Merge from rustc

7 files changed, 20 insertions, 10 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 0b5ec9b59ea..36125e138b2 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -32,10 +32,10 @@ use rustc_macros::Subdiagnostic;
 use rustc_session::errors::{report_lit_error, ExprParenthesesNeeded};
 use rustc_session::lint::builtin::BREAK_WITH_LABEL_AND_LOOP;
 use rustc_session::lint::BuiltinLintDiagnostics;
-use rustc_span::source_map::{self, Span, Spanned};
+use rustc_span::source_map::{self, Spanned};
 use rustc_span::symbol::kw::PathRoot;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::{BytePos, Pos};
+use rustc_span::{BytePos, Pos, Span};
 use thin_vec::{thin_vec, ThinVec};
 
 /// Possibly accepts an `token::Interpolated` expression (a pre-parsed expression
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 55ad3f42938..253dd2a3b34 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -22,9 +22,9 @@ use rustc_errors::{
 };
 use rustc_span::edit_distance::edit_distance;
 use rustc_span::edition::Edition;
-use rustc_span::source_map::{self, Span};
+use rustc_span::source_map;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
-use rustc_span::DUMMY_SP;
+use rustc_span::{Span, DUMMY_SP};
 use std::fmt::Write;
 use std::mem;
 use thin_vec::{thin_vec, ThinVec};
@@ -2499,6 +2499,16 @@ impl<'a> Parser<'a> {
     pub(super) fn parse_fn_params(&mut self, req_name: ReqName) -> PResult<'a, ThinVec<Param>> {
         let mut first_param = true;
         // Parse the arguments, starting out with `self` being allowed...
+        if self.token.kind != TokenKind::OpenDelim(Delimiter::Parenthesis)
+        // might be typo'd trait impl, handled elsewhere
+        && !self.token.is_keyword(kw::For)
+        {
+            // recover from missing argument list, e.g. `fn main -> () {}`
+            self.sess
+                .emit_err(errors::MissingFnParams { span: self.prev_token.span.shrink_to_hi() });
+            return Ok(ThinVec::new());
+        }
+
         let (mut params, _) = self.parse_paren_comma_seq(|p| {
             p.recover_diff_marker();
             let snapshot = p.create_snapshot_for_diagnostic();
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 59b51954542..1a7ae406911 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -36,8 +36,8 @@ use rustc_errors::{
     Applicability, DiagnosticBuilder, ErrorGuaranteed, FatalError, IntoDiagnostic, MultiSpan,
 };
 use rustc_session::parse::ParseSess;
-use rustc_span::source_map::{Span, DUMMY_SP};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_span::{Span, DUMMY_SP};
 use std::ops::Range;
 use std::{mem, slice};
 use thin_vec::ThinVec;
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index 3378e4d46b7..0a4c7c17d06 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -20,8 +20,9 @@ use rustc_ast::{
 use rustc_ast_pretty::pprust;
 use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, IntoDiagnostic, PResult};
 use rustc_session::errors::ExprParenthesesNeeded;
-use rustc_span::source_map::{respan, Span, Spanned};
+use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::Span;
 use thin_vec::{thin_vec, ThinVec};
 
 #[derive(PartialEq, Copy, Clone)]
diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index 4969e672a72..8626dbe40af 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -10,8 +10,8 @@ use rustc_ast::{
     Path, PathSegment, QSelf,
 };
 use rustc_errors::{Applicability, IntoDiagnostic, PResult};
-use rustc_span::source_map::{BytePos, Span};
 use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::{BytePos, Span};
 use std::mem;
 use thin_vec::ThinVec;
 use tracing::debug;
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index 8e3c4568694..aa939a71d63 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -20,8 +20,8 @@ use rustc_ast::{AttrStyle, AttrVec, LocalKind, MacCall, MacCallStmt, MacStmtStyl
 use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, HasAttrs, Local, Stmt};
 use rustc_ast::{StmtKind, DUMMY_NODE_ID};
 use rustc_errors::{Applicability, DiagnosticBuilder, ErrorGuaranteed, PResult};
-use rustc_span::source_map::{BytePos, Span};
 use rustc_span::symbol::{kw, sym, Ident};
+use rustc_span::{BytePos, Span};
 
 use std::borrow::Cow;
 use std::mem;
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index badea5d6133..be2cbaf3020 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -18,9 +18,8 @@ use rustc_ast::{
     TraitObjectSyntax, Ty, TyKind,
 };
 use rustc_errors::{Applicability, PResult};
-use rustc_span::source_map::Span;
 use rustc_span::symbol::{kw, sym, Ident};
-use rustc_span::Symbol;
+use rustc_span::{Span, Symbol};
 use thin_vec::{thin_vec, ThinVec};
 
 /// Any `?`, `!`, or `~const` modifiers that appear at the start of a bound.