Rollup of 4 pull requests

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -263,14 +263,17 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         self.strsep(",", false, b, elts, op)
     }
 
-    fn maybe_print_comment(&mut self, pos: BytePos) {
+    fn maybe_print_comment(&mut self, pos: BytePos) -> bool {
+        let mut has_comment = false;
         while let Some(ref cmnt) = self.next_comment() {
             if cmnt.pos < pos {
+                has_comment = true;
                 self.print_comment(cmnt);
             } else {
                 break;
             }
         }
+        has_comment
     }
 
     fn print_comment(&mut self, cmnt: &Comment) {
@@ -570,7 +573,10 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         self.print_tts(tts, convert_dollar_crate);
         self.end();
         match delim {
-            DelimToken::Brace => self.bclose(span),
+            DelimToken::Brace => {
+                let empty = tts.is_empty();
+                self.bclose(span, empty);
+            }
             _ => {
                 let token_str = self.token_kind_to_string(&token::CloseDelim(delim));
                 self.word(token_str)
@@ -642,17 +648,20 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
         self.end(); // Close the head-box.
     }
 
-    fn bclose_maybe_open(&mut self, span: rustc_span::Span, close_box: bool) {
-        self.maybe_print_comment(span.hi());
-        self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
+    fn bclose_maybe_open(&mut self, span: rustc_span::Span, empty: bool, close_box: bool) {
+        let has_comment = self.maybe_print_comment(span.hi());
+        if !empty || has_comment {
+            self.break_offset_if_not_bol(1, -(INDENT_UNIT as isize));
+        }
         self.word("}");
         if close_box {
             self.end(); // Close the outer-box.
         }
     }
 
-    fn bclose(&mut self, span: rustc_span::Span) {
-        self.bclose_maybe_open(span, true)
+    fn bclose(&mut self, span: rustc_span::Span, empty: bool) {
+        let close_box = true;
+        self.bclose_maybe_open(span, empty, close_box)
     }
 
     fn break_offset_if_not_bol(&mut self, n: usize, off: isize) {
@@ -1196,7 +1205,8 @@ impl<'a> State<'a> {
                         for item in items {
                             self.print_item(item);
                         }
-                        self.bclose(item.span);
+                        let empty = item.attrs.is_empty() && items.is_empty();
+                        self.bclose(item.span, empty);
                     }
                     ModKind::Unloaded => {
                         self.s.word(";");
@@ -1216,7 +1226,8 @@ impl<'a> State<'a> {
                 }
                 self.bopen();
                 self.print_foreign_mod(nmod, &item.attrs);
-                self.bclose(item.span);
+                let empty = item.attrs.is_empty() && nmod.items.is_empty();
+                self.bclose(item.span, empty);
             }
             ast::ItemKind::GlobalAsm(ref asm) => {
                 self.head(visibility_qualified(&item.vis, "global_asm!"));
@@ -1291,7 +1302,8 @@ impl<'a> State<'a> {
                 for impl_item in items {
                     self.print_assoc_item(impl_item);
                 }
-                self.bclose(item.span);
+                let empty = item.attrs.is_empty() && items.is_empty();
+                self.bclose(item.span, empty);
             }
             ast::ItemKind::Trait(box ast::Trait {
                 is_auto,
@@ -1326,7 +1338,8 @@ impl<'a> State<'a> {
                 for trait_item in items {
                     self.print_assoc_item(trait_item);
                 }
-                self.bclose(item.span);
+                let empty = item.attrs.is_empty() && items.is_empty();
+                self.bclose(item.span, empty);
             }
             ast::ItemKind::TraitAlias(ref generics, ref bounds) => {
                 self.head("");
@@ -1410,7 +1423,8 @@ impl<'a> State<'a> {
             self.end();
             self.maybe_print_trailing_comment(v.span, None);
         }
-        self.bclose(span)
+        let empty = variants.is_empty();
+        self.bclose(span, empty)
     }
 
     crate fn print_visibility(&mut self, vis: &ast::Visibility) {
@@ -1441,20 +1455,24 @@ impl<'a> State<'a> {
     crate fn print_record_struct_body(&mut self, fields: &[ast::FieldDef], span: rustc_span::Span) {
         self.nbsp();
         self.bopen();
-        self.hardbreak_if_not_bol();
 
-        for field in fields {
+        let empty = fields.is_empty();
+        if !empty {
             self.hardbreak_if_not_bol();
-            self.maybe_print_comment(field.span.lo());
-            self.print_outer_attributes(&field.attrs);
-            self.print_visibility(&field.vis);
-            self.print_ident(field.ident.unwrap());
-            self.word_nbsp(":");
-            self.print_type(&field.ty);
-            self.s.word(",");
+
+            for field in fields {
+                self.hardbreak_if_not_bol();
+                self.maybe_print_comment(field.span.lo());
+                self.print_outer_attributes(&field.attrs);
+                self.print_visibility(&field.vis);
+                self.print_ident(field.ident.unwrap());
+                self.word_nbsp(":");
+                self.print_type(&field.ty);
+                self.s.word(",");
+            }
         }
 
-        self.bclose(span)
+        self.bclose(span, empty);
     }
 
     crate fn print_struct(
@@ -1633,7 +1651,8 @@ impl<'a> State<'a> {
             }
         }
 
-        self.bclose_maybe_open(blk.span, close_box);
+        let empty = attrs.is_empty() && blk.stmts.is_empty();
+        self.bclose_maybe_open(blk.span, empty, close_box);
         self.ann.post(self, AnnNode::Block(blk))
     }
 
@@ -2010,7 +2029,8 @@ impl<'a> State<'a> {
                 for arm in arms {
                     self.print_arm(arm);
                 }
-                self.bclose(expr.span);
+                let empty = attrs.is_empty() && arms.is_empty();
+                self.bclose(expr.span, empty);
             }
             ast::ExprKind::Closure(
                 capture_clause,

compiler/rustc_hir_pretty/src/lib.rs

@@ -2174,7 +2174,7 @@ impl<'a> State<'a> {
         match decl.output {
             hir::FnRetTy::Return(ref ty) => {
                 self.print_type(&ty);
-                self.maybe_print_comment(ty.span.lo())
+                self.maybe_print_comment(ty.span.lo());
             }
             hir::FnRetTy::DefaultReturn(..) => unreachable!(),
         }
@@ -2368,7 +2368,7 @@ impl<'a> State<'a> {
         self.end();
 
         if let hir::FnRetTy::Return(ref output) = decl.output {
-            self.maybe_print_comment(output.span.lo())
+            self.maybe_print_comment(output.span.lo());
         }
     }
 

compiler/rustc_interface/src/tests.rs

@@ -651,7 +651,6 @@ fn test_debugging_options_tracking_hash() {
     untracked!(dump_mir_dir, String::from("abc"));
     untracked!(dump_mir_exclude_pass_number, true);
     untracked!(dump_mir_graphviz, true);
-    untracked!(emit_future_incompat_report, true);
     untracked!(emit_stack_sizes, true);
     untracked!(future_incompat_test, true);
     untracked!(hir_stats, true);

compiler/rustc_session/src/config.rs

@@ -746,6 +746,7 @@ impl Default for Options {
             edition: DEFAULT_EDITION,
             json_artifact_notifications: false,
             json_unused_externs: false,
+            json_future_incompat: false,
             pretty: None,
             working_dir: RealFileName::LocalPath(std::env::current_dir().unwrap()),
         }
@@ -1257,6 +1258,7 @@ pub struct JsonConfig {
     pub json_rendered: HumanReadableErrorType,
     pub json_artifact_notifications: bool,
     pub json_unused_externs: bool,
+    pub json_future_incompat: bool,
 }
 
 /// Parse the `--json` flag.
@@ -1269,6 +1271,7 @@ pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
     let mut json_color = ColorConfig::Never;
     let mut json_artifact_notifications = false;
     let mut json_unused_externs = false;
+    let mut json_future_incompat = false;
     for option in matches.opt_strs("json") {
         // For now conservatively forbid `--color` with `--json` since `--json`
         // won't actually be emitting any colors and anything colorized is
@@ -1286,6 +1289,7 @@ pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
                 "diagnostic-rendered-ansi" => json_color = ColorConfig::Always,
                 "artifacts" => json_artifact_notifications = true,
                 "unused-externs" => json_unused_externs = true,
+                "future-incompat" => json_future_incompat = true,
                 s => early_error(
                     ErrorOutputType::default(),
                     &format!("unknown `--json` option `{}`", s),
@@ -1298,6 +1302,7 @@ pub fn parse_json(matches: &getopts::Matches) -> JsonConfig {
         json_rendered: json_rendered(json_color),
         json_artifact_notifications,
         json_unused_externs,
+        json_future_incompat,
     }
 }
 
@@ -2011,8 +2016,12 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
 
     let edition = parse_crate_edition(matches);
 
-    let JsonConfig { json_rendered, json_artifact_notifications, json_unused_externs } =
-        parse_json(matches);
+    let JsonConfig {
+        json_rendered,
+        json_artifact_notifications,
+        json_unused_externs,
+        json_future_incompat,
+    } = parse_json(matches);
 
     let error_format = parse_error_format(matches, color, json_rendered);
 
@@ -2248,6 +2257,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
         edition,
         json_artifact_notifications,
         json_unused_externs,
+        json_future_incompat,
         pretty,
         working_dir,
     }

compiler/rustc_session/src/options.rs

@@ -228,6 +228,9 @@ top_level_options!(
         /// `true` if we're emitting a JSON blob containing the unused externs
         json_unused_externs: bool [UNTRACKED],
 
+        /// `true` if we're emitting a JSON job containg a future-incompat report for lints
+        json_future_incompat: bool [TRACKED],
+
         pretty: Option<PpMode> [UNTRACKED],
 
         /// The (potentially remapped) working directory
@@ -1147,8 +1150,6 @@ options! {
         computed `block` spans (one span encompassing a block's terminator and \
         all statements). If `-Z instrument-coverage` is also enabled, create \
         an additional `.html` file showing the computed coverage spans."),
-    emit_future_incompat_report: bool = (false, parse_bool, [UNTRACKED],
-        "emits a future-incompatibility report for lints (RFC 2834)"),
     emit_stack_sizes: bool = (false, parse_bool, [UNTRACKED],
         "emit a section containing stack size metadata (default: no)"),
     fewer_names: Option<bool> = (None, parse_opt_bool, [TRACKED],

compiler/rustc_session/src/session.rs

@@ -280,7 +280,7 @@ impl Session {
     }
 
     fn emit_future_breakage(&self) {
-        if !self.opts.debugging_opts.emit_future_incompat_report {
+        if !self.opts.json_future_incompat {
             return;
         }
 

compiler/rustc_trait_selection/src/traits/const_evaluatable.rs

@@ -399,13 +399,25 @@ impl<'a, 'tcx> AbstractConstBuilder<'a, 'tcx> {
                 let arg = self.recurse_build(source)?;
                 self.nodes.push(Node::Cast(abstract_const::CastKind::As, arg, node.ty))
             }
-
+            ExprKind::Borrow{ arg, ..} => {
+                let arg_node = &self.body.exprs[*arg];
+
+                // Skip reborrows for now until we allow Deref/Borrow/AddressOf
+                // expressions.
+                // FIXME(generic_const_exprs): Verify/explain why this is sound
+                if let ExprKind::Deref {arg} = arg_node.kind {
+                    self.recurse_build(arg)?
+                } else {
+                    self.maybe_supported_error(
+                        node.span,
+                        "borrowing is not supported in generic constants",
+                    )?
+                }
+            }
             // FIXME(generic_const_exprs): We may want to support these.
-            ExprKind::AddressOf { .. }
-            | ExprKind::Borrow { .. }
-            | ExprKind::Deref { .. } => self.maybe_supported_error(
+            ExprKind::AddressOf { .. } | ExprKind::Deref {..}=> self.maybe_supported_error(
                 node.span,
-                "dereferencing is not supported in generic constants",
+                "dereferencing or taking the address is not supported in generic constants",
             )?,
             ExprKind::Repeat { .. } | ExprKind::Array { .. } =>  self.maybe_supported_error(
                 node.span,

compiler/rustc_typeck/src/collect.rs

@@ -41,7 +41,7 @@ use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::util::Discr;
 use rustc_middle::ty::util::IntTypeExt;
 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
-use rustc_middle::ty::{ReprOptions, ToPredicate, WithConstness};
+use rustc_middle::ty::{ReprOptions, ToPredicate, TypeFoldable, WithConstness};
 use rustc_session::lint;
 use rustc_session::parse::feature_err;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -1777,7 +1777,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
                     visitor.visit_ty(ty);
                     let mut diag = bad_placeholder_type(tcx, visitor.0, "return type");
                     let ret_ty = fn_sig.skip_binder().output();
-                    if ret_ty != tcx.ty_error() {
+                    if !ret_ty.references_error() {
                         if !ret_ty.is_closure() {
                             let ret_ty_str = match ret_ty.kind() {
                                 // Suggest a function pointer return type instead of a unique function definition

src/test/pretty/ast-stmt-expr-attr.rs

@@ -1,6 +1,6 @@
 // pp-exact
 
-fn main() { }
+fn main() {}
 
 #[cfg(FALSE)]
 fn syntax() {
@@ -117,7 +117,7 @@ fn syntax() {
     let _ = #[attr] foo!(#! [attr]);
     let _ = #[attr] foo![];
     let _ = #[attr] foo![#! [attr]];
-    let _ = #[attr] foo! { };
+    let _ = #[attr] foo! {};
     let _ = #[attr] foo! { #! [attr] };
     let _ = #[attr] Foo{bar: baz,};
     let _ = #[attr] Foo{..foo};
@@ -135,7 +135,7 @@ fn syntax() {
         foo!();
 
         #[attr]
-        foo! { }
+        foo! {}
 
         #[attr]
         foo![];
@@ -170,6 +170,6 @@ fn syntax() {
     {
 
         #[attr]
-        foo! { }
+        foo! {}
     }
 }

src/test/pretty/attr-derive.rs

@@ -29,4 +29,4 @@ enum Enum {
     Qwerty,
 }
 
-fn main() { }
+fn main() {}

src/test/pretty/auto-trait.rs

@@ -2,8 +2,8 @@
 
 // pp-exact
 
-auto trait MyTrait { }
+auto trait MyTrait {}
 
-unsafe auto trait UnsafeMyTrait { }
+unsafe auto trait UnsafeMyTrait {}
 
-pub fn main() { }
+pub fn main() {}

src/test/pretty/block-comment-trailing-whitespace2.rs

@@ -1,9 +1,8 @@
 // compile-flags: --crate-type=lib
 
 // pp-exact
-fn f() {
-} /*
-  The next line should not be indented.
+fn f() {} /*
+          The next line should not be indented.
 
-  That one. It shouldn't have been indented.
-  */
+          That one. It shouldn't have been indented.
+          */