Address review comments

Clean up code and add comments

Author: matthewjasper

compiler/rustc_middle/src/thir.rs

@@ -749,8 +749,15 @@ pub enum PatKind<'tcx> {
         value: mir::Const<'tcx>,
     },
 
+    /// Pattern lowered from an inline constant
     InlineConstant {
+        /// Unevaluated version of the constant, we need this for:
+        /// 1. Having a reference that can be used by unsafety checking to visit nested
+        ///    unevaluated constants.
+        /// 2. During THIR building we turn this back to a [Self::Constant] in range patterns.
         value: mir::UnevaluatedConst<'tcx>,
+        /// Actual pattern that the constant lowered to. As with other constants, inline constants
+        /// are matched structurally where possible.
         subpattern: Box<Pat<'tcx>>,
     },
 

compiler/rustc_mir_build/src/build/mod.rs

@@ -67,7 +67,6 @@ fn mir_build<'tcx>(tcx: TyCtxt<'tcx>, def: LocalDefId) -> Body<'tcx> {
                 thir::BodyTy::Const(ty) => construct_const(tcx, def, thir, expr, ty),
             };
 
-            tcx.ensure().check_match(def);
             // this must run before MIR dump, because
             // "not all control paths return a value" is reported here.
             //

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -124,7 +124,8 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
     /// Handle closures/generators/inline-consts, which is unsafecked with their parent body.
     fn visit_inner_body(&mut self, def: LocalDefId) {
         if let Ok((inner_thir, expr)) = self.tcx.thir_body(def) {
-            let _ = self.tcx.ensure_with_value().mir_built(def);
+            // Runs all other queries that depend on THIR.
+            self.tcx.ensure_with_value().mir_built(def);
             let inner_thir = &inner_thir.steal();
             let hir_context = self.tcx.hir().local_def_id_to_hir_id(def);
             let mut inner_visitor = UnsafetyVisitor { thir: inner_thir, hir_context, ..*self };
@@ -804,7 +805,8 @@ pub fn thir_check_unsafety(tcx: TyCtxt<'_>, def: LocalDefId) {
     }
 
     let Ok((thir, expr)) = tcx.thir_body(def) else { return };
-    let _ = tcx.ensure_with_value().mir_built(def);
+    // Runs all other queries that depend on THIR.
+    tcx.ensure_with_value().mir_built(def);
     let thir = &thir.steal();
     // If `thir` is empty, a type error occurred, skip this body.
     if thir.exprs.is_empty() {

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

@@ -606,11 +606,9 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         // const eval path below.
         // FIXME: investigate the performance impact of removing this.
         let lit_input = match expr.kind {
-            hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
-            hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
-                hir::ExprKind::Lit(ref lit) => {
-                    Some(LitToConstInput { lit: &lit.node, ty, neg: true })
-                }
+            hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
+            hir::ExprKind::Unary(hir::UnOp::Neg, expr) => match expr.kind {
+                hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: true }),
                 _ => None,
             },
             _ => None,

compiler/rustc_mir_build/src/thir/print.rs

@@ -692,7 +692,7 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
             }
             PatKind::Deref { subpattern } => {
                 print_indented!(self, "Deref { ", depth_lvl + 1);
-                print_indented!(self, "subpattern: ", depth_lvl + 2);
+                print_indented!(self, "subpattern:", depth_lvl + 2);
                 self.print_pat(subpattern, depth_lvl + 2);
                 print_indented!(self, "}", depth_lvl + 1);
             }
@@ -704,7 +704,7 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
             PatKind::InlineConstant { value, subpattern } => {
                 print_indented!(self, "InlineConstant {", depth_lvl + 1);
                 print_indented!(self, format!("value: {:?}", value), depth_lvl + 2);
-                print_indented!(self, "subpattern: ", depth_lvl + 2);
+                print_indented!(self, "subpattern:", depth_lvl + 2);
                 self.print_pat(subpattern, depth_lvl + 2);
                 print_indented!(self, "}", depth_lvl + 1);
             }