Merge branch 'master' into abi

7 files changed, 124 insertions, 61 deletions

diff --git a/src/librustc_parse/lexer/mod.rs b/src/librustc_parse/lexer/mod.rs
index ac58cbb9e8d..96321ef2145 100644
--- a/src/librustc_parse/lexer/mod.rs
+++ b/src/librustc_parse/lexer/mod.rs
@@ -1,20 +1,20 @@
 use rustc_ast::token::{self, Token, TokenKind};
 use rustc_ast::util::comments;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::{error_code, DiagnosticBuilder, FatalError};
-use rustc_lexer::unescape;
+use rustc_errors::{error_code, Applicability, DiagnosticBuilder, FatalError};
 use rustc_lexer::Base;
+use rustc_lexer::{unescape, LexRawStrError, UnvalidatedRawStr, ValidatedRawStr};
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{BytePos, Pos, Span};
 
 use log::debug;
 use std::char;
-use std::convert::TryInto;
 
 mod tokentrees;
 mod unescape_error_reporting;
 mod unicode_chars;
+
 use unescape_error_reporting::{emit_unescape_error, push_escaped_char};
 
 #[derive(Clone, Debug)]
@@ -93,9 +93,6 @@ impl<'a> StringReader<'a> {
     }
 
     /// Returns the next token, including trivia like whitespace or comments.
-    ///
-    /// `Err(())` means that some errors were encountered, which can be
-    /// retrieved using `buffer_fatal_errors`.
     pub fn next_token(&mut self) -> Token {
         let start_src_index = self.src_index(self.pos);
         let text: &str = &self.src[start_src_index..self.end_src_index];
@@ -376,30 +373,22 @@ impl<'a> StringReader<'a> {
                 let id = self.symbol_from_to(content_start, content_end);
                 (token::ByteStr, id)
             }
-            rustc_lexer::LiteralKind::RawStr { n_hashes, started, terminated } => {
-                if !started {
-                    self.report_non_started_raw_string(start);
-                }
-                if !terminated {
-                    self.report_unterminated_raw_string(start, n_hashes)
-                }
-                let n_hashes: u16 = self.restrict_n_hashes(start, n_hashes);
+            rustc_lexer::LiteralKind::RawStr(unvalidated_raw_str) => {
+                let valid_raw_str = self.validate_and_report_errors(start, unvalidated_raw_str);
+                let n_hashes = valid_raw_str.num_hashes();
                 let n = u32::from(n_hashes);
+
                 let content_start = start + BytePos(2 + n);
                 let content_end = suffix_start - BytePos(1 + n);
                 self.validate_raw_str_escape(content_start, content_end);
                 let id = self.symbol_from_to(content_start, content_end);
                 (token::StrRaw(n_hashes), id)
             }
-            rustc_lexer::LiteralKind::RawByteStr { n_hashes, started, terminated } => {
-                if !started {
-                    self.report_non_started_raw_string(start);
-                }
-                if !terminated {
-                    self.report_unterminated_raw_string(start, n_hashes)
-                }
-                let n_hashes: u16 = self.restrict_n_hashes(start, n_hashes);
+            rustc_lexer::LiteralKind::RawByteStr(unvalidated_raw_str) => {
+                let validated_raw_str = self.validate_and_report_errors(start, unvalidated_raw_str);
+                let n_hashes = validated_raw_str.num_hashes();
                 let n = u32::from(n_hashes);
+
                 let content_start = start + BytePos(3 + n);
                 let content_end = suffix_start - BytePos(1 + n);
                 self.validate_raw_byte_str_escape(content_start, content_end);
@@ -485,6 +474,26 @@ impl<'a> StringReader<'a> {
         }
     }
 
+    fn validate_and_report_errors(
+        &self,
+        start: BytePos,
+        unvalidated_raw_str: UnvalidatedRawStr,
+    ) -> ValidatedRawStr {
+        match unvalidated_raw_str.validate() {
+            Err(LexRawStrError::InvalidStarter) => self.report_non_started_raw_string(start),
+            Err(LexRawStrError::NoTerminator { expected, found, possible_terminator_offset }) => {
+                self.report_unterminated_raw_string(
+                    start,
+                    expected,
+                    possible_terminator_offset,
+                    found,
+                )
+            }
+            Err(LexRawStrError::TooManyDelimiters) => self.report_too_many_hashes(start),
+            Ok(valid) => valid,
+        }
+    }
+
     fn report_non_started_raw_string(&self, start: BytePos) -> ! {
         let bad_char = self.str_from(start).chars().last().unwrap();
         self.struct_fatal_span_char(
@@ -498,38 +507,51 @@ impl<'a> StringReader<'a> {
         FatalError.raise()
     }
 
-    fn report_unterminated_raw_string(&self, start: BytePos, n_hashes: usize) -> ! {
+    fn report_unterminated_raw_string(
+        &self,
+        start: BytePos,
+        n_hashes: usize,
+        possible_offset: Option<usize>,
+        found_terminators: usize,
+    ) -> ! {
         let mut err = self.sess.span_diagnostic.struct_span_fatal_with_code(
             self.mk_sp(start, start),
             "unterminated raw string",
             error_code!(E0748),
         );
+
         err.span_label(self.mk_sp(start, start), "unterminated raw string");
 
         if n_hashes > 0 {
             err.note(&format!(
                 "this raw string should be terminated with `\"{}`",
-                "#".repeat(n_hashes as usize)
+                "#".repeat(n_hashes)
             ));
         }
 
+        if let Some(possible_offset) = possible_offset {
+            let lo = start + BytePos(possible_offset as u32);
+            let hi = lo + BytePos(found_terminators as u32);
+            let span = self.mk_sp(lo, hi);
+            err.span_suggestion(
+                span,
+                "consider terminating the string here",
+                "#".repeat(n_hashes),
+                Applicability::MaybeIncorrect,
+            );
+        }
+
         err.emit();
         FatalError.raise()
     }
 
-    fn restrict_n_hashes(&self, start: BytePos, n_hashes: usize) -> u16 {
-        match n_hashes.try_into() {
-            Ok(n_hashes) => n_hashes,
-            Err(_) => {
-                self.fatal_span_(
-                    start,
-                    self.pos,
-                    "too many `#` symbols: raw strings may be \
-                                  delimited by up to 65535 `#` symbols",
-                )
-                .raise();
-            }
-        }
+    fn report_too_many_hashes(&self, start: BytePos) -> ! {
+        self.fatal_span_(
+            start,
+            self.pos,
+            "too many `#` symbols: raw strings may be delimited by up to 65535 `#` symbols",
+        )
+        .raise();
     }
 
     fn validate_char_escape(&self, content_start: BytePos, content_end: BytePos) {
diff --git a/src/librustc_parse/lib.rs b/src/librustc_parse/lib.rs
index 13fb85db847..8e2a9513d6b 100644
--- a/src/librustc_parse/lib.rs
+++ b/src/librustc_parse/lib.rs
@@ -4,6 +4,7 @@
 #![feature(crate_visibility_modifier)]
 #![feature(bindings_after_at)]
 #![feature(try_blocks)]
+#![feature(or_patterns)]
 
 use rustc_ast::ast;
 use rustc_ast::token::{self, Nonterminal};
diff --git a/src/librustc_parse/parser/diagnostics.rs b/src/librustc_parse/parser/diagnostics.rs
index c4546dedfcd..12b9b682682 100644
--- a/src/librustc_parse/parser/diagnostics.rs
+++ b/src/librustc_parse/parser/diagnostics.rs
@@ -6,7 +6,7 @@ use rustc_ast::ast::{
 };
 use rustc_ast::ast::{AttrVec, ItemKind, Mutability, Pat, PatKind, PathSegment, QSelf, Ty, TyKind};
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, TokenKind};
+use rustc_ast::token::{self, Lit, LitKind, TokenKind};
 use rustc_ast::util::parser::AssocOp;
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
@@ -255,6 +255,10 @@ impl<'a> Parser<'a> {
             }
         }
 
+        if self.check_too_many_raw_str_terminators(&mut err) {
+            return Err(err);
+        }
+
         let sm = self.sess.source_map();
         if self.prev_token.span == DUMMY_SP {
             // Account for macro context where the previous span might not be
@@ -282,6 +286,29 @@ impl<'a> Parser<'a> {
         Err(err)
     }
 
+    fn check_too_many_raw_str_terminators(&mut self, err: &mut DiagnosticBuilder<'_>) -> bool {
+        match (&self.prev_token.kind, &self.token.kind) {
+            (
+                TokenKind::Literal(Lit {
+                    kind: LitKind::StrRaw(n_hashes) | LitKind::ByteStrRaw(n_hashes),
+                    ..
+                }),
+                TokenKind::Pound,
+            ) => {
+                err.set_primary_message("too many `#` when terminating raw string");
+                err.span_suggestion(
+                    self.token.span,
+                    "remove the extra `#`",
+                    String::new(),
+                    Applicability::MachineApplicable,
+                );
+                err.note(&format!("the raw string started with {} `#`s", n_hashes));
+                true
+            }
+            _ => false,
+        }
+    }
+
     pub fn maybe_annotate_with_ascription(
         &mut self,
         err: &mut DiagnosticBuilder<'_>,
@@ -491,7 +518,7 @@ impl<'a> Parser<'a> {
                             .unwrap_or_else(|_| pprust::expr_to_string(&e))
                     };
                     err.span_suggestion_verbose(
-                            inner_op.span.shrink_to_hi(),
+                        inner_op.span.shrink_to_hi(),
                         "split the comparison into two",
                         format!(" && {}", expr_to_str(&r1)),
                         Applicability::MaybeIncorrect,
@@ -1086,7 +1113,7 @@ impl<'a> Parser<'a> {
             self.look_ahead(2, |t| t.is_ident())
             || self.look_ahead(1, |t| t == &token::ModSep)
                 && (self.look_ahead(2, |t| t.is_ident()) ||   // `foo:bar::baz`
-             self.look_ahead(2, |t| t == &token::Lt)) // `foo:bar::<baz>`
+            self.look_ahead(2, |t| t == &token::Lt)) // `foo:bar::<baz>`
     }
 
     pub(super) fn recover_seq_parse_error(
diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs
index b205a4b3222..cbff99f8da6 100644
--- a/src/librustc_parse/parser/expr.rs
+++ b/src/librustc_parse/parser/expr.rs
@@ -638,6 +638,7 @@ impl<'a> Parser<'a> {
                     ExprKind::MethodCall(_, _) => "a method call",
                     ExprKind::Call(_, _) => "a function call",
                     ExprKind::Await(_) => "`.await`",
+                    ExprKind::Err => return Ok(with_postfix),
                     _ => unreachable!("parse_dot_or_call_expr_with_ shouldn't produce this"),
                 }
             );
diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs
index 6b7a9ec658d..798eb85f36f 100644
--- a/src/librustc_parse/parser/item.rs
+++ b/src/librustc_parse/parser/item.rs
@@ -1496,7 +1496,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Is the current token the start of an `FnHeader` / not a valid parse?
-    fn check_fn_front_matter(&mut self) -> bool {
+    pub(super) fn check_fn_front_matter(&mut self) -> bool {
         // We use an over-approximation here.
         // `const const`, `fn const` won't parse, but we're not stepping over other syntax either.
         const QUALS: [Symbol; 4] = [kw::Const, kw::Async, kw::Unsafe, kw::Extern];
@@ -1523,7 +1523,7 @@ impl<'a> Parser<'a> {
     /// FnQual = "const"? "async"? "unsafe"? Extern? ;
     /// FnFrontMatter = FnQual? "fn" ;
     /// ```
-    fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> {
+    pub(super) fn parse_fn_front_matter(&mut self) -> PResult<'a, FnHeader> {
         let constness = self.parse_constness();
         let asyncness = self.parse_asyncness();
         let unsafety = self.parse_unsafety();
diff --git a/src/librustc_parse/parser/stmt.rs b/src/librustc_parse/parser/stmt.rs
index fddfe48bf86..b3764d2d47b 100644
--- a/src/librustc_parse/parser/stmt.rs
+++ b/src/librustc_parse/parser/stmt.rs
@@ -165,9 +165,9 @@ impl<'a> Parser<'a> {
                     // Rewind to before attempting to parse the type and continue parsing.
                     let parser_snapshot_after_type = self.clone();
                     mem::replace(self, parser_snapshot_before_type);
-
-                    let snippet = self.span_to_snippet(pat.span).unwrap();
-                    err.span_label(pat.span, format!("while parsing the type for `{}`", snippet));
+                    if let Ok(snip) = self.span_to_snippet(pat.span) {
+                        err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
+                    }
                     (Some((parser_snapshot_after_type, colon_sp, err)), None)
                 }
             }
diff --git a/src/librustc_parse/parser/ty.rs b/src/librustc_parse/parser/ty.rs
index c21ac8d04f1..a6015504a32 100644
--- a/src/librustc_parse/parser/ty.rs
+++ b/src/librustc_parse/parser/ty.rs
@@ -127,16 +127,16 @@ impl<'a> Parser<'a> {
         } else if self.eat_keyword(kw::Underscore) {
             // A type to be inferred `_`
             TyKind::Infer
-        } else if self.token_is_bare_fn_keyword() {
+        } else if self.check_fn_front_matter() {
             // Function pointer type
-            self.parse_ty_bare_fn(Vec::new())?
+            self.parse_ty_bare_fn(lo, Vec::new())?
         } else if self.check_keyword(kw::For) {
             // Function pointer type or bound list (trait object type) starting with a poly-trait.
             //   `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
             //   `for<'lt> Trait1<'lt> + Trait2 + 'a`
             let lifetime_defs = self.parse_late_bound_lifetime_defs()?;
-            if self.token_is_bare_fn_keyword() {
-                self.parse_ty_bare_fn(lifetime_defs)?
+            if self.check_fn_front_matter() {
+                self.parse_ty_bare_fn(lo, lifetime_defs)?
             } else {
                 let path = self.parse_path(PathStyle::Type)?;
                 let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus();
@@ -291,13 +291,6 @@ impl<'a> Parser<'a> {
         Ok(TyKind::Typeof(expr))
     }
 
-    /// Is the current token one of the keywords that signals a bare function type?
-    fn token_is_bare_fn_keyword(&mut self) -> bool {
-        self.check_keyword(kw::Fn)
-            || self.check_keyword(kw::Unsafe)
-            || self.check_keyword(kw::Extern)
-    }
-
     /// Parses a function pointer type (`TyKind::BareFn`).
     /// ```
     /// [unsafe] [extern "ABI"] fn (S) -> T
@@ -306,12 +299,31 @@ impl<'a> Parser<'a> {
     ///    |               |        |   Return type
     /// Function Style    ABI  Parameter types
     /// ```
-    fn parse_ty_bare_fn(&mut self, generic_params: Vec<GenericParam>) -> PResult<'a, TyKind> {
-        let unsafety = self.parse_unsafety();
-        let ext = self.parse_extern()?;
-        self.expect_keyword(kw::Fn)?;
+    /// We actually parse `FnHeader FnDecl`, but we error on `const` and `async` qualifiers.
+    fn parse_ty_bare_fn(&mut self, lo: Span, params: Vec<GenericParam>) -> PResult<'a, TyKind> {
+        let ast::FnHeader { ext, unsafety, constness, asyncness } = self.parse_fn_front_matter()?;
         let decl = self.parse_fn_decl(|_| false, AllowPlus::No)?;
-        Ok(TyKind::BareFn(P(BareFnTy { ext, unsafety, generic_params, decl })))
+        let whole_span = lo.to(self.prev_token.span);
+        if let ast::Const::Yes(span) = constness {
+            self.error_fn_ptr_bad_qualifier(whole_span, span, "const");
+        }
+        if let ast::Async::Yes { span, .. } = asyncness {
+            self.error_fn_ptr_bad_qualifier(whole_span, span, "async");
+        }
+        Ok(TyKind::BareFn(P(BareFnTy { ext, unsafety, generic_params: params, decl })))
+    }
+
+    /// Emit an error for the given bad function pointer qualifier.
+    fn error_fn_ptr_bad_qualifier(&self, span: Span, qual_span: Span, qual: &str) {
+        self.struct_span_err(span, &format!("an `fn` pointer type cannot be `{}`", qual))
+            .span_label(qual_span, format!("`{}` because of this", qual))
+            .span_suggestion_short(
+                qual_span,
+                &format!("remove the `{}` qualifier", qual),
+                String::new(),
+                Applicability::MaybeIncorrect,
+            )
+            .emit();
     }
 
     /// Parses an `impl B0 + ... + Bn` type.