicability);
             }
+            return true;
         } else if self.suggest_else_fn_with_closure(err, expr, found, expected)
         {
+            return true;
         } else if self.suggest_fn_call(err, expr, found, |output| self.can_coerce(output, expected))
             && let ty::FnDef(def_id, ..) = &found.kind()
             && let Some(sp) = self.tcx.hir().span_if_local(*def_id)
         {
             err.span_label(sp, format!("{found} defined here"));
-        } else if !self.check_for_cast(err, expr, found, expected, expected_ty_expr) {
+            return true;
+        } else if self.check_for_cast(err, expr, found, expected, expected_ty_expr) {
+            return true;
+        } else {
             let methods = self.get_conversion_methods(expr.span, expected, found, expr.hir_id);
             if !methods.is_empty() {
                 let mut suggestions = methods.iter()
@@ -395,6 +400,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         suggestions,
                         Applicability::MaybeIncorrect,
                     );
+                    return true;
                 }
             } else if let ty::Adt(found_adt, found_substs) = found.kind()
                 && self.tcx.is_diagnostic_item(sym::Option, found_adt.did())
@@ -419,9 +425,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         format!(".map(|x| &*{}x)", "*".repeat(ref_cnt)),
                         Applicability::MaybeIncorrect,
                     );
+                    return true;
                 }
             }
         }
+
+        false
     }
 
     /// When encountering the expected boxed value allocated in the stack, suggest allocating it
@@ -432,13 +441,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &hir::Expr<'_>,
         expected: Ty<'tcx>,
         found: Ty<'tcx>,
-    ) {
+    ) -> bool {
         if self.tcx.hir().is_inside_const_context(expr.hir_id) {
             // Do not suggest `Box::new` in const context.
-            return;
+            return false;
         }
         if !expected.is_box() || found.is_box() {
-            return;
+            return false;
         }
         let boxed_found = self.tcx.mk_box(found);
         if self.can_coerce(boxed_found, expected) {
@@ -456,6 +465,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                  https://doc.rust-lang.org/rust-by-example/std/box.html, and \
                  https://doc.rust-lang.org/std/boxed/index.html",
             );
+            true
+        } else {
+            false
         }
     }
 
@@ -466,7 +478,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err: &mut Diagnostic,
         expected: Ty<'tcx>,
         found: Ty<'tcx>,
-    ) {
+    ) -> bool {
         if let (ty::FnPtr(_), ty::Closure(def_id, _)) = (expected.kind(), found.kind()) {
             if let Some(upvars) = self.tcx.upvars_mentioned(*def_id) {
                 // Report upto four upvars being captured to reduce the amount error messages
@@ -490,8 +502,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     multi_span,
                     "closures can only be coerced to `fn` types if they do not capture any variables"
                 );
+                return true;
             }
         }
+        false
     }
 
     /// When encountering an `impl Future` where `BoxFuture` is expected, suggest `Box::pin`.
@@ -893,11 +907,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         err: &mut Diagnostic,
         expr: &hir::Expr<'_>,
-    ) {
+    ) -> bool {
         let sp = self.tcx.sess.source_map().start_point(expr.span);
         if let Some(sp) = self.tcx.sess.parse_sess.ambiguous_block_expr_parse.borrow().get(&sp) {
             // `{ 42 } &&x` (#61475) or `{ 42 } && if x { 1 } else { 0 }`
             err.subdiagnostic(ExprParenthesesNeeded::surrounding(*sp));
+            true
+        } else {
+            false
         }
     }
 
@@ -910,7 +927,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         mut expr: &hir::Expr<'_>,
         mut expr_ty: Ty<'tcx>,
         mut expected_ty: Ty<'tcx>,
-    ) {
+    ) -> bool {
         loop {
             match (&expr.kind, expr_ty.kind(), expected_ty.kind()) {
                 (
@@ -924,9 +941,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
                 (hir::ExprKind::Block(blk, _), _, _) => {
                     self.suggest_block_to_brackets(diag, *blk, expr_ty, expected_ty);
-                    break;
+                    break true;
                 }
-                _ => break,
+                _ => break false,
             }
         }
     }
@@ -937,11 +954,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &hir::Expr<'_>,
         expr_ty: Ty<'tcx>,
         expected_ty: Ty<'tcx>,
-    ) {
-        let ty::Adt(adt_def, substs) = expr_ty.kind() else { return; };
-        let ty::Adt(expected_adt_def, expected_substs) = expected_ty.kind() else { return; };
+    ) -> bool {
+        let ty::Adt(adt_def, substs) = expr_ty.kind() else { return false; };
+        let ty::Adt(expected_adt_def, expected_substs) = expected_ty.kind() else { return false; };
         if adt_def != expected_adt_def {
-            return;
+            return false;
         }
 
         let mut suggest_copied_or_cloned = || {
@@ -960,6 +977,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         ".copied()",
                         Applicability::MachineApplicable,
                     );
+                    return true;
                 } else if let Some(clone_did) = self.tcx.lang_items().clone_trait()
                     && rustc_trait_selection::traits::type_known_to_meet_bound_modulo_regions(
                         self,
@@ -977,8 +995,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         ".cloned()",
                         Applicability::MachineApplicable,
                     );
+                    return true;
                 }
             }
+            false
         };
 
         if let Some(result_did) = self.tcx.get_diagnostic_item(sym::Result)
@@ -986,12 +1006,67 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Check that the error types are equal
             && self.can_eq(self.param_env, substs.type_at(1), expected_substs.type_at(1)).is_ok()
         {
-            suggest_copied_or_cloned();
+            return suggest_copied_or_cloned();
         } else if let Some(option_did) = self.tcx.get_diagnostic_item(sym::Option)
             && adt_def.did() == option_did
         {
-            suggest_copied_or_cloned();
+            return suggest_copied_or_cloned();
+        }
+
+        false
+    }
+
+    pub(crate) fn suggest_into(
+        &self,
+        diag: &mut Diagnostic,
+        expr: &hir::Expr<'_>,
+        expr_ty: Ty<'tcx>,
+        expected_ty: Ty<'tcx>,
+    ) -> bool {
+        let expr = expr.peel_blocks();
+
+        // We have better suggestions for scalar interconversions...
+        if expr_ty.is_scalar() && expected_ty.is_scalar() {
+            return false;
         }
+
+        // Don't suggest turning a block into another type (e.g. `{}.into()`)
+        if matches!(expr.kind, hir::ExprKind::Block(..)) {
+            return false;
+        }
+
+        // We'll later suggest `.as_ref` when noting the type error,
+        // so skip if we will suggest that instead.
+        if self.should_suggest_as_ref(expected_ty, expr_ty).is_some() {
+            return false;
+        }
+
+        if let Some(into_def_id) = self.tcx.get_diagnostic_item(sym::Into)
+            && self.predicate_must_hold_modulo_regions(&traits::Obligation::new(
+                self.misc(expr.span),
+                self.param_env,
+                ty::Binder::dummy(ty::TraitRef {
+                    def_id: into_def_id,
+                    substs: self.tcx.mk_substs_trait(expr_ty, &[expected_ty.into()]),
+                })
+                .to_poly_trait_predicate()
+                .to_predicate(self.tcx),
+            ))
+        {
+            let sugg = if expr.precedence().order() >= PREC_POSTFIX {
+                vec![(expr.span.shrink_to_hi(), ".into()".to_owned())]
+            } else {
+                vec![(expr.span.shrink_to_lo(), "(".to_owned()), (expr.span.shrink_to_hi(), ").into()".to_owned())]
+            };
+            diag.multipart_suggestion(
+                format!("call `Into::into` on this expression to convert `{expr_ty}` into `{expected_ty}`"),
+                sugg,
+                Applicability::MaybeIncorrect
+            );
+            return true;
+        }
+
+        false
     }
 
     /// Suggest wrapping the block in square brackets instead of curly braces
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 99de5b65981..9d56764d489 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -2158,8 +2158,22 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
         diag: &mut Diagnostic,
     ) {
+        if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
+            && let Some(msg) = self.should_suggest_as_ref(exp_found.expected, exp_found.found)
+        {
+            diag.span_suggestion(
+                span,
+                msg,
+                // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&`
+                format!("{}.as_ref()", snippet.trim_start_matches('&')),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+
+    pub fn should_suggest_as_ref(&self, expected: Ty<'tcx>, found: Ty<'tcx>) -> Option<&str> {
         if let (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) =
-            (exp_found.expected.kind(), exp_found.found.kind())
+            (expected.kind(), found.kind())
         {
             if let ty::Adt(found_def, found_substs) = *found_ty.kind() {
                 if exp_def == &found_def {
@@ -2197,21 +2211,14 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                                 _ => show_suggestion = false,
                             }
                         }
-                        if let (Ok(snippet), true) =
-                            (self.tcx.sess.source_map().span_to_snippet(span), show_suggestion)
-                        {
-                            diag.span_suggestion(
-                                span,
-                                *msg,
-                                // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&`
-                                format!("{}.as_ref()", snippet.trim_start_matches('&')),
-                                Applicability::MachineApplicable,
-                            );
+                        if show_suggestion {
+                            return Some(*msg);
                         }
                     }
                 }
             }
         }
+        None
     }
 
     pub fn report_and_explain_type_error(
diff --git a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
index 03116d59bf4..2775d14a847 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
@@ -435,6 +435,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 generics_def_id,
                 def_id: _,
                 generic_args,
+                have_turbofish,
             } => {
                 let generics = self.tcx.generics_of(generics_def_id);
                 let is_type = matches!(arg.unpack(), GenericArgKind::Type(_));
@@ -482,11 +483,13 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     .unwrap()
                     .into_buffer();
 
-                infer_subdiags.push(SourceKindSubdiag::GenericSuggestion {
-                    span: insert_span,
-                    arg_count: generic_args.len(),
-                    args,
-                });
+                if !have_turbofish {
+                    infer_subdiags.push(SourceKindSubdiag::GenericSuggestion {
+                        span: insert_span,
+                        arg_count: generic_args.len(),
+                        args,
+                    });
+                }
             }
             InferSourceKind::FullyQualifiedMethodCall { receiver, successor, substs, def_id } => {
                 let printer = fmt_printer(self, Namespace::ValueNS);
@@ -616,6 +619,7 @@ enum InferSourceKind<'tcx> {
         generics_def_id: DefId,
         def_id: DefId,
         generic_args: &'tcx [GenericArg<'tcx>],
+        have_turbofish: bool,
     },
     FullyQualifiedMethodCall {
         receiver: &'tcx Expr<'tcx>,
@@ -676,6 +680,7 @@ struct InsertableGenericArgs<'tcx> {
     substs: SubstsRef<'tcx>,
     generics_def_id: DefId,
     def_id: DefId,
+    have_turbofish: bool,
 }
 
 /// A visitor which searches for the "best" spot to use in the inference error.
@@ -916,6 +921,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
                             substs,
                             generics_def_id: def_id,
                             def_id,
+                            have_turbofish: false,
                         }
                     };
                     return Box::new(insertable.into_iter());
@@ -933,6 +939,9 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
         substs: SubstsRef<'tcx>,
     ) -> impl Iterator<Item = InsertableGenericArgs<'tcx>> + 'a {
         let tcx = self.infcx.tcx;
+        let have_turbofish = path.segments.iter().any(|segment| {
+            segment.args.map_or(false, |args| args.args.iter().any(|arg| arg.is_ty_or_const()))
+        });
         // The last segment of a path often has `Res::Err` and the
         // correct `Res` is the one of the whole path.
         //
@@ -942,7 +951,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
             let generics_def_id = tcx.res_generics_def_id(path.res)?;
             let generics = tcx.generics_of(generics_def_id);
             if generics.has_impl_trait() {
-                None?
+                None?;
             }
             let insert_span =
                 path.segments.last().unwrap().ident.span.shrink_to_hi().with_hi(path.span.hi());
@@ -951,6 +960,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
                 substs,
                 generics_def_id,
                 def_id: path.res.def_id(),
+                have_turbofish,
             }
         };
 
@@ -970,6 +980,7 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
                     substs,
                     generics_def_id,
                     def_id: res.def_id(),
+                    have_turbofish,
                 })
             })
             .chain(last_segment_using_path_data)
@@ -998,7 +1009,13 @@ impl<'a, 'tcx> FindInferSourceVisitor<'a, 'tcx> {
                     }
                     let span = tcx.hir().span(segment.hir_id);
                     let insert_span = segment.ident.span.shrink_to_hi().with_hi(span.hi());
-                    InsertableGenericArgs { insert_span, substs, generics_def_id: def_id, def_id }
+                    InsertableGenericArgs {
+                        insert_span,
+                        substs,
+                        generics_def_id: def_id,
+                        def_id,
+                        have_turbofish: false,
+                    }
                 };
 
                 let parent_def_id = generics.parent.unwrap();
@@ -1121,7 +1138,13 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
 
         for args in self.expr_inferred_subst_iter(expr) {
             debug!(?args);
-            let InsertableGenericArgs { insert_span, substs, generics_def_id, def_id } = args;
+            let InsertableGenericArgs {
+                insert_span,
+                substs,
+                generics_def_id,
+                def_id,
+                have_turbofish,
+            } = args;
             let generics = tcx.generics_of(generics_def_id);
             if let Some(argument_index) = generics
                 .own_substs(substs)
@@ -1144,6 +1167,7 @@ impl<'a, 'tcx> Visitor<'tcx> for FindInferSourceVisitor<'a, 'tcx> {
                         generics_def_id,
                         def_id,
                         generic_args,
+                        have_turbofish,
                     },
                 });
             }
diff --git a/compiler/rustc_target/src/abi/mod.rs b/compiler/rustc_target/src/abi/mod.rs
index ec334e5887a..7171ca7bf89 100644
--- a/compiler/rustc_target/src/abi/mod.rs
+++ b/compiler/rustc_target/src/abi/mod.rs
@@ -1392,7 +1392,7 @@ pub struct PointeeInfo {
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum InitKind {
     Zero,
-    Uninit,
+    UninitMitigated0x01Fill,
 }
 
 /// Trait that needs to be implemented by the higher-level type representation
@@ -1498,72 +1498,4 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
             Abi::Aggregate { sized } => sized && self.size.bytes() == 0,
         }
     }
-
-    /// Determines if this type permits "raw" initialization by just transmuting some
-    /// memory into an instance of `T`.
-    ///
-    /// `init_kind` indicates if the memory is zero-initialized or left uninitialized.
-    ///
-    /// This code is intentionally conservative, and will not detect
-    /// * zero init of an enum whose 0 variant does not allow zero initialization
-    /// * making uninitialized types who have a full valid range (ints, floats, raw pointers)
-    /// * Any form of invalid value being made inside an array (unless the value is uninhabited)
-    ///
-    /// A strict form of these checks that uses const evaluation exists in
-    /// `rustc_const_eval::might_permit_raw_init`, and a tracking issue for making these checks
-    /// stricter is <https://github.com/rust-lang/rust/issues/66151>.
-    ///
-    /// FIXME: Once all the conservatism is removed from here, and the checks are ran by default,
-    /// we can use the const evaluation checks always instead.
-    pub fn might_permit_raw_init<C>(self, cx: &C, init_kind: InitKind) -> bool
-    where
-        Self: Copy,
-        Ty: TyAbiInterface<'a, C>,
-        C: HasDataLayout,
-    {
-        let scalar_allows_raw_init = move |s: Scalar| -> bool {
-            match init_kind {
-                InitKind::Zero => {
-                    // The range must contain 0.
-                    s.valid_range(cx).contains(0)
-                }
-                InitKind::Uninit => {
-                    // The range must include all values.
-                    s.is_always_valid(cx)
-                }
-            }
-        };
-
-        // Check the ABI.
-        let valid = match self.abi {
-            Abi::Uninhabited => false, // definitely UB
-            Abi::Scalar(s) => scalar_allows_raw_init(s),
-            Abi::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
-            Abi::Vector { element: s, count } => count == 0 || scalar_allows_raw_init(s),
-            Abi::Aggregate { .. } => true, // Fields are checked below.
-        };
-        if !valid {
-            // This is definitely not okay.
-            return false;
-        }
-
-        // If we have not found an error yet, we need to recursively descend into fields.
-        match &self.fields {
-            FieldsShape::Primitive | FieldsShape::Union { .. } => {}
-            FieldsShape::Array { .. } => {
-                // FIXME(#66151): For now, we are conservative and do not check arrays by default.
-            }
-            FieldsShape::Arbitrary { offsets, .. } => {
-                for idx in 0..offsets.len() {
-                    if !self.field(cx, idx).might_permit_raw_init(cx, init_kind) {
-                        // We found a field that is unhappy with this kind of initialization.
-                        return false;
-                    }
-                }
-            }
-        }
-
-        // FIXME(#66151): For now, we are conservative and do not check `self.variants`.
-        true
-    }
 }
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 96876a30a4e..140ce3ba9fc 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -1826,6 +1826,7 @@ in storage.js plus the media query with (min-width: 701px)
 		   as an icon, it's okay to specify its sizes in pixels. */
 		font-size: 32px;
 		border: none;
+		color: var(--main-color);
 	}
 
 	.sidebar-elems {
diff --git a/src/test/rustdoc-gui/sidebar-mobile.goml b/src/test/rustdoc-gui/sidebar-mobile.goml
index 033c6578349..04dcb532504 100644
--- a/src/test/rustdoc-gui/sidebar-mobile.goml
+++ b/src/test/rustdoc-gui/sidebar-mobile.goml
@@ -42,23 +42,24 @@ scroll-to: ".block.keyword li:nth-child(1)"
 compare-elements-position-near: (".block.keyword li:nth-child(1)", ".mobile-topbar", {"y": 543})
 
 // Now checking the background color of the sidebar.
+show-text: true
 local-storage: {"rustdoc-use-system-theme": "false", "rustdoc-theme": "dark"}
 reload:
 
 // Open the sidebar menu.
 click: ".sidebar-menu-toggle"
-assert-css: (".sidebar", {"background-color": "rgb(80, 80, 80)"})
+assert-css: (".sidebar", {"background-color": "rgb(80, 80, 80)", "color": "rgb(221, 221, 221)"})
 
 local-storage: {"rustdoc-use-system-theme": "false", "rustdoc-theme": "ayu"}
 reload:
 
 // Open the sidebar menu.
 click: ".sidebar-menu-toggle"
-assert-css: (".sidebar", {"background-color": "rgb(20, 25, 31)"})
+assert-css: (".sidebar", {"background-color": "rgb(20, 25, 31)", "color": "rgb(197, 197, 197)"})
 
 local-storage: {"rustdoc-use-system-theme": "false", "rustdoc-theme": "light"}
 reload:
 
 // Open the sidebar menu.
 click: ".sidebar-menu-toggle"
-assert-css: (".sidebar", {"background-color": "rgb(245, 245, 245)"})
+assert-css: (".sidebar", {"background-color": "rgb(245, 245, 245)", "color": "rgb(0, 0, 0)"})
diff --git a/src/test/ui/consts/assert-type-intrinsics.rs b/src/test/ui/consts/assert-type-intrinsics.rs
index 3ce3e1bdbac..6b5612dda90 100644
--- a/src/test/ui/consts/assert-type-intrinsics.rs
+++ b/src/test/ui/consts/assert-type-intrinsics.rs
@@ -11,12 +11,15 @@ fn main() {
     use std::mem::MaybeUninit;
 
     const _BAD1: () = unsafe {
-        MaybeUninit::<!>::uninit().assume_init();
+        intrinsics::assert_inhabited::<!>(); //~ERROR: any use of this value will cause an error
+        //~^WARN: previously accepted
     };
     const _BAD2: () = {
-        intrinsics::assert_uninit_valid::<bool>();
+        intrinsics::assert_uninit_valid::<!>(); //~ERROR: any use of this value will cause an error
+        //~^WARN: previously accepted
     };
     const _BAD3: () = {
-        intrinsics::assert_zero_valid::<&'static i32>();
+        intrinsics::assert_zero_valid::<&'static i32>(); //~ERROR: any use of this value will cause an error
+        //~^WARN: previously accepted
     };
 }
diff --git a/src/test/ui/consts/assert-type-intrinsics.stderr b/src/test/ui/consts/assert-type-intrinsics.stderr
index a183856dff8..9f97d836705 100644
--- a/src/test/ui/consts/assert-type-intrinsics.stderr
+++ b/src/test/ui/consts/assert-type-intrinsics.stderr
@@ -3,26 +3,26 @@ error: any use of this value will cause an error
    |
 LL |     const _BAD1: () = unsafe {
    |     ---------------
-LL |         MaybeUninit::<!>::uninit().assume_init();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
+LL |         intrinsics::assert_inhabited::<!>();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
    = note: `#[deny(const_err)]` on by default
 
 error: any use of this value will cause an error
-  --> $DIR/assert-type-intrinsics.rs:17:9
+  --> $DIR/assert-type-intrinsics.rs:18:9
    |
 LL |     const _BAD2: () = {
    |     ---------------
-LL |         intrinsics::assert_uninit_valid::<bool>();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to leave type `bool` uninitialized, which is invalid
+LL |         intrinsics::assert_uninit_valid::<!>();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
 error: any use of this value will cause an error
-  --> $DIR/assert-type-intrinsics.rs:20:9
+  --> $DIR/assert-type-intrinsics.rs:22:9
    |
 LL |     const _BAD3: () = {
    |     ---------------
@@ -40,8 +40,8 @@ error: any use of this value will cause an error
    |
 LL |     const _BAD1: () = unsafe {
    |     ---------------
-LL |         MaybeUninit::<!>::uninit().assume_init();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
+LL |         intrinsics::assert_inhabited::<!>();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
@@ -49,12 +49,12 @@ LL |         MaybeUninit::<!>::uninit().assume_init();
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/assert-type-intrinsics.rs:17:9
+  --> $DIR/assert-type-intrinsics.rs:18:9
    |
 LL |     const _BAD2: () = {
    |     ---------------
-LL |         intrinsics::assert_uninit_valid::<bool>();
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to leave type `bool` uninitialized, which is invalid
+LL |         intrinsics::assert_uninit_valid::<!>();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ aborted execution: attempted to instantiate uninhabited type `!`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
@@ -62,7 +62,7 @@ LL |         intrinsics::assert_uninit_valid::<bool>();
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/assert-type-intrinsics.rs:20:9
+  --> $DIR/assert-type-intrinsics.rs:22:9
    |
 LL |     const _BAD3: () = {
    |     ---------------
diff --git a/src/test/ui/inference/need_type_info/concrete-impl.stderr b/src/test/ui/inference/need_type_info/concrete-impl.stderr
index b79d34affa2..aa32969950d 100644
--- a/src/test/ui/inference/need_type_info/concrete-impl.stderr
+++ b/src/test/ui/inference/need_type_info/concrete-impl.stderr
@@ -3,11 +3,6 @@ error[E0282]: type annotations needed
    |
 LL |     <Struct as Ambiguous<_>>::method();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `Self` declared on the trait `Ambiguous`
-   |
-help: consider specifying the generic argument
-   |
-LL |     <Struct as Ambiguous::<_>>::method();
-   |                         ~~~~~
 
 error[E0283]: type annotations needed
   --> $DIR/concrete-impl.rs:13:5
@@ -22,10 +17,6 @@ LL | impl Ambiguous<One> for Struct {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 LL | impl Ambiguous<Two> for Struct {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: consider specifying the generic argument
-   |
-LL |     <Struct as Ambiguous::<_>>::method();
-   |                         ~~~~~
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/inference/need_type_info/do-not-suggest-generic-arguments-for-turbofish.rs b/src/test/ui/inference/need_type_info/do-not-suggest-generic-arguments-for-turbofish.rs
new file mode 100644
index 00000000000..3084f6eac67
--- /dev/null
+++ b/src/test/ui/inference/need_type_info/do-not-suggest-generic-arguments-for-turbofish.rs
@@ -0,0 +1,11 @@
+enum OhNo<T, U> {
+    A(T),
+    B(U),
+    C,
+}
+
+fn uwu() {
+    OhNo::C::<u32, _>; //~ ERROR type annotations needed
+}
+
+fn main() {}
diff --git a/src/test/ui/inference/need_type_info/do-not-suggest-generic-arguments-for-turbofish.stderr b/src/test/ui/inference/need_type_info/do-not-suggest-generic-arguments-for-turbofish.stderr
new file mode 100644
index 00000000000..2ad35ab039f
--- /dev/null
+++ b/src/test/ui/inference/need_type_info/do-not-suggest-generic-arguments-for-turbofish.stderr
@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/do-not-suggest-generic-arguments-for-turbofish.rs:8:5
+   |
+LL |     OhNo::C::<u32, _>;
+   |     ^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `U` declared on the enum `OhNo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs b/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
index 4aa869cca35..ae44ffd29bd 100644
--- a/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
+++ b/src/test/ui/intrinsics/panic-uninitialized-zeroed.rs
@@ -34,6 +34,12 @@ enum OneVariant_NonZero {
     DeadVariant(Bar),
 }
 
+#[allow(dead_code, non_camel_case_types)]
+enum OneVariant_Ref {
+    Variant(&'static i32),
+    DeadVariant(Bar),
+}
+
 // An `Aggregate` abi enum where 0 is not a valid discriminant.
 #[allow(dead_code)]
 #[repr(i32)]
@@ -63,6 +69,7 @@ enum ZeroIsValid {
     One(NonNull<()>) = 1,
 }
 
+#[track_caller]
 fn test_panic_msg<T>(op: impl (FnOnce() -> T) + panic::UnwindSafe, msg: &str) {
     let err = panic::catch_unwind(op).err();
     assert_eq!(
@@ -71,6 +78,15 @@ fn test_panic_msg<T>(op: impl (FnOnce() -> T) + panic::UnwindSafe, msg: &str) {
     );
 }
 
+#[track_caller]
+fn test_panic_msg_only_if_strict<T>(op: impl (FnOnce() -> T) + panic::UnwindSafe, msg: &str) {
+    let err = panic::catch_unwind(op).err();
+    assert_eq!(
+        err.as_ref().and_then(|a| a.downcast_ref::<&str>()),
+        if cfg!(strict) { Some(&msg) } else { None },
+    );
+}
+
 fn main() {
     unsafe {
         // Uninhabited types
@@ -139,92 +155,216 @@ fn main() {
             "attempted to instantiate uninhabited type `[Bar; 2]`"
         );
 
-        // Types that do not like zero-initialziation
+        // Types that don't allow either.
         test_panic_msg(
-            || mem::uninitialized::<fn()>(),
-            "attempted to leave type `fn()` uninitialized, which is invalid"
+            || mem::zeroed::<&i32>(),
+            "attempted to zero-initialize type `&i32`, which is invalid"
         );
         test_panic_msg(
-            || mem::zeroed::<fn()>(),
-            "attempted to zero-initialize type `fn()`, which is invalid"
+            || mem::uninitialized::<&i32>(),
+            "attempted to leave type `&i32` uninitialized, which is invalid"
         );
 
         test_panic_msg(
-            || mem::uninitialized::<*const dyn Send>(),
-            "attempted to leave type `*const dyn core::marker::Send` uninitialized, which is invalid"
+            || mem::zeroed::<Box<[i32; 0]>>(),
+            "attempted to zero-initialize type `alloc::boxed::Box<[i32; 0]>`, which is invalid"
+        );
+        test_panic_msg(
+            || mem::uninitialized::<Box<[i32; 0]>>(),
+            "attempted to leave type `alloc::boxed::Box<[i32; 0]>` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<Box<u8>>(),
+            "attempted to zero-initialize type `alloc::boxed::Box<u8>`, which is invalid"
         );
         test_panic_msg(
+            || mem::uninitialized::<Box<u8>>(),
+            "attempted to leave type `alloc::boxed::Box<u8>` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<&[i32]>(),
+            "attempted to zero-initialize type `&[i32]`, which is invalid"
+        );
+        test_panic_msg(
+            || mem::uninitialized::<&[i32]>(),
+            "attempted to leave type `&[i32]` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<&(u8, [u8])>(),
+            "attempted to zero-initialize type `&(u8, [u8])`, which is invalid"
+        );
+        test_panic_msg(
+            || mem::uninitialized::<&(u8, [u8])>(),
+            "attempted to leave type `&(u8, [u8])` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<&dyn Send>(),
+            "attempted to zero-initialize type `&dyn core::marker::Send`, which is invalid"
+        );
+        test_panic_msg(
+            || mem::uninitialized::<&dyn Send>(),
+            "attempted to leave type `&dyn core::marker::Send` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
             || mem::zeroed::<*const dyn Send>(),
             "attempted to zero-initialize type `*const dyn core::marker::Send`, which is invalid"
         );
+        test_panic_msg(
+            || mem::uninitialized::<*const dyn Send>(),
+            "attempted to leave type `*const dyn core::marker::Send` uninitialized, which is invalid"
+        );
 
         test_panic_msg(
-            || mem::uninitialized::<(NonNull<u32>, u32, u32)>(),
-            "attempted to leave type `(core::ptr::non_null::NonNull<u32>, u32, u32)` uninitialized, \
+            || mem::uninitialized::<NoNullVariant>(),
+            "attempted to leave type `NoNullVariant` uninitialized, \
+                which is invalid"
+        );
+        test_panic_msg(
+            || mem::zeroed::<NoNullVariant>(),
+            "attempted to zero-initialize type `NoNullVariant`, \
                 which is invalid"
         );
 
         test_panic_msg(
-            || mem::zeroed::<(NonNull<u32>, u32, u32)>(),
-            "attempted to zero-initialize type `(core::ptr::non_null::NonNull<u32>, u32, u32)`, \
+            || mem::zeroed::<OneVariant_Ref>(),
+            "attempted to zero-initialize type `OneVariant_Ref`, \
                 which is invalid"
         );
+        test_panic_msg(
+            || mem::uninitialized::<OneVariant_Ref>(),
+            "attempted to leave type `OneVariant_Ref` uninitialized, which is invalid"
+        );
 
+        // Types where both are invalid, but we allow uninit since the 0x01-filling is not LLVM UB.
         test_panic_msg(
-            || mem::uninitialized::<OneVariant_NonZero>(),
-            "attempted to leave type `OneVariant_NonZero` uninitialized, \
+            || mem::zeroed::<fn()>(),
+            "attempted to zero-initialize type `fn()`, which is invalid"
+        );
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<fn()>(),
+            "attempted to leave type `fn()` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<&()>(),
+            "attempted to zero-initialize type `&()`, which is invalid"
+        );
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<&()>(),
+            "attempted to leave type `&()` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<&[u8]>(),
+            "attempted to zero-initialize type `&[u8]`, which is invalid"
+        );
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<&[u8]>(),
+            "attempted to leave type `&[u8]` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<&str>(),
+            "attempted to zero-initialize type `&str`, which is invalid"
+        );
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<&str>(),
+            "attempted to leave type `&str` uninitialized, which is invalid"
+        );
+
+        test_panic_msg(
+            || mem::zeroed::<(NonNull<u32>, u32, u32)>(),
+            "attempted to zero-initialize type `(core::ptr::non_null::NonNull<u32>, u32, u32)`, \
                 which is invalid"
         );
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<(NonNull<u32>, u32, u32)>(),
+            "attempted to leave type `(core::ptr::non_null::NonNull<u32>, u32, u32)` uninitialized, which is invalid"
+        );
+
         test_panic_msg(
             || mem::zeroed::<OneVariant_NonZero>(),
             "attempted to zero-initialize type `OneVariant_NonZero`, \
                 which is invalid"
         );
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<OneVariant_NonZero>(),
+            "attempted to leave type `OneVariant_NonZero` uninitialized, which is invalid"
+        );
 
+        // Types where both are invalid but we allow the zeroed form since it is not LLVM UB.
+        test_panic_msg_only_if_strict(
+            || mem::zeroed::<LR_NonZero>(),
+            "attempted to zero-initialize type `LR_NonZero`, which is invalid"
+        );
         test_panic_msg(
             || mem::uninitialized::<LR_NonZero>(),
             "attempted to leave type `LR_NonZero` uninitialized, which is invalid"
         );
 
+        test_panic_msg_only_if_strict(
+            || mem::zeroed::<ManuallyDrop<LR_NonZero>>(),
+            "attempted to zero-initialize type `core::mem::manually_drop::ManuallyDrop<LR_NonZero>`, \
+             which is invalid"
+        );
         test_panic_msg(
             || mem::uninitialized::<ManuallyDrop<LR_NonZero>>(),
             "attempted to leave type `core::mem::manually_drop::ManuallyDrop<LR_NonZero>` uninitialized, \
              which is invalid"
         );
 
-        test_panic_msg(
-            || mem::uninitialized::<NoNullVariant>(),
-            "attempted to leave type `NoNullVariant` uninitialized, \
-                which is invalid"
+        // Some strict-only things
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<i32>(),
+            "attempted to leave type `i32` uninitialized, which is invalid"
         );
 
-        test_panic_msg(
-            || mem::zeroed::<NoNullVariant>(),
-            "attempted to zero-initialize type `NoNullVariant`, \
-                which is invalid"
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<*const ()>(),
+            "attempted to leave type `*const ()` uninitialized, which is invalid"
         );
 
-        // Types that can be zero, but not uninit.
-        test_panic_msg(
-            || mem::uninitialized::<bool>(),
-            "attempted to leave type `bool` uninitialized, which is invalid"
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<[i32; 1]>(),
+            "attempted to leave type `[i32; 1]` uninitialized, which is invalid"
         );
 
+        test_panic_msg_only_if_strict(
+            || mem::zeroed::<[NonNull<()>; 1]>(),
+            "attempted to zero-initialize type `[core::ptr::non_null::NonNull<()>; 1]`, which is invalid"
+        );
+
+        // Types that can be zero, but not uninit (though some are mitigated).
+        let _val = mem::zeroed::<LR>();
         test_panic_msg(
             || mem::uninitialized::<LR>(),
             "attempted to leave type `LR` uninitialized, which is invalid"
         );
 
+        let _val = mem::zeroed::<ManuallyDrop<LR>>();
         test_panic_msg(
             || mem::uninitialized::<ManuallyDrop<LR>>(),
             "attempted to leave type `core::mem::manually_drop::ManuallyDrop<LR>` uninitialized, which is invalid"
         );
 
-        // Some things that should work.
         let _val = mem::zeroed::<bool>();
-        let _val = mem::zeroed::<LR>();
-        let _val = mem::zeroed::<ManuallyDrop<LR>>();
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<bool>(),
+            "attempted to leave type `bool` uninitialized, which is invalid"
+        );
+
         let _val = mem::zeroed::<OneVariant>();
+        test_panic_msg_only_if_strict(
+            || mem::uninitialized::<OneVariant>(),
+            "attempted to leave type `OneVariant` uninitialized, which is invalid"
+        );
+
+        // Some things that are actually allowed.
         let _val = mem::zeroed::<Option<&'static i32>>();
         let _val = mem::zeroed::<MaybeUninit<NonNull<u32>>>();
         let _val = mem::zeroed::<[!; 0]>();
@@ -233,59 +373,5 @@ fn main() {
         let _val = mem::uninitialized::<[!; 0]>();
         let _val = mem::uninitialized::<()>();
         let _val = mem::uninitialized::<ZeroSized>();
-
-        if cfg!(strict) {
-            test_panic_msg(
-                || mem::uninitialized::<i32>(),
-                "attempted to leave type `i32` uninitialized, which is invalid"
-            );
-
-            test_panic_msg(
-                || mem::uninitialized::<*const ()>(),
-                "attempted to leave type `*const ()` uninitialized, which is invalid"
-            );
-
-            test_panic_msg(
-                || mem::uninitialized::<[i32; 1]>(),
-                "attempted to leave type `[i32; 1]` uninitialized, which is invalid"
-            );
-
-            test_panic_msg(
-                || mem::zeroed::<NonNull<()>>(),
-                "attempted to zero-initialize type `core::ptr::non_null::NonNull<()>`, which is invalid"
-            );
-
-            test_panic_msg(
-                || mem::zeroed::<[NonNull<()>; 1]>(),
-                "attempted to zero-initialize type `[core::ptr::non_null::NonNull<()>; 1]`, which is invalid"
-            );
-
-            // FIXME(#66151) we conservatively do not error here yet (by default).
-            test_panic_msg(
-                || mem::zeroed::<LR_NonZero>(),
-                "attempted to zero-initialize type `LR_NonZero`, which is invalid"
-            );
-
-            test_panic_msg(
-                || mem::zeroed::<ManuallyDrop<LR_NonZero>>(),
-                "attempted to zero-initialize type `core::mem::manually_drop::ManuallyDrop<LR_NonZero>`, \
-                 which is invalid"
-            );
-        } else {
-            // These are UB because they have not been officially blessed, but we await the resolution
-            // of <https://github.com/rust-lang/unsafe-code-guidelines/issues/71> before doing
-            // anything about that.
-            let _val = mem::uninitialized::<i32>();
-            let _val = mem::uninitialized::<*const ()>();
-
-            // These are UB, but best to test them to ensure we don't become unintentionally
-            // stricter.
-
-            // It's currently unchecked to create invalid enums and values inside arrays.
-            let _val = mem::zeroed::<LR_NonZero>();
-            let _val = mem::zeroed::<[LR_NonZero; 1]>();
-            let _val = mem::zeroed::<[NonNull<()>; 1]>();
-            let _val = mem::uninitialized::<[NonNull<()>; 1]>();
-        }
     }
 }
diff --git a/src/test/ui/issues/issue-24013.stderr b/src/test/ui/issues/issue-24013.stderr
index 995dce552e3..72102f460e0 100644
--- a/src/test/ui/issues/issue-24013.stderr
+++ b/src/test/ui/issues/issue-24013.stderr
@@ -3,11 +3,6 @@ error[E0282]: type annotations needed
    |
 LL |     unsafe {swap::<&mut _>(transmute(&a), transmute(&b))};
    |             ^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `swap`
-   |
-help: consider specifying the generic argument
-   |
-LL |     unsafe {swap::<&mut _>(transmute(&a), transmute(&b))};
-   |                 ~~~~~~~~~~
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-47486.stderr b/src/test/ui/issues/issue-47486.stderr
index b45f57b7b84..2bd24f08c1e 100644
--- a/src/test/ui/issues/issue-47486.stderr
+++ b/src/test/ui/issues/issue-47486.stderr
@@ -9,11 +9,6 @@ error[E0282]: type annotations needed
    |
 LL |     [0u8; std::mem::size_of::<_>()];
    |           ^^^^^^^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `size_of`
-   |
-help: consider specifying the generic argument
-   |
-LL |     [0u8; std::mem::size_of::<_>()];
-   |                            ~~~~~
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/lint/invalid_value.rs b/src/test/ui/lint/invalid_value.rs
index 51edb2b7baf..946a0e38861 100644
--- a/src/test/ui/lint/invalid_value.rs
+++ b/src/test/ui/lint/invalid_value.rs
@@ -88,6 +88,9 @@ fn main() {
         let _val: NonNull<i32> = mem::zeroed(); //~ ERROR: does not permit zero-initialization
         let _val: NonNull<i32> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
 
+        let _val: (NonZeroU32, i32) = mem::zeroed(); //~ ERROR: does not permit zero-initialization
+        let _val: (NonZeroU32, i32) = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
+
         let _val: *const dyn Send = mem::zeroed(); //~ ERROR: does not permit zero-initialization
         let _val: *const dyn Send = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
 
@@ -133,7 +136,7 @@ fn main() {
         let _val: Result<i32, i32> = mem::zeroed();
         let _val: Result<i32, i32> = mem::uninitialized(); //~ ERROR: does not permit being left uninitialized
 
-        // Some things that happen to work due to rustc implementation details,
+        // Some things that happen to be UB-free due to rustc implementation details,
         // but are not guaranteed to keep working.
         let _val: OneFruit = mem::zeroed();
         let _val: OneFruit = mem::uninitialized();
diff --git a/src/test/ui/lint/invalid_value.stderr b/src/test/ui/lint/invalid_value.stderr
index f0dcf53dfee..3901692001a 100644
--- a/src/test/ui/lint/invalid_value.stderr
+++ b/src/test/ui/lint/invalid_value.stderr
@@ -315,8 +315,30 @@ LL |         let _val: NonNull<i32> = mem::uninitialized();
    |
    = note: `std::ptr::NonNull<i32>` must be non-null
 
+error: the type `(NonZeroU32, i32)` does not permit zero-initialization
+  --> $DIR/invalid_value.rs:91:39
+   |
+LL |         let _val: (NonZeroU32, i32) = mem::zeroed();
+   |                                       ^^^^^^^^^^^^^
+   |                                       |
+   |                                       this code causes undefined behavior when executed
+   |                                       help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
+   |
+   = note: `std::num::NonZeroU32` must be non-null
+
+error: the type `(NonZeroU32, i32)` does not permit being left uninitialized
+  --> $DIR/invalid_value.rs:92:39
+   |
+LL |         let _val: (NonZeroU32, i32) = mem::uninitialized();
+   |                                       ^^^^^^^^^^^^^^^^^^^^
+   |                                       |
+   |                                       this code causes undefined behavior when executed
+   |                                       help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
+   |
+   = note: `std::num::NonZeroU32` must be non-null
+
 error: the type `*const dyn Send` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:91:37
+  --> $DIR/invalid_value.rs:94:37
    |
 LL |         let _val: *const dyn Send = mem::zeroed();
    |                                     ^^^^^^^^^^^^^
@@ -327,7 +349,7 @@ LL |         let _val: *const dyn Send = mem::zeroed();
    = note: the vtable of a wide raw pointer must be non-null
 
 error: the type `*const dyn Send` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:92:37
+  --> $DIR/invalid_value.rs:95:37
    |
 LL |         let _val: *const dyn Send = mem::uninitialized();
    |                                     ^^^^^^^^^^^^^^^^^^^^
@@ -338,7 +360,7 @@ LL |         let _val: *const dyn Send = mem::uninitialized();
    = note: the vtable of a wide raw pointer must be non-null
 
 error: the type `[fn(); 2]` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:94:31
+  --> $DIR/invalid_value.rs:97:31
    |
 LL |         let _val: [fn(); 2] = mem::zeroed();
    |                               ^^^^^^^^^^^^^
@@ -349,7 +371,7 @@ LL |         let _val: [fn(); 2] = mem::zeroed();
    = note: function pointers must be non-null
 
 error: the type `[fn(); 2]` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:95:31
+  --> $DIR/invalid_value.rs:98:31
    |
 LL |         let _val: [fn(); 2] = mem::uninitialized();
    |                               ^^^^^^^^^^^^^^^^^^^^
@@ -360,7 +382,7 @@ LL |         let _val: [fn(); 2] = mem::uninitialized();
    = note: function pointers must be non-null
 
 error: the type `TwoUninhabited` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:97:36
+  --> $DIR/invalid_value.rs:100:36
    |
 LL |         let _val: TwoUninhabited = mem::zeroed();
    |                                    ^^^^^^^^^^^^^
@@ -375,7 +397,7 @@ LL | enum TwoUninhabited {
    | ^^^^^^^^^^^^^^^^^^^
 
 error: the type `TwoUninhabited` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:98:36
+  --> $DIR/invalid_value.rs:101:36
    |
 LL |         let _val: TwoUninhabited = mem::uninitialized();
    |                                    ^^^^^^^^^^^^^^^^^^^^
@@ -390,7 +412,7 @@ LL | enum TwoUninhabited {
    | ^^^^^^^^^^^^^^^^^^^
 
 error: the type `OneFruitNonZero` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:100:37
+  --> $DIR/invalid_value.rs:103:37
    |
 LL |         let _val: OneFruitNonZero = mem::zeroed();
    |                                     ^^^^^^^^^^^^^
@@ -405,7 +427,7 @@ LL |     Banana(NonZeroU32),
    |            ^^^^^^^^^^
 
 error: the type `OneFruitNonZero` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:101:37
+  --> $DIR/invalid_value.rs:104:37
    |
 LL |         let _val: OneFruitNonZero = mem::uninitialized();
    |                                     ^^^^^^^^^^^^^^^^^^^^
@@ -420,7 +442,7 @@ LL |     Banana(NonZeroU32),
    |            ^^^^^^^^^^
 
 error: the type `bool` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:105:26
+  --> $DIR/invalid_value.rs:108:26
    |
 LL |         let _val: bool = mem::uninitialized();
    |                          ^^^^^^^^^^^^^^^^^^^^
@@ -431,7 +453,7 @@ LL |         let _val: bool = mem::uninitialized();
    = note: booleans must be either `true` or `false`
 
 error: the type `Wrap<char>` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:108:32
+  --> $DIR/invalid_value.rs:111:32
    |
 LL |         let _val: Wrap<char> = mem::uninitialized();
    |                                ^^^^^^^^^^^^^^^^^^^^
@@ -446,7 +468,7 @@ LL | struct Wrap<T> { wrapped: T }
    |                  ^^^^^^^^^^
 
 error: the type `NonBig` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:111:28
+  --> $DIR/invalid_value.rs:114:28
    |
 LL |         let _val: NonBig = mem::uninitialized();
    |                            ^^^^^^^^^^^^^^^^^^^^
@@ -457,7 +479,7 @@ LL |         let _val: NonBig = mem::uninitialized();
    = note: `NonBig` must be initialized inside its custom valid range
 
 error: the type `Fruit` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:114:27
+  --> $DIR/invalid_value.rs:117:27
    |
 LL |         let _val: Fruit = mem::uninitialized();
    |                           ^^^^^^^^^^^^^^^^^^^^
@@ -472,7 +494,7 @@ LL | enum Fruit {
    | ^^^^^^^^^^
 
 error: the type `[bool; 2]` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:117:31
+  --> $DIR/invalid_value.rs:120:31
    |
 LL |         let _val: [bool; 2] = mem::uninitialized();
    |                               ^^^^^^^^^^^^^^^^^^^^
@@ -483,7 +505,7 @@ LL |         let _val: [bool; 2] = mem::uninitialized();
    = note: booleans must be either `true` or `false`
 
 error: the type `i32` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:120:25
+  --> $DIR/invalid_value.rs:123:25
    |
 LL |         let _val: i32 = mem::uninitialized();
    |                         ^^^^^^^^^^^^^^^^^^^^
@@ -494,7 +516,7 @@ LL |         let _val: i32 = mem::uninitialized();
    = note: integers must not be uninitialized
 
 error: the type `f32` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:123:25
+  --> $DIR/invalid_value.rs:126:25
    |
 LL |         let _val: f32 = mem::uninitialized();
    |                         ^^^^^^^^^^^^^^^^^^^^
@@ -505,7 +527,7 @@ LL |         let _val: f32 = mem::uninitialized();
    = note: floats must not be uninitialized
 
 error: the type `*const ()` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:126:31
+  --> $DIR/invalid_value.rs:129:31
    |
 LL |         let _val: *const () = mem::uninitialized();
    |                               ^^^^^^^^^^^^^^^^^^^^
@@ -516,7 +538,7 @@ LL |         let _val: *const () = mem::uninitialized();
    = note: raw pointers must not be uninitialized
 
 error: the type `*const [()]` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:129:33
+  --> $DIR/invalid_value.rs:132:33
    |
 LL |         let _val: *const [()] = mem::uninitialized();
    |                                 ^^^^^^^^^^^^^^^^^^^^
@@ -527,7 +549,7 @@ LL |         let _val: *const [()] = mem::uninitialized();
    = note: raw pointers must not be uninitialized
 
 error: the type `Result<i32, i32>` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:134:38
+  --> $DIR/invalid_value.rs:137:38
    |
 LL |         let _val: Result<i32, i32> = mem::uninitialized();
    |                                      ^^^^^^^^^^^^^^^^^^^^
@@ -542,7 +564,7 @@ LL | pub enum Result<T, E> {
    | ^^^^^^^^^^^^^^^^^^^^^
 
 error: the type `&i32` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:142:34
+  --> $DIR/invalid_value.rs:145:34
    |
 LL |         let _val: &'static i32 = mem::transmute(0usize);
    |                                  ^^^^^^^^^^^^^^^^^^^^^^
@@ -553,7 +575,7 @@ LL |         let _val: &'static i32 = mem::transmute(0usize);
    = note: references must be non-null
 
 error: the type `&[i32]` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:143:36
+  --> $DIR/invalid_value.rs:146:36
    |
 LL |         let _val: &'static [i32] = mem::transmute((0usize, 0usize));
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -564,7 +586,7 @@ LL |         let _val: &'static [i32] = mem::transmute((0usize, 0usize));
    = note: references must be non-null
 
 error: the type `NonZeroU32` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:144:32
+  --> $DIR/invalid_value.rs:147:32
    |
 LL |         let _val: NonZeroU32 = mem::transmute(0);
    |                                ^^^^^^^^^^^^^^^^^
@@ -575,7 +597,7 @@ LL |         let _val: NonZeroU32 = mem::transmute(0);
    = note: `std::num::NonZeroU32` must be non-null
 
 error: the type `NonNull<i32>` does not permit zero-initialization
-  --> $DIR/invalid_value.rs:147:34
+  --> $DIR/invalid_value.rs:150:34
    |
 LL |         let _val: NonNull<i32> = MaybeUninit::zeroed().assume_init();
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -586,7 +608,7 @@ LL |         let _val: NonNull<i32> = MaybeUninit::zeroed().assume_init();
    = note: `std::ptr::NonNull<i32>` must be non-null
 
 error: the type `NonNull<i32>` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:148:34
+  --> $DIR/invalid_value.rs:151:34
    |
 LL |         let _val: NonNull<i32> = MaybeUninit::uninit().assume_init();
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -597,7 +619,7 @@ LL |         let _val: NonNull<i32> = MaybeUninit::uninit().assume_init();
    = note: `std::ptr::NonNull<i32>` must be non-null
 
 error: the type `bool` does not permit being left uninitialized
-  --> $DIR/invalid_value.rs:149:26
+  --> $DIR/invalid_value.rs:152:26
    |
 LL |         let _val: bool = MaybeUninit::uninit().assume_init();
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -607,5 +629,5 @@ LL |         let _val: bool = MaybeUninit::uninit().assume_init();
    |
    = note: booleans must be either `true` or `false`
 
-error: aborting due to 48 previous errors
+error: aborting due to 50 previous errors
 
diff --git a/src/test/ui/parser/expr-as-stmt-2.stderr b/src/test/ui/parser/expr-as-stmt-2.stderr
index 9b939f05e02..2b6314c38ce 100644
--- a/src/test/ui/parser/expr-as-stmt-2.stderr
+++ b/src/test/ui/parser/expr-as-stmt-2.stderr
@@ -36,11 +36,6 @@ LL | /     &&
 LL | |     if let Some(y) = a { true } else { false }
    | |______________________________________________^ expected `bool`, found `&&bool`
    |
-help: consider removing the `&&`
-   |
-LL -     &&
-LL +     if let Some(y) = a { true } else { false }
-   |
 help: parentheses are required to parse this as an expression
    |
 LL |     (if let Some(x) = a { true } else { false })
diff --git a/src/test/ui/parser/expr-as-stmt.stderr b/src/test/ui/parser/expr-as-stmt.stderr
index 858b4e8db05..6da4ac34067 100644
--- a/src/test/ui/parser/expr-as-stmt.stderr
+++ b/src/test/ui/parser/expr-as-stmt.stderr
@@ -170,11 +170,6 @@ LL | fn revenge_from_mars() -> bool {
 LL |     { true } && { true }
    |              ^^^^^^^^^^^ expected `bool`, found `&&bool`
    |
-help: consider removing the `&&`
-   |
-LL -     { true } && { true }
-LL +     { true } { true }
-   |
 help: parentheses are required to parse this as an expression
    |
 LL |     ({ true }) && { true }
@@ -201,10 +196,6 @@ LL |     { true } || { true }
    |
    = note: expected type `bool`
            found closure `[closure@$DIR/expr-as-stmt.rs:51:14: 51:16]`
-help: use parentheses to call this closure
-   |
-LL |     { true } (|| { true })()
-   |              +           +++
 help: parentheses are required to parse this as an expression
    |
 LL |     ({ true }) || { true }
diff --git a/src/test/ui/suggestions/boxed-variant-field.rs b/src/test/ui/suggestions/boxed-variant-field.rs
index e79be2f6127..6050963c4ee 100644
--- a/src/test/ui/suggestions/boxed-variant-field.rs
+++ b/src/test/ui/suggestions/boxed-variant-field.rs
@@ -9,7 +9,6 @@ fn foo(x: Ty) -> Ty {
         Ty::List(elem) => foo(elem),
         //~^ ERROR mismatched types
         //~| HELP consider unboxing the value
-        //~| HELP try wrapping
     }
 }
 
diff --git a/src/test/ui/suggestions/boxed-variant-field.stderr b/src/test/ui/suggestions/boxed-variant-field.stderr
index 6dfb73480a2..9ae36a06a71 100644
--- a/src/test/ui/suggestions/boxed-variant-field.stderr
+++ b/src/test/ui/suggestions/boxed-variant-field.stderr
@@ -17,10 +17,6 @@ help: consider unboxing the value
    |
 LL |         Ty::List(elem) => foo(*elem),
    |                               +
-help: try wrapping the expression in `Ty::List`
-   |
-LL |         Ty::List(elem) => foo(Ty::List(elem)),
-   |                               +++++++++    +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/suggestions/into-convert.rs b/src/test/ui/suggestions/into-convert.rs
new file mode 100644
index 00000000000..1c9a9e0aaf5
--- /dev/null
+++ b/src/test/ui/suggestions/into-convert.rs
@@ -0,0 +1,26 @@
+use std::path::{Path, PathBuf};
+use std::sync::atomic::AtomicU32;
+use std::sync::Arc;
+
+fn main() {
+    let x: A = B;
+    //~^ ERROR mismatched types
+    //~| HELP call `Into::into` on this expression to convert `B` into `A`
+
+    let y: Arc<Path> = PathBuf::new();
+    //~^ ERROR mismatched types
+    //~| HELP call `Into::into` on this expression to convert `PathBuf` into `Arc<Path>`
+
+    let z: AtomicU32 = 1;
+    //~^ ERROR mismatched types
+    //~| HELP call `Into::into` on this expression to convert `{integer}` into `AtomicU32`
+}
+
+struct A;
+struct B;
+
+impl From<B> for A {
+    fn from(_: B) -> Self {
+        A
+    }
+}
diff --git a/src/test/ui/suggestions/into-convert.stderr b/src/test/ui/suggestions/into-convert.stderr
new file mode 100644
index 00000000000..d43104a2172
--- /dev/null
+++ b/src/test/ui/suggestions/into-convert.stderr
@@ -0,0 +1,44 @@
+error[E0308]: mismatched types
+  --> $DIR/into-convert.rs:6:16
+   |
+LL |     let x: A = B;
+   |            -   ^ expected struct `A`, found struct `B`
+   |            |
+   |            expected due to this
+   |
+help: call `Into::into` on this expression to convert `B` into `A`
+   |
+LL |     let x: A = B.into();
+   |                 +++++++
+
+error[E0308]: mismatched types
+  --> $DIR/into-convert.rs:10:24
+   |
+LL |     let y: Arc<Path> = PathBuf::new();
+   |            ---------   ^^^^^^^^^^^^^^ expected struct `Arc`, found struct `PathBuf`
+   |            |
+   |            expected due to this
+   |
+   = note: expected struct `Arc<Path>`
+              found struct `PathBuf`
+help: call `Into::into` on this expression to convert `PathBuf` into `Arc<Path>`
+   |
+LL |     let y: Arc<Path> = PathBuf::new().into();
+   |                                      +++++++
+
+error[E0308]: mismatched types
+  --> $DIR/into-convert.rs:14:24
+   |
+LL |     let z: AtomicU32 = 1;
+   |            ---------   ^ expected struct `AtomicU32`, found integer
+   |            |
+   |            expected due to this
+   |
+help: call `Into::into` on this expression to convert `{integer}` into `AtomicU32`
+   |
+LL |     let z: AtomicU32 = 1.into();
+   |                         +++++++
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.