use let chains in mir, resolve, target

Author: Kivooeo

compiler/rustc_mir_transform/src/promote_consts.rs

@@ -997,12 +997,11 @@ fn promote_candidates<'tcx>(
     for candidate in candidates.into_iter().rev() {
         let Location { block, statement_index } = candidate.location;
         if let StatementKind::Assign(box (place, _)) = &body[block].statements[statement_index].kind
+            && let Some(local) = place.as_local()
         {
-            if let Some(local) = place.as_local() {
-                if temps[local] == TempState::PromotedOut {
-                    // Already promoted.
-                    continue;
-                }
+            if temps[local] == TempState::PromotedOut {
+                // Already promoted.
+                continue;
             }
         }
 
@@ -1066,11 +1065,11 @@ fn promote_candidates<'tcx>(
             _ => true,
         });
         let terminator = block.terminator_mut();
-        if let TerminatorKind::Drop { place, target, .. } = &terminator.kind {
-            if let Some(index) = place.as_local() {
-                if promoted(index) {
-                    terminator.kind = TerminatorKind::Goto { target: *target };
-                }
+        if let TerminatorKind::Drop { place, target, .. } = &terminator.kind
+            && let Some(index) = place.as_local()
+        {
+            if promoted(index) {
+                terminator.kind = TerminatorKind::Goto { target: *target };
             }
         }
     }

compiler/rustc_mir_transform/src/remove_noop_landing_pads.rs

@@ -48,14 +48,13 @@ impl<'tcx> crate::MirPass<'tcx> for RemoveNoopLandingPads {
         let postorder: Vec<_> = traversal::postorder(body).map(|(bb, _)| bb).collect();
         for bb in postorder {
             debug!("  processing {:?}", bb);
-            if let Some(unwind) = body[bb].terminator_mut().unwind_mut() {
-                if let UnwindAction::Cleanup(unwind_bb) = *unwind {
-                    if nop_landing_pads.contains(unwind_bb) {
-                        debug!("    removing noop landing pad");
-                        landing_pads_removed += 1;
-                        *unwind = UnwindAction::Continue;
-                    }
-                }
+            if let Some(unwind) = body[bb].terminator_mut().unwind_mut()
+                && let UnwindAction::Cleanup(unwind_bb) = *unwind
+                && nop_landing_pads.contains(unwind_bb)
+            {
+                debug!("    removing noop landing pad");
+                landing_pads_removed += 1;
+                *unwind = UnwindAction::Continue;
             }
 
             body[bb].terminator_mut().successors_mut(|target| {

compiler/rustc_mir_transform/src/validate.rs

@@ -80,15 +80,14 @@ impl<'tcx> crate::MirPass<'tcx> for Validator {
             cfg_checker.fail(location, msg);
         }
 
-        if let MirPhase::Runtime(_) = body.phase {
-            if let ty::InstanceKind::Item(_) = body.source.instance {
-                if body.has_free_regions() {
-                    cfg_checker.fail(
-                        Location::START,
-                        format!("Free regions in optimized {} MIR", body.phase.name()),
-                    );
-                }
-            }
+        if let MirPhase::Runtime(_) = body.phase
+            && let ty::InstanceKind::Item(_) = body.source.instance
+            && body.has_free_regions()
+        {
+            cfg_checker.fail(
+                Location::START,
+                format!("Free regions in optimized {} MIR", body.phase.name()),
+            );
         }
     }
 

compiler/rustc_monomorphize/src/partitioning.rs

@@ -1178,12 +1178,11 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
     let autodiff_items = tcx.arena.alloc_from_iter(autodiff_items);
 
     // Output monomorphization stats per def_id
-    if let SwitchWithOptPath::Enabled(ref path) = tcx.sess.opts.unstable_opts.dump_mono_stats {
-        if let Err(err) =
+    if let SwitchWithOptPath::Enabled(ref path) = tcx.sess.opts.unstable_opts.dump_mono_stats
+        && let Err(err) =
             dump_mono_items_stats(tcx, codegen_units, path, tcx.crate_name(LOCAL_CRATE))
-        {
-            tcx.dcx().emit_fatal(CouldntDumpMonoStats { error: err.to_string() });
-        }
+    {
+        tcx.dcx().emit_fatal(CouldntDumpMonoStats { error: err.to_string() });
     }
 
     if tcx.sess.opts.unstable_opts.print_mono_items {

compiler/rustc_parse/src/parser/item.rs

@@ -1973,21 +1973,21 @@ impl<'a> Parser<'a> {
                     format!("expected `,`, or `}}`, found {}", super::token_descr(&self.token));
 
                 // Try to recover extra trailing angle brackets
-                if let TyKind::Path(_, Path { segments, .. }) = &a_var.ty.kind {
-                    if let Some(last_segment) = segments.last() {
-                        let guar = self.check_trailing_angle_brackets(
-                            last_segment,
-                            &[exp!(Comma), exp!(CloseBrace)],
-                        );
-                        if let Some(_guar) = guar {
-                            // Handle a case like `Vec<u8>>,` where we can continue parsing fields
-                            // after the comma
-                            let _ = self.eat(exp!(Comma));
-
-                            // `check_trailing_angle_brackets` already emitted a nicer error, as
-                            // proven by the presence of `_guar`. We can continue parsing.
-                            return Ok(a_var);
-                        }
+                if let TyKind::Path(_, Path { segments, .. }) = &a_var.ty.kind
+                    && let Some(last_segment) = segments.last()
+                {
+                    let guar = self.check_trailing_angle_brackets(
+                        last_segment,
+                        &[exp!(Comma), exp!(CloseBrace)],
+                    );
+                    if let Some(_guar) = guar {
+                        // Handle a case like `Vec<u8>>,` where we can continue parsing fields
+                        // after the comma
+                        let _ = self.eat(exp!(Comma));
+
+                        // `check_trailing_angle_brackets` already emitted a nicer error, as
+                        // proven by the presence of `_guar`. We can continue parsing.
+                        return Ok(a_var);
                     }
                 }
 
@@ -3034,18 +3034,16 @@ impl<'a> Parser<'a> {
 
                 if let Ok(t) = &ty {
                     // Check for trailing angle brackets
-                    if let TyKind::Path(_, Path { segments, .. }) = &t.kind {
-                        if let Some(segment) = segments.last() {
-                            if let Some(guar) =
-                                this.check_trailing_angle_brackets(segment, &[exp!(CloseParen)])
-                            {
-                                return Ok((
-                                    dummy_arg(segment.ident, guar),
-                                    Trailing::No,
-                                    UsePreAttrPos::No,
-                                ));
-                            }
-                        }
+                    if let TyKind::Path(_, Path { segments, .. }) = &t.kind
+                        && let Some(segment) = segments.last()
+                        && let Some(guar) =
+                            this.check_trailing_angle_brackets(segment, &[exp!(CloseParen)])
+                    {
+                        return Ok((
+                            dummy_arg(segment.ident, guar),
+                            Trailing::No,
+                            UsePreAttrPos::No,
+                        ));
                     }
 
                     if this.token != token::Comma && this.token != token::CloseParen {

compiler/rustc_passes/src/reachable.rs

@@ -104,10 +104,10 @@ impl<'tcx> Visitor<'tcx> for ReachableContext<'tcx> {
 
     fn visit_inline_asm(&mut self, asm: &'tcx hir::InlineAsm<'tcx>, id: hir::HirId) {
         for (op, _) in asm.operands {
-            if let hir::InlineAsmOperand::SymStatic { def_id, .. } = op {
-                if let Some(def_id) = def_id.as_local() {
-                    self.reachable_symbols.insert(def_id);
-                }
+            if let hir::InlineAsmOperand::SymStatic { def_id, .. } = op
+                && let Some(def_id) = def_id.as_local()
+            {
+                self.reachable_symbols.insert(def_id);
             }
         }
         intravisit::walk_inline_asm(self, asm, id);

compiler/rustc_passes/src/stability.rs

@@ -929,10 +929,10 @@ struct CheckTraitImplStable<'tcx> {
 
 impl<'tcx> Visitor<'tcx> for CheckTraitImplStable<'tcx> {
     fn visit_path(&mut self, path: &hir::Path<'tcx>, _id: hir::HirId) {
-        if let Some(def_id) = path.res.opt_def_id() {
-            if let Some(stab) = self.tcx.lookup_stability(def_id) {
-                self.fully_stable &= stab.level.is_stable();
-            }
+        if let Some(def_id) = path.res.opt_def_id()
+            && let Some(stab) = self.tcx.lookup_stability(def_id)
+        {
+            self.fully_stable &= stab.level.is_stable();
         }
         intravisit::walk_path(self, path)
     }
@@ -1055,10 +1055,10 @@ pub fn check_unused_or_stable_features(tcx: TyCtxt<'_>) {
             // implications from this crate.
             remaining_implications.remove(&feature);
 
-            if let FeatureStability::Unstable { old_name: Some(alias) } = stability {
-                if let Some(span) = remaining_lib_features.swap_remove(&alias) {
-                    tcx.dcx().emit_err(errors::RenamedFeature { span, feature, alias });
-                }
+            if let FeatureStability::Unstable { old_name: Some(alias) } = stability
+                && let Some(span) = remaining_lib_features.swap_remove(&alias)
+            {
+                tcx.dcx().emit_err(errors::RenamedFeature { span, feature, alias });
             }
 
             if remaining_lib_features.is_empty() && remaining_implications.is_empty() {

compiler/rustc_passes/src/upvars.rs

@@ -75,19 +75,19 @@ impl<'tcx> Visitor<'tcx> for CaptureCollector<'_, 'tcx> {
     }
 
     fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
-        if let hir::ExprKind::Closure(closure) = expr.kind {
-            if let Some(upvars) = self.tcx.upvars_mentioned(closure.def_id) {
-                // Every capture of a closure expression is a local in scope,
-                // that is moved/copied/borrowed into the closure value, and
-                // for this analysis they are like any other access to a local.
-                //
-                // E.g. in `|b| |c| (a, b, c)`, the upvars of the inner closure
-                // are `a` and `b`, and while `a` is not directly used in the
-                // outer closure, it needs to be an upvar there too, so that
-                // the inner closure can take it (from the outer closure's env).
-                for (&var_id, upvar) in upvars {
-                    self.visit_local_use(var_id, upvar.span);
-                }
+        if let hir::ExprKind::Closure(closure) = expr.kind
+            && let Some(upvars) = self.tcx.upvars_mentioned(closure.def_id)
+        {
+            // Every capture of a closure expression is a local in scope,
+            // that is moved/copied/borrowed into the closure value, and
+            // for this analysis they are like any other access to a local.
+            //
+            // E.g. in `|b| |c| (a, b, c)`, the upvars of the inner closure
+            // are `a` and `b`, and while `a` is not directly used in the
+            // outer closure, it needs to be an upvar there too, so that
+            // the inner closure can take it (from the outer closure's env).
+            for (&var_id, upvar) in upvars {
+                self.visit_local_use(var_id, upvar.span);
             }
         }
 

compiler/rustc_privacy/src/lib.rs

@@ -204,12 +204,10 @@ where
                 // Something like `fn() {my_method}` type of the method
                 // `impl Pub<Priv> { pub fn my_method() {} }` is considered a private type,
                 // so we need to visit the self type additionally.
-                if let Some(assoc_item) = tcx.opt_associated_item(def_id) {
-                    if let Some(impl_def_id) = assoc_item.impl_container(tcx) {
-                        try_visit!(
-                            tcx.type_of(impl_def_id).instantiate_identity().visit_with(self)
-                        );
-                    }
+                if let Some(assoc_item) = tcx.opt_associated_item(def_id)
+                    && let Some(impl_def_id) = assoc_item.impl_container(tcx)
+                {
+                    try_visit!(tcx.type_of(impl_def_id).instantiate_identity().visit_with(self));
                 }
             }
             ty::Alias(kind @ (ty::Inherent | ty::Free | ty::Projection), data) => {
@@ -734,6 +732,7 @@ impl<'tcx> Visitor<'tcx> for EmbargoVisitor<'tcx> {
                         if let Some(ctor_def_id) = variant.data.ctor_def_id() {
                             self.update(ctor_def_id, variant_ev, Level::Reachable);
                         }
+
                         for field in variant.data.fields() {
                             self.update(field.def_id, variant_ev, Level::Reachable);
                             self.reach(field.def_id, variant_ev).ty();

compiler/rustc_query_system/src/dep_graph/graph.rs

@@ -498,12 +498,12 @@ impl<D: Deps> DepGraph<D> {
 
                     #[cfg(debug_assertions)]
                     {
-                        if let Some(target) = task_deps.node {
-                            if let Some(ref forbidden_edge) = data.current.forbidden_edge {
-                                let src = forbidden_edge.index_to_node.lock()[&dep_node_index];
-                                if forbidden_edge.test(&src, &target) {
-                                    panic!("forbidden edge {:?} -> {:?} created", src, target)
-                                }
+                        if let Some(target) = task_deps.node
+                            && let Some(ref forbidden_edge) = data.current.forbidden_edge
+                        {
+                            let src = forbidden_edge.index_to_node.lock()[&dep_node_index];
+                            if forbidden_edge.test(&src, &target) {
+                                panic!("forbidden edge {:?} -> {:?} created", src, target)
                             }
                         }
                     }