Add early errors for escaped identifiers (#2546)

This Pull Request changes the following:

- Add early errors for escaped characters in object and class setters and getters.
- Add early errors for escaped characters in class `static`.
- Add early errors for escaped characters in `new.target`.
- Add early errors for legacy octal/decial escapes that are used in string literals before a `"use strict"` directive.

boa_parser/src/lexer/identifier.rs

@@ -1,6 +1,8 @@
 //! This module implements lexing for identifiers (foo, myvar, etc.) used in ECMAScript.
 
-use crate::lexer::{Cursor, Error, StringLiteral, Token, TokenKind, Tokenizer};
+use crate::lexer::{
+    token::ContainsEscapeSequence, Cursor, Error, StringLiteral, Token, TokenKind, Tokenizer,
+};
 use boa_ast::{Keyword, Position, Span};
 use boa_interner::Interner;
 use boa_profiler::Profiler;
@@ -71,7 +73,10 @@ impl<R> Tokenizer<R> for Identifier {
             Ok(Keyword::False) => TokenKind::BooleanLiteral(false),
             Ok(Keyword::Null) => TokenKind::NullLiteral,
             Ok(keyword) => TokenKind::Keyword((keyword, contains_escaped_chars)),
-            _ => TokenKind::identifier(interner.get_or_intern(identifier_name.as_str())),
+            _ => TokenKind::Identifier((
+                interner.get_or_intern(identifier_name.as_str()),
+                ContainsEscapeSequence(contains_escaped_chars),
+            )),
         };
 
         Ok(Token::new(token_kind, Span::new(start_pos, cursor.pos())))

boa_parser/src/lexer/string.rs

@@ -1,6 +1,6 @@
 //! Boa's lexing for ECMAScript string literals.
 
-use crate::lexer::{Cursor, Error, Token, TokenKind, Tokenizer};
+use crate::lexer::{token::EscapeSequence, Cursor, Error, Token, TokenKind, Tokenizer};
 use boa_ast::{Position, Span};
 use boa_interner::Interner;
 use boa_profiler::Profiler;
@@ -88,11 +88,11 @@ impl<R> Tokenizer<R> for StringLiteral {
     {
         let _timer = Profiler::global().start_event("StringLiteral", "Lexing");
 
-        let (lit, span) =
+        let (lit, span, escape_sequence) =
             Self::take_string_characters(cursor, start_pos, self.terminator, cursor.strict_mode())?;
 
         Ok(Token::new(
-            TokenKind::string_literal(interner.get_or_intern(&lit[..])),
+            TokenKind::string_literal(interner.get_or_intern(&lit[..]), escape_sequence),
             span,
         ))
     }
@@ -117,11 +117,13 @@ impl StringLiteral {
         start_pos: Position,
         terminator: StringTerminator,
         is_strict_mode: bool,
-    ) -> Result<(Vec<u16>, Span), Error>
+    ) -> Result<(Vec<u16>, Span, Option<EscapeSequence>), Error>
     where
         R: Read,
     {
         let mut buf = Vec::new();
+        let mut escape_sequence = None;
+
         loop {
             let ch_start_pos = cursor.pos();
             let ch = cursor.next_char()?;
@@ -133,12 +135,15 @@ impl StringLiteral {
                     let _timer =
                         Profiler::global().start_event("StringLiteral - escape sequence", "Lexing");
 
-                    if let Some(escape_value) = Self::take_escape_sequence_or_line_continuation(
-                        cursor,
-                        ch_start_pos,
-                        is_strict_mode,
-                        false,
-                    )? {
+                    if let Some((escape_value, escape)) =
+                        Self::take_escape_sequence_or_line_continuation(
+                            cursor,
+                            ch_start_pos,
+                            is_strict_mode,
+                            false,
+                        )?
+                    {
+                        escape_sequence = escape_sequence.or(escape);
                         buf.push_code_point(escape_value);
                     }
                 }
@@ -156,15 +161,15 @@ impl StringLiteral {
             }
         }
 
-        Ok((buf, Span::new(start_pos, cursor.pos())))
+        Ok((buf, Span::new(start_pos, cursor.pos()), escape_sequence))
     }
 
     pub(super) fn take_escape_sequence_or_line_continuation<R>(
         cursor: &mut Cursor<R>,
         start_pos: Position,
         is_strict_mode: bool,
         is_template_literal: bool,
-    ) -> Result<Option<u32>, Error>
+    ) -> Result<Option<(u32, Option<EscapeSequence>)>, Error>
     where
         R: Read,
     {
@@ -176,25 +181,25 @@ impl StringLiteral {
         })?;
 
         let escape_value = match escape_ch {
-            0x0062 /* b */ => Some(0x0008 /* <BS> */),
-            0x0074 /* t */ => Some(0x0009 /* <HT> */),
-            0x006E /* n */ => Some(0x000A /* <LF> */),
-            0x0076 /* v */ => Some(0x000B /* <VT> */),
-            0x0066 /* f */ => Some(0x000C /* <FF> */),
-            0x0072 /* r */ => Some(0x000D /* <CR> */),
-            0x0022 /* " */ => Some(0x0022 /* " */),
-            0x0027 /* ' */ => Some(0x0027 /* ' */),
-            0x005C /* \ */ => Some(0x005C /* \ */),
+            0x0062 /* b */ => Some((0x0008 /* <BS> */, None)),
+            0x0074 /* t */ => Some((0x0009 /* <HT> */, None)),
+            0x006E /* n */ => Some((0x000A /* <LF> */, None)),
+            0x0076 /* v */ => Some((0x000B /* <VT> */, None)),
+            0x0066 /* f */ => Some((0x000C /* <FF> */, None)),
+            0x0072 /* r */ => Some((0x000D /* <CR> */, None)),
+            0x0022 /* " */ => Some((0x0022 /* " */, None)),
+            0x0027 /* ' */ => Some((0x0027 /* ' */, None)),
+            0x005C /* \ */ => Some((0x005C /* \ */, None)),
             0x0030 /* 0 */ if cursor
                 .peek()?
                 .filter(|next_byte| (b'0'..=b'9').contains(next_byte))
                 .is_none() =>
-                Some(0x0000 /* NULL */),
+                Some((0x0000 /* NULL */, None)),
             0x0078 /* x */ => {
-                Some(Self::take_hex_escape_sequence(cursor, start_pos)?)
+                Some((Self::take_hex_escape_sequence(cursor, start_pos)?, None))
             }
             0x0075 /* u */ => {
-                Some(Self::take_unicode_escape_sequence(cursor, start_pos)?)
+                Some((Self::take_unicode_escape_sequence(cursor, start_pos)?, None))
             }
             0x0038 /* 8 */ | 0x0039 /* 9 */ => {
                 // Grammar: NonOctalDecimalEscapeSequence
@@ -209,7 +214,7 @@ impl StringLiteral {
                         start_pos,
                     ));
                 }
-                    Some(escape_ch)
+                    Some((escape_ch, Some(EscapeSequence::NonOctalDecimal)))
             }
             _ if (0x0030..=0x0037 /* '0'..='7' */).contains(&escape_ch) => {
                 if is_template_literal {
@@ -226,10 +231,10 @@ impl StringLiteral {
                     ));
                 }
 
-                Some(Self::take_legacy_octal_escape_sequence(
+                Some((Self::take_legacy_octal_escape_sequence(
                     cursor,
                     escape_ch.try_into().expect("an ascii char must not fail to convert"),
-                )?)
+                )?, Some(EscapeSequence::LegacyOctal)))
             }
             _ if Self::is_line_terminator(escape_ch) => {
                 // Grammar: LineContinuation
@@ -238,7 +243,7 @@ impl StringLiteral {
                 None
             }
             _ => {
-                Some(escape_ch)
+                Some((escape_ch, None))
             }
         };
 

boa_parser/src/lexer/template.rs

@@ -60,7 +60,7 @@ impl TemplateString {
                         true,
                     )?;
 
-                    if let Some(escape_value) = escape_value {
+                    if let Some((escape_value, _)) = escape_value {
                         buf.push_code_point(escape_value);
                     }
                 }

boa_parser/src/lexer/tests.rs

@@ -2,8 +2,9 @@
 #![allow(clippy::indexing_slicing)]
 
 use crate::lexer::{
-    template::TemplateString, token::Numeric, Cursor, Error, Interner, Lexer, Position, Punctuator,
-    Read, Span, TokenKind,
+    template::TemplateString,
+    token::{ContainsEscapeSequence, EscapeSequence, Numeric},
+    Cursor, Error, Interner, Lexer, Position, Punctuator, Read, Span, TokenKind,
 };
 use boa_ast::Keyword;
 use boa_interner::Sym;
@@ -94,9 +95,18 @@ fn check_identifier() {
         TokenKind::identifier(
             interner.get_or_intern_static("x\u{200C}\u{200D}", utf16!("x\u{200C}\u{200D}")),
         ),
-        TokenKind::identifier(interner.get_or_intern_static("x", utf16!("x"))),
-        TokenKind::identifier(interner.get_or_intern_static("xx", utf16!("xx"))),
-        TokenKind::identifier(interner.get_or_intern_static("xxx", utf16!("xxx"))),
+        TokenKind::Identifier((
+            interner.get_or_intern_static("x", utf16!("x")),
+            ContainsEscapeSequence(true),
+        )),
+        TokenKind::Identifier((
+            interner.get_or_intern_static("xx", utf16!("xx")),
+            ContainsEscapeSequence(true),
+        )),
+        TokenKind::Identifier((
+            interner.get_or_intern_static("xxx", utf16!("xxx")),
+            ContainsEscapeSequence(true),
+        )),
     ];
 
     expect_tokens(&mut lexer, &expected, interner);
@@ -141,8 +151,8 @@ fn check_string() {
     let a_sym = interner.get_or_intern_static("aaa", utf16!("aaa"));
     let b_sym = interner.get_or_intern_static("bbb", utf16!("bbb"));
     let expected = [
-        TokenKind::string_literal(a_sym),
-        TokenKind::string_literal(b_sym),
+        TokenKind::string_literal(a_sym, None),
+        TokenKind::string_literal(b_sym, None),
     ];
 
     expect_tokens(&mut lexer, &expected, interner);
@@ -305,7 +315,7 @@ fn check_variable_definition_tokens() {
         TokenKind::Keyword((Keyword::Let, false)),
         TokenKind::identifier(a_sym),
         TokenKind::Punctuator(Punctuator::Assign),
-        TokenKind::string_literal(hello_sym),
+        TokenKind::string_literal(hello_sym, None),
         TokenKind::Punctuator(Punctuator::Semicolon),
     ];
 
@@ -943,7 +953,7 @@ fn string_unicode() {
 
     let sym = interner.get_or_intern_static("中文", utf16!("中文"));
     let expected = [
-        TokenKind::StringLiteral(sym),
+        TokenKind::StringLiteral((sym, None)),
         TokenKind::Punctuator(Punctuator::Semicolon),
     ];
 
@@ -957,7 +967,7 @@ fn string_unicode_escape_with_braces() {
 
     let sym =
         interner.get_or_intern_static("{\u{20ac}\u{a0}\u{a0}}", utf16!("{\u{20ac}\u{a0}\u{a0}}"));
-    let expected = [TokenKind::StringLiteral(sym)];
+    let expected = [TokenKind::StringLiteral((sym, None))];
 
     expect_tokens(&mut lexer, &expected, interner);
 
@@ -992,7 +1002,7 @@ fn string_unicode_escape_with_braces_2() {
     let interner = &mut Interner::default();
 
     let sym = interner.get_or_intern_static("\u{20ac}\u{a0}\u{a0}", utf16!("\u{20ac}\u{a0}\u{a0}"));
-    let expected = [TokenKind::StringLiteral(sym)];
+    let expected = [TokenKind::StringLiteral((sym, None))];
 
     expect_tokens(&mut lexer, &expected, interner);
 }
@@ -1005,7 +1015,7 @@ fn string_with_single_escape() {
     let interner = &mut Interner::default();
 
     let sym = interner.get_or_intern_static("Б", utf16!("Б"));
-    let expected = [TokenKind::StringLiteral(sym)];
+    let expected = [TokenKind::StringLiteral((sym, None))];
 
     expect_tokens(&mut lexer, &expected, interner);
 }
@@ -1027,7 +1037,10 @@ fn string_legacy_octal_escape() {
         let interner = &mut Interner::default();
 
         let sym = interner.get_or_intern(expected.encode_utf16().collect::<Vec<_>>().as_slice());
-        let expected_tokens = [TokenKind::StringLiteral(sym)];
+        let expected_tokens = [TokenKind::StringLiteral((
+            sym,
+            Some(EscapeSequence::LegacyOctal),
+        ))];
 
         expect_tokens(&mut lexer, &expected_tokens, interner);
     }
@@ -1057,7 +1070,7 @@ fn string_zero_escape() {
         let interner = &mut Interner::default();
 
         let sym = interner.get_or_intern(expected.encode_utf16().collect::<Vec<_>>().as_slice());
-        let expected_tokens = [TokenKind::StringLiteral(sym)];
+        let expected_tokens = [TokenKind::StringLiteral((sym, None))];
 
         expect_tokens(&mut lexer, &expected_tokens, interner);
     }
@@ -1072,7 +1085,10 @@ fn string_non_octal_decimal_escape() {
         let interner = &mut Interner::default();
 
         let sym = interner.get_or_intern(expected.encode_utf16().collect::<Vec<_>>().as_slice());
-        let expected_tokens = [TokenKind::StringLiteral(sym)];
+        let expected_tokens = [TokenKind::StringLiteral((
+            sym,
+            Some(EscapeSequence::NonOctalDecimal),
+        ))];
 
         expect_tokens(&mut lexer, &expected_tokens, interner);
     }
@@ -1101,7 +1117,7 @@ fn string_line_continuation() {
     let interner = &mut Interner::default();
 
     let sym = interner.get_or_intern_static("hello world", utf16!("hello world"));
-    let expected_tokens = [TokenKind::StringLiteral(sym)];
+    let expected_tokens = [TokenKind::StringLiteral((sym, None))];
 
     expect_tokens(&mut lexer, &expected_tokens, interner);
 }

boa_parser/src/lexer/token.rs

@@ -99,7 +99,7 @@ pub enum TokenKind {
     EOF,
 
     /// An identifier.
-    Identifier(Sym),
+    Identifier((Sym, ContainsEscapeSequence)),
 
     /// A private identifier.
     PrivateIdentifier(Sym),
@@ -117,7 +117,7 @@ pub enum TokenKind {
     Punctuator(Punctuator),
 
     /// A string literal.
-    StringLiteral(Sym),
+    StringLiteral((Sym, Option<EscapeSequence>)),
 
     /// A part of a template literal without substitution.
     TemplateNoSubstitution(TemplateString),
@@ -175,7 +175,7 @@ impl TokenKind {
     /// Creates an `Identifier` token type.
     #[must_use]
     pub const fn identifier(ident: Sym) -> Self {
-        Self::Identifier(ident)
+        Self::Identifier((ident, ContainsEscapeSequence(false)))
     }
 
     /// Creates a `NumericLiteral` token kind.
@@ -194,8 +194,8 @@ impl TokenKind {
 
     /// Creates a `StringLiteral` token type.
     #[must_use]
-    pub const fn string_literal(lit: Sym) -> Self {
-        Self::StringLiteral(lit)
+    pub const fn string_literal(lit: Sym, escape_sequence: Option<EscapeSequence>) -> Self {
+        Self::StringLiteral((lit, escape_sequence))
     }
 
     /// Creates a `TemplateMiddle` token type.
@@ -234,15 +234,15 @@ impl TokenKind {
         match *self {
             Self::BooleanLiteral(val) => val.to_string(),
             Self::EOF => "end of file".to_owned(),
-            Self::Identifier(ident) => interner.resolve_expect(ident).to_string(),
+            Self::Identifier((ident, _)) => interner.resolve_expect(ident).to_string(),
             Self::PrivateIdentifier(ident) => format!("#{}", interner.resolve_expect(ident)),
             Self::Keyword((word, _)) => word.to_string(),
             Self::NullLiteral => "null".to_owned(),
             Self::NumericLiteral(Numeric::Rational(num)) => num.to_string(),
             Self::NumericLiteral(Numeric::Integer(num)) => num.to_string(),
             Self::NumericLiteral(Numeric::BigInt(ref num)) => format!("{num}n"),
             Self::Punctuator(punc) => punc.to_string(),
-            Self::StringLiteral(lit) => interner.resolve_expect(lit).to_string(),
+            Self::StringLiteral((lit, _)) => interner.resolve_expect(lit).to_string(),
             Self::TemplateNoSubstitution(ts) | Self::TemplateMiddle(ts) => {
                 interner.resolve_expect(ts.as_raw()).to_string()
             }
@@ -258,3 +258,29 @@ impl TokenKind {
         }
     }
 }
+
+/// Indicates the type of an escape sequence.
+#[cfg_attr(feature = "deser", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum EscapeSequence {
+    /// A legacy escape sequence starting with `0` - `7`.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#prod-LegacyOctalEscapeSequence
+    LegacyOctal,
+
+    /// A octal escape sequence starting with `8` - `9`.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#prod-NonOctalDecimalEscapeSequence
+    NonOctalDecimal,
+}
+
+/// Indicates if an identifier contains an escape sequence.
+#[cfg_attr(feature = "deser", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct ContainsEscapeSequence(pub bool);