Auto merge of #67112 - Centril:expr-polish, r=estebank

Refactor expression parsing thoroughly Based on #66994 together with which this has refactored basically the entirety of `expr.rs`. r? @estebank

Author: bors

src/librustc_parse/parser/attr.rs

@@ -2,6 +2,7 @@ use super::{Parser, PathStyle, TokenType};
 use rustc_errors::PResult;
 use syntax::ast;
 use syntax::attr;
+use syntax::print::pprust;
 use syntax::token::{self, Nonterminal};
 use syntax::util::comments;
 use syntax_pos::{Span, Symbol};
@@ -154,7 +155,7 @@ impl<'a> Parser<'a> {
  (attr_sp, item, style)
  }
  _ => {
- let token_str = self.this_token_to_string();
+ let token_str = pprust::token_to_string(&self.token);
  return Err(self.fatal(&format!("expected `#`, found `{}`", token_str)));
  }
  };
@@ -329,7 +330,7 @@ impl<'a> Parser<'a> {
  Err(ref mut err) => err.cancel(),
  }
 
- let found = self.this_token_to_string();
+ let found = pprust::token_to_string(&self.token);
  let msg = format!("expected unsuffixed literal or identifier, found `{}`", found);
  Err(self.diagnostic().struct_span_err(self.token.span, &msg))
  }

src/librustc_parse/parser/diagnostics.rs

@@ -200,7 +200,7 @@ impl<'a> Parser<'a> {
  pub(super) fn expected_ident_found(&self) -> DiagnosticBuilder<'a> {
  let mut err = self.struct_span_err(
  self.token.span,
- &format!("expected identifier, found {}", self.this_token_descr()),
+ &format!("expected identifier, found {}", super::token_descr(&self.token)),
  );
  let valid_follow = &[
  TokenKind::Eq,
@@ -225,7 +225,7 @@ impl<'a> Parser<'a> {
  );
  }
  }
- if let Some(token_descr) = self.token_descr() {
+ if let Some(token_descr) = super::token_descr_opt(&self.token) {
  err.span_label(self.token.span, format!("expected identifier, found {}", token_descr));
  } else {
  err.span_label(self.token.span, "expected identifier");
@@ -272,7 +272,7 @@ impl<'a> Parser<'a> {
  expected.sort_by_cached_key(|x| x.to_string());
  expected.dedup();
  let expect = tokens_to_string(&expected[..]);
- let actual = self.this_token_descr();
+ let actual = super::token_descr(&self.token);
  let (msg_exp, (label_sp, label_exp)) = if expected.len() > 1 {
  let short_expect = if expected.len() > 6 {
  format!("{} possible tokens", expected.len())
@@ -815,7 +815,7 @@ impl<'a> Parser<'a> {
  t: &TokenKind,
  ) -> PResult<'a, bool /* recovered */> {
  let token_str = pprust::token_kind_to_string(t);
- let this_token_str = self.this_token_descr();
+ let this_token_str = super::token_descr(&self.token);
  let (prev_sp, sp) = match (&self.token.kind, self.subparser_name) {
  // Point at the end of the macro call when reaching end of macro arguments.
  (token::Eof, Some(_)) => {
@@ -862,7 +862,7 @@ impl<'a> Parser<'a> {
  return Ok(());
  }
  let sm = self.sess.source_map();
- let msg = format!("expected `;`, found `{}`", self.this_token_descr());
+ let msg = format!("expected `;`, found `{}`", super::token_descr(&self.token));
  let appl = Applicability::MachineApplicable;
  if self.token.span == DUMMY_SP || self.prev_span == DUMMY_SP {
  // Likely inside a macro, can't provide meaninful suggestions.
@@ -1270,7 +1270,7 @@ impl<'a> Parser<'a> {
  }
 
  pub(super) fn expected_semi_or_open_brace<T>(&mut self) -> PResult<'a, T> {
- let token_str = self.this_token_descr();
+ let token_str = super::token_descr(&self.token);
  let mut err = self.fatal(&format!("expected `;` or `{{`, found {}", token_str));
  err.span_label(self.token.span, "expected `;` or `{`");
  Err(err)
@@ -1447,7 +1447,7 @@ impl<'a> Parser<'a> {
  }
  _ => (
  self.token.span,
- format!("expected expression, found {}", self.this_token_descr(),),
+ format!("expected expression, found {}", super::token_descr(&self.token),),
  ),
  };
  let mut err = self.struct_span_err(span, &msg);