8 files changed, 159 insertions, 386 deletions

diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index f8f4b64c1..cc02c4be5 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -41,11 +41,9 @@ use crate::syntax_node::GreenNode;
 pub use crate::{
     algo::InsertPosition,
     ast::{AstNode, AstToken},
-    parsing::{
-        lex_single_syntax_kind, lex_single_valid_syntax_kind, tokenize, Token, TokenizeError,
-    },
+    parsing::{lex_single_syntax_kind, lex_single_valid_syntax_kind, tokenize, Token},
     ptr::{AstPtr, SyntaxNodePtr},
-    syntax_error::{Location, SyntaxError, SyntaxErrorKind},
+    syntax_error::SyntaxError,
     syntax_node::{
         Direction, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken, SyntaxTreeBuilder,
     },
@@ -117,7 +115,7 @@ impl Parse<SourceFile> {
     pub fn debug_dump(&self) -> String {
         let mut buf = format!("{:#?}", self.tree().syntax());
         for err in self.errors.iter() {
-            writeln!(buf, "error {:?}: {}", err.location(), err.kind()).unwrap();
+            writeln!(buf, "error {:?}: {}", err.range(), err.message()).unwrap();
         }
         buf
     }
diff --git a/crates/ra_syntax/src/parsing/lexer.rs b/crates/ra_syntax/src/parsing/lexer.rs
index f889e6a1d..f2684c852 100644
--- a/crates/ra_syntax/src/parsing/lexer.rs
+++ b/crates/ra_syntax/src/parsing/lexer.rs
@@ -2,7 +2,7 @@
 //! It is just a bridge to `rustc_lexer`.
 
 use crate::{
-    SyntaxError, SyntaxErrorKind,
+    SyntaxError,
     SyntaxKind::{self, *},
     TextRange, TextUnit,
 };
@@ -41,13 +41,13 @@ pub fn tokenize(text: &str) -> (Vec<Token>, Vec<SyntaxError>) {
         let token_len = TextUnit::from_usize(rustc_token.len);
         let token_range = TextRange::offset_len(TextUnit::from_usize(offset), token_len);
 
-        let (syntax_kind, error) =
+        let (syntax_kind, err_message) =
             rustc_token_kind_to_syntax_kind(&rustc_token.kind, &text[token_range]);
 
         tokens.push(Token { kind: syntax_kind, len: token_len });
 
-        if let Some(error) = error {
-            errors.push(SyntaxError::new(SyntaxErrorKind::TokenizeError(error), token_range));
+        if let Some(err_message) = err_message {
+            errors.push(SyntaxError::new(err_message, token_range));
         }
 
         offset += rustc_token.len;
@@ -94,61 +94,21 @@ fn lex_first_token(text: &str) -> Option<(Token, Option<SyntaxError>)> {
     }
 
     let rustc_token = rustc_lexer::first_token(text);
-    let (syntax_kind, error) = rustc_token_kind_to_syntax_kind(&rustc_token.kind, text);
+    let (syntax_kind, err_message) = rustc_token_kind_to_syntax_kind(&rustc_token.kind, text);
 
     let token = Token { kind: syntax_kind, len: TextUnit::from_usize(rustc_token.len) };
-    let error = error.map(|error| {
-        SyntaxError::new(
-            SyntaxErrorKind::TokenizeError(error),
-            TextRange::from_to(TextUnit::from(0), TextUnit::of_str(text)),
-        )
+    let optional_error = err_message.map(|err_message| {
+        SyntaxError::new(err_message, TextRange::from_to(0.into(), TextUnit::of_str(text)))
     });
 
-    Some((token, error))
-}
-
-// FIXME: simplify TokenizeError to `SyntaxError(String, TextRange)` as per @matklad advice:
-// https://github.com/rust-analyzer/rust-analyzer/pull/2911/files#r371175067
-
-/// Describes the values of `SyntaxErrorKind::TokenizeError` enum variant.
-/// It describes all the types of errors that may happen during the tokenization
-/// of Rust source.
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum TokenizeError {
-    /// Base prefix was provided, but there were no digits
-    /// after it, e.g. `0x`, `0b`.
-    EmptyInt,
-    /// Float exponent lacks digits e.g. `12.34e+`, `12.3E+`, `12e-`, `1_E-`,
-    EmptyExponent,
-
-    /// Block comment lacks trailing delimiter `*/`
-    UnterminatedBlockComment,
-    /// Character literal lacks trailing delimiter `'`
-    UnterminatedChar,
-    /// Characterish byte literal lacks trailing delimiter `'`
-    UnterminatedByte,
-    /// String literal lacks trailing delimiter `"`
-    UnterminatedString,
-    /// Byte string literal lacks trailing delimiter `"`
-    UnterminatedByteString,
-    /// Raw literal lacks trailing delimiter e.g. `"##`
-    UnterminatedRawString,
-    /// Raw byte string literal lacks trailing delimiter e.g. `"##`
-    UnterminatedRawByteString,
-
-    /// Raw string lacks a quote after the pound characters e.g. `r###`
-    UnstartedRawString,
-    /// Raw byte string lacks a quote after the pound characters e.g. `br###`
-    UnstartedRawByteString,
-
-    /// Lifetime starts with a number e.g. `'4ever`
-    LifetimeStartsWithNumber,
+    Some((token, optional_error))
 }
 
+/// Returns `SyntaxKind` and an optional tokenize error message.
 fn rustc_token_kind_to_syntax_kind(
     rustc_token_kind: &rustc_lexer::TokenKind,
     token_text: &str,
-) -> (SyntaxKind, Option<TokenizeError>) {
+) -> (SyntaxKind, Option<&'static str>) {
     // A note on an intended tradeoff:
     // We drop some useful infromation here (see patterns with double dots `..`)
     // Storing that info in `SyntaxKind` is not possible due to its layout requirements of
@@ -156,14 +116,15 @@ fn rustc_token_kind_to_syntax_kind(
 
     let syntax_kind = {
         use rustc_lexer::TokenKind as TK;
-        use TokenizeError as TE;
-
         match rustc_token_kind {
             TK::LineComment => COMMENT,
 
             TK::BlockComment { terminated: true } => COMMENT,
             TK::BlockComment { terminated: false } => {
-                return (COMMENT, Some(TE::UnterminatedBlockComment));
+                return (
+                    COMMENT,
+                    Some("Missing trailing `*/` symbols to terminate the block comment"),
+                );
             }
 
             TK::Whitespace => WHITESPACE,
@@ -181,7 +142,7 @@ fn rustc_token_kind_to_syntax_kind(
 
             TK::Lifetime { starts_with_number: false } => LIFETIME,
             TK::Lifetime { starts_with_number: true } => {
-                return (LIFETIME, Some(TE::LifetimeStartsWithNumber))
+                return (LIFETIME, Some("Lifetime name cannot start with a number"))
             }
 
             TK::Semi => SEMI,
@@ -217,57 +178,56 @@ fn rustc_token_kind_to_syntax_kind(
 
     return (syntax_kind, None);
 
-    fn match_literal_kind(kind: &rustc_lexer::LiteralKind) -> (SyntaxKind, Option<TokenizeError>) {
+    fn match_literal_kind(kind: &rustc_lexer::LiteralKind) -> (SyntaxKind, Option<&'static str>) {
         use rustc_lexer::LiteralKind as LK;
-        use TokenizeError as TE;
 
         #[rustfmt::skip]
         let syntax_kind = match *kind {
             LK::Int { empty_int: false, .. } => INT_NUMBER,
             LK::Int { empty_int: true, .. } => {
-                return (INT_NUMBER, Some(TE::EmptyInt))
+                return (INT_NUMBER, Some("Missing digits after the integer base prefix"))
             }
 
             LK::Float { empty_exponent: false, .. } => FLOAT_NUMBER,
             LK::Float { empty_exponent: true, .. } => {
-                return (FLOAT_NUMBER, Some(TE::EmptyExponent))
+                return (FLOAT_NUMBER, Some("Missing digits after the exponent symbol"))
             }
 
             LK::Char { terminated: true } => CHAR,
             LK::Char { terminated: false } => {
-                return (CHAR, Some(TE::UnterminatedChar))
+                return (CHAR, Some("Missing trailing `'` symbol to terminate the character literal"))
             }
 
             LK::Byte { terminated: true } => BYTE,
             LK::Byte { terminated: false } => {
-                return (BYTE, Some(TE::UnterminatedByte))
+                return (BYTE, Some("Missing trailing `'` symbol to terminate the byte literal"))
             }
 
             LK::Str { terminated: true } => STRING,
             LK::Str { terminated: false } => {
-                return (STRING, Some(TE::UnterminatedString))
+                return (STRING, Some("Missing trailing `\"` symbol to terminate the string literal"))
             }
 
 
             LK::ByteStr { terminated: true } => BYTE_STRING,
             LK::ByteStr { terminated: false } => {
-                return (BYTE_STRING, Some(TE::UnterminatedByteString))
+                return (BYTE_STRING, Some("Missing trailing `\"` symbol to terminate the byte string literal"))
             }
 
             LK::RawStr { started: true, terminated: true, .. } => RAW_STRING,
             LK::RawStr { started: true, terminated: false, .. } => {
-                return (RAW_STRING, Some(TE::UnterminatedRawString))
+                return (RAW_STRING, Some("Missing trailing `\"` with `#` symbols to terminate the raw string literal"))
             }
             LK::RawStr { started: false, .. } => {
-                return (RAW_STRING, Some(TE::UnstartedRawString))
+                return (RAW_STRING, Some("Missing `\"` symbol after `#` symbols to begin the raw string literal"))
             }
 
             LK::RawByteStr { started: true, terminated: true, .. } => RAW_BYTE_STRING,
             LK::RawByteStr { started: true, terminated: false, .. } => {
-                return (RAW_BYTE_STRING, Some(TE::UnterminatedRawByteString))
+                return (RAW_BYTE_STRING, Some("Missing trailing `\"` with `#` symbols to terminate the raw byte string literal"))
             }
             LK::RawByteStr { started: false, .. } => {
-                return (RAW_BYTE_STRING, Some(TE::UnstartedRawByteString))
+                return (RAW_BYTE_STRING, Some("Missing `\"` symbol after `#` symbols to begin the raw byte string literal"))
             }
         };
 
diff --git a/crates/ra_syntax/src/parsing/reparsing.rs b/crates/ra_syntax/src/parsing/reparsing.rs
index a86da0675..41a355ec7 100644
--- a/crates/ra_syntax/src/parsing/reparsing.rs
+++ b/crates/ra_syntax/src/parsing/reparsing.rs
@@ -87,7 +87,7 @@ fn reparse_block<'node>(
     edit: &AtomTextEdit,
 ) -> Option<(GreenNode, Vec<SyntaxError>, TextRange)> {
     let (node, reparser) = find_reparsable_node(root, edit.delete)?;
-    let text = get_text_after_edit(node.clone().into(), &edit);
+    let text = get_text_after_edit(node.clone().into(), edit);
 
     let (tokens, new_lexer_errors) = tokenize(&text);
     if !is_balanced(&tokens) {
@@ -162,20 +162,27 @@ fn is_balanced(tokens: &[Token]) -> bool {
 fn merge_errors(
     old_errors: Vec<SyntaxError>,
     new_errors: Vec<SyntaxError>,
-    old_range: TextRange,
+    range_before_reparse: TextRange,
     edit: &AtomTextEdit,
 ) -> Vec<SyntaxError> {
     let mut res = Vec::new();
-    for e in old_errors {
-        if e.offset() <= old_range.start() {
-            res.push(e)
-        } else if e.offset() >= old_range.end() {
-            res.push(e.add_offset(TextUnit::of_str(&edit.insert), edit.delete.len()));
+
+    for old_err in old_errors {
+        let old_err_range = *old_err.range();
+        // FIXME: make sure that .start() was here previously by a mistake
+        if old_err_range.end() <= range_before_reparse.start() {
+            res.push(old_err);
+        } else if old_err_range.start() >= range_before_reparse.end() {
+            let inserted_len = TextUnit::of_str(&edit.insert);
+            res.push(old_err.with_range((old_err_range + inserted_len) - edit.delete.len()));
+            // Note: extra parens are intentional to prevent uint underflow, HWAB (here was a bug)
         }
     }
-    for e in new_errors {
-        res.push(e.add_offset(old_range.start(), 0.into()));
-    }
+    res.extend(new_errors.into_iter().map(|new_err| {
+        // fighting borrow checker with a variable ;)
+        let offseted_range = *new_err.range() + range_before_reparse.start();
+        new_err.with_range(offseted_range)
+    }));
     res
 }
 
diff --git a/crates/ra_syntax/src/syntax_error.rs b/crates/ra_syntax/src/syntax_error.rs
index 7f9d36618..460552103 100644
--- a/crates/ra_syntax/src/syntax_error.rs
+++ b/crates/ra_syntax/src/syntax_error.rs
@@ -1,209 +1,47 @@
-//! FIXME: write short doc here
+//! Module that defines `SyntaxError`.
 
 use std::fmt;
 
-use ra_parser::ParseError;
-
-use crate::{validation::EscapeError, TextRange, TextUnit, TokenizeError};
+use crate::{TextRange, TextUnit};
 
+/// Represents the result of unsuccessful tokenization, parsing
+/// or semmantical analyzis.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct SyntaxError {
-    kind: SyntaxErrorKind,
-    location: Location,
-}
-
-// FIXME: Location should be just `Location(TextRange)`
-// TextUnit enum member just unnecessarily compicates things,
-// we should'n treat it specially, it just as a `TextRange { start: x, end: x + 1 }`
-// see `location_to_range()` in ra_ide/src/diagnostics
-#[derive(Clone, PartialEq, Eq, Hash)]
-pub enum Location {
-    Offset(TextUnit),
-    Range(TextRange),
-}
-
-impl From<TextUnit> for Location {
-    fn from(offset: TextUnit) -> Location {
-        Location::Offset(offset)
-    }
-}
-
-impl From<TextRange> for Location {
-    fn from(range: TextRange) -> Location {
-        Location::Range(range)
-    }
-}
-
-impl fmt::Debug for Location {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
-            Location::Offset(it) => fmt::Debug::fmt(it, f),
-            Location::Range(it) => fmt::Debug::fmt(it, f),
-        }
-    }
-}
+pub struct SyntaxError(String, TextRange);
+
+// FIXME: there was an unused SyntaxErrorKind previously (before this enum was removed)
+// It was introduced in this PR: https://github.com/rust-analyzer/rust-analyzer/pull/846/files#diff-827da9b03b8f9faa1bade5cdd44d5dafR95
+// but it was not removed by a mistake.
+//
+// So, we need to find a place where to stick validation for attributes in match clauses.
+// Code before refactor:
+// InvalidMatchInnerAttr => {
+//    write!(f, "Inner attributes are only allowed directly after the opening brace of the match expression")
+// }
 
 impl SyntaxError {
-    pub fn new<L: Into<Location>>(kind: SyntaxErrorKind, loc: L) -> SyntaxError {
-        SyntaxError { kind, location: loc.into() }
+    pub fn new(message: impl Into<String>, range: TextRange) -> Self {
+        Self(message.into(), range)
     }
-
-    pub fn kind(&self) -> SyntaxErrorKind {
-        self.kind.clone()
+    pub fn new_at_offset(message: impl Into<String>, offset: TextUnit) -> Self {
+        Self(message.into(), TextRange::offset_len(offset, 1.into()))
     }
 
-    pub fn location(&self) -> Location {
-        self.location.clone()
+    pub fn message(&self) -> &str {
+        &self.0
     }
-
-    pub fn offset(&self) -> TextUnit {
-        match self.location {
-            Location::Offset(offset) => offset,
-            Location::Range(range) => range.start(),
-        }
+    pub fn range(&self) -> &TextRange {
+        &self.1
     }
 
-    pub fn add_offset(mut self, plus_offset: TextUnit, minus_offset: TextUnit) -> SyntaxError {
-        self.location = match self.location {
-            Location::Range(range) => Location::Range(range + plus_offset - minus_offset),
-            Location::Offset(offset) => Location::Offset(offset + plus_offset - minus_offset),
-        };
-
+    pub fn with_range(mut self, range: TextRange) -> Self {
+        self.1 = range;
         self
     }
-
-    pub fn debug_dump(&self, acc: &mut impl fmt::Write) {
-        writeln!(acc, "error {:?}: {}", self.location(), self.kind()).unwrap();
-    }
 }
 
 impl fmt::Display for SyntaxError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.kind.fmt(f)
-    }
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum SyntaxErrorKind {
-    ParseError(ParseError),
-    EscapeError(EscapeError),
-    TokenizeError(TokenizeError),
-    // FIXME: the obvious pattern of this enum dictates that the following enum variants
-    // should be wrapped into something like `SemmanticError(SemmanticError)`
-    // or `ValidateError(ValidateError)` or `SemmanticValidateError(...)`
-    InvalidBlockAttr,
-    InvalidMatchInnerAttr,
-    InvalidTupleIndexFormat,
-    VisibilityNotAllowed,
-    InclusiveRangeMissingEnd,
-}
-
-impl fmt::Display for SyntaxErrorKind {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use self::SyntaxErrorKind::*;
-        match self {
-            InvalidBlockAttr => {
-                write!(f, "A block in this position cannot accept inner attributes")
-            }
-            InvalidMatchInnerAttr => {
-                write!(f, "Inner attributes are only allowed directly after the opening brace of the match expression")
-            }
-            InvalidTupleIndexFormat => {
-                write!(f, "Tuple (struct) field access is only allowed through decimal integers with no underscores or suffix")
-            }
-            ParseError(msg) => write!(f, "{}", msg.0),
-            EscapeError(err) => write!(f, "{}", err),
-            TokenizeError(err) => write!(f, "{}", err),
-            VisibilityNotAllowed => {
-                write!(f, "unnecessary visibility qualifier")
-            }
-            InclusiveRangeMissingEnd => {
-                write!(f, "An inclusive range must have an end expression")
-            }
-        }
-    }
-}
-
-impl fmt::Display for TokenizeError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        #[rustfmt::skip]
-        let msg = match self {
-            TokenizeError::EmptyInt => {
-                "Missing digits after the integer base prefix"
-            }
-            TokenizeError::EmptyExponent => {
-                "Missing digits after the exponent symbol"
-            }
-            TokenizeError::UnterminatedBlockComment => {
-                "Missing trailing `*/` symbols to terminate the block comment"
-            }
-            TokenizeError::UnterminatedChar => {
-                "Missing trailing `'` symbol to terminate the character literal"
-            }
-            TokenizeError::UnterminatedByte => {
-                "Missing trailing `'` symbol to terminate the byte literal"
-            }
-            TokenizeError::UnterminatedString => {
-                "Missing trailing `\"` symbol to terminate the string literal"
-            }
-            TokenizeError::UnterminatedByteString => {
-                "Missing trailing `\"` symbol to terminate the byte string literal"
-            }
-            TokenizeError::UnterminatedRawString => {
-                "Missing trailing `\"` with `#` symbols to terminate the raw string literal"
-            }
-            TokenizeError::UnterminatedRawByteString => {
-                "Missing trailing `\"` with `#` symbols to terminate the raw byte string literal"
-            }
-            TokenizeError::UnstartedRawString => {
-                "Missing `\"` symbol after `#` symbols to begin the raw string literal"
-            }
-            TokenizeError::UnstartedRawByteString => {
-                "Missing `\"` symbol after `#` symbols to begin the raw byte string literal"
-            }
-            TokenizeError::LifetimeStartsWithNumber => {
-                "Lifetime name cannot start with a number"
-            }
-        };
-        write!(f, "{}", msg)
-    }
-}
-
-impl fmt::Display for EscapeError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let msg = match self {
-            EscapeError::ZeroChars => "Empty literal",
-            EscapeError::MoreThanOneChar => "Literal should be one character long",
-            EscapeError::LoneSlash => "Character must be escaped: '\\'",
-            EscapeError::InvalidEscape => "Invalid escape sequence",
-            EscapeError::BareCarriageReturn => "Character must be escaped: '\r'",
-            EscapeError::EscapeOnlyChar => "Character must be escaped",
-            EscapeError::TooShortHexEscape => "Escape sequence should have two digits",
-            EscapeError::InvalidCharInHexEscape => "Escape sequence should be a hexadecimal number",
-            EscapeError::OutOfRangeHexEscape => "Escape sequence should be ASCII",
-            EscapeError::NoBraceInUnicodeEscape => "Invalid escape sequence",
-            EscapeError::InvalidCharInUnicodeEscape => "Invalid escape sequence",
-            EscapeError::EmptyUnicodeEscape => "Invalid escape sequence",
-            EscapeError::UnclosedUnicodeEscape => "Missing '}'",
-            EscapeError::LeadingUnderscoreUnicodeEscape => "Invalid escape sequence",
-            EscapeError::OverlongUnicodeEscape => {
-                "Unicode escape sequence should have at most 6 digits"
-            }
-            EscapeError::LoneSurrogateUnicodeEscape => {
-                "Unicode escape code should not be a surrogate"
-            }
-            EscapeError::OutOfRangeUnicodeEscape => {
-                "Unicode escape code should be at most 0x10FFFF"
-            }
-            EscapeError::UnicodeEscapeInByte => "Unicode escapes are not allowed in bytes",
-            EscapeError::NonAsciiCharInByte => "Non ASCII characters are not allowed in bytes",
-        };
-        write!(f, "{}", msg)
-    }
-}
-
-impl From<EscapeError> for SyntaxErrorKind {
-    fn from(err: EscapeError) -> Self {
-        SyntaxErrorKind::EscapeError(err)
+        self.0.fmt(f)
     }
 }
diff --git a/crates/ra_syntax/src/syntax_node.rs b/crates/ra_syntax/src/syntax_node.rs
index 7c2b18af3..251668996 100644
--- a/crates/ra_syntax/src/syntax_node.rs
+++ b/crates/ra_syntax/src/syntax_node.rs
@@ -6,15 +6,10 @@
 //! The *real* implementation is in the (language-agnostic) `rowan` crate, this
 //! module just wraps its API.
 
-use ra_parser::ParseError;
+pub(crate) use rowan::{GreenNode, GreenToken};
 use rowan::{GreenNodeBuilder, Language};
 
-use crate::{
-    syntax_error::{SyntaxError, SyntaxErrorKind},
-    Parse, SmolStr, SyntaxKind, TextUnit,
-};
-
-pub(crate) use rowan::{GreenNode, GreenToken};
+use crate::{Parse, SmolStr, SyntaxError, SyntaxKind, TextUnit};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum RustLanguage {}
@@ -73,8 +68,7 @@ impl SyntaxTreeBuilder {
         self.inner.finish_node()
     }
 
-    pub fn error(&mut self, error: ParseError, text_pos: TextUnit) {
-        let error = SyntaxError::new(SyntaxErrorKind::ParseError(error), text_pos);
-        self.errors.push(error)
+    pub fn error(&mut self, error: ra_parser::ParseError, text_pos: TextUnit) {
+        self.errors.push(SyntaxError::new_at_offset(error.0, text_pos))
     }
 }
diff --git a/crates/ra_syntax/src/tests.rs b/crates/ra_syntax/src/tests.rs
index fb22b9e54..2533d0c44 100644
--- a/crates/ra_syntax/src/tests.rs
+++ b/crates/ra_syntax/src/tests.rs
@@ -5,7 +5,7 @@ use std::{
 
 use test_utils::{collect_tests, dir_tests, project_dir, read_text};
 
-use crate::{fuzz, tokenize, Location, SourceFile, SyntaxError, TextRange, Token};
+use crate::{fuzz, tokenize, SourceFile, SyntaxError, Token};
 
 #[test]
 fn lexer_tests() {
@@ -128,25 +128,14 @@ fn dump_tokens_and_errors(tokens: &[Token], errors: &[SyntaxError], text: &str)
         writeln!(acc, "{:?} {} {:?}", token.kind, token_len, token_text).unwrap();
     }
     for err in errors {
-        let err_range = location_to_range(err.location());
         writeln!(
             acc,
             "> error{:?} token({:?}) msg({})",
-            err.location(),
-            &text[err_range],
-            err.kind()
+            err.range(),
+            &text[*err.range()],
+            err.message()
         )
         .unwrap();
     }
-    return acc;
-
-    // FIXME: copy-pasted this from `ra_ide/src/diagnostics.rs`
-    // `Location` will be refactored soon in new PR, see todos here:
-    // https://github.com/rust-analyzer/rust-analyzer/issues/223
-    fn location_to_range(location: Location) -> TextRange {
-        match location {
-            Location::Offset(offset) => TextRange::offset_len(offset, 1.into()),
-            Location::Range(range) => range,
-        }
-    }
+    acc
 }
diff --git a/crates/ra_syntax/src/validation.rs b/crates/ra_syntax/src/validation.rs
index 8a5f0e4b7..863859dca 100644
--- a/crates/ra_syntax/src/validation.rs
+++ b/crates/ra_syntax/src/validation.rs
@@ -5,92 +5,76 @@ mod block;
 use rustc_lexer::unescape;
 
 use crate::{
-    ast, match_ast, AstNode, SyntaxError, SyntaxErrorKind,
+    ast, match_ast, AstNode, SyntaxError,
     SyntaxKind::{BYTE, BYTE_STRING, CHAR, CONST_DEF, FN_DEF, INT_NUMBER, STRING, TYPE_ALIAS_DEF},
     SyntaxNode, SyntaxToken, TextUnit, T,
 };
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub enum EscapeError {
-    ZeroChars,
-    MoreThanOneChar,
-    LoneSlash,
-    InvalidEscape,
-    BareCarriageReturn,
-    EscapeOnlyChar,
-    TooShortHexEscape,
-    InvalidCharInHexEscape,
-    OutOfRangeHexEscape,
-    NoBraceInUnicodeEscape,
-    InvalidCharInUnicodeEscape,
-    EmptyUnicodeEscape,
-    UnclosedUnicodeEscape,
-    LeadingUnderscoreUnicodeEscape,
-    OverlongUnicodeEscape,
-    LoneSurrogateUnicodeEscape,
-    OutOfRangeUnicodeEscape,
-    UnicodeEscapeInByte,
-    NonAsciiCharInByte,
-}
+fn rustc_unescape_error_to_string(err: unescape::EscapeError) -> &'static str {
+    use unescape::EscapeError as EE;
 
-impl From<rustc_lexer::unescape::EscapeError> for EscapeError {
-    fn from(err: rustc_lexer::unescape::EscapeError) -> Self {
-        match err {
-            rustc_lexer::unescape::EscapeError::ZeroChars => EscapeError::ZeroChars,
-            rustc_lexer::unescape::EscapeError::MoreThanOneChar => EscapeError::MoreThanOneChar,
-            rustc_lexer::unescape::EscapeError::LoneSlash => EscapeError::LoneSlash,
-            rustc_lexer::unescape::EscapeError::InvalidEscape => EscapeError::InvalidEscape,
-            rustc_lexer::unescape::EscapeError::BareCarriageReturn
-            | rustc_lexer::unescape::EscapeError::BareCarriageReturnInRawString => {
-                EscapeError::BareCarriageReturn
-            }
-            rustc_lexer::unescape::EscapeError::EscapeOnlyChar => EscapeError::EscapeOnlyChar,
-            rustc_lexer::unescape::EscapeError::TooShortHexEscape => EscapeError::TooShortHexEscape,
-            rustc_lexer::unescape::EscapeError::InvalidCharInHexEscape => {
-                EscapeError::InvalidCharInHexEscape
-            }
-            rustc_lexer::unescape::EscapeError::OutOfRangeHexEscape => {
-                EscapeError::OutOfRangeHexEscape
-            }
-            rustc_lexer::unescape::EscapeError::NoBraceInUnicodeEscape => {
-                EscapeError::NoBraceInUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::InvalidCharInUnicodeEscape => {
-                EscapeError::InvalidCharInUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::EmptyUnicodeEscape => {
-                EscapeError::EmptyUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::UnclosedUnicodeEscape => {
-                EscapeError::UnclosedUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::LeadingUnderscoreUnicodeEscape => {
-                EscapeError::LeadingUnderscoreUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::OverlongUnicodeEscape => {
-                EscapeError::OverlongUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::LoneSurrogateUnicodeEscape => {
-                EscapeError::LoneSurrogateUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::OutOfRangeUnicodeEscape => {
-                EscapeError::OutOfRangeUnicodeEscape
-            }
-            rustc_lexer::unescape::EscapeError::UnicodeEscapeInByte => {
-                EscapeError::UnicodeEscapeInByte
-            }
-            rustc_lexer::unescape::EscapeError::NonAsciiCharInByte
-            | rustc_lexer::unescape::EscapeError::NonAsciiCharInByteString => {
-                EscapeError::NonAsciiCharInByte
-            }
+    #[rustfmt::skip]
+    let err_message = match err {
+        EE::ZeroChars => {
+            "Literal must not be empty"
         }
-    }
-}
+        EE::MoreThanOneChar => {
+            "Literal must be one character long"
+        }
+        EE::LoneSlash => {
+            "Character must be escaped: `\\`"
+        }
+        EE::InvalidEscape => {
+            "Invalid escape"
+        }
+        EE::BareCarriageReturn | EE::BareCarriageReturnInRawString => {
+            "Character must be escaped: `\r`"
+        }
+        EE::EscapeOnlyChar => {
+            "Escape character `\\` must be escaped itself"
+        }
+        EE::TooShortHexEscape => {
+            "ASCII hex escape code must have exactly two digits"
+        }
+        EE::InvalidCharInHexEscape => {
+            "ASCII hex escape code must contain only hex characters"
+        }
+        EE::OutOfRangeHexEscape => {
+            "ASCII hex escape code must be at most 0x7F"
+        }
+        EE::NoBraceInUnicodeEscape => {
+            "Missing `{` to begin the unicode escape"
+        }
+        EE::InvalidCharInUnicodeEscape => {
+            "Unicode escape must contain only hex characters and underscores"
+        }
+        EE::EmptyUnicodeEscape => {
+            "Unicode escape must not be empty"
+        }
+        EE::UnclosedUnicodeEscape => {
+            "Missing '}' to terminate the unicode escape"
+        }
+        EE::LeadingUnderscoreUnicodeEscape => {
+            "Unicode escape code must not begin with an underscore"
+        }
+        EE::OverlongUnicodeEscape => {
+            "Unicode escape code must have at most 6 digits"
+        }
+        EE::LoneSurrogateUnicodeEscape => {
+            "Unicode escape code must not be a surrogate"
+        }
+        EE::OutOfRangeUnicodeEscape => {
+            "Unicode escape code must be at most 0x10FFFF"
+        }
+        EE::UnicodeEscapeInByte => {
+            "Byte literals must not contain unicode escapes"
+        }
+        EE::NonAsciiCharInByte | EE::NonAsciiCharInByteString => {
+            "Byte literals must not contain non-ASCII characters"
+        }
+    };
 
-impl From<rustc_lexer::unescape::EscapeError> for SyntaxErrorKind {
-    fn from(err: rustc_lexer::unescape::EscapeError) -> Self {
-        SyntaxErrorKind::EscapeError(err.into())
-    }
+    err_message
 }
 
 pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
@@ -118,6 +102,7 @@ pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
 }
 
 fn validate_literal(literal: ast::Literal, acc: &mut Vec<SyntaxError>) {
+    // FIXME: move this function to outer scope (https://github.com/rust-analyzer/rust-analyzer/pull/2834#discussion_r366196658)
     fn unquote(text: &str, prefix_len: usize, end_delimiter: char) -> Option<&str> {
         text.rfind(end_delimiter).and_then(|end| text.get(prefix_len..end))
     }
@@ -125,9 +110,10 @@ fn validate_literal(literal: ast::Literal, acc: &mut Vec<SyntaxError>) {
     let token = literal.token();
     let text = token.text().as_str();
 
+    // FIXME: lift this lambda refactor to `fn` (https://github.com/rust-analyzer/rust-analyzer/pull/2834#discussion_r366199205)
     let mut push_err = |prefix_len, (off, err): (usize, unescape::EscapeError)| {
         let off = token.text_range().start() + TextUnit::from_usize(off + prefix_len);
-        acc.push(SyntaxError::new(err.into(), off));
+        acc.push(SyntaxError::new_at_offset(rustc_unescape_error_to_string(err), off));
     };
 
     match token.kind() {
@@ -195,7 +181,8 @@ fn validate_numeric_name(name_ref: Option<ast::NameRef>, errors: &mut Vec<Syntax
     if let Some(int_token) = int_token(name_ref) {
         if int_token.text().chars().any(|c| !c.is_digit(10)) {
             errors.push(SyntaxError::new(
-                SyntaxErrorKind::InvalidTupleIndexFormat,
+                "Tuple (struct) field access is only allowed through \
+                decimal integers with no underscores or suffix",
                 int_token.text_range(),
             ));
         }
@@ -215,21 +202,21 @@ fn validate_visibility(vis: ast::Visibility, errors: &mut Vec<SyntaxError>) {
         FN_DEF | CONST_DEF | TYPE_ALIAS_DEF => (),
         _ => return,
     }
+
     let impl_block = match parent.parent().and_then(|it| it.parent()).and_then(ast::ImplBlock::cast)
     {
         Some(it) => it,
         None => return,
     };
     if impl_block.target_trait().is_some() {
-        errors
-            .push(SyntaxError::new(SyntaxErrorKind::VisibilityNotAllowed, vis.syntax.text_range()))
+        errors.push(SyntaxError::new("Unnecessary visibility qualifier", vis.syntax.text_range()));
     }
 }
 
 fn validate_range_expr(expr: ast::RangeExpr, errors: &mut Vec<SyntaxError>) {
     if expr.op_kind() == Some(ast::RangeOp::Inclusive) && expr.end().is_none() {
         errors.push(SyntaxError::new(
-            SyntaxErrorKind::InclusiveRangeMissingEnd,
+            "An inclusive range must have an end expression",
             expr.syntax().text_range(),
         ));
     }
diff --git a/crates/ra_syntax/src/validation/block.rs b/crates/ra_syntax/src/validation/block.rs
index c85bbc1f4..8e962ab5b 100644
--- a/crates/ra_syntax/src/validation/block.rs
+++ b/crates/ra_syntax/src/validation/block.rs
@@ -1,9 +1,8 @@
-//! FIXME: write short doc here
+//! Logic for validating block expressions i.e. `ast::BlockExpr`.
 
 use crate::{
     ast::{self, AstNode, AttrsOwner},
     SyntaxError,
-    SyntaxErrorKind::*,
     SyntaxKind::*,
 };
 
@@ -15,10 +14,11 @@ pub(crate) fn validate_block_expr(expr: ast::BlockExpr, errors: &mut Vec<SyntaxE
         }
     }
     if let Some(block) = expr.block() {
-        errors.extend(
-            block
-                .attrs()
-                .map(|attr| SyntaxError::new(InvalidBlockAttr, attr.syntax().text_range())),
-        )
+        errors.extend(block.attrs().map(|attr| {
+            SyntaxError::new(
+                "A block in this position cannot accept inner attributes",
+                attr.syntax().text_range(),
+            )
+        }))
     }
 }