Auto merge of rust-lang#134248 - oli-obk:patkind-path-removal, r=<try>

Merge `PatKind::Path` into `PatKind::Lit`

Follow-up to rust-lang#134228

We always had a duplication where `Path`s could be represented as `PatKind::Path` or `PatKind::Lit(ExprKind::Path)`. We had to handle both everywhere, and still do after rust-lang#134228, so I'm removing it now.

compiler/rustc_ast_lowering/src/index.rs

@@ -213,7 +213,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         self.insert(expr.span, expr.hir_id, Node::PatExpr(expr));
 
         self.with_parent(expr.hir_id, |this| {
-            intravisit::walk_pat_expr(this, expr);
+            intravisit::walk_pat_expr(this, expr.hir_id, expr.span, &expr.kind);
         });
     }
 

compiler/rustc_ast_lowering/src/pat.rs

@@ -117,9 +117,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         break hir::PatKind::Ref(self.lower_pat(inner), *mutbl);
                     }
                     PatKind::Range(e1, e2, Spanned { node: end, .. }) => {
+                        let mut lower_end = |e: &Expr| {
+                            &*self.arena.alloc(hir::PatExpr {
+                                hir_id: self.lower_node_id(e.id),
+                                span: e.span,
+                                kind: self.lower_expr_within_pat(e, true),
+                            })
+                        };
                         break hir::PatKind::Range(
-                            e1.as_deref().map(|e| self.lower_expr_within_pat(e, true)),
-                            e2.as_deref().map(|e| self.lower_expr_within_pat(e, true)),
+                            e1.as_deref().map(|e| lower_end(e)),
+                            e2.as_deref().map(|e| lower_end(e)),
                             self.lower_range_end(end, e2.is_some()),
                         );
                     }
@@ -370,16 +377,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     // }
     // m!(S);
     // ```
-    fn lower_expr_within_pat(
-        &mut self,
-        expr: &Expr,
-        allow_paths: bool,
-    ) -> &'hir hir::PatExpr<'hir> {
+    fn lower_expr_within_pat(&mut self, expr: &Expr, allow_paths: bool) -> hir::PatExprKind<'hir> {
         let err = |guar| hir::PatExprKind::Lit {
             lit: self.arena.alloc(respan(self.lower_span(expr.span), LitKind::Err(guar))),
             negated: false,
         };
-        let kind = match &expr.kind {
+        match &expr.kind {
             ExprKind::Lit(lit) => {
                 hir::PatExprKind::Lit { lit: self.lower_lit(lit, expr.span), negated: false }
             }
@@ -413,11 +416,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 });
                 err(guar)
             }
-        };
-        self.arena.alloc(hir::PatExpr {
-            hir_id: self.lower_node_id(expr.id),
-            span: expr.span,
-            kind,
-        })
+        }
     }
 }

compiler/rustc_hir/src/hir.rs

@@ -1521,6 +1521,7 @@ impl fmt::Debug for DotDotPos {
 
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct PatExpr<'hir> {
+    #[stable_hasher(ignore)]
     pub hir_id: HirId,
     pub span: Span,
     pub kind: PatExprKind<'hir>,
@@ -1584,7 +1585,7 @@ pub enum PatKind<'hir> {
     Ref(&'hir Pat<'hir>, Mutability),
 
     /// A literal, const block or path.
-    Expr(&'hir PatExpr<'hir>),
+    Expr(PatExprKind<'hir>),
 
     /// A guard pattern (e.g., `x if guard(x)`).
     Guard(&'hir Pat<'hir>, &'hir Expr<'hir>),

compiler/rustc_hir/src/intravisit.rs

@@ -343,7 +343,7 @@ pub trait Visitor<'v>: Sized {
         walk_pat_field(self, f)
     }
     fn visit_pat_expr(&mut self, expr: &'v PatExpr<'v>) -> Self::Result {
-        walk_pat_expr(self, expr)
+        walk_pat_expr(self, expr.hir_id, expr.span, &expr.kind)
     }
     fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result {
         walk_anon_const(self, c)
@@ -688,7 +688,9 @@ pub fn walk_pat<'v, V: Visitor<'v>>(visitor: &mut V, pattern: &'v Pat<'v>) -> V:
             try_visit!(visitor.visit_ident(ident));
             visit_opt!(visitor, visit_pat, optional_subpattern);
         }
-        PatKind::Expr(ref expression) => try_visit!(visitor.visit_pat_expr(expression)),
+        PatKind::Expr(ref expression) => {
+            try_visit!(walk_pat_expr(visitor, pattern.hir_id, pattern.span, expression))
+        }
         PatKind::Range(ref lower_bound, ref upper_bound, _) => {
             visit_opt!(visitor, visit_pat_expr, lower_bound);
             visit_opt!(visitor, visit_pat_expr, upper_bound);
@@ -713,12 +715,17 @@ pub fn walk_pat_field<'v, V: Visitor<'v>>(visitor: &mut V, field: &'v PatField<'
     visitor.visit_pat(field.pat)
 }
 
-pub fn walk_pat_expr<'v, V: Visitor<'v>>(visitor: &mut V, expr: &'v PatExpr<'v>) -> V::Result {
-    try_visit!(visitor.visit_id(expr.hir_id));
-    match &expr.kind {
+pub fn walk_pat_expr<'v, V: Visitor<'v>>(
+    visitor: &mut V,
+    hir_id: HirId,
+    span: Span,
+    kind: &'v PatExprKind<'v>,
+) -> V::Result {
+    try_visit!(visitor.visit_id(hir_id));
+    match kind {
         PatExprKind::Lit { .. } => V::Result::output(),
         PatExprKind::ConstBlock(c) => visitor.visit_inline_const(c),
-        PatExprKind::Path(qpath) => visitor.visit_qpath(qpath, expr.hir_id, expr.span),
+        PatExprKind::Path(qpath) => visitor.visit_qpath(qpath, hir_id, span),
     }
 }
 

compiler/rustc_hir_pretty/src/lib.rs

@@ -199,7 +199,7 @@ impl<'a> State<'a> {
             Node::OpaqueTy(o) => self.print_opaque_ty(o),
             Node::Pat(a) => self.print_pat(a),
             Node::PatField(a) => self.print_patfield(a),
-            Node::PatExpr(a) => self.print_pat_expr(a),
+            Node::PatExpr(a) => self.print_pat_expr(&a.kind),
             Node::Arm(a) => self.print_arm(a),
             Node::Infer(_) => self.word("_"),
             Node::PreciseCapturingNonLifetimeArg(param) => self.print_ident(param.ident),
@@ -1850,8 +1850,8 @@ impl<'a> State<'a> {
         }
     }
 
-    fn print_pat_expr(&mut self, expr: &hir::PatExpr<'_>) {
-        match &expr.kind {
+    fn print_pat_expr(&mut self, kind: &hir::PatExprKind<'_>) {
+        match kind {
             hir::PatExprKind::Lit { lit, negated } => {
                 if *negated {
                     self.word("-");
@@ -1980,17 +1980,17 @@ impl<'a> State<'a> {
                     self.pclose();
                 }
             }
-            PatKind::Expr(e) => self.print_pat_expr(e),
+            PatKind::Expr(ref e) => self.print_pat_expr(e),
             PatKind::Range(begin, end, end_kind) => {
                 if let Some(expr) = begin {
-                    self.print_pat_expr(expr);
+                    self.print_pat_expr(&expr.kind);
                 }
                 match end_kind {
                     RangeEnd::Included => self.word("..."),
                     RangeEnd::Excluded => self.word(".."),
                 }
                 if let Some(expr) = end {
-                    self.print_pat_expr(expr);
+                    self.print_pat_expr(&expr.kind);
                 }
             }
             PatKind::Slice(before, slice, after) => {

compiler/rustc_hir_typeck/src/pat.rs

@@ -256,7 +256,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             _ => None,
         };
-        let adjust_mode = self.calc_adjust_mode(pat, path_res.map(|(res, ..)| res));
+        let (adjust_mode, opt_expr_ty) = self.calc_adjust_mode(pat, path_res.map(|(res, ..)| res));
         let (expected, binding_mode, max_ref_mutbl) =
             self.calc_default_binding_mode(pat, expected, binding_mode, adjust_mode, max_ref_mutbl);
         let pat_info = PatInfo {
@@ -271,7 +271,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             PatKind::Wild | PatKind::Err(_) => expected,
             // We allow any type here; we ensure that the type is uninhabited during match checking.
             PatKind::Never => expected,
-            PatKind::Expr(lt) => self.check_pat_lit(pat.span, lt, expected, ti),
+            PatKind::Expr(ref lt) => {
+                self.check_pat_lit(pat.hir_id, pat.span, lt, expected, ti, opt_expr_ty.unwrap())
+            }
             PatKind::Range(lhs, rhs, _) => self.check_pat_range(pat.span, lhs, rhs, expected, ti),
             PatKind::Binding(ba, var_id, ident, sub) => {
                 self.check_pat_ident(pat, ba, var_id, ident, sub, expected, pat_info)
@@ -376,13 +378,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// How should the binding mode and expected type be adjusted?
     ///
     /// When the pattern is a path pattern, `opt_path_res` must be `Some(res)`.
-    fn calc_adjust_mode(&self, pat: &'tcx Pat<'tcx>, opt_path_res: Option<Res>) -> AdjustMode {
+    ///
+    /// Returns the unadjusted type for expr patterns.
+    fn calc_adjust_mode(
+        &self,
+        pat: &'tcx Pat<'tcx>,
+        opt_path_res: Option<Res>,
+    ) -> (AdjustMode, Option<Ty<'tcx>>) {
         // When we perform destructuring assignment, we disable default match bindings, which are
         // unintuitive in this context.
         if !pat.default_binding_modes {
-            return AdjustMode::Reset;
+            return (AdjustMode::Reset, None);
         }
-        match &pat.kind {
+        let adjust = match &pat.kind {
             // Type checking these product-like types successfully always require
             // that the expected type be of those types and not reference types.
             PatKind::Struct(..)
@@ -399,9 +407,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // As a result, we allow `if let 0 = &&0 {}` but not `if let "foo" = &&"foo" {}`.
             //
             // Call `resolve_vars_if_possible` here for inline const blocks.
-            PatKind::Expr(lt) => match self.resolve_vars_if_possible(self.check_pat_expr_unadjusted(lt)).kind() {
-                ty::Ref(..) => AdjustMode::Pass,
-                _ => AdjustMode::Peel,
+            PatKind::Expr(lt) => {
+                let ty = self.resolve_vars_if_possible(self.check_pat_expr_unadjusted(lt, pat.hir_id, pat.span));
+                let adjust = match ty.kind() {
+                    ty::Ref(..) => AdjustMode::Pass,
+                    _ => AdjustMode::Peel,
+                };
+                return (adjust, Some(ty))
             },
             PatKind::Path(_) => match opt_path_res.unwrap() {
                 // These constants can be of a reference type, e.g. `const X: &u8 = &0;`.
@@ -431,7 +443,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             | PatKind::Or(_)
             // Like or-patterns, guard patterns just propogate to their subpatterns.
             | PatKind::Guard(..) => AdjustMode::Pass,
-        }
+        };
+        (adjust, None)
     }
 
     /// Peel off as many immediately nested `& mut?` from the expected type as possible
@@ -494,8 +507,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         (expected, def_br, max_ref_mutbl)
     }
 
-    fn check_pat_expr_unadjusted(&self, lt: &'tcx hir::PatExpr<'tcx>) -> Ty<'tcx> {
-        let ty = match &lt.kind {
+    fn check_pat_expr_unadjusted(
+        &self,
+        kind: &'tcx hir::PatExprKind<'tcx>,
+        hir_id: HirId,
+        span: Span,
+    ) -> Ty<'tcx> {
+        match kind {
             rustc_hir::PatExprKind::Lit { lit, .. } => {
                 self.check_expr_lit(lit, Expectation::NoExpectation)
             }
@@ -504,42 +522,34 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             rustc_hir::PatExprKind::Path(qpath) => {
                 let (res, opt_ty, segments) =
-                    self.resolve_ty_and_res_fully_qualified_call(qpath, lt.hir_id, lt.span);
-                self.instantiate_value_path(segments, opt_ty, res, lt.span, lt.span, lt.hir_id).0
+                    self.resolve_ty_and_res_fully_qualified_call(qpath, hir_id, span);
+                self.instantiate_value_path(segments, opt_ty, res, span, span, hir_id).0
             }
-        };
-        self.write_ty(lt.hir_id, ty);
-        ty
+        }
     }
 
     fn check_pat_lit(
         &self,
+        hir_id: HirId,
         span: Span,
-        lt: &hir::PatExpr<'tcx>,
+        lt: &hir::PatExprKind<'tcx>,
         expected: Ty<'tcx>,
         ti: &TopInfo<'tcx>,
+        mut pat_ty: Ty<'tcx>,
     ) -> Ty<'tcx> {
-        // We've already computed the type above (when checking for a non-ref pat),
-        // so avoid computing it again.
-        let ty = self.node_ty(lt.hir_id);
-
         // Byte string patterns behave the same way as array patterns
         // They can denote both statically and dynamically-sized byte arrays.
-        let mut pat_ty = ty;
         if let hir::PatExprKind::Lit {
             lit: Spanned { node: ast::LitKind::ByteStr(..), .. }, ..
-        } = lt.kind
+        } = lt
         {
             let expected = self.structurally_resolve_type(span, expected);
             if let ty::Ref(_, inner_ty, _) = *expected.kind()
                 && self.try_structurally_resolve_type(span, inner_ty).is_slice()
             {
                 let tcx = self.tcx;
-                trace!(?lt.hir_id.local_id, "polymorphic byte string lit");
-                self.typeck_results
-                    .borrow_mut()
-                    .treat_byte_string_as_slice
-                    .insert(lt.hir_id.local_id);
+                trace!(?hir_id.local_id, "polymorphic byte string lit");
+                self.typeck_results.borrow_mut().lit_pat_type_adjusted.insert(hir_id.local_id);
                 pat_ty =
                     Ty::new_imm_ref(tcx, tcx.lifetimes.re_static, Ty::new_slice(tcx, tcx.types.u8));
             }
@@ -548,10 +558,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         if self.tcx.features().string_deref_patterns()
             && let hir::PatExprKind::Lit {
                 lit: Spanned { node: ast::LitKind::Str(..), .. }, ..
-            } = lt.kind
+            } = lt
         {
             let tcx = self.tcx;
             let expected = self.resolve_vars_if_possible(expected);
+            self.typeck_results.borrow_mut().lit_pat_type_adjusted.insert(hir_id.local_id);
             pat_ty = match expected.kind() {
                 ty::Adt(def, _) if tcx.is_lang_item(def.did(), LangItem::String) => expected,
                 ty::Str => Ty::new_static_str(tcx),
@@ -597,7 +608,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let calc_side = |opt_expr: Option<&'tcx hir::PatExpr<'tcx>>| match opt_expr {
             None => None,
             Some(expr) => {
-                let ty = self.check_pat_expr_unadjusted(expr);
+                let ty = self.check_pat_expr_unadjusted(&expr.kind, expr.hir_id, expr.span);
+
+                self.write_ty(expr.hir_id, ty);
                 // Check that the end-point is possibly of numeric or char type.
                 // The early check here is not for correctness, but rather better
                 // diagnostics (e.g. when `&str` is being matched, `expected` will

compiler/rustc_hir_typeck/src/writeback.rs

@@ -79,8 +79,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         debug!("used_trait_imports({:?}) = {:?}", item_def_id, used_trait_imports);
         wbcx.typeck_results.used_trait_imports = used_trait_imports;
 
-        wbcx.typeck_results.treat_byte_string_as_slice =
-            mem::take(&mut self.typeck_results.borrow_mut().treat_byte_string_as_slice);
+        wbcx.typeck_results.lit_pat_type_adjusted =
+            mem::take(&mut self.typeck_results.borrow_mut().lit_pat_type_adjusted);
 
         debug!("writeback: typeck results for {:?} are {:#?}", item_def_id, wbcx.typeck_results);
 
@@ -328,6 +328,9 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
                     self.visit_field_id(field.hir_id);
                 }
             }
+            hir::PatKind::Expr(hir::PatExprKind::ConstBlock(ref c)) => {
+                self.visit_const_block(p.span, c);
+            }
             _ => {}
         };
 
@@ -344,7 +347,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
         if let hir::PatExprKind::ConstBlock(c) = &expr.kind {
             self.visit_const_block(expr.span, c);
         }
-        intravisit::walk_pat_expr(self, expr);
+        intravisit::walk_pat_expr(self, expr.hir_id, expr.span, &expr.kind);
     }
 
     fn visit_local(&mut self, l: &'tcx hir::LetStmt<'tcx>) {

compiler/rustc_middle/src/ty/typeck_results.rs

@@ -199,11 +199,13 @@ pub struct TypeckResults<'tcx> {
     /// formatting modified file tests/ui/coroutine/retain-resume-ref.rs
     pub coroutine_stalled_predicates: FxIndexSet<(ty::Predicate<'tcx>, ObligationCause<'tcx>)>,
 
-    /// We sometimes treat byte string literals (which are of type `&[u8; N]`)
-    /// as `&[u8]`, depending on the pattern in which they are used.
+    /// We sometimes treat
+    /// * byte string literals (which are of type `&[u8; N]`)
+    ///   as `&[u8]`, depending on the pattern in which they are used.
+    /// * string literals (which are of type `&str`) as `String`
     /// This hashset records all instances where we behave
     /// like this to allow `const_to_pat` to reliably handle this situation.
-    pub treat_byte_string_as_slice: ItemLocalSet,
+    pub lit_pat_type_adjusted: ItemLocalSet,
 
     /// Contains the data for evaluating the effect of feature `capture_disjoint_fields`
     /// on closure size.
@@ -239,7 +241,7 @@ impl<'tcx> TypeckResults<'tcx> {
             closure_fake_reads: Default::default(),
             rvalue_scopes: Default::default(),
             coroutine_stalled_predicates: Default::default(),
-            treat_byte_string_as_slice: Default::default(),
+            lit_pat_type_adjusted: Default::default(),
             closure_size_eval: Default::default(),
             offset_of_data: Default::default(),
         }

compiler/rustc_mir_build/src/thir/constant.rs

@@ -33,7 +33,7 @@ pub(crate) fn lit_to_const<'tcx>(
     };
 
     let valtree = match (lit, ty.kind()) {
-        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
+        (ast::LitKind::Str(s, _), _) => {
             let str_bytes = s.as_str().as_bytes();
             ty::ValTree::from_raw_bytes(tcx, str_bytes)
         }