Rollup of 10 pull requests

.github/ISSUE_TEMPLATE/library_tracking_issue.md

@@ -2,7 +2,7 @@
 name: Library Tracking Issue
 about: A tracking issue for an unstable library feature.
 title: Tracking Issue for XXX
-labels: C-tracking-issue T-libs
+labels: C-tracking-issue, T-libs
 ---
 <!--
 Thank you for creating a tracking issue!

Cargo.lock

@@ -4396,7 +4396,7 @@ dependencies = [
 
 [[package]]
 name = "rustfmt-nightly"
-version = "1.4.29"
+version = "1.4.30"
 dependencies = [
  "annotate-snippets 0.6.1",
  "anyhow",
@@ -5342,7 +5342,7 @@ dependencies = [
  "chrono",
  "lazy_static",
  "matchers",
- "parking_lot 0.11.0",
+ "parking_lot 0.9.0",
  "regex",
  "serde",
  "serde_json",

compiler/rustc_expand/src/mbe.rs

@@ -84,7 +84,7 @@ enum TokenTree {
     /// e.g., `$var`
     MetaVar(Span, Ident),
     /// e.g., `$var:expr`. This is only used in the left hand side of MBE macros.
-    MetaVarDecl(Span, Ident /* name to bind */, NonterminalKind),
+    MetaVarDecl(Span, Ident /* name to bind */, Option<NonterminalKind>),
 }
 
 impl TokenTree {

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -378,6 +378,11 @@ fn nameize<I: Iterator<Item = NamedMatch>>(
                     n_rec(sess, next_m, res.by_ref(), ret_val)?;
                 }
             }
+            TokenTree::MetaVarDecl(span, _, None) => {
+                if sess.missing_fragment_specifiers.borrow_mut().remove(&span).is_some() {
+                    return Err((span, "missing fragment specifier".to_string()));
+                }
+            }
             TokenTree::MetaVarDecl(sp, bind_name, _) => match ret_val
                 .entry(MacroRulesNormalizedIdent::new(bind_name))
             {
@@ -446,6 +451,7 @@ fn or_pat_mode(edition: Edition) -> OrPatNonterminalMode {
 ///
 /// A `ParseResult`. Note that matches are kept track of through the items generated.
 fn inner_parse_loop<'root, 'tt>(
+    sess: &ParseSess,
     cur_items: &mut SmallVec<[MatcherPosHandle<'root, 'tt>; 1]>,
     next_items: &mut Vec<MatcherPosHandle<'root, 'tt>>,
     eof_items: &mut SmallVec<[MatcherPosHandle<'root, 'tt>; 1]>,
@@ -563,9 +569,16 @@ fn inner_parse_loop<'root, 'tt>(
                     })));
                 }
 
+                // We need to match a metavar (but the identifier is invalid)... this is an error
+                TokenTree::MetaVarDecl(span, _, None) => {
+                    if sess.missing_fragment_specifiers.borrow_mut().remove(&span).is_some() {
+                        return Error(span, "missing fragment specifier".to_string());
+                    }
+                }
+
                 // We need to match a metavar with a valid ident... call out to the black-box
                 // parser by adding an item to `bb_items`.
-                TokenTree::MetaVarDecl(span, _, kind) => {
+                TokenTree::MetaVarDecl(span, _, Some(kind)) => {
                     // Built-in nonterminals never start with these tokens, so we can eliminate
                     // them from consideration.
                     //
@@ -640,6 +653,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
         // parsing from the black-box parser done. The result is that `next_items` will contain a
         // bunch of possible next matcher positions in `next_items`.
         match inner_parse_loop(
+            parser.sess,
             &mut cur_items,
             &mut next_items,
             &mut eof_items,
@@ -701,7 +715,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
             let nts = bb_items
                 .iter()
                 .map(|item| match item.top_elts.get_tt(item.idx) {
-                    TokenTree::MetaVarDecl(_, bind, kind) => format!("{} ('{}')", kind, bind),
+                    TokenTree::MetaVarDecl(_, bind, Some(kind)) => format!("{} ('{}')", kind, bind),
                     _ => panic!(),
                 })
                 .collect::<Vec<String>>()
@@ -731,7 +745,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
             assert_eq!(bb_items.len(), 1);
 
             let mut item = bb_items.pop().unwrap();
-            if let TokenTree::MetaVarDecl(span, _, kind) = item.top_elts.get_tt(item.idx) {
+            if let TokenTree::MetaVarDecl(span, _, Some(kind)) = item.top_elts.get_tt(item.idx) {
                 let match_cur = item.match_cur;
                 // We use the span of the metavariable declaration to determine any
                 // edition-specific matching behavior for non-terminals.

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -401,7 +401,7 @@ pub fn compile_declarative_macro(
     let diag = &sess.parse_sess.span_diagnostic;
     let lhs_nm = Ident::new(sym::lhs, def.span);
     let rhs_nm = Ident::new(sym::rhs, def.span);
-    let tt_spec = NonterminalKind::TT;
+    let tt_spec = Some(NonterminalKind::TT);
 
     // Parse the macro_rules! invocation
     let (macro_rules, body) = match &def.kind {
@@ -578,7 +578,7 @@ fn check_lhs_no_empty_seq(sess: &ParseSess, tts: &[mbe::TokenTree]) -> bool {
             TokenTree::Sequence(span, ref seq) => {
                 if seq.separator.is_none()
                     && seq.tts.iter().all(|seq_tt| match *seq_tt {
-                        TokenTree::MetaVarDecl(_, _, NonterminalKind::Vis) => true,
+                        TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Vis)) => true,
                         TokenTree::Sequence(_, ref sub_seq) => {
                             sub_seq.kleene.op == mbe::KleeneOp::ZeroOrMore
                                 || sub_seq.kleene.op == mbe::KleeneOp::ZeroOrOne
@@ -961,7 +961,7 @@ fn check_matcher_core(
         // Now `last` holds the complete set of NT tokens that could
         // end the sequence before SUFFIX. Check that every one works with `suffix`.
         for token in &last.tokens {
-            if let TokenTree::MetaVarDecl(_, name, kind) = *token {
+            if let TokenTree::MetaVarDecl(_, name, Some(kind)) = *token {
                 for next_token in &suffix_first.tokens {
                     match is_in_follow(next_token, kind) {
                         IsInFollow::Yes => {}
@@ -1019,7 +1019,7 @@ fn check_matcher_core(
 }
 
 fn token_can_be_followed_by_any(tok: &mbe::TokenTree) -> bool {
-    if let mbe::TokenTree::MetaVarDecl(_, _, kind) = *tok {
+    if let mbe::TokenTree::MetaVarDecl(_, _, Some(kind)) = *tok {
         frag_can_be_followed_by_any(kind)
     } else {
         // (Non NT's can always be followed by anything in matchers.)
@@ -1123,7 +1123,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
                         }
                         _ => IsInFollow::No(TOKENS),
                     },
-                    TokenTree::MetaVarDecl(_, _, NonterminalKind::Block) => IsInFollow::Yes,
+                    TokenTree::MetaVarDecl(_, _, Some(NonterminalKind::Block)) => IsInFollow::Yes,
                     _ => IsInFollow::No(TOKENS),
                 }
             }
@@ -1158,7 +1158,7 @@ fn is_in_follow(tok: &mbe::TokenTree, kind: NonterminalKind) -> IsInFollow {
                     TokenTree::MetaVarDecl(
                         _,
                         _,
-                        NonterminalKind::Ident | NonterminalKind::Ty | NonterminalKind::Path,
+                        Some(NonterminalKind::Ident | NonterminalKind::Ty | NonterminalKind::Path),
                     ) => IsInFollow::Yes,
                     _ => IsInFollow::No(TOKENS),
                 }
@@ -1171,7 +1171,8 @@ fn quoted_tt_to_string(tt: &mbe::TokenTree) -> String {
     match *tt {
         mbe::TokenTree::Token(ref token) => pprust::token_to_string(&token),
         mbe::TokenTree::MetaVar(_, name) => format!("${}", name),
-        mbe::TokenTree::MetaVarDecl(_, name, kind) => format!("${}:{}", name, kind),
+        mbe::TokenTree::MetaVarDecl(_, name, Some(kind)) => format!("${}:{}", name, kind),
+        mbe::TokenTree::MetaVarDecl(_, name, None) => format!("${}:", name),
         _ => panic!(
             "{}",
             "unexpected mbe::TokenTree::{Sequence or Delimited} \

compiler/rustc_expand/src/mbe/quoted.rs

@@ -3,7 +3,7 @@ use crate::mbe::{Delimited, KleeneOp, KleeneToken, SequenceRepetition, TokenTree
 
 use rustc_ast::token::{self, Token};
 use rustc_ast::tokenstream;
-use rustc_ast::NodeId;
+use rustc_ast::{NodeId, DUMMY_NODE_ID};
 use rustc_ast_pretty::pprust;
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::{kw, Ident};
@@ -73,7 +73,7 @@ pub(super) fn parse(
                                                 .emit();
                                             token::NonterminalKind::Ident
                                         });
-                                    result.push(TokenTree::MetaVarDecl(span, ident, kind));
+                                    result.push(TokenTree::MetaVarDecl(span, ident, Some(kind)));
                                     continue;
                                 }
                                 _ => token.span,
@@ -83,8 +83,11 @@ pub(super) fn parse(
                     }
                     tree => tree.as_ref().map(tokenstream::TokenTree::span).unwrap_or(start_sp),
                 };
-                sess.span_diagnostic.struct_span_err(span, "missing fragment specifier").emit();
-                continue;
+                if node_id != DUMMY_NODE_ID {
+                    // Macros loaded from other crates have dummy node ids.
+                    sess.missing_fragment_specifiers.borrow_mut().insert(span, node_id);
+                }
+                result.push(TokenTree::MetaVarDecl(span, ident, None));
             }
 
             // Not a metavar or no matchers allowed, so just return the tree

compiler/rustc_interface/src/passes.rs

@@ -29,6 +29,7 @@ use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
 use rustc_resolve::{Resolver, ResolverArenas};
 use rustc_session::config::{CrateType, Input, OutputFilenames, OutputType, PpMode, PpSourceMode};
+use rustc_session::lint;
 use rustc_session::output::{filename_for_input, filename_for_metadata};
 use rustc_session::search_paths::PathKind;
 use rustc_session::Session;
@@ -306,11 +307,27 @@ fn configure_and_expand_inner<'a>(
             ecx.check_unused_macros();
         });
 
+        let mut missing_fragment_specifiers: Vec<_> = ecx
+            .sess
+            .parse_sess
+            .missing_fragment_specifiers
+            .borrow()
+            .iter()
+            .map(|(span, node_id)| (*span, *node_id))
+            .collect();
+        missing_fragment_specifiers.sort_unstable_by_key(|(span, _)| *span);
+
+        let recursion_limit_hit = ecx.reduced_recursion_limit.is_some();
+
+        for (span, node_id) in missing_fragment_specifiers {
+            let lint = lint::builtin::MISSING_FRAGMENT_SPECIFIER;
+            let msg = "missing fragment specifier";
+            resolver.lint_buffer().buffer_lint(lint, node_id, span, msg);
+        }
         if cfg!(windows) {
             env::set_var("PATH", &old_path);
         }
 
-        let recursion_limit_hit = ecx.reduced_recursion_limit.is_some();
         if recursion_limit_hit {
             // If we hit a recursion limit, exit early to avoid later passes getting overwhelmed
             // with a large AST

compiler/rustc_lint/src/lib.rs

@@ -70,7 +70,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::builtin::{
     BARE_TRAIT_OBJECTS, BROKEN_INTRA_DOC_LINKS, ELIDED_LIFETIMES_IN_PATHS,
     EXPLICIT_OUTLIVES_REQUIREMENTS, INVALID_CODEBLOCK_ATTRIBUTES, INVALID_HTML_TAGS,
-    MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
+    INVALID_RUST_CODEBLOCK, MISSING_DOC_CODE_EXAMPLES, NON_AUTOLINKS, PRIVATE_DOC_TESTS,
 };
 use rustc_span::symbol::{Ident, Symbol};
 use rustc_span::Span;
@@ -319,6 +319,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
         BROKEN_INTRA_DOC_LINKS,
         PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
+        INVALID_RUST_CODEBLOCK,
         MISSING_DOC_CODE_EXAMPLES,
         PRIVATE_DOC_TESTS,
         INVALID_HTML_TAGS

compiler/rustc_lint_defs/src/builtin.rs

@@ -1227,6 +1227,50 @@ declare_lint! {
     };
 }
 
+declare_lint! {
+    /// The `missing_fragment_specifier` lint is issued when an unused pattern in a
+    /// `macro_rules!` macro definition has a meta-variable (e.g. `$e`) that is not
+    /// followed by a fragment specifier (e.g. `:expr`).
+    ///
+    /// This warning can always be fixed by removing the unused pattern in the
+    /// `macro_rules!` macro definition.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// macro_rules! foo {
+    ///    () => {};
+    ///    ($name) => { };
+    /// }
+    ///
+    /// fn main() {
+    ///    foo!();
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// To fix this, remove the unused pattern from the `macro_rules!` macro definition:
+    ///
+    /// ```rust
+    /// macro_rules! foo {
+    ///     () => {};
+    /// }
+    /// fn main() {
+    ///     foo!();
+    /// }
+    /// ```
+    pub MISSING_FRAGMENT_SPECIFIER,
+    Deny,
+    "detects missing fragment specifiers in unused `macro_rules!` patterns",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #40107 <https://github.com/rust-lang/rust/issues/40107>",
+        edition: None,
+    };
+}
+
 declare_lint! {
     /// The `late_bound_lifetime_arguments` lint detects generic lifetime
     /// arguments in path segments with late bound lifetime parameters.
@@ -1846,6 +1890,18 @@ declare_lint! {
     "codeblock attribute looks a lot like a known one"
 }
 
+declare_lint! {
+    /// The `invalid_rust_codeblock` lint detects Rust code blocks in
+    /// documentation examples that are invalid (e.g. empty, not parsable as
+    /// Rust code). This is a `rustdoc` only lint, see the documentation in the
+    /// [rustdoc book].
+    ///
+    /// [rustdoc book]: ../../../rustdoc/lints.html#invalid_rust_codeblock
+    pub INVALID_RUST_CODEBLOCK,
+    Warn,
+    "codeblock could not be parsed as valid Rust or is empty"
+}
+
 declare_lint! {
     /// The `missing_crate_level_docs` lint detects if documentation is
     /// missing at the crate root. This is a `rustdoc` only lint, see the
@@ -2827,6 +2883,7 @@ declare_lint_pass! {
         CONST_ITEM_MUTATION,
         SAFE_PACKED_BORROWS,
         PATTERNS_IN_FNS_WITHOUT_BODY,
+        MISSING_FRAGMENT_SPECIFIER,
         LATE_BOUND_LIFETIME_ARGUMENTS,
         ORDER_DEPENDENT_TRAIT_OBJECTS,
         COHERENCE_LEAK_CHECK,
@@ -2846,6 +2903,7 @@ declare_lint_pass! {
         BROKEN_INTRA_DOC_LINKS,
         PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
+        INVALID_RUST_CODEBLOCK,
         MISSING_CRATE_LEVEL_DOCS,
         MISSING_DOC_CODE_EXAMPLES,
         INVALID_HTML_TAGS,

compiler/rustc_middle/src/lint.rs

@@ -22,8 +22,8 @@ pub enum LintSource {
     Node(Symbol, Span, Option<Symbol> /* RFC 2383 reason */),
 
     /// Lint level was set by a command-line flag.
-    /// The provided `Level` is the level specified on the command line -
-    /// the actual level may be lower due to `--cap-lints`
+    /// The provided `Level` is the level specified on the command line.
+    /// (The actual level may be lower due to `--cap-lints`.)
     CommandLine(Symbol, Level),
 }
 

compiler/rustc_middle/src/ty/query/on_disk_cache.rs

@@ -648,7 +648,7 @@ impl<'sess> OnDiskCache<'sess> {
 
 //- DECODING -------------------------------------------------------------------
 
-/// A decoder that can read from the incr. comp. cache. It is similar to the one
+/// A decoder that can read from the incremental compilation cache. It is similar to the one
 /// we use for crate metadata decoding in that it can rebase spans and eventually
 /// will also handle things that contain `Ty` instances.
 crate struct CacheDecoder<'a, 'tcx> {
@@ -936,7 +936,7 @@ impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [Span] {
 
 //- ENCODING -------------------------------------------------------------------
 
-/// An encoder that can write the incr. comp. cache.
+/// An encoder that can write to the incremental compilation cache.
 struct CacheEncoder<'a, 'tcx, E: OpaqueEncoder> {
     tcx: TyCtxt<'tcx>,
     encoder: &'a mut E,

compiler/rustc_mir/src/transform/coverage/mod.rs

@@ -30,6 +30,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
+use rustc_span::source_map::SourceMap;
 use rustc_span::{CharPos, Pos, SourceFile, Span, Symbol};
 
 /// A simple error message wrapper for `coverage::Error`s.
@@ -311,7 +312,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
                 self.mir_body,
                 counter_kind,
                 self.bcb_leader_bb(bcb),
-                Some(make_code_region(file_name, &self.source_file, span, body_span)),
+                Some(make_code_region(source_map, file_name, &self.source_file, span, body_span)),
             );
         }
     }
@@ -489,6 +490,7 @@ fn inject_intermediate_expression(mir_body: &mut mir::Body<'tcx>, expression: Co
 
 /// Convert the Span into its file name, start line and column, and end line and column
 fn make_code_region(
+    source_map: &SourceMap,
     file_name: Symbol,
     source_file: &Lrc<SourceFile>,
     span: Span,
@@ -508,6 +510,8 @@ fn make_code_region(
     } else {
         source_file.lookup_file_pos(span.hi())
     };
+    let start_line = source_map.doctest_offset_line(&source_file.name, start_line);
+    let end_line = source_map.doctest_offset_line(&source_file.name, end_line);
     CodeRegion {
         file_name,
         start_line: start_line as u32,