Fix lifetimes in StringReader.

Two different lifetimes are conflated. This doesn't matter right now,
but needs to be fixed for the next commit to work. And the more
descriptive lifetime names make the code easier to read.

compiler/rustc_parse/src/lexer/mod.rs

@@ -42,9 +42,9 @@ pub struct UnmatchedDelim {
     pub candidate_span: Option<Span>,
 }
 
-pub(crate) fn parse_token_trees<'a>(
-    sess: &'a ParseSess,
-    mut src: &'a str,
+pub(crate) fn parse_token_trees<'sess, 'src>(
+    sess: &'sess ParseSess,
+    mut src: &'src str,
     mut start_pos: BytePos,
     override_span: Option<Span>,
 ) -> Result<TokenStream, Vec<Diagnostic>> {
@@ -90,16 +90,16 @@ pub(crate) fn parse_token_trees<'a>(
     }
 }
 
-struct StringReader<'a> {
-    sess: &'a ParseSess,
+struct StringReader<'sess, 'src> {
+    sess: &'sess ParseSess,
     /// Initial position, read-only.
     start_pos: BytePos,
     /// The absolute offset within the source_map of the current character.
     pos: BytePos,
     /// Source text to tokenize.
-    src: &'a str,
+    src: &'src str,
     /// Cursor for getting lexer tokens.
-    cursor: Cursor<'a>,
+    cursor: Cursor<'src>,
     override_span: Option<Span>,
     /// When a "unknown start of token: \u{a0}" has already been emitted earlier
     /// in this file, it's safe to treat further occurrences of the non-breaking
@@ -107,8 +107,8 @@ struct StringReader<'a> {
     nbsp_is_whitespace: bool,
 }
 
-impl<'a> StringReader<'a> {
-    pub fn dcx(&self) -> &'a DiagCtxt {
+impl<'sess, 'src> StringReader<'sess, 'src> {
+    pub fn dcx(&self) -> &'sess DiagCtxt {
         &self.sess.dcx
     }
 
@@ -526,7 +526,7 @@ impl<'a> StringReader<'a> {
 
     /// Slice of the source text from `start` up to but excluding `self.pos`,
     /// meaning the slice does not include the character `self.ch`.
-    fn str_from(&self, start: BytePos) -> &'a str {
+    fn str_from(&self, start: BytePos) -> &'src str {
         self.str_from_to(start, self.pos)
     }
 
@@ -537,12 +537,12 @@ impl<'a> StringReader<'a> {
     }
 
     /// Slice of the source text spanning from `start` up to but excluding `end`.
-    fn str_from_to(&self, start: BytePos, end: BytePos) -> &'a str {
+    fn str_from_to(&self, start: BytePos, end: BytePos) -> &'src str {
         &self.src[self.src_index(start)..self.src_index(end)]
     }
 
     /// Slice of the source text spanning from `start` until the end
-    fn str_from_to_end(&self, start: BytePos) -> &'a str {
+    fn str_from_to_end(&self, start: BytePos) -> &'src str {
         &self.src[self.src_index(start)..]
     }
 

compiler/rustc_parse/src/lexer/tokentrees.rs

@@ -8,18 +8,18 @@ use rustc_ast_pretty::pprust::token_to_string;
 use rustc_errors::{Applicability, PErr};
 use rustc_span::symbol::kw;
 
-pub(super) struct TokenTreesReader<'a> {
-    string_reader: StringReader<'a>,
+pub(super) struct TokenTreesReader<'sess, 'src> {
+    string_reader: StringReader<'sess, 'src>,
     /// The "next" token, which has been obtained from the `StringReader` but
     /// not yet handled by the `TokenTreesReader`.
     token: Token,
     diag_info: TokenTreeDiagInfo,
 }
 
-impl<'a> TokenTreesReader<'a> {
+impl<'sess, 'src> TokenTreesReader<'sess, 'src> {
     pub(super) fn parse_all_token_trees(
-        string_reader: StringReader<'a>,
-    ) -> (TokenStream, Result<(), Vec<PErr<'a>>>, Vec<UnmatchedDelim>) {
+        string_reader: StringReader<'sess, 'src>,
+    ) -> (TokenStream, Result<(), Vec<PErr<'sess>>>, Vec<UnmatchedDelim>) {
         let mut tt_reader = TokenTreesReader {
             string_reader,
             token: Token::dummy(),
@@ -35,7 +35,7 @@ impl<'a> TokenTreesReader<'a> {
     fn parse_token_trees(
         &mut self,
         is_delimited: bool,
-    ) -> (Spacing, TokenStream, Result<(), Vec<PErr<'a>>>) {
+    ) -> (Spacing, TokenStream, Result<(), Vec<PErr<'sess>>>) {
         // Move past the opening delimiter.
         let (_, open_spacing) = self.bump(false);
 
@@ -71,7 +71,7 @@ impl<'a> TokenTreesReader<'a> {
         }
     }
 
-    fn eof_err(&mut self) -> PErr<'a> {
+    fn eof_err(&mut self) -> PErr<'sess> {
         let msg = "this file contains an unclosed delimiter";
         let mut err = self.string_reader.sess.dcx.struct_span_err(self.token.span, msg);
         for &(_, sp) in &self.diag_info.open_braces {
@@ -99,7 +99,7 @@ impl<'a> TokenTreesReader<'a> {
     fn parse_token_tree_open_delim(
         &mut self,
         open_delim: Delimiter,
-    ) -> Result<TokenTree, Vec<PErr<'a>>> {
+    ) -> Result<TokenTree, Vec<PErr<'sess>>> {
         // The span for beginning of the delimited section
         let pre_span = self.token.span;
 
@@ -229,7 +229,11 @@ impl<'a> TokenTreesReader<'a> {
         (this_tok, this_spacing)
     }
 
-    fn unclosed_delim_err(&mut self, tts: TokenStream, mut errs: Vec<PErr<'a>>) -> Vec<PErr<'a>> {
+    fn unclosed_delim_err(
+        &mut self,
+        tts: TokenStream,
+        mut errs: Vec<PErr<'sess>>,
+    ) -> Vec<PErr<'sess>> {
         // If there are unclosed delims, see if there are diff markers and if so, point them
         // out instead of complaining about the unclosed delims.
         let mut parser = crate::stream_to_parser(self.string_reader.sess, tts, None);
@@ -285,7 +289,7 @@ impl<'a> TokenTreesReader<'a> {
         return errs;
     }
 
-    fn close_delim_err(&mut self, delim: Delimiter) -> PErr<'a> {
+    fn close_delim_err(&mut self, delim: Delimiter) -> PErr<'sess> {
         // An unexpected closing delimiter (i.e., there is no
         // matching opening delimiter).
         let token_str = token_to_string(&self.token);

compiler/rustc_parse/src/lexer/unicode_chars.rs

@@ -337,7 +337,7 @@ const ASCII_ARRAY: &[(&str, &str, Option<token::TokenKind>)] = &[
 ];
 
 pub(super) fn check_for_substitution(
-    reader: &StringReader<'_>,
+    reader: &StringReader<'_, '_>,
     pos: BytePos,
     ch: char,
     count: usize,