fix(parser): Disallow CR in frontmatter

compiler/rustc_parse/messages.ftl

@@ -98,6 +98,8 @@ parse_bare_cr = {$double_quotes ->
     }
     .escape = escape the character
 
+parse_bare_cr_in_frontmatter = bare CR not allowed in frontmatter
+
 parse_bare_cr_in_raw_string = bare CR not allowed in raw string
 
 parse_binder_and_polarity = `for<...>` binder not allowed with `{$polarity}` trait polarity modifier
@@ -350,7 +352,6 @@ parse_frontmatter_length_mismatch = frontmatter close does not match the opening
 parse_frontmatter_too_many_dashes = too many `-` symbols: frontmatter openings may be delimited by up to 255 `-` symbols, but found {$len_opening}
 parse_frontmatter_unclosed = unclosed frontmatter
     .note = frontmatter opening here was not closed
-
 parse_function_body_equals_expr = function body cannot be `= expression;`
     .suggestion = surround the expression with `{"{"}` and `{"}"}` instead of `=` and `;`
 

compiler/rustc_parse/src/errors.rs

@@ -829,6 +829,13 @@ pub(crate) struct FrontmatterTooManyDashes {
     pub len_opening: usize,
 }
 
+#[derive(Diagnostic)]
+#[diag(parse_bare_cr_in_frontmatter)]
+pub(crate) struct BareCrFrontmatter {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(parse_leading_plus_not_supported)]
 pub(crate) struct LeadingPlusNotSupported {

compiler/rustc_parse/src/lexer/mod.rs

@@ -595,9 +595,9 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
         let s = self.str_from(start);
         let real_start = s.find("---").unwrap();
         let frontmatter_opening_pos = BytePos(real_start as u32) + start;
-        let s_new = &s[real_start..];
-        let within = s_new.trim_start_matches('-');
-        let len_opening = s_new.len() - within.len();
+        let real_s = &s[real_start..];
+        let within = real_s.trim_start_matches('-');
+        let len_opening = real_s.len() - within.len();
 
         let frontmatter_opening_end_pos = frontmatter_opening_pos + BytePos(len_opening as u32);
         if has_invalid_preceding_whitespace {
@@ -611,19 +611,27 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
             });
         }
 
+        let line_end = real_s.find('\n').unwrap_or(real_s.len());
         if invalid_infostring {
-            let line_end = s[real_start..].find('\n').unwrap_or(s[real_start..].len());
             let span = self.mk_sp(
                 frontmatter_opening_end_pos,
                 frontmatter_opening_pos + BytePos(line_end as u32),
             );
             self.dcx().emit_err(errors::FrontmatterInvalidInfostring { span });
         }
 
-        let last_line_start = within.rfind('\n').map_or(0, |i| i + 1);
-        let last_line = &within[last_line_start..];
+        let last_line_start = real_s.rfind('\n').map_or(0, |i| i + 1);
+
+        let content = &real_s[line_end..last_line_start];
+        if let Some(cr_offset) = content.find('\r') {
+            let cr_pos = start + BytePos((real_start + line_end + cr_offset) as u32);
+            let span = self.mk_sp(cr_pos, cr_pos + BytePos(1 as u32));
+            self.dcx().emit_err(errors::BareCrFrontmatter { span });
+        }
+
+        let last_line = &real_s[last_line_start..];
         let last_line_trimmed = last_line.trim_start_matches(is_horizontal_whitespace);
-        let last_line_start_pos = frontmatter_opening_end_pos + BytePos(last_line_start as u32);
+        let last_line_start_pos = frontmatter_opening_pos + BytePos(last_line_start as u32);
 
         let frontmatter_span = self.mk_sp(frontmatter_opening_pos, self.pos);
         self.psess.gated_spans.gate(sym::frontmatter, frontmatter_span);

tests/ui/frontmatter/content-cr.rs

@@ -0,0 +1,10 @@
+---
+package.name = "" # //~ ERROR bare CR not allowed in frontmatter
+package.description = "é"
+---
+
+// ignore-tidy-cr
+
+#![feature(frontmatter)]
+
+pub fn main() {}

tests/ui/frontmatter/content-cr.stderr

@@ -0,0 +1,8 @@
+error: bare CR not allowed in frontmatter
+  --> $DIR/content-cr.rs:2:17
+   |
+LL | package.name = "␍" #
+   |                 ^
+
+error: aborting due to 1 previous error
+