Auto merge of #14836 - Veykril:rustc-lexer, r=Veykril

internal: Bump rustc_lexer

26 files changed, 134 insertions, 73 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 4b22a58e568..7980823a854 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1193,7 +1193,7 @@ dependencies = [
  "drop_bomb",
  "expect-test",
  "limit",
- "rustc-ap-rustc_lexer",
+ "ra-ap-rustc_lexer",
  "sourcegen",
  "stdx",
 ]
@@ -1397,6 +1397,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "ra-ap-rustc_lexer"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1c145702ed3f237918e512685185dc8a4d0edc3a5326c63d20361d8ba9b45b3"
+dependencies = [
+ "unic-emoji-char",
+ "unicode-xid",
+]
+
+[[package]]
 name = "rayon"
 version = "1.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1525,15 +1535,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "rustc-ap-rustc_lexer"
-version = "727.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f40f26e7abdcd3b982f36c09a634cc6187988fbf6ec466c91f8d30a12ac0237"
-dependencies = [
- "unicode-xid",
-]
-
-[[package]]
 name = "rustc-demangle"
 version = "0.1.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1753,9 +1754,9 @@ dependencies = [
  "proc-macro2",
  "profile",
  "quote",
+ "ra-ap-rustc_lexer",
  "rayon",
  "rowan",
- "rustc-ap-rustc_lexer",
  "rustc-hash",
  "smol_str",
  "sourcegen",
@@ -1999,6 +2000,47 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a3e5df347f0bf3ec1d670aad6ca5c6a1859cd9ea61d2113125794654ccced68f"
 
 [[package]]
+name = "unic-char-property"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a8c57a407d9b6fa02b4795eb81c5b6652060a15a7903ea981f3d723e6c0be221"
+dependencies = [
+ "unic-char-range",
+]
+
+[[package]]
+name = "unic-char-range"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0398022d5f700414f6b899e10b8348231abf9173fa93144cbc1a43b9793c1fbc"
+
+[[package]]
+name = "unic-common"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "80d7ff825a6a654ee85a63e80f92f054f904f21e7d12da4e22f9834a4aaa35bc"
+
+[[package]]
+name = "unic-emoji-char"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b07221e68897210270a38bde4babb655869637af0f69407f96053a34f76494d"
+dependencies = [
+ "unic-char-property",
+ "unic-char-range",
+ "unic-ucd-version",
+]
+
+[[package]]
+name = "unic-ucd-version"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96bd2f2237fe450fcd0a1d2f5f4e91711124f7857ba2e964247776ebeeb7b0c4"
+dependencies = [
+ "unic-common",
+]
+
+[[package]]
 name = "unicase"
 version = "2.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.toml b/Cargo.toml
index c7b0228e331..513a769ca17 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -89,3 +89,5 @@ text-size = "1.1.0"
 serde = { version = "=1.0.156", features = ["derive"] }
 serde_json = "1.0.94"
 triomphe = { version = "0.1.8", default-features = false, features = ["std"] }
+
+rustc_lexer = { version = "0.1.0", package = "ra-ap-rustc_lexer" }
diff --git a/crates/parser/Cargo.toml b/crates/parser/Cargo.toml
index 6e962abd754..09e62c35278 100644
--- a/crates/parser/Cargo.toml
+++ b/crates/parser/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 
 [dependencies]
 drop_bomb = "0.1.5"
-rustc_lexer = { version = "727.0.0", package = "rustc-ap-rustc_lexer" }
+rustc_lexer.workspace = true
 
 limit.workspace = true
 
diff --git a/crates/parser/src/lexed_str.rs b/crates/parser/src/lexed_str.rs
index 100deff462d..ace6985a583 100644
--- a/crates/parser/src/lexed_str.rs
+++ b/crates/parser/src/lexed_str.rs
@@ -36,7 +36,7 @@ impl<'a> LexedStr<'a> {
         };
 
         for token in rustc_lexer::tokenize(&text[conv.offset..]) {
-            let token_text = &text[conv.offset..][..token.len];
+            let token_text = &text[conv.offset..][..token.len as usize];
 
             conv.extend_token(&token.kind, token_text);
         }
@@ -49,8 +49,8 @@ impl<'a> LexedStr<'a> {
             return None;
         }
 
-        let token = rustc_lexer::first_token(text);
-        if token.len != text.len() {
+        let token = rustc_lexer::tokenize(text).next()?;
+        if token.len as usize != text.len() {
             return None;
         }
 
@@ -175,6 +175,10 @@ impl<'a> Converter<'a> {
                 rustc_lexer::TokenKind::Ident => {
                     SyntaxKind::from_keyword(token_text).unwrap_or(IDENT)
                 }
+                rustc_lexer::TokenKind::InvalidIdent => {
+                    err = "Ident contains invalid characters";
+                    IDENT
+                }
 
                 rustc_lexer::TokenKind::RawIdent => IDENT,
                 rustc_lexer::TokenKind::Literal { kind, .. } => {
@@ -221,6 +225,7 @@ impl<'a> Converter<'a> {
                     err = "unknown literal prefix";
                     IDENT
                 }
+                rustc_lexer::TokenKind::Eof => EOF,
             }
         };
 
@@ -268,35 +273,30 @@ impl<'a> Converter<'a> {
                 }
                 BYTE_STRING
             }
-            rustc_lexer::LiteralKind::RawStr { err: raw_str_err, .. } => {
-                if let Some(raw_str_err) = raw_str_err {
-                    err = match raw_str_err {
-                        rustc_lexer::RawStrError::InvalidStarter { .. } => "Missing `\"` symbol after `#` symbols to begin the raw string literal",
-                        rustc_lexer::RawStrError::NoTerminator { expected, found, .. } => if expected == found {
-                            "Missing trailing `\"` to terminate the raw string literal"
-                        } else {
-                            "Missing trailing `\"` with `#` symbols to terminate the raw string literal"
-                        },
-                        rustc_lexer::RawStrError::TooManyDelimiters { .. } => "Too many `#` symbols: raw strings may be delimited by up to 65535 `#` symbols",
-                    };
-                };
+            rustc_lexer::LiteralKind::CStr { terminated } => {
+                if !terminated {
+                    err = "Missing trailing `\"` symbol to terminate the string literal";
+                }
                 STRING
             }
-            rustc_lexer::LiteralKind::RawByteStr { err: raw_str_err, .. } => {
-                if let Some(raw_str_err) = raw_str_err {
-                    err = match raw_str_err {
-                        rustc_lexer::RawStrError::InvalidStarter { .. } => "Missing `\"` symbol after `#` symbols to begin the raw byte string literal",
-                        rustc_lexer::RawStrError::NoTerminator { expected, found, .. } => if expected == found {
-                            "Missing trailing `\"` to terminate the raw byte string literal"
-                        } else {
-                            "Missing trailing `\"` with `#` symbols to terminate the raw byte string literal"
-                        },
-                        rustc_lexer::RawStrError::TooManyDelimiters { .. } => "Too many `#` symbols: raw byte strings may be delimited by up to 65535 `#` symbols",
-                    };
-                };
-
+            rustc_lexer::LiteralKind::RawStr { n_hashes } => {
+                if n_hashes.is_none() {
+                    err = "Invalid raw string literal";
+                }
+                STRING
+            }
+            rustc_lexer::LiteralKind::RawByteStr { n_hashes } => {
+                if n_hashes.is_none() {
+                    err = "Invalid raw string literal";
+                }
                 BYTE_STRING
             }
+            rustc_lexer::LiteralKind::RawCStr { n_hashes } => {
+                if n_hashes.is_none() {
+                    err = "Invalid raw string literal";
+                }
+                STRING
+            }
         };
 
         let err = if err.is_empty() { None } else { Some(err) };
diff --git a/crates/parser/src/syntax_kind/generated.rs b/crates/parser/src/syntax_kind/generated.rs
index 2af6e1b9867..a8fbcfacf7e 100644
--- a/crates/parser/src/syntax_kind/generated.rs
+++ b/crates/parser/src/syntax_kind/generated.rs
@@ -117,6 +117,7 @@ pub enum SyntaxKind {
     BYTE,
     STRING,
     BYTE_STRING,
+    C_STRING,
     ERROR,
     IDENT,
     WHITESPACE,
@@ -379,7 +380,7 @@ impl SyntaxKind {
         )
     }
     pub fn is_literal(self) -> bool {
-        matches!(self, INT_NUMBER | FLOAT_NUMBER | CHAR | BYTE | STRING | BYTE_STRING)
+        matches!(self, INT_NUMBER | FLOAT_NUMBER | CHAR | BYTE | STRING | BYTE_STRING | C_STRING)
     }
     pub fn from_keyword(ident: &str) -> Option<SyntaxKind> {
         let kw = match ident {
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_at_eof.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_at_eof.rast
index 6ec1780c30b..cab02d38af2 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_at_eof.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_at_eof.rast
@@ -1 +1 @@
-BYTE_STRING "br##\"" error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\"" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ascii_escape.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ascii_escape.rast
index d65f1bb2ff0..0486a1e8e1d 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ascii_escape.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ascii_escape.rast
@@ -1 +1 @@
-BYTE_STRING "br##\"\\x7f" error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\"\\x7f" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ferris.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ferris.rast
index 0f9e0a1657a..41e3455c1f3 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ferris.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_ferris.rast
@@ -1 +1 @@
-BYTE_STRING "br##\"🦀" error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\"🦀" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash.rast
index 202dcd2d43e..a11208a81fe 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash.rast
@@ -1 +1 @@
-BYTE_STRING "br##\"\\" error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\"\\" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash_n.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash_n.rast
index d45485b529e..10a47ab8447 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash_n.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_slash_n.rast
@@ -1 +1 @@
-BYTE_STRING "br##\"\\n" error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\"\\n" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_space.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_space.rast
index 1bfabbc3ab6..b41ea3a1701 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_space.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_space.rast
@@ -1 +1 @@
-BYTE_STRING "br##\" " error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\" " error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_unicode_escape.rast b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_unicode_escape.rast
index 104ab8aaeef..63b8a5af809 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_unicode_escape.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_byte_string_with_unicode_escape.rast
@@ -1 +1 @@
-BYTE_STRING "br##\"\\u{20AA}" error: Missing trailing `"` with `#` symbols to terminate the raw byte string literal
+BYTE_STRING "br##\"\\u{20AA}" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_at_eof.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_at_eof.rast
index 71b20fd19db..096bb940315 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_at_eof.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_at_eof.rast
@@ -1 +1 @@
-STRING "r##\"" error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\"" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ascii_escape.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ascii_escape.rast
index dc106dd24a1..f0ad200fea5 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ascii_escape.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ascii_escape.rast
@@ -1 +1 @@
-STRING "r##\"\\x7f" error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\"\\x7f" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ferris.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ferris.rast
index 30ee029f656..bc5996d1e67 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ferris.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_ferris.rast
@@ -1 +1 @@
-STRING "r##\"🦀" error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\"🦀" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash.rast
index 8a6f6cc4366..b48ec5ddabb 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash.rast
@@ -1 +1 @@
-STRING "r##\"\\" error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\"\\" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash_n.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash_n.rast
index f46eff2516a..9f32f677766 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash_n.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_slash_n.rast
@@ -1 +1 @@
-STRING "r##\"\\n" error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\"\\n" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_space.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_space.rast
index 49b6afea45a..2804a43cf1f 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_space.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_space.rast
@@ -1 +1 @@
-STRING "r##\" " error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\" " error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_unicode_escape.rast b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_unicode_escape.rast
index d10d6d8e8c2..eb0a2d2da10 100644
--- a/crates/parser/test_data/lexer/err/unclosed_raw_string_with_unicode_escape.rast
+++ b/crates/parser/test_data/lexer/err/unclosed_raw_string_with_unicode_escape.rast
@@ -1 +1 @@
-STRING "r##\"\\u{20AA}" error: Missing trailing `"` with `#` symbols to terminate the raw string literal
+STRING "r##\"\\u{20AA}" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_at_eof.rast b/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_at_eof.rast
index cf942c92f3b..52a7f03b6f5 100644
--- a/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_at_eof.rast
+++ b/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_at_eof.rast
@@ -1 +1 @@
-BYTE_STRING "br##" error: Missing `"` symbol after `#` symbols to begin the raw byte string literal
+BYTE_STRING "br##" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_with_ascii.rast b/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_with_ascii.rast
index 042769c2756..da5550d4cc1 100644
--- a/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_with_ascii.rast
+++ b/crates/parser/test_data/lexer/err/unstarted_raw_byte_string_with_ascii.rast
@@ -1,4 +1,4 @@
-BYTE_STRING "br## " error: Missing `"` symbol after `#` symbols to begin the raw byte string literal
+BYTE_STRING "br## " error: Invalid raw string literal
 IDENT "I"
 WHITESPACE " "
 IDENT "lack"
diff --git a/crates/parser/test_data/lexer/err/unstarted_raw_string_at_eof.rast b/crates/parser/test_data/lexer/err/unstarted_raw_string_at_eof.rast
index 2f7c7529a95..50b962e77a4 100644
--- a/crates/parser/test_data/lexer/err/unstarted_raw_string_at_eof.rast
+++ b/crates/parser/test_data/lexer/err/unstarted_raw_string_at_eof.rast
@@ -1 +1 @@
-STRING "r##" error: Missing `"` symbol after `#` symbols to begin the raw string literal
+STRING "r##" error: Invalid raw string literal
diff --git a/crates/parser/test_data/lexer/err/unstarted_raw_string_with_ascii.rast b/crates/parser/test_data/lexer/err/unstarted_raw_string_with_ascii.rast
index 4a06b0abe74..1f484299af1 100644
--- a/crates/parser/test_data/lexer/err/unstarted_raw_string_with_ascii.rast
+++ b/crates/parser/test_data/lexer/err/unstarted_raw_string_with_ascii.rast
@@ -1,4 +1,4 @@
-STRING "r## " error: Missing `"` symbol after `#` symbols to begin the raw string literal
+STRING "r## " error: Invalid raw string literal
 IDENT "I"
 WHITESPACE " "
 IDENT "lack"
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index ac5b3058b97..fb38d25ab54 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -17,13 +17,14 @@ cov-mark = "2.0.0-pre.1"
 either = "1.7.0"
 itertools = "0.10.5"
 rowan = "0.15.11"
-rustc_lexer = { version = "727.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 once_cell = "1.17.0"
 indexmap = "1.9.1"
 smol_str.workspace = true
 triomphe.workspace = true
 
+rustc_lexer.workspace = true
+
 parser.workspace = true
 profile.workspace = true
 stdx.workspace = true
diff --git a/crates/syntax/src/tests/ast_src.rs b/crates/syntax/src/tests/ast_src.rs
index caef6a79539..c5783b91a0f 100644
--- a/crates/syntax/src/tests/ast_src.rs
+++ b/crates/syntax/src/tests/ast_src.rs
@@ -71,7 +71,7 @@ pub(crate) const KINDS_SRC: KindsSrc<'_> = KindsSrc {
         "super", "trait", "true", "try", "type", "unsafe", "use", "where", "while", "yield",
     ],
     contextual_keywords: &["auto", "default", "existential", "union", "raw", "macro_rules", "yeet"],
-    literals: &["INT_NUMBER", "FLOAT_NUMBER", "CHAR", "BYTE", "STRING", "BYTE_STRING"],
+    literals: &["INT_NUMBER", "FLOAT_NUMBER", "CHAR", "BYTE", "STRING", "BYTE_STRING", "C_STRING"],
     tokens: &["ERROR", "IDENT", "WHITESPACE", "LIFETIME_IDENT", "COMMENT", "SHEBANG"],
     nodes: &[
         "SOURCE_FILE",
diff --git a/crates/syntax/src/validation.rs b/crates/syntax/src/validation.rs
index 5ff01eb44e7..089ad74dadc 100644
--- a/crates/syntax/src/validation.rs
+++ b/crates/syntax/src/validation.rs
@@ -5,7 +5,7 @@
 mod block;
 
 use rowan::Direction;
-use rustc_lexer::unescape::{self, unescape_byte, unescape_char, unescape_literal, Mode};
+use rustc_lexer::unescape::{self, unescape_literal, Mode};
 
 use crate::{
     algo,
@@ -44,7 +44,7 @@ pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
     errors
 }
 
-fn rustc_unescape_error_to_string(err: unescape::EscapeError) -> &'static str {
+fn rustc_unescape_error_to_string(err: unescape::EscapeError) -> (&'static str, bool) {
     use unescape::EscapeError as EE;
 
     #[rustfmt::skip]
@@ -103,12 +103,15 @@ fn rustc_unescape_error_to_string(err: unescape::EscapeError) -> &'static str {
         EE::UnicodeEscapeInByte => {
             "Byte literals must not contain unicode escapes"
         }
-        EE::NonAsciiCharInByte | EE::NonAsciiCharInByteString => {
+        EE::NonAsciiCharInByte  => {
             "Byte literals must not contain non-ASCII characters"
         }
+        EE::UnskippedWhitespaceWarning => "Whitespace after this escape is not skipped",
+        EE::MultipleSkippedLinesWarning => "Multiple lines are skipped by this escape",
+
     };
 
-    err_message
+    (err_message, err.is_fatal())
 }
 
 fn validate_literal(literal: ast::Literal, acc: &mut Vec<SyntaxError>) {
@@ -121,9 +124,13 @@ fn validate_literal(literal: ast::Literal, acc: &mut Vec<SyntaxError>) {
     let text = token.text();
 
     // FIXME: lift this lambda refactor to `fn` (https://github.com/rust-lang/rust-analyzer/pull/2834#discussion_r366199205)
-    let mut push_err = |prefix_len, (off, err): (usize, unescape::EscapeError)| {
+    let mut push_err = |prefix_len, off, err: unescape::EscapeError| {
         let off = token.text_range().start() + TextSize::try_from(off + prefix_len).unwrap();
-        acc.push(SyntaxError::new_at_offset(rustc_unescape_error_to_string(err), off));
+        let (message, is_err) = rustc_unescape_error_to_string(err);
+        // FIXME: Emit lexer warnings
+        if is_err {
+            acc.push(SyntaxError::new_at_offset(message, off));
+        }
     };
 
     match literal.kind() {
@@ -132,7 +139,7 @@ fn validate_literal(literal: ast::Literal, acc: &mut Vec<SyntaxError>) {
                 if let Some(without_quotes) = unquote(text, 1, '"') {
                     unescape_literal(without_quotes, Mode::Str, &mut |range, char| {
                         if let Err(err) = char {
-                            push_err(1, (range.start, err));
+                            push_err(1, range.start, err);
                         }
                     });
                 }
@@ -143,20 +150,28 @@ fn validate_literal(literal: ast::Literal, acc: &mut Vec<SyntaxError>) {
                 if let Some(without_quotes) = unquote(text, 2, '"') {
                     unescape_literal(without_quotes, Mode::ByteStr, &mut |range, char| {
                         if let Err(err) = char {
-                            push_err(2, (range.start, err));
+                            push_err(1, range.start, err);
                         }
                     });
                 }
             }
         }
         ast::LiteralKind::Char(_) => {
-            if let Some(Err(e)) = unquote(text, 1, '\'').map(unescape_char) {
-                push_err(1, e);
+            if let Some(without_quotes) = unquote(text, 1, '\'') {
+                unescape_literal(without_quotes, Mode::Char, &mut |range, char| {
+                    if let Err(err) = char {
+                        push_err(1, range.start, err);
+                    }
+                });
             }
         }
         ast::LiteralKind::Byte(_) => {
-            if let Some(Err(e)) = unquote(text, 2, '\'').map(unescape_byte) {
-                push_err(2, e);
+            if let Some(without_quotes) = unquote(text, 2, '\'') {
+                unescape_literal(without_quotes, Mode::Byte, &mut |range, char| {
+                    if let Err(err) = char {
+                        push_err(2, range.start, err);
+                    }
+                });
             }
         }
         ast::LiteralKind::IntNumber(_)