Replace some thens with some then_somes

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -271,7 +271,7 @@ fn invalid_visibility(&self, vis: &Visibility, note: Option<InvalidVisibilityNot
 
         self.session.emit_err(InvalidVisibility {
             span: vis.span,
-            implied: vis.kind.is_pub().then(|| vis.span),
+            implied: vis.kind.is_pub().then_some(vis.span),
             note,
         });
     }

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1186,7 +1186,7 @@ fn suggest_using_local_if_applicable(
                 return None;
             };
             debug!("checking call args for uses of inner_param: {:?}", args);
-            args.contains(&Operand::Move(inner_param)).then(|| (loc, term))
+            args.contains(&Operand::Move(inner_param)).then_some((loc, term))
         }) else {
             debug!("no uses of inner_param found as a by-move call arg");
             return;

compiler/rustc_builtin_macros/src/standard_library_imports.rs

@@ -62,7 +62,7 @@ pub fn inject(
     // the one with the prelude.
     let name = names[0];
 
-    let root = (edition == Edition2015).then(|| kw::PathRoot);
+    let root = (edition == Edition2015).then_some(kw::PathRoot);
 
     let import_path = root
         .iter()

compiler/rustc_codegen_llvm/src/type_of.rs

@@ -154,7 +154,7 @@ fn struct_llfields<'a, 'tcx>(
     } else {
         debug!("struct_llfields: offset: {:?} stride: {:?}", offset, layout.size);
     }
-    let field_remapping = padding_used.then(|| field_remapping);
+    let field_remapping = padding_used.then_some(field_remapping);
     (result, packed, field_remapping)
 }
 

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2024,7 +2024,7 @@ fn linker_with_args<'a>(
         .native_libraries
         .iter()
         .filter_map(|(cnum, libraries)| {
-            (dependency_linkage[cnum.as_usize() - 1] != Linkage::Static).then(|| libraries)
+            (dependency_linkage[cnum.as_usize() - 1] != Linkage::Static).then_some(libraries)
         })
         .flatten();
     for (raw_dylib_name, raw_dylib_imports) in

compiler/rustc_expand/src/config.rs

@@ -255,7 +255,7 @@ fn try_configure_tokens<T: HasTokens>(&self, node: &mut T) {
 
     fn configure_krate_attrs(&self, mut attrs: ast::AttrVec) -> Option<ast::AttrVec> {
         attrs.flat_map_in_place(|attr| self.process_cfg_attr(attr));
-        self.in_cfg(&attrs).then(|| attrs)
+        self.in_cfg(&attrs).then_some(attrs)
     }
 
     /// Performs cfg-expansion on `stream`, producing a new `AttrTokenStream`.

compiler/rustc_hir_analysis/src/lib.rs

@@ -204,7 +204,7 @@ fn main_fn_generics_params_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span>
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
         match tcx.hir().find(hir_id) {
             Some(Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, generics, _), .. })) => {
-                generics.params.is_empty().not().then(|| generics.span)
+                generics.params.is_empty().not().then_some(generics.span)
             }
             _ => {
                 span_bug!(tcx.def_span(def_id), "main has a non-function type");

compiler/rustc_hir_typeck/src/coercion.rs

@@ -1046,7 +1046,7 @@ pub fn deref_once_mutably_for_diagnostic(&self, expr_ty: Ty<'tcx>) -> Option<Ty<
                     self.param_env,
                 )
                 .may_apply()
-                .then(|| deref_ty)
+                .then_some(deref_ty)
         })
     }
 

compiler/rustc_lint/src/builtin.rs

@@ -2308,7 +2308,8 @@ fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
             .for_each(|(&name, &span)| {
                 let note = rustc_feature::find_feature_issue(name, GateIssue::Language)
                     .map(|n| BuiltinIncompleteFeaturesNote { n });
-                let help = HAS_MIN_FEATURES.contains(&name).then(|| BuiltinIncompleteFeaturesHelp);
+                let help =
+                    HAS_MIN_FEATURES.contains(&name).then_some(BuiltinIncompleteFeaturesHelp);
                 cx.emit_spanned_lint(
                     INCOMPLETE_FEATURES,
                     span,

compiler/rustc_lint/src/context.rs

@@ -487,7 +487,7 @@ fn no_lint_suggestion(&self, lint_name: &str) -> CheckLintNameResult<'_> {
         let mut groups: Vec<_> = self
             .lint_groups
             .iter()
-            .filter_map(|(k, LintGroup { depr, .. })| depr.is_none().then(|| k))
+            .filter_map(|(k, LintGroup { depr, .. })| depr.is_none().then_some(k))
             .collect();
         groups.sort();
         let groups = groups.iter().map(|k| Symbol::intern(k));

compiler/rustc_middle/src/mir/mod.rs

@@ -414,7 +414,7 @@ pub fn mut_vars_iter<'a>(&'a self) -> impl Iterator<Item = Local> + Captures<'tc
         (self.arg_count + 1..self.local_decls.len()).filter_map(move |index| {
             let local = Local::new(index);
             let decl = &self.local_decls[local];
-            (decl.is_user_variable() && decl.mutability.is_mut()).then(|| local)
+            (decl.is_user_variable() && decl.mutability.is_mut()).then_some(local)
         })
     }
 

compiler/rustc_middle/src/ty/instance.rs

@@ -584,7 +584,7 @@ pub fn fn_once_adapter_instance(
     /// this function returns `None`, then the MIR body does not require substitution during
     /// codegen.
     fn substs_for_mir_body(&self) -> Option<SubstsRef<'tcx>> {
-        self.def.has_polymorphic_mir_body().then(|| self.substs)
+        self.def.has_polymorphic_mir_body().then_some(self.substs)
     }
 
     pub fn subst_mir<T>(&self, tcx: TyCtxt<'tcx>, v: &T) -> T

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -203,7 +203,7 @@ fn lower_pattern_range(
                 if !lower_overflow && !higher_overflow {
                     self.tcx.sess.emit_err(LowerRangeBoundMustBeLessThanOrEqualToUpper {
                         span,
-                        teach: self.tcx.sess.teach(&error_code!(E0030)).then(|| ()),
+                        teach: self.tcx.sess.teach(&error_code!(E0030)).then_some(()),
                     });
                 }
                 PatKind::Wild

compiler/rustc_mir_dataflow/src/impls/liveness.rs

@@ -254,7 +254,7 @@ fn apply_statement_effect(
     ) {
         // Compute the place that we are storing to, if any
         let destination = match &statement.kind {
-            StatementKind::Assign(assign) => assign.1.is_safe_to_remove().then(|| assign.0),
+            StatementKind::Assign(assign) => assign.1.is_safe_to_remove().then_some(assign.0),
             StatementKind::SetDiscriminant { place, .. } | StatementKind::Deinit(place) => {
                 Some(**place)
             }

compiler/rustc_parse/src/parser/ty.rs

@@ -870,7 +870,7 @@ fn parse_ty_bound_modifiers(&mut self) -> PResult<'a, BoundModifiers> {
             None
         };
 
-        let maybe = self.eat(&token::Question).then(|| self.prev_token.span);
+        let maybe = self.eat(&token::Question).then_some(self.prev_token.span);
 
         Ok(BoundModifiers { maybe, maybe_const })
     }

compiler/rustc_parse_format/src/lib.rs

@@ -835,7 +835,7 @@ fn integer(&mut self) -> Option<usize> {
             );
         }
 
-        found.then(|| cur)
+        found.then_some(cur)
     }
 
     fn suggest_format(&mut self) {

compiler/rustc_passes/src/stability.rs

@@ -281,7 +281,7 @@ fn annotate<F>(
         self.recurse_with_stability_attrs(
             depr.map(|(d, _)| DeprecationEntry::local(d, def_id)),
             stab,
-            inherit_const_stability.yes().then(|| const_stab).flatten(),
+            inherit_const_stability.yes().then_some(const_stab).flatten(),
             visit_children,
         );
     }

compiler/rustc_session/src/config.rs

@@ -2544,7 +2544,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         }
 
         // Only use this directory if it has a file we can expect to always find.
-        candidate.join("library/std/src/lib.rs").is_file().then(|| candidate)
+        candidate.join("library/std/src/lib.rs").is_file().then_some(candidate)
     };
 
     let working_dir = std::env::current_dir().unwrap_or_else(|e| {

compiler/rustc_session/src/filesearch.rs

@@ -217,7 +217,7 @@ fn from_env_args_next() -> Option<PathBuf> {
                 // Look for the target rustlib directory in the suspected sysroot.
                 let mut rustlib_path = rustc_target::target_rustlib_path(&p, "dummy");
                 rustlib_path.pop(); // pop off the dummy target.
-                rustlib_path.exists().then(|| p)
+                rustlib_path.exists().then_some(p)
             }
             None => None,
         }

compiler/rustc_session/src/options.rs

@@ -809,7 +809,7 @@ pub(crate) fn parse_mir_spanview(slot: &mut Option<MirSpanview>, v: Option<&str>
         if v.is_some() {
             let mut bool_arg = None;
             if parse_opt_bool(&mut bool_arg, v) {
-                *slot = bool_arg.unwrap().then(|| MirSpanview::Statement);
+                *slot = bool_arg.unwrap().then_some(MirSpanview::Statement);
                 return true;
             }
         }
@@ -850,7 +850,7 @@ pub(crate) fn parse_instrument_coverage(
         if v.is_some() {
             let mut bool_arg = None;
             if parse_opt_bool(&mut bool_arg, v) {
-                *slot = bool_arg.unwrap().then(|| InstrumentCoverage::All);
+                *slot = bool_arg.unwrap().then_some(InstrumentCoverage::All);
                 return true;
             }
         }

compiler/rustc_span/src/def_id.rs

@@ -320,7 +320,7 @@ pub fn is_crate_root(self) -> bool {
 
     #[inline]
     pub fn as_crate_root(self) -> Option<CrateNum> {
-        self.is_crate_root().then(|| self.krate)
+        self.is_crate_root().then_some(self.krate)
     }
 
     #[inline]

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -771,7 +771,7 @@ fn suggest_dereferences(
                             .iter()
                             .chain([&obligation])
                             .all(|obligation| self.predicate_may_hold(obligation))
-                            .then(|| steps);
+                            .then_some(steps);
 
                         may_hold
                     })

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -307,7 +307,7 @@ fn predicate_references_self<'tcx>(
     match predicate.kind().skip_binder() {
         ty::PredicateKind::Clause(ty::Clause::Trait(ref data)) => {
             // In the case of a trait predicate, we can skip the "self" type.
-            data.trait_ref.substs[1..].iter().any(has_self_ty).then(|| sp)
+            data.trait_ref.substs[1..].iter().any(has_self_ty).then_some(sp)
         }
         ty::PredicateKind::Clause(ty::Clause::Projection(ref data)) => {
             // And similarly for projections. This should be redundant with
@@ -325,7 +325,7 @@ fn predicate_references_self<'tcx>(
             //
             // This is ALT2 in issue #56288, see that for discussion of the
             // possible alternatives.
-            data.projection_ty.substs[1..].iter().any(has_self_ty).then(|| sp)
+            data.projection_ty.substs[1..].iter().any(has_self_ty).then_some(sp)
         }
         ty::PredicateKind::AliasEq(..) => bug!("`AliasEq` not allowed as assumption"),
 

compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs

@@ -113,7 +113,7 @@ fn insert(
                     // Only report the `Self` type if it has at least
                     // some outer concrete shell; otherwise, it's
                     // not adding much information.
-                    self_ty: self_ty.has_concrete_skeleton().then(|| self_ty),
+                    self_ty: self_ty.has_concrete_skeleton().then_some(self_ty),
                     intercrate_ambiguity_causes: overlap.intercrate_ambiguity_causes,
                     involves_placeholder: overlap.involves_placeholder,
                 }