rustc_resolve: reduce rightwards drift with let..else 👉💨

compiler/rustc_resolve/src/diagnostics.rs

@@ -1038,14 +1038,16 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     if filter_fn(res) {
                         for derive in parent_scope.derives {
                             let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
-                            if let Ok((Some(ext), _)) = this.resolve_macro_path(
+                            let Ok((Some(ext), _)) = this.resolve_macro_path(
                                 derive,
                                 Some(MacroKind::Derive),
                                 parent_scope,
                                 false,
                                 false,
                                 None,
-                            ) {
+                            ) else {
+                                continue;
+                            };
                             suggestions.extend(
                                 ext.helper_attrs
                                     .iter()
@@ -1054,7 +1056,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         }
                     }
                 }
-                }
                 Scope::MacroRules(macro_rules_scope) => {
                     if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
                         let res = macro_rules_binding.binding.res();
@@ -1362,8 +1363,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     // otherwise cause duplicate suggestions.
                     continue;
                 }
-                let crate_id = self.crate_loader(|c| c.maybe_process_path_extern(ident.name));
-                if let Some(crate_id) = crate_id {
+                let Some(crate_id) = self.crate_loader(|c| c.maybe_process_path_extern(ident.name))
+                else {
+                    continue;
+                };
+
                 let crate_def_id = crate_id.as_def_id();
                 let crate_root = self.expect_module(crate_def_id);
 
@@ -1405,7 +1409,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 ));
             }
         }
-        }
 
         suggestions
     }
@@ -1500,7 +1503,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             });
         }
         for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] {
-            if let Ok(binding) = self.early_resolve_ident_in_lexical_scope(
+            let Ok(binding) = self.early_resolve_ident_in_lexical_scope(
                 ident,
                 ScopeSet::All(ns),
                 parent_scope,
@@ -1508,11 +1511,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 false,
                 None,
                 None,
-            ) {
+            ) else {
+                continue;
+            };
+
             let desc = match binding.res() {
-                    Res::Def(DefKind::Macro(MacroKind::Bang), _) => {
-                        "a function-like macro".to_string()
-                    }
+                Res::Def(DefKind::Macro(MacroKind::Bang), _) => "a function-like macro".to_string(),
                 Res::Def(DefKind::Macro(MacroKind::Attr), _) | Res::NonMacroAttr(..) => {
                     format!("an attribute: `#[{ident}]`")
                 }
@@ -1556,7 +1560,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             return;
         }
     }
-    }
 
     pub(crate) fn add_typo_suggestion(
         &self,
@@ -1738,15 +1741,16 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     /// If the binding refers to a tuple struct constructor with fields,
     /// returns the span of its fields.
     fn ctor_fields_span(&self, binding: NameBinding<'_>) -> Option<Span> {
-        if let NameBindingKind::Res(Res::Def(
+        let NameBindingKind::Res(Res::Def(
             DefKind::Ctor(CtorOf::Struct, CtorKind::Fn),
             ctor_def_id,
         )) = binding.kind
-        {
+        else {
+            return None;
+        };
+
         let def_id = self.tcx.parent(ctor_def_id);
-            return self.field_idents(def_id)?.iter().map(|&f| f.span).reduce(Span::to); // None for `struct Foo()`
-        }
-        None
+        self.field_idents(def_id)?.iter().map(|&f| f.span).reduce(Span::to) // None for `struct Foo()`
     }
 
     fn report_privacy_error(&mut self, privacy_error: &PrivacyError<'ra>) {
@@ -2399,7 +2403,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let binding_key = BindingKey::new(ident, MacroNS);
         let resolution = resolutions.get(&binding_key)?;
         let binding = resolution.borrow().binding()?;
-        if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
+        let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() else {
+            return None;
+        };
         let module_name = crate_module.kind.name().unwrap();
         let import_snippet = match import.kind {
             ImportKind::Single { source, target, .. } if source != target => {
@@ -2451,11 +2457,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             //               ^^^^^^^^^
             //   or  `use a::{b, c, d}};`
             //               ^^^^^^^^^^^
-                let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
-                    self.tcx.sess,
-                    module_name,
-                    import.use_span,
-                );
+            let (has_nested, after_crate_name) =
+                find_span_immediately_after_crate_name(self.tcx.sess, module_name, import.use_span);
             debug!(has_nested, ?after_crate_name);
 
             let source_map = self.tcx.sess.source_map();
@@ -2485,8 +2488,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
                 // Add a `};` to the end if nested, matching the `{` added at the start.
                 if !has_nested {
-                        corrections
-                            .push((source_map.end_point(after_crate_name), "};".to_string()));
+                    corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
                 }
             } else {
                 // If the root import is module-relative, add the import separately
@@ -2502,12 +2504,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             String::from("a macro with this name exists at the root of the crate"),
             Applicability::MaybeIncorrect,
         ));
-            Some((suggestion, Some("this could be because a macro annotated with `#[macro_export]` will be exported \
+        Some((
+            suggestion,
+            Some(
+                "this could be because a macro annotated with `#[macro_export]` will be exported \
             at the root of the crate instead of the module where it is defined"
-               .to_string())))
-        } else {
-            None
-        }
+                    .to_string(),
+            ),
+        ))
     }
 
     /// Finds a cfg-ed out item inside `module` with the matching name.

compiler/rustc_resolve/src/effective_visibilities.rs

@@ -118,7 +118,9 @@ impl<'a, 'ra, 'tcx> EffectiveVisibilitiesVisitor<'a, 'ra, 'tcx> {
         let resolutions = self.r.resolutions(module);
 
         for (_, name_resolution) in resolutions.borrow().iter() {
-            if let Some(mut binding) = name_resolution.borrow().binding() {
+            let Some(mut binding) = name_resolution.borrow().binding() else {
+                continue;
+            };
             // Set the given effective visibility level to `Level::Direct` and
             // sets the rest of the `use` chain to `Level::Reexported` until
             // we hit the actual exported item.
@@ -151,7 +153,6 @@ impl<'a, 'ra, 'tcx> EffectiveVisibilitiesVisitor<'a, 'ra, 'tcx> {
             }
         }
     }
-    }
 
     fn effective_vis_or_private(&mut self, parent_id: ParentId<'ra>) -> EffectiveVisibility {
         // Private nodes are only added to the table for caching, they could be added or removed at

compiler/rustc_resolve/src/imports.rs

@@ -542,7 +542,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             // resolution for it so that later resolve stages won't complain.
             self.import_dummy_binding(*import, is_indeterminate);
 
-            if let Some(err) = unresolved_import_error {
+            let Some(err) = unresolved_import_error else { continue };
+
             glob_error |= import.is_glob();
 
             if let ImportKind::Single { source, ref source_bindings, .. } = import.kind
@@ -553,9 +554,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 continue;
             }
 
-                if prev_root_id != NodeId::ZERO
-                    && prev_root_id != import.root_id
-                    && !errors.is_empty()
+            if prev_root_id != NodeId::ZERO && prev_root_id != import.root_id && !errors.is_empty()
             {
                 // In the case of a new import line, throw a diagnostic message
                 // for the previous line.
@@ -567,7 +566,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 prev_root_id = import.root_id;
             }
         }
-        }
 
         if !errors.is_empty() {
             self.throw_unresolved_import_error(errors, glob_error);
@@ -607,7 +605,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             for (key, resolution) in self.resolutions(*module).borrow().iter() {
                 let resolution = resolution.borrow();
 
-                if let Some(binding) = resolution.binding {
+                let Some(binding) = resolution.binding else { continue };
+
                 if let NameBindingKind::Import { import, .. } = binding.kind
                     && let Some((amb_binding, _)) = binding.ambiguity
                     && binding.res() != Res::Err
@@ -664,7 +663,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             }
         }
     }
-    }
 
     fn throw_unresolved_import_error(
         &mut self,
@@ -1242,7 +1240,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let mut any_successful_reexport = false;
         let mut crate_private_reexport = false;
         self.per_ns(|this, ns| {
-            if let Ok(binding) = source_bindings[ns].get() {
+            let Ok(binding) = source_bindings[ns].get() else {
+                return;
+            };
+
             if !binding.vis.is_at_least(import.vis, this.tcx) {
                 reexport_error = Some((ns, binding));
                 if let ty::Visibility::Restricted(binding_def_id) = binding.vis
@@ -1253,7 +1254,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             } else {
                 any_successful_reexport = true;
             }
-            }
         });
 
         // All namespaces must be re-exported with extra visibility for an error to occur.
@@ -1469,7 +1469,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // Since import resolution is finished, globs will not define any more names.
         *module.globs.borrow_mut() = Vec::new();
 
-        if let Some(def_id) = module.opt_def_id() {
+        let Some(def_id) = module.opt_def_id() else { return };
+
         let mut children = Vec::new();
 
         module.for_each_child(self, |this, ident, _, binding| {
@@ -1492,7 +1493,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             self.module_children.insert(def_id.expect_local(), children);
         }
     }
-    }
 }
 
 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {

compiler/rustc_resolve/src/late.rs

@@ -1234,7 +1234,10 @@ impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'r
     }
 
     fn visit_path_segment(&mut self, path_segment: &'ast PathSegment) {
-        if let Some(ref args) = path_segment.args {
+        let Some(ref args) = path_segment.args else {
+            return;
+        };
+
         match &**args {
             GenericArgs::AngleBracketed(..) => visit::walk_generic_args(self, args),
             GenericArgs::Parenthesized(p_args) => {
@@ -1283,7 +1286,6 @@ impl<'ra: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'_, 'ast, 'r
             GenericArgs::ParenthesizedElided(_) => {}
         }
     }
-    }
 
     fn visit_where_predicate(&mut self, p: &'ast WherePredicate) {
         debug!("visit_where_predicate {:?}", p);
@@ -3496,7 +3498,7 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             self.visit_ty(&qself.ty);
         }
         self.visit_path(&delegation.path, delegation.id);
-        if let Some(body) = &delegation.body {
+        let Some(body) = &delegation.body else { return };
         self.with_rib(ValueNS, RibKind::FnOrCoroutine, |this| {
             // `PatBoundCtx` is not necessary in this context
             let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];
@@ -3511,7 +3513,6 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             this.visit_block(body);
         });
     }
-    }
 
     fn resolve_params(&mut self, params: &'ast [Param]) {
         let mut bindings = smallvec![(PatBoundCtx::Product, Default::default())];