Support length for ByteStrings

I am not confident that my added byte string parsing is right.

crates/hir_def/src/body/lower.rs

@@ -1022,7 +1022,10 @@ impl From<ast::LiteralKind> for Literal {
                 let ty = lit.suffix().and_then(|it| BuiltinFloat::from_suffix(&it));
                 Literal::Float(Default::default(), ty)
             }
-            LiteralKind::ByteString(_) => Literal::ByteString(Default::default()),
+            LiteralKind::ByteString(bs) => {
+                let text = bs.value().map(Vec::from).unwrap_or_else(Default::default);
+                Literal::ByteString(text)
+            }
             LiteralKind::String(_) => Literal::String(Default::default()),
             LiteralKind::Byte => Literal::Uint(Default::default(), Some(BuiltinUint::U8)),
             LiteralKind::Bool(val) => Literal::Bool(val),

crates/hir_ty/src/infer/expr.rs

@@ -16,7 +16,7 @@ use stdx::always;
 use syntax::ast::RangeOp;
 
 use crate::{
-    autoderef, dummy_usize_const,
+    autoderef,
     lower::lower_to_chalk_mutability,
     mapping::from_chalk,
     method_resolution, op,
@@ -24,8 +24,9 @@ use crate::{
     static_lifetime, to_chalk_trait_id,
     traits::FnTrait,
     utils::{generics, Generics},
-    AdtId, Binders, CallableDefId, ConstValue, FnPointer, FnSig, FnSubst, InEnvironment, Interner,
-    ProjectionTyExt, Rawness, Scalar, Substitution, TraitRef, Ty, TyBuilder, TyExt, TyKind,
+    AdtId, Binders, CallableDefId, ConcreteConst, ConstValue, FnPointer, FnSig, FnSubst,
+    InEnvironment, Interner, ProjectionTyExt, Rawness, Scalar, Substitution, TraitRef, Ty,
+    TyBuilder, TyExt, TyKind,
 };
 
 use super::{
@@ -758,11 +759,18 @@ impl<'a> InferenceContext<'a> {
                     TyKind::Ref(Mutability::Not, static_lifetime(), TyKind::Str.intern(&Interner))
                         .intern(&Interner)
                 }
-                Literal::ByteString(..) => {
+                Literal::ByteString(bs) => {
                     let byte_type = TyKind::Scalar(Scalar::Uint(UintTy::U8)).intern(&Interner);
 
-                    let array_type =
-                        TyKind::Array(byte_type, dummy_usize_const()).intern(&Interner);
+                    let len = ConstData {
+                        ty: TyKind::Scalar(Scalar::Uint(UintTy::Usize)).intern(&Interner),
+                        value: ConstValue::Concrete(ConcreteConst {
+                            interned: ConstScalar::Usize(bs.len() as u64),
+                        }),
+                    }
+                    .intern(&Interner);
+
+                    let array_type = TyKind::Array(byte_type, len).intern(&Interner);
                     TyKind::Ref(Mutability::Not, static_lifetime(), array_type).intern(&Interner)
                 }
                 Literal::Char(..) => TyKind::Scalar(Scalar::Char).intern(&Interner),

crates/hir_ty/src/tests/simple.rs

@@ -496,7 +496,7 @@ fn infer_literals() {
             26..30 '5f32': f32
             36..40 '5f64': f64
             46..53 '"hello"': &str
-            59..67 'b"bytes"': &[u8; _]
+            59..67 'b"bytes"': &[u8; 5]
             73..76 ''c'': char
             82..86 'b'b'': u8
             92..96 '3.14': f64
@@ -504,7 +504,7 @@ fn infer_literals() {
             112..117 'false': bool
             123..127 'true': bool
             133..197 'r#"   ...    "#': &str
-            203..213 'br#"yolo"#': &[u8; _]
+            203..213 'br#"yolo"#': &[u8; 4]
         "##]],
     );
 }

crates/ide/src/join_lines.rs

@@ -4,7 +4,7 @@ use ide_assists::utils::extract_trivial_expression;
 use itertools::Itertools;
 use syntax::{
     algo::non_trivia_sibling,
-    ast::{self, AstNode, AstToken},
+    ast::{self, AstNode, AstToken, IsString},
     Direction, NodeOrToken, SourceFile,
     SyntaxKind::{self, USE_TREE, WHITESPACE},
     SyntaxNode, SyntaxToken, TextRange, TextSize, T,

crates/ide/src/syntax_highlighting/inject.rs

@@ -6,7 +6,7 @@ use either::Either;
 use hir::{InFile, Semantics};
 use ide_db::{call_info::ActiveParameter, helpers::rust_doc::is_rust_fence, SymbolKind};
 use syntax::{
-    ast::{self, AstNode},
+    ast::{self, AstNode, IsString},
     AstToken, NodeOrToken, SyntaxNode, SyntaxToken, TextRange, TextSize,
 };
 

crates/ide_assists/src/handlers/raw_string.rs

@@ -1,6 +1,6 @@
 use std::borrow::Cow;
 
-use syntax::{ast, AstToken, TextRange, TextSize};
+use syntax::{ast, ast::IsString, AstToken, TextRange, TextSize};
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 

crates/ide_assists/src/handlers/replace_string_with_char.rs

@@ -1,4 +1,4 @@
-use syntax::{ast, AstToken, SyntaxKind::STRING};
+use syntax::{ast, ast::IsString, AstToken, SyntaxKind::STRING};
 
 use crate::{AssistContext, AssistId, AssistKind, Assists};
 

crates/syntax/src/ast/token_ext.rs

@@ -143,6 +143,30 @@ impl QuoteOffsets {
     }
 }
 
+pub trait IsString: AstToken {
+    fn quote_offsets(&self) -> Option<QuoteOffsets> {
+        let text = self.text();
+        let offsets = QuoteOffsets::new(text)?;
+        let o = self.syntax().text_range().start();
+        let offsets = QuoteOffsets {
+            quotes: (offsets.quotes.0 + o, offsets.quotes.1 + o),
+            contents: offsets.contents + o,
+        };
+        Some(offsets)
+    }
+    fn text_range_between_quotes(&self) -> Option<TextRange> {
+        self.quote_offsets().map(|it| it.contents)
+    }
+    fn open_quote_text_range(&self) -> Option<TextRange> {
+        self.quote_offsets().map(|it| it.quotes.0)
+    }
+    fn close_quote_text_range(&self) -> Option<TextRange> {
+        self.quote_offsets().map(|it| it.quotes.1)
+    }
+}
+
+impl IsString for ast::String {}
+
 impl ast::String {
     pub fn is_raw(&self) -> bool {
         self.text().starts_with('r')
@@ -187,32 +211,49 @@ impl ast::String {
             (false, false) => Some(Cow::Owned(buf)),
         }
     }
-
-    pub fn quote_offsets(&self) -> Option<QuoteOffsets> {
-        let text = self.text();
-        let offsets = QuoteOffsets::new(text)?;
-        let o = self.syntax().text_range().start();
-        let offsets = QuoteOffsets {
-            quotes: (offsets.quotes.0 + o, offsets.quotes.1 + o),
-            contents: offsets.contents + o,
-        };
-        Some(offsets)
-    }
-    pub fn text_range_between_quotes(&self) -> Option<TextRange> {
-        self.quote_offsets().map(|it| it.contents)
-    }
-    pub fn open_quote_text_range(&self) -> Option<TextRange> {
-        self.quote_offsets().map(|it| it.quotes.0)
-    }
-    pub fn close_quote_text_range(&self) -> Option<TextRange> {
-        self.quote_offsets().map(|it| it.quotes.1)
-    }
 }
 
+impl IsString for ast::ByteString {}
+
 impl ast::ByteString {
     pub fn is_raw(&self) -> bool {
         self.text().starts_with("br")
     }
+
+    pub fn value(&self) -> Option<Cow<'_, [u8]>> {
+        if self.is_raw() {
+            let text = self.text();
+            let text =
+                &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
+            return Some(Cow::Borrowed(text.as_bytes()));
+        }
+
+        let text = self.text();
+        let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
+
+        let mut buf: Vec<u8> = Vec::new();
+        let mut text_iter = text.chars();
+        let mut has_error = false;
+        unescape_literal(text, Mode::ByteStr, &mut |char_range, unescaped_char| match (
+            unescaped_char,
+            buf.capacity() == 0,
+        ) {
+            (Ok(c), false) => buf.push(c as u8),
+            (Ok(c), true) if char_range.len() == 1 && Some(c) == text_iter.next() => (),
+            (Ok(c), true) => {
+                buf.reserve_exact(text.len());
+                buf.extend_from_slice(&text[..char_range.start].as_bytes());
+                buf.push(c as u8);
+            }
+            (Err(_), _) => has_error = true,
+        });
+
+        match (has_error, buf.capacity() == 0) {
+            (true, _) => None,
+            (false, true) => Some(Cow::Borrowed(text.as_bytes())),
+            (false, false) => Some(Cow::Owned(buf)),
+        }
+    }
 }
 
 #[derive(Debug)]