Flatten and simplify some control flow

compiler/rustc_borrowck/src/lib.rs

@@ -2479,20 +2479,16 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
         let body = self.body;
         for local in body.mut_vars_and_args_iter().filter(|local| !self.used_mut.contains(local)) {
             let local_decl = &body.local_decls[local];
-            let lint_root = match &body.source_scopes[local_decl.source_info.scope].local_data {
+            let ClearCrossCrate::Set(SourceScopeLocalData { lint_root, .. }) =
-                ClearCrossCrate::Set(data) => data.lint_root,
+                body.source_scopes[local_decl.source_info.scope].local_data
-                _ => continue,
+            else {
+                continue;
             };
 
             // Skip over locals that begin with an underscore or have no name
-            match self.local_names[local] {
+            if self.local_names[local].is_none_or(|name| name.as_str().starts_with('_')) {
-                Some(name) => {
-                    if name.as_str().starts_with('_') {
                 continue;
             }
-                }
-                None => continue,
-            }
 
             let span = local_decl.source_info.span;
             if span.desugaring_kind().is_some() {

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -153,10 +153,9 @@ pub(super) fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDef
     }
 
     // If `#[link_section]` is missing, then nothing to verify
-    let attrs = tcx.codegen_fn_attrs(id);
+    let Some(link_section) = tcx.codegen_fn_attrs(id).link_section else {
-    if attrs.link_section.is_none() {
         return;
-    }
+    };
 
     // For the wasm32 target statics with `#[link_section]` other than `.init_array`
     // are placed into custom sections of the final output file, but this isn't like
@@ -182,11 +181,8 @@ pub(super) fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDef
     //  continue to work, but would no longer be necessary.
 
     if let Ok(alloc) = tcx.eval_static_initializer(id.to_def_id())
-        && alloc.inner().provenance().ptrs().len() != 0
+        && !alloc.inner().provenance().ptrs().is_empty()
-        && attrs
+        && !link_section.as_str().starts_with(".init_array")
-            .link_section
-            .map(|link_section| !link_section.as_str().starts_with(".init_array"))
-            .unwrap()
     {
         let msg = "statics with a custom `#[link_section]` must be a \
                         simple list of bytes on the wasm target with no \

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -1532,10 +1532,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             if self.may_coerce(blk_ty, *elem_ty)
                 && blk.stmts.is_empty()
                 && blk.rules == hir::BlockCheckMode::DefaultBlock
+                && let source_map = self.tcx.sess.source_map()
+                && let Ok(snippet) = source_map.span_to_snippet(blk.span)
+                && snippet.starts_with('{')
+                && snippet.ends_with('}')
             {
-                let source_map = self.tcx.sess.source_map();
-                if let Ok(snippet) = source_map.span_to_snippet(blk.span) {
-                    if snippet.starts_with('{') && snippet.ends_with('}') {
                 diag.multipart_suggestion_verbose(
                     "to create an array, use square brackets instead of curly braces",
                     vec![
@@ -1557,8 +1558,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
         }
     }
-        }
-    }
 
     #[instrument(skip(self, err))]
     pub(crate) fn suggest_floating_point_literal(

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -843,9 +843,8 @@ fn analyze_attr(attr: &impl AttributeExt, state: &mut AnalyzeAttrState<'_>) -> b
                 }
             }
         }
-    } else if attr.path().starts_with(&[sym::diagnostic]) && attr.path().len() == 2 {
+    } else if let &[sym::diagnostic, seg] = &*attr.path() {
-        should_encode =
+        should_encode = rustc_feature::is_stable_diagnostic_attribute(seg, state.features);
-            rustc_feature::is_stable_diagnostic_attribute(attr.path()[1], state.features);
     } else {
         should_encode = true;
     }

compiler/rustc_middle/src/ty/diagnostics.rs

@@ -641,22 +641,20 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for IsSuggestableVisitor<'tcx> {
                 }
             }
 
-            Alias(Projection, AliasTy { def_id, .. }) => {
+            Alias(Projection, AliasTy { def_id, .. })
-                if self.tcx.def_kind(def_id) != DefKind::AssocTy {
+                if self.tcx.def_kind(def_id) != DefKind::AssocTy =>
+            {
                 return ControlFlow::Break(());
             }
-            }
 
-            Param(param) => {
             // FIXME: It would be nice to make this not use string manipulation,
             // but it's pretty hard to do this, since `ty::ParamTy` is missing
             // sufficient info to determine if it is synthetic, and we don't
             // always have a convenient way of getting `ty::Generics` at the call
             // sites we invoke `IsSuggestable::is_suggestable`.
-                if param.name.as_str().starts_with("impl ") {
+            Param(param) if param.name.as_str().starts_with("impl ") => {
                 return ControlFlow::Break(());
             }
-            }
 
             _ => {}
         }
@@ -733,19 +731,15 @@ impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for MakeSuggestableFolder<'tcx> {
                 }
             }
 
-            Param(param) => {
             // FIXME: It would be nice to make this not use string manipulation,
             // but it's pretty hard to do this, since `ty::ParamTy` is missing
             // sufficient info to determine if it is synthetic, and we don't
             // always have a convenient way of getting `ty::Generics` at the call
             // sites we invoke `IsSuggestable::is_suggestable`.
-                if param.name.as_str().starts_with("impl ") {
+            Param(param) if param.name.as_str().starts_with("impl ") => {
                 return Err(());
             }
 
-                t
-            }
-
             _ => t,
         };
 

compiler/rustc_passes/src/dead.rs

@@ -1132,7 +1132,7 @@ impl<'tcx> DeadVisitor<'tcx> {
             return;
         }
         dead_codes.sort_by_key(|v| v.level);
-        for group in dead_codes[..].chunk_by(|a, b| a.level == b.level) {
+        for group in dead_codes.chunk_by(|a, b| a.level == b.level) {
             self.lint_at_single_level(&group, participle, Some(def_id), report_on);
         }
     }