diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 7c56fc620..7bf9efea7 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -97,6 +97,13 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - name: Use a short Cargo home on Windows
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          "CARGO_HOME=$env:RUNNER_TEMP\c" >> $env:GITHUB_ENV
+          git config --global core.longpaths true
+
       - name: Restore cache
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
@@ -105,6 +112,9 @@ jobs:
             ~/.cargo/registry/index/
             ~/.cargo/registry/cache/
             ~/.cargo/git/db/
+            ${{ runner.temp }}/c/registry/index/
+            ${{ runner.temp }}/c/registry/cache/
+            ${{ runner.temp }}/c/git/db/
             target/
           key: ${{ runner.os }}-${{ hashFiles('**/Cargo.toml') }}-
           restore-keys: |
@@ -338,6 +348,13 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - name: Use a short Cargo home on Windows
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          "CARGO_HOME=$env:RUNNER_TEMP\c" >> $env:GITHUB_ENV
+          git config --global core.longpaths true
+
       - name: Restore cache
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
@@ -346,6 +363,9 @@ jobs:
             ~/.cargo/registry/index/
             ~/.cargo/registry/cache/
             ~/.cargo/git/db/
+            ${{ runner.temp }}/c/registry/index/
+            ${{ runner.temp }}/c/registry/cache/
+            ${{ runner.temp }}/c/git/db/
             target/
           key: ${{ runner.os }}-${{ hashFiles('**/Cargo.toml') }}-
           restore-keys: |
@@ -499,6 +519,13 @@ jobs:
         with:
           components: clippy
 
+      - name: Use a short Cargo home on Windows
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          "CARGO_HOME=$env:RUNNER_TEMP\c" >> $env:GITHUB_ENV
+          git config --global core.longpaths true
+
       - name: Restore cache
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
@@ -507,6 +534,9 @@ jobs:
             ~/.cargo/registry/index/
             ~/.cargo/registry/cache/
             ~/.cargo/git/db/
+            ${{ runner.temp }}/c/registry/index/
+            ${{ runner.temp }}/c/registry/cache/
+            ${{ runner.temp }}/c/git/db/
             target/
           key: ${{ runner.os }}-${{ hashFiles('**/Cargo.toml') }}-
           restore-keys: |
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 5957666de..6fa03af23 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -60,6 +60,13 @@ jobs:
         with:
           target: ${{ matrix.target }}
 
+      - name: Use a short Cargo home on Windows
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          "CARGO_HOME=$env:RUNNER_TEMP\c" >> $env:GITHUB_ENV
+          git config --global core.longpaths true
+
       - name: Install macOS dependencies
         uses: ./.github/actions/install-macos-deps
         with:
diff --git a/.github/workflows/update-caches.yml b/.github/workflows/update-caches.yml
index 4667c07fe..d3f5da9c1 100644
--- a/.github/workflows/update-caches.yml
+++ b/.github/workflows/update-caches.yml
@@ -52,6 +52,13 @@ jobs:
           toolchain: ${{ matrix.toolchain }}
           target: ${{ matrix.target }}
 
+      - name: Use a short Cargo home on Windows
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          "CARGO_HOME=$env:RUNNER_TEMP\c" >> $env:GITHUB_ENV
+          git config --global core.longpaths true
+
       - name: Install macos dependencies
         uses: ./.github/actions/install-macos-deps
         with:
@@ -74,5 +81,8 @@ jobs:
             ~/.cargo/registry/index/
             ~/.cargo/registry/cache/
             ~/.cargo/git/db/
+            ${{ runner.temp }}/c/registry/index/
+            ${{ runner.temp }}/c/registry/cache/
+            ${{ runner.temp }}/c/git/db/
             target/
           key: ${{ runner.os }}-${{ matrix.toolchain }}-${{ matrix.target }}-${{ hashFiles('**/Cargo.toml') }}-${{ hashFiles('Cargo.lock') }}-${{ github.sha }}
diff --git a/Cargo.lock b/Cargo.lock
index 0b0487982..2f99dfac9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -502,6 +502,18 @@ dependencies = [
  "rand_core 0.10.1",
 ]
 
+[[package]]
+name = "char_str"
+version = "0.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "576ba56f6ca18ebb069d0d07260407171712aff4dfe15ee3f8982dc16a455bcf"
+dependencies = [
+ "castaway",
+ "get-size2",
+ "itoa",
+ "ryu",
+]
+
 [[package]]
 name = "ciborium"
 version = "0.2.2"
@@ -691,16 +703,15 @@ dependencies = [
 
 [[package]]
 name = "compact_str"
-version = "0.9.1"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9dfdd1c2274d9aa354115b09dc9a901d6c5576818cdf70d14cae2bdb47df00ab"
+checksum = "79fcda08c33bb58b97008b2cdada6622500e949e060f5913361763121abd2416"
 dependencies = [
  "castaway",
  "cfg-if",
  "itoa",
- "rustversion",
- "ryu",
  "static_assertions",
+ "zmij",
 ]
 
 [[package]]
@@ -1190,6 +1201,12 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "drop_bomb"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9bda8e21c04aca2ae33ffc2fd8c23134f3cac46db123ba97bd9d3f3b8a4a85e1"
+
 [[package]]
 name = "dunce"
 version = "1.0.5"
@@ -1378,9 +1395,9 @@ dependencies = [
 
 [[package]]
 name = "get-size-derive2"
-version = "0.7.4"
+version = "0.10.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f2b6d1e2f75c16bfbcd0f95d84f99858a6e2f885c2287d1f5c3a96e8444a34b4"
+checksum = "c736d226c32e496b8377813b52269e11ad3a48d8373b68862d0364f04fd1229d"
 dependencies = [
  "attribute-derive",
  "quote",
@@ -1389,15 +1406,16 @@ dependencies = [
 
 [[package]]
 name = "get-size2"
-version = "0.7.4"
+version = "0.10.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49cf31a6d70300cf81461098f7797571362387ef4bf85d32ac47eaa59b3a5a1a"
+checksum = "b411f34418305908ab15a82ff78958c2a9aee9a272b2a2e663836b20a4e4b9d3"
 dependencies = [
  "compact_str",
  "get-size-derive2",
- "hashbrown 0.16.1",
+ "hashbrown 0.17.1",
  "ordermap",
  "smallvec",
+ "thin-vec",
 ]
 
 [[package]]
@@ -3510,11 +3528,13 @@ dependencies = [
 
 [[package]]
 name = "rustpython-ruff_python_ast"
-version = "0.15.9"
-source = "git+https://github.com/RustPython/ruff.git?tag=0.15.19-rustpython#3c1ab2dd9987f190f3df94d28452ed5e65e106af"
+version = "0.16.5"
+source = "git+https://github.com/RustPython/ruff.git?tag=0.16.5-rustpython#df59fe4c720b48a29fe8726a37e2ef06322096f8"
 dependencies = [
  "aho-corasick",
+ "arrayvec",
  "bitflags 2.13.1",
+ "char_str",
  "compact_str",
  "get-size2",
  "is-macro",
@@ -3523,24 +3543,27 @@ dependencies = [
  "rustpython-ruff_python_trivia",
  "rustpython-ruff_source_file",
  "rustpython-ruff_text_size",
+ "thin-vec",
  "thiserror",
 ]
 
 [[package]]
 name = "rustpython-ruff_python_parser"
-version = "0.15.9"
-source = "git+https://github.com/RustPython/ruff.git?tag=0.15.19-rustpython#3c1ab2dd9987f190f3df94d28452ed5e65e106af"
+version = "0.16.5"
+source = "git+https://github.com/RustPython/ruff.git?tag=0.16.5-rustpython#df59fe4c720b48a29fe8726a37e2ef06322096f8"
 dependencies = [
  "bitflags 2.13.1",
  "bstr",
- "compact_str",
+ "drop_bomb",
  "get-size2",
  "memchr",
  "rustc-hash",
  "rustpython-ruff_python_ast",
  "rustpython-ruff_python_trivia",
  "rustpython-ruff_text_size",
+ "stacker",
  "static_assertions",
+ "thin-vec",
  "unicode-ident",
  "unicode-normalization",
  "unicode_names2 1.3.0",
@@ -3548,10 +3571,11 @@ dependencies = [
 
 [[package]]
 name = "rustpython-ruff_python_trivia"
-version = "0.15.9"
-source = "git+https://github.com/RustPython/ruff.git?tag=0.15.19-rustpython#3c1ab2dd9987f190f3df94d28452ed5e65e106af"
+version = "0.16.5"
+source = "git+https://github.com/RustPython/ruff.git?tag=0.16.5-rustpython#df59fe4c720b48a29fe8726a37e2ef06322096f8"
 dependencies = [
- "itertools 0.14.0",
+ "itertools 0.15.0",
+ "rustc-hash",
  "rustpython-ruff_source_file",
  "rustpython-ruff_text_size",
  "unicode-ident",
@@ -3559,8 +3583,8 @@ dependencies = [
 
 [[package]]
 name = "rustpython-ruff_source_file"
-version = "0.15.9"
-source = "git+https://github.com/RustPython/ruff.git?tag=0.15.19-rustpython#3c1ab2dd9987f190f3df94d28452ed5e65e106af"
+version = "0.16.5"
+source = "git+https://github.com/RustPython/ruff.git?tag=0.16.5-rustpython#df59fe4c720b48a29fe8726a37e2ef06322096f8"
 dependencies = [
  "memchr",
  "rustpython-ruff_text_size",
@@ -3568,8 +3592,8 @@ dependencies = [
 
 [[package]]
 name = "rustpython-ruff_text_size"
-version = "0.15.9"
-source = "git+https://github.com/RustPython/ruff.git?tag=0.15.19-rustpython#3c1ab2dd9987f190f3df94d28452ed5e65e106af"
+version = "0.16.5"
+source = "git+https://github.com/RustPython/ruff.git?tag=0.16.5-rustpython#df59fe4c720b48a29fe8726a37e2ef06322096f8"
 dependencies = [
  "get-size2",
 ]
@@ -4077,6 +4101,19 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
 
+[[package]]
+name = "stacker"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "707f49d46706bacf8a2b00d51dace3f9de527c13eec3778f570c411f89e69967"
+dependencies = [
+ "cc",
+ "cfg-if",
+ "libc",
+ "psm",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "static_assertions"
 version = "1.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 3fd59e088..7f5a0b64a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -184,10 +184,10 @@ rustpython-wtf8 = { path = "crates/wtf8", version = "0.5.0" }
 rustpython-doc = { path = "crates/doc", version = "0.5.0" }
 
 # Use the RustPython Ruff fork for RustPython public `_ast` metadata.
-ruff_python_parser = { package = "rustpython-ruff_python_parser", git = "https://github.com/RustPython/ruff.git", tag = "0.15.19-rustpython" }
-ruff_python_ast = { package = "rustpython-ruff_python_ast", git = "https://github.com/RustPython/ruff.git", tag = "0.15.19-rustpython" }
-ruff_text_size = { package = "rustpython-ruff_text_size", git = "https://github.com/RustPython/ruff.git", tag = "0.15.19-rustpython" }
-ruff_source_file = { package = "rustpython-ruff_source_file", git = "https://github.com/RustPython/ruff.git", tag = "0.15.19-rustpython" }
+ruff_python_parser = { package = "rustpython-ruff_python_parser", git = "https://github.com/RustPython/ruff.git", tag = "0.16.5-rustpython" }
+ruff_python_ast = { package = "rustpython-ruff_python_ast", git = "https://github.com/RustPython/ruff.git", tag = "0.16.5-rustpython" }
+ruff_text_size = { package = "rustpython-ruff_text_size", git = "https://github.com/RustPython/ruff.git", tag = "0.16.5-rustpython" }
+ruff_source_file = { package = "rustpython-ruff_source_file", git = "https://github.com/RustPython/ruff.git", tag = "0.16.5-rustpython" }
 
 der = { version = "0.8", features = ["alloc", "oid", "pem", "zeroize"] }
 phf = { version = "0.14.0", default-features = false, features = ["macros"]}
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 6dab7dfa1..44d0cc7aa 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -1468,7 +1468,7 @@ Ensure that early = are not matched by the parser as invalid comparisons
    Traceback (most recent call last):
    SyntaxError: invalid syntax
 
-   >>> dict(x=34, x=1, y=2); x $ y  # TODO: RUSTPYTHON; Wrong error message # doctest: +EXPECTED_FAILURE
+   >>> dict(x=34, x=1, y=2); x $ y
    Traceback (most recent call last):
    SyntaxError: invalid syntax
 
diff --git a/crates/codegen/src/compile.rs b/crates/codegen/src/compile.rs
index 8a4a37319..6f06eb4ee 100644
--- a/crates/codegen/src/compile.rs
+++ b/crates/codegen/src/compile.rs
@@ -24,7 +24,7 @@ use malachite_bigint::BigInt;
 use num_complex::Complex;
 use num_traits::{Num, ToPrimitive, Zero};
 use ruff_python_ast::{self as ast, name::Name};
-use ruff_text_size::{Ranged, TextRange, TextSize};
+use ruff_text_size::{Ranged, TextRange, TextSize, TextSlice};
 use rustpython_compiler_core::{
     Mode, OneIndexed, PositionEncoding, SourceFile, SourceLocation,
     bytecode::{
@@ -9129,7 +9129,12 @@ impl<'warnings> Compiler<'warnings> {
                 range,
                 ..
             }) => {
-                let key = key.as_ref();
+                let Some(key) = key.as_deref() else {
+                    self.set_source_range(*range);
+                    return Err(self.error(CodegenErrorType::SyntaxError(
+                        "dict unpacking cannot be used in dict comprehension".to_owned(),
+                    )));
+                };
                 self.compile_comprehension(
                     "<dictcomp>",
                     Some(
@@ -9644,7 +9649,11 @@ impl<'warnings> Compiler<'warnings> {
                 continue;
             };
             for other in &keywords[i + 1..] {
-                if other.arg.as_ref() == Some(arg) {
+                if other
+                    .arg
+                    .as_ref()
+                    .is_some_and(|other| other.as_str() == arg.as_str())
+                {
                     return Err(self.error_ranged(
                         CodegenErrorType::SyntaxError(format!("keyword argument repeated: {arg}")),
                         other.range,
@@ -10067,7 +10076,11 @@ impl<'warnings> Compiler<'warnings> {
                             self.visit_expr(&first.iter);
                         }
                         if self.consume_inlined_comprehension_scope() {
-                            self.visit_comprehension_tail(key, Some(value), generators);
+                            if let Some(key) = key.as_deref() {
+                                self.visit_comprehension_tail(key, Some(value), generators);
+                            } else {
+                                self.visit_comprehension_tail(value, None, generators);
+                            }
                         } else {
                             self.consume_scope();
                         }
@@ -13249,9 +13262,10 @@ impl<'warnings> Compiler<'warnings> {
             {
                 let after_brace = interp.range.start() + TextSize::new(1);
                 self.source_file
+                    .source_text()
                     .slice(TextRange::new(after_brace, expr_range.end()))
             } else {
-                self.source_file.slice(expr_range)
+                self.source_file.source_text().slice(expr_range)
             }
             .to_string();
             self.set_source_range(interp.range);
@@ -13843,7 +13857,7 @@ mod tests {
     fn frozenset_call_expr() -> ast::Expr {
         ast::Expr::Call(ast::ExprCall {
             node_index: ast::AtomicNodeIndex::NONE,
-            range: TextRange::default(),
+            range_start: TextSize::default(),
             func: Box::new(ast::Expr::Name(ast::ExprName {
                 node_index: ast::AtomicNodeIndex::NONE,
                 range: TextRange::default(),
@@ -13996,7 +14010,7 @@ mod tests {
         );
         let message = first_ast_constant_warning(ast::Expr::Call(ast::ExprCall {
             node_index: ast::AtomicNodeIndex::NONE,
-            range: TextRange::default(),
+            range_start: TextSize::default(),
             func: Box::new(func),
             arguments: ast::Arguments {
                 node_index: ast::AtomicNodeIndex::NONE,
diff --git a/crates/codegen/src/lib.rs b/crates/codegen/src/lib.rs
index b7ddb357e..0bc16d72d 100644
--- a/crates/codegen/src/lib.rs
+++ b/crates/codegen/src/lib.rs
@@ -24,7 +24,7 @@ mod unparse;
 
 pub use compile::CompileOpts;
 use ruff_python_ast as ast;
-use ruff_text_size::{Ranged, TextRange, TextSize};
+use ruff_text_size::{Ranged, TextRange, TextSize, TextSlice};
 use rustpython_compiler_core::SourceFile;
 use rustpython_wtf8::Wtf8Buf;
 
@@ -116,7 +116,7 @@ pub fn decorated_definition_range(
         return statement_range;
     }
     let search_range = TextRange::new(search_start, statement_range.end());
-    let source = source_file.slice(search_range);
+    let source = source_file.source_text().slice(search_range);
     let Some(keyword_offset) = source.find(keyword) else {
         return statement_range;
     };
@@ -151,7 +151,7 @@ pub fn string_literal_value(source_file: &SourceFile, string: &ast::StringLitera
 #[must_use]
 pub fn string_literal_part_value(source_file: &SourceFile, string: &ast::StringLiteral) -> Wtf8Buf {
     if string.value.contains(char::REPLACEMENT_CHARACTER) {
-        let source = source_file.slice(string.range);
+        let source = source_file.source_text().slice(string.range);
         string_parser::parse_string_literal(source, string.flags.into()).into()
     } else {
         string.value.to_string().into()
@@ -167,7 +167,7 @@ pub fn interpolated_string_literal_value(
     flags: ast::AnyStringFlags,
 ) -> Wtf8Buf {
     if element.value.contains(char::REPLACEMENT_CHARACTER) {
-        let source = source_file.slice(element.range);
+        let source = source_file.source_text().slice(element.range);
         string_parser::parse_fstring_literal_element(source.into(), flags).into()
     } else {
         element.value.to_string().into()
@@ -186,11 +186,11 @@ pub fn interpolation_debug_text(
     debug_text: &ast::DebugText,
     expression_range: TextRange,
 ) -> (String, TextRange) {
-    let leading = debug_text.leading.as_str();
-    let trailing = debug_text.trailing.as_str();
+    let leading = debug_text.leading();
+    let trailing = debug_text.trailing();
     let text = [
         strip_python_comments(leading).as_str(),
-        source_file.slice(expression_range),
+        source_file.source_text().slice(expression_range),
         strip_python_comments(trailing).as_str(),
     ]
     .concat();
diff --git a/crates/codegen/src/symboltable.rs b/crates/codegen/src/symboltable.rs
index 173921654..d936bfc1a 100644
--- a/crates/codegen/src/symboltable.rs
+++ b/crates/codegen/src/symboltable.rs
@@ -2376,7 +2376,12 @@ impl SymbolTableBuilder {
                         self.in_iter_def_exp = true;
                     }
                     // Dict comprehension - is_generator = false (can be inlined)
-                    let key = key.as_ref();
+                    let Some(key) = key.as_deref() else {
+                        return Err(self.error_ranged(
+                            "dict unpacking cannot be used in dict comprehension".to_owned(),
+                            *range,
+                        ));
+                    };
                     self.scan_comprehension(
                         &"<dictcomp>".into(),
                         key,
diff --git a/crates/codegen/src/unparse.rs b/crates/codegen/src/unparse.rs
index f890edf37..86744a601 100644
--- a/crates/codegen/src/unparse.rs
+++ b/crates/codegen/src/unparse.rs
@@ -2,7 +2,7 @@ use crate::strip_python_comments;
 use alloc::fmt;
 use core::fmt::Display as _;
 use ruff_python_ast as ast;
-use ruff_text_size::{Ranged, TextSize};
+use ruff_text_size::{Ranged, TextSize, TextSlice};
 use rustpython_compiler_core::SourceFile;
 use rustpython_literal::escape::{AsciiEscape, UnicodeEscape};
 
@@ -322,8 +322,12 @@ impl<'a, 'b, 'c> Unparser<'a, 'b, 'c> {
                 ..
             }) => {
                 self.p("{")?;
-                self.unparse_expr(key, precedence::TEST)?;
-                self.p(": ")?;
+                if let Some(key) = key {
+                    self.unparse_expr(key, precedence::TEST)?;
+                    self.p(": ")?;
+                } else {
+                    self.p("**")?;
+                }
                 self.unparse_expr(value, precedence::TEST)?;
                 self.unparse_comp(generators)?;
                 self.p("}")?;
@@ -399,7 +403,7 @@ impl<'a, 'b, 'c> Unparser<'a, 'b, 'c> {
                 func,
                 arguments: ast::Arguments { args, keywords, .. },
                 node_index: _,
-                range: _range,
+                range_start: _range_start,
                 ..
             }) => {
                 self.unparse_expr(func, precedence::ATOM)?;
@@ -618,10 +622,10 @@ impl<'a, 'b, 'c> Unparser<'a, 'b, 'c> {
             fmt::from_fn(|f| Unparser::new(f, self.source).unparse_expr(val, precedence::TEST + 1))
                 .to_string();
         if let Some(debug_text) = debug_text {
-            let leading = debug_text.leading.as_str();
-            let trailing = debug_text.trailing.as_str();
+            let leading = debug_text.leading();
+            let trailing = debug_text.trailing();
             self.p(leading)?;
-            self.p(self.source.slice(val.range()))?;
+            self.p(self.source.source_text().slice(val.range()))?;
             self.p(trailing)?;
             if conversion == ast::ConversionFlag::None && spec.is_none() {
                 conversion = ast::ConversionFlag::Repr;
@@ -744,9 +748,13 @@ impl<'a, 'b, 'c> Unparser<'a, 'b, 'c> {
         let mut conversion = source_conversion;
         let debug_parts = interpolation.debug_text.as_ref().map(|debug_text| {
             (
-                strip_python_comments(debug_text.leading.as_str()),
-                strip_python_comments(self.source.slice(interpolation.expression.range())),
-                strip_python_comments(debug_text.trailing.as_str()),
+                strip_python_comments(debug_text.leading()),
+                strip_python_comments(
+                    self.source
+                        .source_text()
+                        .slice(interpolation.expression.range()),
+                ),
+                strip_python_comments(debug_text.trailing()),
             )
         });
         if let Some((leading, source, trailing)) = &debug_parts {
@@ -784,6 +792,7 @@ impl<'a, 'b, 'c> Unparser<'a, 'b, 'c> {
             {
                 strip_python_comments(
                     self.source
+                        .source_text()
                         .slice(ruff_text_size::TextRange::new(after_brace, expression_end)),
                 )
                 .trim_end()
diff --git a/crates/compiler/src/lib.rs b/crates/compiler/src/lib.rs
index 633587020..e8b24a632 100644
--- a/crates/compiler/src/lib.rs
+++ b/crates/compiler/src/lib.rs
@@ -6520,11 +6520,11 @@ mod tests {
             ),
             (
                 "t\"x\" b\"y\"",
-                "cannot mix t-string literals with string or bytes literals",
+                "Cannot mix t-string literals with string or bytes literals",
             ),
             (
                 "b\"x\" t\"y\"",
-                "cannot mix t-string literals with string or bytes literals",
+                "Cannot mix t-string literals with string or bytes literals",
             ),
             // The literals ahead of the first t-string already mix, so CPython's first pass
             // raises from `_PyPegen_concatenate_strings` before the t-string rule is reached.
diff --git a/crates/vm/src/stdlib/_ast.rs b/crates/vm/src/stdlib/_ast.rs
index 887c3cc7d..7ce719da0 100644
--- a/crates/vm/src/stdlib/_ast.rs
+++ b/crates/vm/src/stdlib/_ast.rs
@@ -21,7 +21,7 @@ use crate::{
 };
 use node::Node;
 use ruff_python_ast as ast;
-use ruff_text_size::{Ranged, TextRange, TextSize};
+use ruff_text_size::{Ranged, TextRange, TextSize, TextSlice};
 use rustpython_compiler_core::{
     LineIndex, OneIndexed, PositionEncoding, SourceFile, SourceFileBuilder, SourceLocation,
 };
diff --git a/crates/vm/src/stdlib/_ast/argument.rs b/crates/vm/src/stdlib/_ast/argument.rs
index 5019c4366..0ea9725a1 100644
--- a/crates/vm/src/stdlib/_ast/argument.rs
+++ b/crates/vm/src/stdlib/_ast/argument.rs
@@ -137,7 +137,7 @@ pub(super) fn merge_function_call_arguments(
         node_index: Default::default(),
         range,
         args,
-        keywords: key_args.keywords,
+        keywords: key_args.keywords.into(),
         runtime_args,
         runtime_bases: None,
     }
@@ -173,7 +173,7 @@ pub(super) fn split_function_call_arguments(
     // debug_assert!(range.contains_range(keyword_arguments_range));
     let keyword_arguments = KeywordArguments {
         range: keyword_arguments_range,
-        keywords,
+        keywords: keywords.into(),
     };
 
     (positional_arguments, keyword_arguments)
@@ -214,7 +214,7 @@ pub(super) fn split_class_def_args(
     // debug_assert!(range.contains_range(keyword_arguments_range));
     let keyword_arguments = KeywordArguments {
         range: keyword_arguments_range,
-        keywords,
+        keywords: keywords.into(),
     };
 
     (Some(positional_arguments), Some(keyword_arguments))
@@ -243,7 +243,7 @@ pub(super) fn merge_class_def_args(
         node_index: Default::default(),
         range: Default::default(), // TODO
         args,
-        keywords,
+        keywords: keywords.into(),
         runtime_args: None,
         runtime_bases,
     }))
diff --git a/crates/vm/src/stdlib/_ast/expression.rs b/crates/vm/src/stdlib/_ast/expression.rs
index 97a3519ea..7c64e4f79 100644
--- a/crates/vm/src/stdlib/_ast/expression.rs
+++ b/crates/vm/src/stdlib/_ast/expression.rs
@@ -855,7 +855,13 @@ fn expr_dict_comp_from_object_with_range(
 ) -> PyResult<ast::ExprDictComp> {
     Ok(ast::ExprDictComp {
         node_index: Default::default(),
-        key: get_required_node_field(vm, source_file, &object, "key", "DictComp")?,
+        key: Some(get_required_node_field(
+            vm,
+            source_file,
+            &object,
+            "key",
+            "DictComp",
+        )?),
         value: get_required_node_field(vm, source_file, &object, "value", "DictComp")?,
         generators: get_node_list_field(vm, source_file, &object, "generators", "DictComp")?,
         range,
@@ -1130,24 +1136,27 @@ fn expr_call_from_object_with_range(
     object: PyObjectRef,
     range: TextRange,
 ) -> PyResult<ast::ExprCall> {
+    let mut arguments = merge_function_call_arguments(
+        PositionalArguments::ast_from_field(vm, source_file, &object, "args", "Call")?,
+        KeywordArguments::ast_from_field(vm, source_file, &object, "keywords", "Call")?,
+    );
+    arguments.range = range;
     Ok(ast::ExprCall {
         node_index: Default::default(),
         func: get_required_node_field(vm, source_file, &object, "func", "Call")?,
-        arguments: merge_function_call_arguments(
-            PositionalArguments::ast_from_field(vm, source_file, &object, "args", "Call")?,
-            KeywordArguments::ast_from_field(vm, source_file, &object, "keywords", "Call")?,
-        ),
-        range,
+        arguments,
+        range_start: range.start(),
     })
 }
 
 impl Node for ast::ExprCall {
     fn ast_to_object(self, vm: &VirtualMachine, source_file: &SourceFile) -> PyObjectRef {
+        let range = self.range();
         let Self {
             node_index: _,
             func,
             arguments,
-            range,
+            range_start: _,
         } = self;
         let (positional_arguments, keyword_arguments) = split_function_call_arguments(arguments);
         let node = NodeAst
diff --git a/crates/vm/src/stdlib/_ast/parameter.rs b/crates/vm/src/stdlib/_ast/parameter.rs
index 1ce4973b4..03ff20f12 100644
--- a/crates/vm/src/stdlib/_ast/parameter.rs
+++ b/crates/vm/src/stdlib/_ast/parameter.rs
@@ -14,10 +14,13 @@ impl Node for ast::Parameters {
             range: _,
             runtime_defaults,
         } = self;
-        let (posonlyargs, args, mut defaults) =
-            extract_positional_parameter_defaults(posonlyargs, args);
+        let (posonlyargs, args, mut defaults) = extract_positional_parameter_defaults(
+            posonlyargs.into_iter().collect(),
+            args.into_iter().collect(),
+        );
         defaults.runtime_defaults = runtime_defaults;
-        let (kwonlyargs, kw_defaults) = extract_keyword_parameter_defaults(kwonlyargs);
+        let (kwonlyargs, kw_defaults) =
+            extract_keyword_parameter_defaults(kwonlyargs.into_iter().collect());
         let node = NodeAst
             .into_ref_with_type(vm, pyast::NodeArguments::static_type().to_owned())
             .unwrap();
@@ -108,10 +111,10 @@ impl Node for ast::Parameters {
 
         Ok(Self {
             node_index: Default::default(),
-            posonlyargs,
-            args,
+            posonlyargs: posonlyargs.into(),
+            args: args.into(),
             vararg,
-            kwonlyargs,
+            kwonlyargs: kwonlyargs.into(),
             kwarg,
             range: Default::default(),
             runtime_defaults,
diff --git a/crates/vm/src/stdlib/_ast/pattern.rs b/crates/vm/src/stdlib/_ast/pattern.rs
index 387fb5900..7c834178b 100644
--- a/crates/vm/src/stdlib/_ast/pattern.rs
+++ b/crates/vm/src/stdlib/_ast/pattern.rs
@@ -384,8 +384,8 @@ fn pattern_match_mapping_from_object_with_range(
         .then(|| patterns.clone());
     Ok(ast::PatternMatchMapping {
         node_index: Default::default(),
-        keys: lower_nullable_exprs(&keys, range),
-        patterns: lower_nullable_patterns(&patterns, range),
+        keys: lower_nullable_exprs(&keys, range).into(),
+        patterns: lower_nullable_patterns(&patterns, range).into(),
         rest: get_node_field_opt(vm, &object, "rest")?
             .map(|obj| Node::ast_from_object(vm, source_file, obj))
             .transpose()?,
@@ -473,7 +473,7 @@ fn pattern_match_class_from_object_with_range(
         arguments: ast::PatternArguments {
             node_index: Default::default(),
             range: Default::default(),
-            patterns,
+            patterns: patterns.into(),
             keywords,
         },
         runtime_patterns,
@@ -744,7 +744,7 @@ fn split_pattern_match_class(
     PatternMatchClassKeywordAttributes,
     PatternMatchClassKeywordPatterns,
 ) {
-    let patterns = PatternMatchClassPatterns(arguments.patterns);
+    let patterns = PatternMatchClassPatterns(arguments.patterns.into_iter().collect());
     let kwd_attrs = PatternMatchClassKeywordAttributes(
         arguments.keywords.iter().map(|k| k.attr.clone()).collect(),
     );
diff --git a/crates/vm/src/stdlib/_ast/statement.rs b/crates/vm/src/stdlib/_ast/statement.rs
index bf8b03476..167f68f63 100644
--- a/crates/vm/src/stdlib/_ast/statement.rs
+++ b/crates/vm/src/stdlib/_ast/statement.rs
@@ -365,7 +365,7 @@ fn stmt_function_def_from_object_with_range(
         name,
         parameters,
         body,
-        decorator_list,
+        decorator_list: decorator_list.into(),
         returns,
         type_params,
         range,
@@ -491,7 +491,7 @@ fn stmt_class_def_from_object_with_range(
         name,
         arguments: merge_class_def_args(Some(bases), Some(keywords)),
         body,
-        decorator_list,
+        decorator_list: decorator_list.into(),
         type_params,
         range,
         runtime_decorator_list,
@@ -1342,7 +1342,7 @@ fn except_handler_list_from_field(
                 range,
                 type_: None,
                 name: None,
-                body: Vec::new(),
+                body: Vec::new().into(),
                 runtime_body: None,
             })
         });
diff --git a/crates/vm/src/stdlib/_ast/string.rs b/crates/vm/src/stdlib/_ast/string.rs
index 2e44ce48f..ec7d6eb5a 100644
--- a/crates/vm/src/stdlib/_ast/string.rs
+++ b/crates/vm/src/stdlib/_ast/string.rs
@@ -801,13 +801,13 @@ fn push_ruff_tstring_element(
                     expression.range(),
                 )));
                 conversion = debug_conversion(conversion, format_spec.is_some());
-                let expr_source = source_file.slice(expr_range);
+                let expr_source = source_file.source_text().slice(expr_range);
                 let mut expr_with_debug = String::with_capacity(
-                    debug_text.leading.len() + expr_source.len() + debug_text.trailing.len(),
+                    debug_text.leading().len() + expr_source.len() + debug_text.trailing().len(),
                 );
-                expr_with_debug.push_str(&debug_text.leading);
+                expr_with_debug.push_str(debug_text.leading());
                 expr_with_debug.push_str(expr_source);
-                expr_with_debug.push_str(&debug_text.trailing);
+                expr_with_debug.push_str(debug_text.trailing());
                 strip_interpolation_expr(&expr_with_debug)
             } else {
                 tstring_interpolation_expr_str(source_file, range, expr_range)
@@ -849,7 +849,9 @@ fn tstring_interpolation_expr_str(
     } else {
         start
     };
-    let expr_source = source_file.slice(TextRange::new(start, expr_range.end()));
+    let expr_source = source_file
+        .source_text()
+        .slice(TextRange::new(start, expr_range.end()));
     strip_interpolation_expr(expr_source)
 }
 
@@ -858,7 +860,7 @@ fn extend_expr_range_with_wrapping_parens(
     interpolation_range: TextRange,
     expr_range: TextRange,
 ) -> Option<TextRange> {
-    let left_slice = source_file.slice(TextRange::new(
+    let left_slice = source_file.source_text().slice(TextRange::new(
         interpolation_range.start(),
         expr_range.start(),
     ));
@@ -879,8 +881,9 @@ fn extend_expr_range_with_wrapping_parens(
         return None;
     }
 
-    let right_slice =
-        source_file.slice(TextRange::new(expr_range.end(), interpolation_range.end()));
+    let right_slice = source_file
+        .source_text()
+        .slice(TextRange::new(expr_range.end(), interpolation_range.end()));
     let mut right_char: Option<(usize, char)> = None;
     for (idx, ch) in right_slice.char_indices() {
         if !ch.is_whitespace() {
diff --git a/crates/vm/src/stdlib/_ast/validate.rs b/crates/vm/src/stdlib/_ast/validate.rs
index b4dd4a76d..cbdc15b53 100644
--- a/crates/vm/src/stdlib/_ast/validate.rs
+++ b/crates/vm/src/stdlib/_ast/validate.rs
@@ -593,7 +593,10 @@ fn validate_expr(vm: &VirtualMachine, expr: &ast::Expr, ctx: ast::ExprContext) -
         }
         ast::Expr::DictComp(dict) => {
             validate_comprehension(vm, &dict.generators)?;
-            validate_expr(vm, &dict.key, ast::ExprContext::Load)?;
+            let key = dict.key.as_deref().ok_or_else(|| {
+                vm.new_value_error("field 'key' is required for DictComp".to_owned())
+            })?;
+            validate_expr(vm, key, ast::ExprContext::Load)?;
             validate_expr(vm, &dict.value, ast::ExprContext::Load)
         }
         ast::Expr::Generator(generator) => {
diff --git a/crates/vm/src/vm/vm_new.rs b/crates/vm/src/vm/vm_new.rs
index d1890bbc0..e2c73daf5 100644
--- a/crates/vm/src/vm/vm_new.rs
+++ b/crates/vm/src/vm/vm_new.rs
@@ -152,10 +152,6 @@ impl SyntaxErrorInfo {
 
             ParseErrorType::EmptyImportNames => "Expected one or more names after 'import'".into(),
 
-            ParseErrorType::DuplicateKeywordArgumentError(arg_name) => {
-                format!("keyword argument repeated: {arg_name}")
-            }
-
             ParseErrorType::UnparenthesizedGeneratorExpression => {
                 "Generator expression must be parenthesized".into()
             }