Auto merge of #63437 - Centril:rollup-ryx881p, r=Centril

Rollup of 4 pull requests

Successful merges:

 - #63400 (Try to break resolve into more isolated parts)
 - #63425 (Cleanup historical stability comments)
 - #63429 (.gitignore: Readd `/tmp/`)
 - #63432 (Cleanup & Simplify stuff in lowering)

Failed merges:

r? @ghost

Author: bors

.gitignore

@@ -27,6 +27,7 @@ __pycache__/
 /inst/
 /llvm/
 /mingw-build/
+# Created by default with `src/ci/docker/run.sh`:
 /obj/
 /rustllvm/
 /src/libcore/unicode/DerivedCoreProperties.txt
@@ -38,6 +39,8 @@ __pycache__/
 /src/libcore/unicode/UnicodeData.txt
 /src/libcore/unicode/downloaded
 /target/
+# Generated by compiletest for incremental:
+/tmp/
 tags
 tags.*
 TAGS

src/librustc/hir/lowering.rs

@@ -37,7 +37,7 @@ use crate::hir::{self, ParamName};
 use crate::hir::HirVec;
 use crate::hir::map::{DefKey, DefPathData, Definitions};
 use crate::hir::def_id::{DefId, DefIndex, CRATE_DEF_INDEX};
-use crate::hir::def::{Res, DefKind, PartialRes, PerNS};
+use crate::hir::def::{Namespace, Res, DefKind, PartialRes, PerNS};
 use crate::hir::{GenericArg, ConstArg};
 use crate::hir::ptr::P;
 use crate::lint::builtin::{self, PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
@@ -148,13 +148,6 @@ pub struct LoweringContext<'a> {
 }
 
 pub trait Resolver {
-    /// Resolve a path generated by the lowerer when expanding `for`, `if let`, etc.
-    fn resolve_ast_path(
-        &mut self,
-        path: &ast::Path,
-        is_value: bool,
-    ) -> Res<NodeId>;
-
     /// Obtain resolution for a `NodeId` with a single resolution.
     fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes>;
 
@@ -175,7 +168,7 @@ pub trait Resolver {
         span: Span,
         crate_root: Option<Symbol>,
         components: &[Symbol],
-        is_value: bool,
+        ns: Namespace,
     ) -> (ast::Path, Res<NodeId>);
 
     fn has_derives(&self, node_id: NodeId, derives: SpecialDerives) -> bool;
@@ -4447,23 +4440,23 @@ impl<'a> LoweringContext<'a> {
         })
     }
 
+    fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> HirVec<hir::Expr> {
+        exprs.iter().map(|x| self.lower_expr(x)).collect()
+    }
+
     fn lower_expr(&mut self, e: &Expr) -> hir::Expr {
         let kind = match e.node {
             ExprKind::Box(ref inner) => hir::ExprKind::Box(P(self.lower_expr(inner))),
-            ExprKind::Array(ref exprs) => {
-                hir::ExprKind::Array(exprs.iter().map(|x| self.lower_expr(x)).collect())
-            }
+            ExprKind::Array(ref exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
             ExprKind::Repeat(ref expr, ref count) => {
                 let expr = P(self.lower_expr(expr));
                 let count = self.lower_anon_const(count);
                 hir::ExprKind::Repeat(expr, count)
             }
-            ExprKind::Tup(ref elts) => {
-                hir::ExprKind::Tup(elts.iter().map(|x| self.lower_expr(x)).collect())
-            }
+            ExprKind::Tup(ref elts) => hir::ExprKind::Tup(self.lower_exprs(elts)),
             ExprKind::Call(ref f, ref args) => {
                 let f = P(self.lower_expr(f));
-                hir::ExprKind::Call(f, args.iter().map(|x| self.lower_expr(x)).collect())
+                hir::ExprKind::Call(f, self.lower_exprs(args))
             }
             ExprKind::MethodCall(ref seg, ref args) => {
                 let hir_seg = P(self.lower_path_segment(
@@ -4475,7 +4468,7 @@ impl<'a> LoweringContext<'a> {
                     ImplTraitContext::disallowed(),
                     None,
                 ));
-                let args = args.iter().map(|x| self.lower_expr(x)).collect();
+                let args = self.lower_exprs(args);
                 hir::ExprKind::MethodCall(hir_seg, seg.ident.span, args)
             }
             ExprKind::Binary(binop, ref lhs, ref rhs) => {
@@ -5049,17 +5042,9 @@ impl<'a> LoweringContext<'a> {
                     ));
                     let arms = hir_vec![pat_arm, break_arm];
 
-                    P(self.expr(
-                        head_sp,
-                        hir::ExprKind::Match(
-                            next_expr,
-                            arms,
-                            hir::MatchSource::ForLoopDesugar
-                        ),
-                        ThinVec::new(),
-                    ))
+                    self.expr_match(head_sp, next_expr, arms, hir::MatchSource::ForLoopDesugar)
                 };
-                let match_stmt = self.stmt(head_sp, hir::StmtKind::Expr(match_expr));
+                let match_stmt = self.stmt_expr(head_sp, match_expr);
 
                 let next_expr = P(self.expr_ident(head_sp, next_ident, next_pat_hid));
 
@@ -5083,8 +5068,8 @@ impl<'a> LoweringContext<'a> {
                 );
 
                 let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
-                let body_expr = P(self.expr_block(body_block, ThinVec::new()));
-                let body_stmt = self.stmt(body.span, hir::StmtKind::Expr(body_expr));
+                let body_expr = self.expr_block(body_block, ThinVec::new());
+                let body_stmt = self.stmt_expr(body.span, body_expr);
 
                 let loop_block = P(self.block_all(
                     e.span,
@@ -5127,8 +5112,10 @@ impl<'a> LoweringContext<'a> {
                 ));
 
                 // This is effectively `{ let _result = ...; _result }`.
-                // The construct was introduced in #21984.
-                // FIXME(60253): Is this still necessary?
+                // The construct was introduced in #21984 and is necessary to make sure that
+                // temporaries in the `head` expression are dropped and do not leak to the
+                // surrounding scope of the `match` since the `match` is not a terminating scope.
+                //
                 // Also, add the attributes to the outer returned expr node.
                 return self.expr_drop_temps(head_sp, match_expr, e.attrs.clone())
             }
@@ -5254,7 +5241,7 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn lower_stmt(&mut self, s: &Stmt) -> SmallVec<[hir::Stmt; 1]> {
-        smallvec![match s.node {
+        let node = match s.node {
             StmtKind::Local(ref l) => {
                 let (l, item_ids) = self.lower_local(l);
                 let mut ids: SmallVec<[hir::Stmt; 1]> = item_ids
@@ -5291,21 +5278,14 @@ impl<'a> LoweringContext<'a> {
                     })
                     .collect();
             }
-            StmtKind::Expr(ref e) => {
-                hir::Stmt {
-                    hir_id: self.lower_node_id(s.id),
-                    node: hir::StmtKind::Expr(P(self.lower_expr(e))),
-                    span: s.span,
-                }
-            },
-            StmtKind::Semi(ref e) => {
-                hir::Stmt {
-                    hir_id: self.lower_node_id(s.id),
-                    node: hir::StmtKind::Semi(P(self.lower_expr(e))),
-                    span: s.span,
-                }
-            },
+            StmtKind::Expr(ref e) => hir::StmtKind::Expr(P(self.lower_expr(e))),
+            StmtKind::Semi(ref e) => hir::StmtKind::Semi(P(self.lower_expr(e))),
             StmtKind::Mac(..) => panic!("Shouldn't exist here"),
+        };
+        smallvec![hir::Stmt {
+            hir_id: self.lower_node_id(s.id),
+            node,
+            span: s.span,
         }]
     }
 
@@ -5567,6 +5547,10 @@ impl<'a> LoweringContext<'a> {
         hir::Stmt { span, node, hir_id: self.next_id() }
     }
 
+    fn stmt_expr(&mut self, span: Span, expr: hir::Expr) -> hir::Stmt {
+        self.stmt(span, hir::StmtKind::Expr(P(expr)))
+    }
+
     fn stmt_let_pat(
         &mut self,
         attrs: ThinVec<Attribute>,
@@ -5717,8 +5701,8 @@ impl<'a> LoweringContext<'a> {
         params: Option<P<hir::GenericArgs>>,
         is_value: bool,
     ) -> hir::Path {
-        let (path, res) = self.resolver
-            .resolve_str_path(span, self.crate_root, components, is_value);
+        let ns = if is_value { Namespace::ValueNS } else { Namespace::TypeNS };
+        let (path, res) = self.resolver.resolve_str_path(span, self.crate_root, components, ns);
 
         let mut segments: Vec<_> = path.segments.iter().map(|segment| {
             let res = self.expect_full_res(segment.id);
@@ -6060,23 +6044,23 @@ impl<'a> LoweringContext<'a> {
         };
 
         let match_stmt = {
-            let match_expr = P(self.expr_match(
+            let match_expr = self.expr_match(
                 span,
                 poll_expr,
                 hir_vec![ready_arm, pending_arm],
                 hir::MatchSource::AwaitDesugar,
-            ));
-            self.stmt(span, hir::StmtKind::Expr(match_expr))
+            );
+            self.stmt_expr(span, match_expr)
         };
 
         let yield_stmt = {
             let unit = self.expr_unit(span);
-            let yield_expr = P(self.expr(
+            let yield_expr = self.expr(
                 span,
                 hir::ExprKind::Yield(P(unit), hir::YieldSource::Await),
                 ThinVec::new(),
-            ));
-            self.stmt(span, hir::StmtKind::Expr(yield_expr))
+            );
+            self.stmt_expr(span, yield_expr)
         };
 
         let loop_block = P(self.block_all(

src/librustc_driver/lib.rs

@@ -957,14 +957,11 @@ fn print_flag_list<T>(cmdline_opt: &str,
 /// otherwise returns `None`.
 ///
 /// The compiler's handling of options is a little complicated as it ties into
-/// our stability story, and it's even *more* complicated by historical
-/// accidents. The current intention of each compiler option is to have one of
-/// three modes:
+/// our stability story. The current intention of each compiler option is to
+/// have one of two modes:
 ///
 /// 1. An option is stable and can be used everywhere.
-/// 2. An option is unstable, but was historically allowed on the stable
-///    channel.
-/// 3. An option is unstable, and can only be used on nightly.
+/// 2. An option is unstable, and can only be used on nightly.
 ///
 /// Like unstable library and language features, however, unstable options have
 /// always required a form of "opt in" to indicate that you're using them. This
@@ -1007,19 +1004,13 @@ pub fn handle_options(args: &[String]) -> Option<getopts::Matches> {
     //   this option that was passed.
     // * If we're a nightly compiler, then unstable options are now unlocked, so
     //   we're good to go.
-    // * Otherwise, if we're a truly unstable option then we generate an error
+    // * Otherwise, if we're an unstable option then we generate an error
     //   (unstable option being used on stable)
-    // * If we're a historically stable-but-should-be-unstable option then we
-    //   emit a warning that we're going to turn this into an error soon.
     nightly_options::check_nightly_options(&matches, &config::rustc_optgroups());
 
     if matches.opt_present("h") || matches.opt_present("help") {
-        // Only show unstable options in --help if we *really* accept unstable
-        // options, which catches the case where we got `-Z unstable-options` on
-        // the stable channel of Rust which was accidentally allowed
-        // historically.
-        usage(matches.opt_present("verbose"),
-              nightly_options::is_unstable_enabled(&matches));
+        // Only show unstable options in --help if we accept unstable options.
+        usage(matches.opt_present("verbose"), nightly_options::is_unstable_enabled(&matches));
         return None;
     }