Auto merge of #90460 - pietroalbini:bidi-stable, r=nikomatsakis,pietroalbini1.56.1

[stable] Fix CVE-2021-42574 and prepare Rust 1.56.1

This PR implements new lints to mitigate the impact of [CVE-2021-42574], caused by the presence of bidirectional-override Unicode codepoints in the compiled source code. [See the advisory][advisory] for more information about the vulnerability.

The changes in this PR will be released later today as part of Rust 1.56.1.

[CVE-2021-42574]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-42574
[advisory]: https://blog.rust-lang.org/2021/11/01/cve-2021-42574.html

15 files changed, 545 insertions, 11 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 4f1a5ca35fa..f7080a91020 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4101,6 +4101,7 @@ dependencies = [
  "rustc_span",
  "tracing",
  "unicode-normalization",
+ "unicode-width",
 ]
 
 [[package]]
diff --git a/RELEASES.md b/RELEASES.md
index 52d823d8aca..59d4d4507ff 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -1,3 +1,11 @@
+Version 1.56.1 (2021-11-01)
+===========================
+
+- New lints to detect the presence of bidirectional-override Unicode
+  codepoints in the compiled source code ([CVE-2021-42574])
+
+[CVE-2021-42574]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-42574
+
 Version 1.56.0 (2021-10-21)
 ========================
 
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 29f352ae585..272e367dd38 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -2054,8 +2054,26 @@ fn num_decimal_digits(num: usize) -> usize {
     MAX_DIGITS
 }
 
+// We replace some characters so the CLI output is always consistent and underlines aligned.
+const OUTPUT_REPLACEMENTS: &[(char, &str)] = &[
+    ('\t', "    "),   // We do our own tab replacement
+    ('\u{202A}', ""), // The following unicode text flow control characters are inconsistently
+    ('\u{202B}', ""), // supported accross CLIs and can cause confusion due to the bytes on disk
+    ('\u{202D}', ""), // not corresponding to the visible source code, so we replace them always.
+    ('\u{202E}', ""),
+    ('\u{2066}', ""),
+    ('\u{2067}', ""),
+    ('\u{2068}', ""),
+    ('\u{202C}', ""),
+    ('\u{2069}', ""),
+];
+
 fn replace_tabs(str: &str) -> String {
-    str.replace('\t', "    ")
+    let mut s = str.to_string();
+    for (c, replacement) in OUTPUT_REPLACEMENTS {
+        s = s.replace(*c, replacement);
+    }
+    s
 }
 
 fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 7dbc3d60439..30ae664917d 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -16,6 +16,7 @@
 
 use self::TargetLint::*;
 
+use crate::hidden_unicode_codepoints::UNICODE_TEXT_FLOW_CHARS;
 use crate::levels::{is_known_lint_tool, LintLevelsBuilder};
 use crate::passes::{EarlyLintPassObject, LateLintPassObject};
 use rustc_ast as ast;
@@ -40,7 +41,7 @@ use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintI
 use rustc_session::Session;
 use rustc_session::SessionLintStore;
 use rustc_span::lev_distance::find_best_match_for_name;
-use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
+use rustc_span::{symbol::Symbol, BytePos, MultiSpan, Span, DUMMY_SP};
 use rustc_target::abi::{self, LayoutOf};
 use tracing::debug;
 
@@ -612,6 +613,42 @@ pub trait LintContext: Sized {
             // Now, set up surrounding context.
             let sess = self.sess();
             match diagnostic {
+                BuiltinLintDiagnostics::UnicodeTextFlow(span, content) => {
+                    let spans: Vec<_> = content
+                        .char_indices()
+                        .filter_map(|(i, c)| {
+                            UNICODE_TEXT_FLOW_CHARS.contains(&c).then(|| {
+                                let lo = span.lo() + BytePos(2 + i as u32);
+                                (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
+                            })
+                        })
+                        .collect();
+                    let (an, s) = match spans.len() {
+                        1 => ("an ", ""),
+                        _ => ("", "s"),
+                    };
+                    db.span_label(span, &format!(
+                        "this comment contains {}invisible unicode text flow control codepoint{}",
+                        an,
+                        s,
+                    ));
+                    for (c, span) in &spans {
+                        db.span_label(*span, format!("{:?}", c));
+                    }
+                    db.note(
+                        "these kind of unicode codepoints change the way text flows on \
+                         applications that support them, but can cause confusion because they \
+                         change the order of characters on the screen",
+                    );
+                    if !spans.is_empty() {
+                        db.multipart_suggestion_with_style(
+                            "if their presence wasn't intentional, you can remove them",
+                            spans.into_iter().map(|(_, span)| (span, "".to_string())).collect(),
+                            Applicability::MachineApplicable,
+                            SuggestionStyle::HideCodeAlways,
+                        );
+                    }
+                },
                 BuiltinLintDiagnostics::Normal => (),
                 BuiltinLintDiagnostics::BareTraitObject(span, is_global) => {
                     let (sugg, app) = match sess.source_map().span_to_snippet(span) {
diff --git a/compiler/rustc_lint/src/hidden_unicode_codepoints.rs b/compiler/rustc_lint/src/hidden_unicode_codepoints.rs
new file mode 100644
index 00000000000..1bcdcb806fc
--- /dev/null
+++ b/compiler/rustc_lint/src/hidden_unicode_codepoints.rs
@@ -0,0 +1,161 @@
+use crate::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_ast as ast;
+use rustc_errors::{Applicability, SuggestionStyle};
+use rustc_span::{BytePos, Span, Symbol};
+
+declare_lint! {
+    /// The `text_direction_codepoint_in_literal` lint detects Unicode codepoints that change the
+    /// visual representation of text on screen in a way that does not correspond to their on
+    /// memory representation.
+    ///
+    /// ### Explanation
+    ///
+    /// The unicode characters `\u{202A}`, `\u{202B}`, `\u{202D}`, `\u{202E}`, `\u{2066}`,
+    /// `\u{2067}`, `\u{2068}`, `\u{202C}` and `\u{2069}` make the flow of text on screen change
+    /// its direction on software that supports these codepoints. This makes the text "abc" display
+    /// as "cba" on screen. By leveraging software that supports these, people can write specially
+    /// crafted literals that make the surrounding code seem like it's performing one action, when
+    /// in reality it is performing another. Because of this, we proactively lint against their
+    /// presence to avoid surprises.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(text_direction_codepoint_in_literal)]
+    /// fn main() {
+    ///     println!("{:?}", '‮');
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    pub TEXT_DIRECTION_CODEPOINT_IN_LITERAL,
+    Deny,
+    "detect special Unicode codepoints that affect the visual representation of text on screen, \
+     changing the direction in which text flows",
+}
+
+declare_lint_pass!(HiddenUnicodeCodepoints => [TEXT_DIRECTION_CODEPOINT_IN_LITERAL]);
+
+crate const UNICODE_TEXT_FLOW_CHARS: &[char] = &[
+    '\u{202A}', '\u{202B}', '\u{202D}', '\u{202E}', '\u{2066}', '\u{2067}', '\u{2068}', '\u{202C}',
+    '\u{2069}',
+];
+
+impl HiddenUnicodeCodepoints {
+    fn lint_text_direction_codepoint(
+        &self,
+        cx: &EarlyContext<'_>,
+        text: Symbol,
+        span: Span,
+        padding: u32,
+        point_at_inner_spans: bool,
+        label: &str,
+    ) {
+        // Obtain the `Span`s for each of the forbidden chars.
+        let spans: Vec<_> = text
+            .as_str()
+            .char_indices()
+            .filter_map(|(i, c)| {
+                UNICODE_TEXT_FLOW_CHARS.contains(&c).then(|| {
+                    let lo = span.lo() + BytePos(i as u32 + padding);
+                    (c, span.with_lo(lo).with_hi(lo + BytePos(c.len_utf8() as u32)))
+                })
+            })
+            .collect();
+
+        cx.struct_span_lint(TEXT_DIRECTION_CODEPOINT_IN_LITERAL, span, |lint| {
+            let mut err = lint.build(&format!(
+                "unicode codepoint changing visible direction of text present in {}",
+                label
+            ));
+            let (an, s) = match spans.len() {
+                1 => ("an ", ""),
+                _ => ("", "s"),
+            };
+            err.span_label(
+                span,
+                &format!(
+                    "this {} contains {}invisible unicode text flow control codepoint{}",
+                    label, an, s,
+                ),
+            );
+            if point_at_inner_spans {
+                for (c, span) in &spans {
+                    err.span_label(*span, format!("{:?}", c));
+                }
+            }
+            err.note(
+                "these kind of unicode codepoints change the way text flows on applications that \
+                 support them, but can cause confusion because they change the order of \
+                 characters on the screen",
+            );
+            if point_at_inner_spans && !spans.is_empty() {
+                err.multipart_suggestion_with_style(
+                    "if their presence wasn't intentional, you can remove them",
+                    spans.iter().map(|(_, span)| (*span, "".to_string())).collect(),
+                    Applicability::MachineApplicable,
+                    SuggestionStyle::HideCodeAlways,
+                );
+                err.multipart_suggestion(
+                    "if you want to keep them but make them visible in your source code, you can \
+                    escape them",
+                    spans
+                        .into_iter()
+                        .map(|(c, span)| {
+                            let c = format!("{:?}", c);
+                            (span, c[1..c.len() - 1].to_string())
+                        })
+                        .collect(),
+                    Applicability::MachineApplicable,
+                );
+            } else {
+                // FIXME: in other suggestions we've reversed the inner spans of doc comments. We
+                // should do the same here to provide the same good suggestions as we do for
+                // literals above.
+                err.note("if their presence wasn't intentional, you can remove them");
+                err.note(&format!(
+                    "if you want to keep them but make them visible in your source code, you can \
+                     escape them: {}",
+                    spans
+                        .into_iter()
+                        .map(|(c, _)| { format!("{:?}", c) })
+                        .collect::<Vec<String>>()
+                        .join(", "),
+                ));
+            }
+            err.emit();
+        });
+    }
+}
+impl EarlyLintPass for HiddenUnicodeCodepoints {
+    fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
+        if let ast::AttrKind::DocComment(_, comment) = attr.kind {
+            if comment.as_str().contains(UNICODE_TEXT_FLOW_CHARS) {
+                self.lint_text_direction_codepoint(cx, comment, attr.span, 0, false, "doc comment");
+            }
+        }
+    }
+
+    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
+        // byte strings are already handled well enough by `EscapeError::NonAsciiCharInByteString`
+        let (text, span, padding) = match &expr.kind {
+            ast::ExprKind::Lit(ast::Lit { token, kind, span }) => {
+                let text = token.symbol;
+                if !text.as_str().contains(UNICODE_TEXT_FLOW_CHARS) {
+                    return;
+                }
+                let padding = match kind {
+                    // account for `"` or `'`
+                    ast::LitKind::Str(_, ast::StrStyle::Cooked) | ast::LitKind::Char(_) => 1,
+                    // account for `r###"`
+                    ast::LitKind::Str(_, ast::StrStyle::Raw(val)) => *val as u32 + 2,
+                    _ => return,
+                };
+                (text, span, padding)
+            }
+            _ => return,
+        };
+        self.lint_text_direction_codepoint(cx, text, *span, padding, true, "literal");
+    }
+}
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index ef4bda666ba..b65fa419fad 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -48,6 +48,7 @@ mod array_into_iter;
 pub mod builtin;
 mod context;
 mod early;
+pub mod hidden_unicode_codepoints;
 mod internal;
 mod late;
 mod levels;
@@ -77,6 +78,7 @@ use rustc_span::Span;
 
 use array_into_iter::ArrayIntoIter;
 use builtin::*;
+use hidden_unicode_codepoints::*;
 use internal::*;
 use methods::*;
 use non_ascii_idents::*;
@@ -128,6 +130,7 @@ macro_rules! early_lint_passes {
                 DeprecatedAttr: DeprecatedAttr::new(),
                 WhileTrue: WhileTrue,
                 NonAsciiIdents: NonAsciiIdents,
+                HiddenUnicodeCodepoints: HiddenUnicodeCodepoints,
                 IncompleteFeatures: IncompleteFeatures,
                 RedundantSemicolons: RedundantSemicolons,
                 UnusedDocComment: UnusedDocComment,
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 8fb678e2d20..e9cd30a058f 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -3416,3 +3416,31 @@ declare_lint! {
     Warn,
     "`break` expression with label and unlabeled loop as value expression"
 }
+
+declare_lint! {
+    /// The `text_direction_codepoint_in_comment` lint detects Unicode codepoints in comments that
+    /// change the visual representation of text on screen in a way that does not correspond to
+    /// their on memory representation.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(text_direction_codepoint_in_comment)]
+    /// fn main() {
+    ///     println!("{:?}"); // '‮');
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Unicode allows changing the visual flow of text on screen in order to support scripts that
+    /// are written right-to-left, but a specially crafted comment can make code that will be
+    /// compiled appear to be part of a comment, depending on the software used to read the code.
+    /// To avoid potential problems or confusion, such as in CVE-2021-42574, by default we deny
+    /// their use.
+    pub TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
+    Deny,
+    "invisible directionality-changing codepoints in comment"
+}
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index f89d531b5ef..feac2a7cfa4 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -306,6 +306,7 @@ pub enum BuiltinLintDiagnostics {
     TrailingMacro(bool, Ident),
     BreakWithLabelAndLoop(Span),
     NamedAsmLabel(String),
+    UnicodeTextFlow(Span, String),
 }
 
 /// Lints that are buffered up early on in the `Session` before the
diff --git a/compiler/rustc_parse/Cargo.toml b/compiler/rustc_parse/Cargo.toml
index 1ca1a92252e..b67195e6e22 100644
--- a/compiler/rustc_parse/Cargo.toml
+++ b/compiler/rustc_parse/Cargo.toml
@@ -18,3 +18,4 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_ast = { path = "../rustc_ast" }
 unicode-normalization = "0.1.11"
+unicode-width = "0.1.4"
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 1e65cc27154..8e90f73b44e 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -4,7 +4,9 @@ use rustc_ast::tokenstream::{Spacing, TokenStream};
 use rustc_errors::{error_code, Applicability, DiagnosticBuilder, FatalError, PResult};
 use rustc_lexer::unescape::{self, Mode};
 use rustc_lexer::{Base, DocStyle, RawStrError};
-use rustc_session::lint::builtin::RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX;
+use rustc_session::lint::builtin::{
+    TEXT_DIRECTION_CODEPOINT_IN_COMMENT, RUST_2021_PREFIXES_INCOMPATIBLE_SYNTAX,
+};
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::{sym, Symbol};
@@ -129,6 +131,28 @@ impl<'a> StringReader<'a> {
             .struct_span_fatal(self.mk_sp(from_pos, to_pos), &format!("{}: {}", m, escaped_char(c)))
     }
 
+    /// Detect usages of Unicode codepoints changing the direction of the text on screen and loudly
+    /// complain about it.
+    fn lint_unicode_text_flow(&self, start: BytePos) {
+        // Opening delimiter of the length 2 is not included into the comment text.
+        let content_start = start + BytePos(2);
+        let content = self.str_from(content_start);
+        let span = self.mk_sp(start, self.pos);
+        const UNICODE_TEXT_FLOW_CHARS: &[char] = &[
+            '\u{202A}', '\u{202B}', '\u{202D}', '\u{202E}', '\u{2066}', '\u{2067}', '\u{2068}',
+            '\u{202C}', '\u{2069}',
+        ];
+        if content.contains(UNICODE_TEXT_FLOW_CHARS) {
+            self.sess.buffer_lint_with_diagnostic(
+                &TEXT_DIRECTION_CODEPOINT_IN_COMMENT,
+                span,
+                ast::CRATE_NODE_ID,
+                "unicode codepoint changing visible direction of text present in comment",
+                BuiltinLintDiagnostics::UnicodeTextFlow(span, content.to_string()),
+            );
+        }
+    }
+
     /// Turns simple `rustc_lexer::TokenKind` enum into a rich
     /// `rustc_ast::TokenKind`. This turns strings into interned
     /// symbols and runs additional validation.
@@ -136,7 +160,12 @@ impl<'a> StringReader<'a> {
         Some(match token {
             rustc_lexer::TokenKind::LineComment { doc_style } => {
                 // Skip non-doc comments
-                let doc_style = doc_style?;
+                let doc_style = if let Some(doc_style) = doc_style {
+                    doc_style
+                } else {
+                    self.lint_unicode_text_flow(start);
+                    return None;
+                };
 
                 // Opening delimiter of the length 3 is not included into the symbol.
                 let content_start = start + BytePos(3);
@@ -158,7 +187,12 @@ impl<'a> StringReader<'a> {
                 }
 
                 // Skip non-doc comments
-                let doc_style = doc_style?;
+                let doc_style = if let Some(doc_style) = doc_style {
+                    doc_style
+                } else {
+                    self.lint_unicode_text_flow(start);
+                    return None;
+                };
 
                 // Opening delimiter of the length 3 and closing delimiter of the length 2
                 // are not included into the symbol.
diff --git a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
index aa6b424ce2b..e26d094a0e2 100644
--- a/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
+++ b/compiler/rustc_parse/src/lexer/unescape_error_reporting.rs
@@ -154,12 +154,17 @@ pub(crate) fn emit_unescape_error(
             assert!(mode.is_bytes());
             let (c, span) = last_char();
             let mut err = handler.struct_span_err(span, "non-ASCII character in byte constant");
-            err.span_label(span, "byte constant must be ASCII");
+            let postfix = if unicode_width::UnicodeWidthChar::width(c).unwrap_or(1) == 0 {
+                format!(" but is {:?}", c)
+            } else {
+                String::new()
+            };
+            err.span_label(span, &format!("byte constant must be ASCII{}", postfix));
             if (c as u32) <= 0xFF {
                 err.span_suggestion(
                     span,
                     &format!(
-                        "if you meant to use the unicode code point for '{}', use a \\xHH escape",
+                        "if you meant to use the unicode code point for {:?}, use a \\xHH escape",
                         c
                     ),
                     format!("\\x{:X}", c as u32),
@@ -173,7 +178,7 @@ pub(crate) fn emit_unescape_error(
                 err.span_suggestion(
                     span,
                     &format!(
-                        "if you meant to use the UTF-8 encoding of '{}', use \\xHH escapes",
+                        "if you meant to use the UTF-8 encoding of {:?}, use \\xHH escapes",
                         c
                     ),
                     utf8.as_bytes()
@@ -187,10 +192,15 @@ pub(crate) fn emit_unescape_error(
         }
         EscapeError::NonAsciiCharInByteString => {
             assert!(mode.is_bytes());
-            let (_c, span) = last_char();
+            let (c, span) = last_char();
+            let postfix = if unicode_width::UnicodeWidthChar::width(c).unwrap_or(1) == 0 {
+                format!(" but is {:?}", c)
+            } else {
+                String::new()
+            };
             handler
                 .struct_span_err(span, "raw byte string must be ASCII")
-                .span_label(span, "must be ASCII")
+                .span_label(span, &format!("must be ASCII{}", postfix))
                 .emit();
         }
         EscapeError::OutOfRangeHexEscape => {
diff --git a/src/test/rustdoc/intra-doc/prim-methods-external-core.rs b/src/test/rustdoc/intra-doc/prim-methods-external-core.rs
index 9347d7bb428..34834583033 100644
--- a/src/test/rustdoc/intra-doc/prim-methods-external-core.rs
+++ b/src/test/rustdoc/intra-doc/prim-methods-external-core.rs
@@ -2,6 +2,7 @@
 // build-aux-docs
 // ignore-cross-compile
 // ignore-windows
+// ignore-macos
 
 #![deny(broken_intra_doc_links)]
 #![feature(no_core, lang_items)]
diff --git a/src/test/ui/parser/unicode-control-codepoints.rs b/src/test/ui/parser/unicode-control-codepoints.rs
new file mode 100644
index 00000000000..5af0b585a12
--- /dev/null
+++ b/src/test/ui/parser/unicode-control-codepoints.rs
@@ -0,0 +1,39 @@
+fn main() {
+    // if access_level != "us‫e‪r" { // Check if admin
+    //~^ ERROR unicode codepoint changing visible direction of text present in comment
+    println!("us\u{202B}e\u{202A}r");
+    println!("{:?}", r#"us\u{202B}e\u{202A}r"#);
+    println!("{:?}", b"us\u{202B}e\u{202A}r");
+    //~^ ERROR unicode escape in byte string
+    //~| ERROR unicode escape in byte string
+    println!("{:?}", br##"us\u{202B}e\u{202A}r"##);
+
+    println!("{:?}", "/*‮ } ⁦if isAdmin⁩ ⁦ begin admins only ");
+    //~^ ERROR unicode codepoint changing visible direction of text present in literal
+
+    println!("{:?}", r##"/*‮ } ⁦if isAdmin⁩ ⁦ begin admins only "##);
+    //~^ ERROR unicode codepoint changing visible direction of text present in literal
+    println!("{:?}", b"/*‮ } ⁦if isAdmin⁩ ⁦ begin admins only ");
+    //~^ ERROR non-ASCII character in byte constant
+    //~| ERROR non-ASCII character in byte constant
+    //~| ERROR non-ASCII character in byte constant
+    //~| ERROR non-ASCII character in byte constant
+    println!("{:?}", br##"/*‮ } ⁦if isAdmin⁩ ⁦ begin admins only "##);
+    //~^ ERROR raw byte string must be ASCII
+    //~| ERROR raw byte string must be ASCII
+    //~| ERROR raw byte string must be ASCII
+    //~| ERROR raw byte string must be ASCII
+    println!("{:?}", '‮');
+    //~^ ERROR unicode codepoint changing visible direction of text present in literal
+}
+
+//"/*‮ } ⁦if isAdmin⁩ ⁦ begin admins only */"
+//~^ ERROR unicode codepoint changing visible direction of text present in comment
+
+/**  '‮'); */fn foo() {}
+//~^ ERROR unicode codepoint changing visible direction of text present in doc comment
+
+/**
+ *
+ *  '‮'); */fn bar() {}
+//~^^^ ERROR unicode codepoint changing visible direction of text present in doc comment
diff --git a/src/test/ui/parser/unicode-control-codepoints.stderr b/src/test/ui/parser/unicode-control-codepoints.stderr
new file mode 100644
index 00000000000..71509fe41a8
--- /dev/null
+++ b/src/test/ui/parser/unicode-control-codepoints.stderr
@@ -0,0 +1,192 @@
+error: unicode escape in byte string
+  --> $DIR/unicode-control-codepoints.rs:6:26
+   |
+LL |     println!("{:?}", b"us\u{202B}e\u{202A}r");
+   |                          ^^^^^^^^ unicode escape in byte string
+   |
+   = help: unicode escape sequences cannot be used as a byte or in a byte string
+
+error: unicode escape in byte string
+  --> $DIR/unicode-control-codepoints.rs:6:35
+   |
+LL |     println!("{:?}", b"us\u{202B}e\u{202A}r");
+   |                                   ^^^^^^^^ unicode escape in byte string
+   |
+   = help: unicode escape sequences cannot be used as a byte or in a byte string
+
+error: non-ASCII character in byte constant
+  --> $DIR/unicode-control-codepoints.rs:16:26
+   |
+LL |     println!("{:?}", b"/* } if isAdmin  begin admins only ");
+   |                          ^ byte constant must be ASCII but is '\u{202e}'
+   |
+help: if you meant to use the UTF-8 encoding of '\u{202e}', use \xHH escapes
+   |
+LL |     println!("{:?}", b"/*\xE2\x80\xAE } if isAdmin  begin admins only ");
+   |                          ~~~~~~~~~~~~
+
+error: non-ASCII character in byte constant
+  --> $DIR/unicode-control-codepoints.rs:16:30
+   |
+LL |     println!("{:?}", b"/* } if isAdmin  begin admins only ");
+   |                             ^ byte constant must be ASCII but is '\u{2066}'
+   |
+help: if you meant to use the UTF-8 encoding of '\u{2066}', use \xHH escapes
+   |
+LL |     println!("{:?}", b"/* } \xE2\x81\xA6if isAdmin  begin admins only ");
+   |                             ~~~~~~~~~~~~
+
+error: non-ASCII character in byte constant
+  --> $DIR/unicode-control-codepoints.rs:16:41
+   |
+LL |     println!("{:?}", b"/* } if isAdmin  begin admins only ");
+   |                                       ^ byte constant must be ASCII but is '\u{2069}'
+   |
+help: if you meant to use the UTF-8 encoding of '\u{2069}', use \xHH escapes
+   |
+LL |     println!("{:?}", b"/* } if isAdmin\xE2\x81\xA9  begin admins only ");
+   |                                       ~~~~~~~~~~~~
+
+error: non-ASCII character in byte constant
+  --> $DIR/unicode-control-codepoints.rs:16:43
+   |
+LL |     println!("{:?}", b"/* } if isAdmin  begin admins only ");
+   |                                        ^ byte constant must be ASCII but is '\u{2066}'
+   |
+help: if you meant to use the UTF-8 encoding of '\u{2066}', use \xHH escapes
+   |
+LL |     println!("{:?}", b"/* } if isAdmin \xE2\x81\xA6 begin admins only ");
+   |                                        ~~~~~~~~~~~~
+
+error: raw byte string must be ASCII
+  --> $DIR/unicode-control-codepoints.rs:21:29
+   |
+LL |     println!("{:?}", br##"/* } if isAdmin  begin admins only "##);
+   |                             ^ must be ASCII but is '\u{202e}'
+
+error: raw byte string must be ASCII
+  --> $DIR/unicode-control-codepoints.rs:21:33
+   |
+LL |     println!("{:?}", br##"/* } if isAdmin  begin admins only "##);
+   |                                ^ must be ASCII but is '\u{2066}'
+
+error: raw byte string must be ASCII
+  --> $DIR/unicode-control-codepoints.rs:21:44
+   |
+LL |     println!("{:?}", br##"/* } if isAdmin  begin admins only "##);
+   |                                          ^ must be ASCII but is '\u{2069}'
+
+error: raw byte string must be ASCII
+  --> $DIR/unicode-control-codepoints.rs:21:46
+   |
+LL |     println!("{:?}", br##"/* } if isAdmin  begin admins only "##);
+   |                                           ^ must be ASCII but is '\u{2066}'
+
+error: unicode codepoint changing visible direction of text present in comment
+  --> $DIR/unicode-control-codepoints.rs:2:5
+   |
+LL |     // if access_level != "user" { // Check if admin
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^--^^^^^^^^^^^^^^^^^^^^^
+   |     |                        ||
+   |     |                        |'\u{202a}'
+   |     |                        '\u{202b}'
+   |     this comment contains invisible unicode text flow control codepoints
+   |
+   = note: `#[deny(text_direction_codepoint_in_comment)]` on by default
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = help: if their presence wasn't intentional, you can remove them
+
+error: unicode codepoint changing visible direction of text present in comment
+  --> $DIR/unicode-control-codepoints.rs:30:1
+   |
+LL | //"/* } if isAdmin  begin admins only */"
+   | ^^^^^-^^-^^^^^^^^^--^^^^^^^^^^^^^^^^^^^^^
+   | |    |  |         ||
+   | |    |  |         |'\u{2066}'
+   | |    |  |         '\u{2069}'
+   | |    |  '\u{2066}'
+   | |    '\u{202e}'
+   | this comment contains invisible unicode text flow control codepoints
+   |
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = help: if their presence wasn't intentional, you can remove them
+
+error: unicode codepoint changing visible direction of text present in literal
+  --> $DIR/unicode-control-codepoints.rs:11:22
+   |
+LL |     println!("{:?}", "/* } if isAdmin  begin admins only ");
+   |                      ^^^-^^-^^^^^^^^^--^^^^^^^^^^^^^^^^^^^
+   |                      |  |  |         ||
+   |                      |  |  |         |'\u{2066}'
+   |                      |  |  |         '\u{2069}'
+   |                      |  |  '\u{2066}'
+   |                      |  '\u{202e}'
+   |                      this literal contains invisible unicode text flow control codepoints
+   |
+   = note: `#[deny(text_direction_codepoint_in_literal)]` on by default
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = help: if their presence wasn't intentional, you can remove them
+help: if you want to keep them but make them visible in your source code, you can escape them
+   |
+LL |     println!("{:?}", "/*\u{202e} } \u{2066}if isAdmin\u{2069} \u{2066} begin admins only ");
+   |                         ~~~~~~~~   ~~~~~~~~          ~~~~~~~~ ~~~~~~~~
+
+error: unicode codepoint changing visible direction of text present in literal
+  --> $DIR/unicode-control-codepoints.rs:14:22
+   |
+LL |     println!("{:?}", r##"/* } if isAdmin  begin admins only "##);
+   |                      ^^^^^^-^^-^^^^^^^^^--^^^^^^^^^^^^^^^^^^^^^
+   |                      |     |  |         ||
+   |                      |     |  |         |'\u{2066}'
+   |                      |     |  |         '\u{2069}'
+   |                      |     |  '\u{2066}'
+   |                      |     '\u{202e}'
+   |                      this literal contains invisible unicode text flow control codepoints
+   |
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = help: if their presence wasn't intentional, you can remove them
+help: if you want to keep them but make them visible in your source code, you can escape them
+   |
+LL |     println!("{:?}", r##"/*\u{202e} } \u{2066}if isAdmin\u{2069} \u{2066} begin admins only "##);
+   |                            ~~~~~~~~   ~~~~~~~~          ~~~~~~~~ ~~~~~~~~
+
+error: unicode codepoint changing visible direction of text present in literal
+  --> $DIR/unicode-control-codepoints.rs:26:22
+   |
+LL |     println!("{:?}", '');
+   |                      ^-
+   |                      ||
+   |                      |'\u{202e}'
+   |                      this literal contains an invisible unicode text flow control codepoint
+   |
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = help: if their presence wasn't intentional, you can remove them
+help: if you want to keep them but make them visible in your source code, you can escape them
+   |
+LL |     println!("{:?}", '\u{202e}');
+   |                       ~~~~~~~~
+
+error: unicode codepoint changing visible direction of text present in doc comment
+  --> $DIR/unicode-control-codepoints.rs:33:1
+   |
+LL | /**  ''); */fn foo() {}
+   | ^^^^^^^^^^^^ this doc comment contains an invisible unicode text flow control codepoint
+   |
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = note: if their presence wasn't intentional, you can remove them
+   = note: if you want to keep them but make them visible in your source code, you can escape them: '\u{202e}'
+
+error: unicode codepoint changing visible direction of text present in doc comment
+  --> $DIR/unicode-control-codepoints.rs:36:1
+   |
+LL | / /**
+LL | |  *
+LL | |  *  ''); */fn bar() {}
+   | |___________^ this doc comment contains an invisible unicode text flow control codepoint
+   |
+   = note: these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+   = note: if their presence wasn't intentional, you can remove them
+   = note: if you want to keep them but make them visible in your source code, you can escape them: '\u{202e}'
+
+error: aborting due to 17 previous errors
+
diff --git a/src/version b/src/version
index 3ebf789f5a8..43c989b5531 100644
--- a/src/version
+++ b/src/version
@@ -1 +1 @@
-1.56.0
+1.56.1