Rollup of 7 pull requests

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2226,8 +2226,8 @@ fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(
                     continue;
                 }
 
-                let canonical = f.replace("-", "_");
-                let canonical_name = name.replace("-", "_");
+                let canonical = f.replace('-', "_");
+                let canonical_name = name.replace('-', "_");
 
                 let is_rust_object =
                     canonical.starts_with(&canonical_name) && looks_like_rust_object_file(&f);

compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -154,7 +154,7 @@ fn is_reachable_non_generic_provider_extern(tcx: TyCtxt<'_>, def_id: DefId) -> b
     tcx.reachable_non_generics(def_id.krate).contains_key(&def_id)
 }
 
-fn exported_symbols_provider_local(
+fn exported_symbols_provider_local<'tcx>(
     tcx: TyCtxt<'tcx>,
     cnum: CrateNum,
 ) -> &'tcx [(ExportedSymbol<'tcx>, SymbolExportLevel)] {

compiler/rustc_codegen_ssa/src/base.rs

@@ -486,7 +486,7 @@ fn get_argc_argv<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
 pub fn codegen_crate<B: ExtraBackendMethods>(
     backend: B,
-    tcx: TyCtxt<'tcx>,
+    tcx: TyCtxt<'_>,
     target_cpu: String,
     metadata: EncodedMetadata,
     need_metadata_module: bool,

compiler/rustc_codegen_ssa/src/coverageinfo/map.rs

@@ -150,9 +150,9 @@ impl<'tcx> FunctionCoverage<'tcx> {
     /// Generate an array of CounterExpressions, and an iterator over all `Counter`s and their
     /// associated `Regions` (from which the LLVM-specific `CoverageMapGenerator` will create
     /// `CounterMappingRegion`s.
-    pub fn get_expressions_and_counter_regions<'a>(
-        &'a self,
-    ) -> (Vec<CounterExpression>, impl Iterator<Item = (Counter, &'a CodeRegion)>) {
+    pub fn get_expressions_and_counter_regions(
+        &self,
+    ) -> (Vec<CounterExpression>, impl Iterator<Item = (Counter, &CodeRegion)>) {
         assert!(
             self.source_hash != 0 || !self.is_used,
             "No counters provided the source_hash for used function: {:?}",
@@ -168,7 +168,7 @@ impl<'tcx> FunctionCoverage<'tcx> {
         (counter_expressions, counter_regions)
     }
 
-    fn counter_regions<'a>(&'a self) -> impl Iterator<Item = (Counter, &'a CodeRegion)> {
+    fn counter_regions(&self) -> impl Iterator<Item = (Counter, &CodeRegion)> {
         self.counters.iter_enumerated().filter_map(|(index, entry)| {
             // Option::map() will return None to filter out missing counters. This may happen
             // if, for example, a MIR-instrumented counter is removed during an optimization.
@@ -177,8 +177,8 @@ impl<'tcx> FunctionCoverage<'tcx> {
     }
 
     fn expressions_with_regions(
-        &'a self,
-    ) -> (Vec<CounterExpression>, impl Iterator<Item = (Counter, &'a CodeRegion)>) {
+        &self,
+    ) -> (Vec<CounterExpression>, impl Iterator<Item = (Counter, &CodeRegion)>) {
         let mut counter_expressions = Vec::with_capacity(self.expressions.len());
         let mut expression_regions = Vec::with_capacity(self.expressions.len());
         let mut new_indexes = IndexVec::from_elem_n(None, self.expressions.len());
@@ -336,7 +336,7 @@ impl<'tcx> FunctionCoverage<'tcx> {
         (counter_expressions, expression_regions.into_iter())
     }
 
-    fn unreachable_regions<'a>(&'a self) -> impl Iterator<Item = (Counter, &'a CodeRegion)> {
+    fn unreachable_regions(&self) -> impl Iterator<Item = (Counter, &CodeRegion)> {
         self.unreachable_regions.iter().map(|region| (Counter::zero(), region))
     }
 

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -376,7 +376,7 @@ fn push_debuginfo_type_name<'tcx>(
     // format (natvis) is able to understand enums and render the active variant correctly in the
     // debugger. For more information, look in `src/etc/natvis/intrinsic.natvis` and
     // `EnumMemberDescriptionFactor::create_member_descriptions`.
-    fn msvc_enum_fallback(
+    fn msvc_enum_fallback<'tcx>(
         tcx: TyCtxt<'tcx>,
         ty: Ty<'tcx>,
         def: &AdtDef,
@@ -496,7 +496,7 @@ pub fn compute_debuginfo_vtable_name<'tcx>(
     vtable_name
 }
 
-pub fn push_item_name(tcx: TyCtxt<'tcx>, def_id: DefId, qualified: bool, output: &mut String) {
+pub fn push_item_name(tcx: TyCtxt<'_>, def_id: DefId, qualified: bool, output: &mut String) {
     let def_key = tcx.def_key(def_id);
     if qualified {
         if let Some(parent) = def_key.parent {
@@ -509,7 +509,7 @@ pub fn push_item_name(tcx: TyCtxt<'tcx>, def_id: DefId, qualified: bool, output:
 }
 
 fn push_unqualified_item_name(
-    tcx: TyCtxt<'tcx>,
+    tcx: TyCtxt<'_>,
     def_id: DefId,
     disambiguated_data: DisambiguatedDefPathData,
     output: &mut String,

compiler/rustc_codegen_ssa/src/lib.rs

@@ -2,7 +2,6 @@
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(try_blocks)]
-#![feature(in_band_lifetimes)]
 #![feature(let_else)]
 #![feature(once_cell)]
 #![feature(nll)]

compiler/rustc_codegen_ssa/src/mir/analyze.rs

@@ -73,7 +73,7 @@ struct LocalAnalyzer<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
     locals: IndexVec<mir::Local, LocalKind>,
 }
 
-impl<Bx: BuilderMethods<'a, 'tcx>> LocalAnalyzer<'mir, 'a, 'tcx, Bx> {
+impl<'mir, 'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> LocalAnalyzer<'mir, 'a, 'tcx, Bx> {
     fn assign(&mut self, local: mir::Local, location: Location) {
         let kind = &mut self.locals[local];
         match *kind {

compiler/rustc_codegen_ssa/src/mir/operand.rs

@@ -47,7 +47,7 @@ pub struct OperandRef<'tcx, V> {
     pub layout: TyAndLayout<'tcx>,
 }
 
-impl<V: CodegenObject> fmt::Debug for OperandRef<'tcx, V> {
+impl<V: CodegenObject> fmt::Debug for OperandRef<'_, V> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "OperandRef({:?} @ {:?})", self.val, self.layout)
     }

compiler/rustc_codegen_ssa/src/traits/type_.rs

@@ -97,7 +97,7 @@ pub trait DerivedTypeMethods<'tcx>: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {
     }
 }
 
-impl<T> DerivedTypeMethods<'tcx> for T where Self: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {}
+impl<'tcx, T> DerivedTypeMethods<'tcx> for T where Self: BaseTypeMethods<'tcx> + MiscMethods<'tcx> {}
 
 pub trait LayoutTypeMethods<'tcx>: Backend<'tcx> {
     fn backend_type(&self, layout: TyAndLayout<'tcx>) -> Self::Type;
@@ -135,4 +135,4 @@ pub trait ArgAbiMethods<'tcx>: HasCodegen<'tcx> {
 
 pub trait TypeMethods<'tcx>: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> {}
 
-impl<T> TypeMethods<'tcx> for T where Self: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> {}
+impl<'tcx, T> TypeMethods<'tcx> for T where Self: DerivedTypeMethods<'tcx> + LayoutTypeMethods<'tcx> {}

compiler/rustc_driver/src/lib.rs

@@ -872,7 +872,7 @@ Available lint options:
 
     let print_lints = |lints: Vec<&Lint>| {
         for lint in lints {
-            let name = lint.name_lower().replace("_", "-");
+            let name = lint.name_lower().replace('_', "-");
             println!(
                 "    {}  {:7.7}  {}",
                 padded(&name),
@@ -908,10 +908,10 @@ Available lint options:
 
     let print_lint_groups = |lints: Vec<(&'static str, Vec<LintId>)>| {
         for (name, to) in lints {
-            let name = name.to_lowercase().replace("_", "-");
+            let name = name.to_lowercase().replace('_', "-");
             let desc = to
                 .into_iter()
-                .map(|x| x.to_string().replace("_", "-"))
+                .map(|x| x.to_string().replace('_', "-"))
                 .collect::<Vec<String>>()
                 .join(", ");
             println!("    {}  {}", padded(&name), desc);
@@ -960,7 +960,7 @@ fn print_flag_list<T>(
         println!(
             "    {} {:>width$}=val -- {}",
             cmdline_opt,
-            name.replace("_", "-"),
+            name.replace('_', "-"),
             desc,
             width = max_len
         );
@@ -1015,7 +1015,7 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
                 .iter()
                 .map(|&(name, ..)| ('C', name))
                 .chain(DB_OPTIONS.iter().map(|&(name, ..)| ('Z', name)))
-                .find(|&(_, name)| *opt == name.replace("_", "-"))
+                .find(|&(_, name)| *opt == name.replace('_', "-"))
                 .map(|(flag, _)| format!("{}. Did you mean `-{} {}`?", e, flag, opt)),
             _ => None,
         };

compiler/rustc_graphviz/src/lib.rs

@@ -472,7 +472,7 @@ pub trait Labeller<'a> {
 /// Escape tags in such a way that it is suitable for inclusion in a
 /// Graphviz HTML label.
 pub fn escape_html(s: &str) -> String {
-    s.replace("&", "&amp;").replace("\"", "&quot;").replace("<", "&lt;").replace(">", "&gt;")
+    s.replace('&', "&amp;").replace('\"', "&quot;").replace('<', "&lt;").replace('>', "&gt;")
 }
 
 impl<'a> LabelText<'a> {

compiler/rustc_interface/src/passes.rs

@@ -584,7 +584,7 @@ fn output_conflicts_with_dir(output_paths: &[PathBuf]) -> Option<PathBuf> {
 fn escape_dep_filename(filename: &str) -> String {
     // Apparently clang and gcc *only* escape spaces:
     // https://llvm.org/klaus/clang/commit/9d50634cfc268ecc9a7250226dd5ca0e945240d4
-    filename.replace(" ", "\\ ")
+    filename.replace(' ', "\\ ")
 }
 
 // Makefile comments only need escaping newlines and `\`.

compiler/rustc_middle/src/lint.rs

@@ -295,7 +295,7 @@ pub fn struct_lint_level<'s, 'd>(
                     Level::Allow => "-A",
                     Level::ForceWarn => "--force-warn",
                 };
-                let hyphen_case_lint_name = name.replace("_", "-");
+                let hyphen_case_lint_name = name.replace('_', "-");
                 if lint_flag_val.as_str() == name {
                     sess.diag_note_once(
                         &mut err,
@@ -306,7 +306,7 @@ pub fn struct_lint_level<'s, 'd>(
                         ),
                     );
                 } else {
-                    let hyphen_case_flag_val = lint_flag_val.as_str().replace("_", "-");
+                    let hyphen_case_flag_val = lint_flag_val.as_str().replace('_', "-");
                     sess.diag_note_once(
                         &mut err,
                         DiagnosticMessageId::from(lint),

compiler/rustc_middle/src/mir/generic_graphviz.rs

@@ -126,7 +126,7 @@ impl<
             write!(
                 w,
                 r#"<tr><td align="left" balign="left">{}</td></tr>"#,
-                dot::escape_html(&section).replace("\n", "<br/>")
+                dot::escape_html(&section).replace('\n', "<br/>")
             )?;
         }
 
@@ -147,7 +147,7 @@ impl<
             let src = self.node(source);
             let trg = self.node(target);
             let escaped_edge_label = if let Some(edge_label) = edge_labels.get(index) {
-                dot::escape_html(edge_label).replace("\n", r#"<br align="left"/>"#)
+                dot::escape_html(edge_label).replace('\n', r#"<br align="left"/>"#)
             } else {
                 "".to_owned()
             };

compiler/rustc_middle/src/mir/spanview.rs

@@ -681,13 +681,13 @@ fn hir_body<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Option<&'tcx rustc_hir::B
 }
 
 fn escape_html(s: &str) -> String {
-    s.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
+    s.replace('&', "&amp;").replace('<', "&lt;").replace('>', "&gt;")
 }
 
 fn escape_attr(s: &str) -> String {
-    s.replace("&", "&amp;")
-        .replace("\"", "&quot;")
-        .replace("'", "&#39;")
-        .replace("<", "&lt;")
-        .replace(">", "&gt;")
+    s.replace('&', "&amp;")
+        .replace('\"', "&quot;")
+        .replace('\'', "&#39;")
+        .replace('<', "&lt;")
+        .replace('>', "&gt;")
 }

compiler/rustc_middle/src/ty/diagnostics.rs

@@ -1,7 +1,12 @@
 //! Diagnostics related methods for `TyS`.
 
+use crate::ty::subst::{GenericArg, GenericArgKind};
 use crate::ty::TyKind::*;
-use crate::ty::{InferTy, TyCtxt, TyS};
+use crate::ty::{
+    ConstKind, ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, InferTy,
+    ProjectionTy, TyCtxt, TyS, TypeAndMut,
+};
+
 use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
@@ -63,16 +68,55 @@ impl<'tcx> TyS<'tcx> {
 
     /// Whether the type can be safely suggested during error recovery.
     pub fn is_suggestable(&self) -> bool {
-        !matches!(
-            self.kind(),
+        fn generic_arg_is_suggestible(arg: GenericArg<'_>) -> bool {
+            match arg.unpack() {
+                GenericArgKind::Type(ty) => ty.is_suggestable(),
+                GenericArgKind::Const(c) => const_is_suggestable(c.val),
+                _ => true,
+            }
+        }
+
+        fn const_is_suggestable(kind: ConstKind<'_>) -> bool {
+            match kind {
+                ConstKind::Infer(..)
+                | ConstKind::Bound(..)
+                | ConstKind::Placeholder(..)
+                | ConstKind::Error(..) => false,
+                _ => true,
+            }
+        }
+
+        // FIXME(compiler-errors): Some types are still not good to suggest,
+        // specifically references with lifetimes within the function. Not
+        //sure we have enough information to resolve whether a region is
+        // temporary, so I'll leave this as a fixme.
+
+        match self.kind() {
             Opaque(..)
-                | FnDef(..)
-                | FnPtr(..)
-                | Dynamic(..)
-                | Closure(..)
-                | Infer(..)
-                | Projection(..)
-        )
+            | FnDef(..)
+            | Closure(..)
+            | Infer(..)
+            | Generator(..)
+            | GeneratorWitness(..)
+            | Bound(_, _)
+            | Placeholder(_)
+            | Error(_) => false,
+            Dynamic(dty, _) => dty.iter().all(|pred| match pred.skip_binder() {
+                ExistentialPredicate::Trait(ExistentialTraitRef { substs, .. }) => {
+                    substs.iter().all(generic_arg_is_suggestible)
+                }
+                ExistentialPredicate::Projection(ExistentialProjection { substs, ty, .. }) => {
+                    ty.is_suggestable() && substs.iter().all(generic_arg_is_suggestible)
+                }
+                _ => true,
+            }),
+            Projection(ProjectionTy { substs: args, .. }) | Adt(_, args) | Tuple(args) => {
+                args.iter().all(generic_arg_is_suggestible)
+            }
+            Slice(ty) | RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => ty.is_suggestable(),
+            Array(ty, c) => ty.is_suggestable() && const_is_suggestable(c.val),
+            _ => true,
+        }
     }
 }
 

compiler/rustc_middle/src/ty/sty.rs

@@ -787,7 +787,7 @@ impl<'tcx> ExistentialPredicate<'tcx> {
                 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
             }
             (AutoTrait(ref a), AutoTrait(ref b)) => {
-                tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash)
+                tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
             }
             (Trait(_), _) => Ordering::Less,
             (Projection(_), Trait(_)) => Ordering::Greater,

compiler/rustc_mir_transform/src/coverage/debug.rs

@@ -148,7 +148,7 @@ impl DebugOptions {
         let mut counter_format = ExpressionFormat::default();
 
         if let Ok(env_debug_options) = std::env::var(RUSTC_COVERAGE_DEBUG_OPTIONS) {
-            for setting_str in env_debug_options.replace(" ", "").replace("-", "_").split(',') {
+            for setting_str in env_debug_options.replace(' ', "").replace('-', "_").split(',') {
                 let (option, value) = match setting_str.split_once('=') {
                     None => (setting_str, None),
                     Some((k, v)) => (k, Some(v)),

compiler/rustc_mir_transform/src/coverage/spans.rs

@@ -155,7 +155,7 @@ impl CoverageSpan {
         format!(
             "{}\n    {}",
             source_range_no_file(tcx, &self.span),
-            self.format_coverage_statements(tcx, mir_body).replace("\n", "\n    "),
+            self.format_coverage_statements(tcx, mir_body).replace('\n', "\n    "),
         )
     }
 

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -2236,7 +2236,7 @@ impl<'a> Parser<'a> {
             err.span_suggestion(
                 seq_span,
                 "...or a vertical bar to match on multiple alternatives",
-                seq_snippet.replace(",", " |"),
+                seq_snippet.replace(',', " |"),
                 Applicability::MachineApplicable,
             );
         }

compiler/rustc_save_analysis/src/lib.rs

@@ -1036,7 +1036,7 @@ fn find_config(supplied: Option<Config>) -> Config {
 
 // Helper function to escape quotes in a string
 fn escape(s: String) -> String {
-    s.replace("\"", "\"\"")
+    s.replace('\"', "\"\"")
 }
 
 // Helper function to determine if a span came from a

compiler/rustc_session/src/config.rs

@@ -1213,7 +1213,7 @@ pub fn get_cmd_lint_options(
             if lint_name == "help" {
                 describe_lints = true;
             } else {
-                lint_opts_with_position.push((arg_pos, lint_name.replace("-", "_"), level));
+                lint_opts_with_position.push((arg_pos, lint_name.replace('-', "_"), level));
             }
         }
     }

compiler/rustc_session/src/options.rs

@@ -335,7 +335,7 @@ fn build_options<O: Default>(
             Some((k, v)) => (k.to_string(), Some(v)),
         };
 
-        let option_to_lookup = key.replace("-", "_");
+        let option_to_lookup = key.replace('-', "_");
         match descrs.iter().find(|(name, ..)| *name == option_to_lookup) {
             Some((_, setter, type_desc, _)) => {
                 if !setter(&mut op, value) {