13 files changed, 187 insertions, 234 deletions

diff --git a/xtask/Cargo.toml b/xtask/Cargo.toml
index b17dde598..e084f0df6 100644
--- a/xtask/Cargo.toml
+++ b/xtask/Cargo.toml
@@ -15,5 +15,5 @@ ungrammar = "=1.11"
 walkdir = "2.3.1"
 write-json = "0.1.0"
 xshell = "0.1"
-xflags = "0.1.2"
+xflags = "0.2.1"
 # Avoid adding more dependencies to this crate
diff --git a/xtask/src/codegen.rs b/xtask/src/codegen.rs
index 2f56c5ad0..2cf3c6fdc 100644
--- a/xtask/src/codegen.rs
+++ b/xtask/src/codegen.rs
@@ -7,68 +7,66 @@
 
 mod gen_syntax;
 mod gen_parser_tests;
+mod gen_lint_completions;
 mod gen_assists_docs;
 mod gen_feature_docs;
-mod gen_lint_completions;
 mod gen_diagnostic_docs;
 
 use std::{
     fmt, mem,
     path::{Path, PathBuf},
 };
-use xshell::{cmd, pushenv, read_file, write_file};
+use xshell::{cmd, pushenv};
 
-use crate::{ensure_rustfmt, flags, project_root, Result};
+use crate::{ensure_rustfmt, project_root, Result};
 
 pub(crate) use self::{
-    gen_assists_docs::{generate_assists_docs, generate_assists_tests},
-    gen_diagnostic_docs::generate_diagnostic_docs,
-    gen_feature_docs::generate_feature_docs,
-    gen_lint_completions::generate_lint_completions,
-    gen_parser_tests::generate_parser_tests,
-    gen_syntax::generate_syntax,
+    gen_assists_docs::generate_assists_tests, gen_lint_completions::generate_lint_completions,
+    gen_parser_tests::generate_parser_tests, gen_syntax::generate_syntax,
 };
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub(crate) enum Mode {
-    Overwrite,
-    Verify,
+pub(crate) fn docs() -> Result<()> {
+    // We don't commit docs to the repo, so we can just overwrite them.
+    gen_assists_docs::generate_assists_docs()?;
+    gen_feature_docs::generate_feature_docs()?;
+    gen_diagnostic_docs::generate_diagnostic_docs()?;
+    Ok(())
 }
 
-impl flags::Codegen {
-    pub(crate) fn run(self) -> Result<()> {
-        if self.features {
-            generate_lint_completions(Mode::Overwrite)?;
-        }
-        generate_syntax(Mode::Overwrite)?;
-        generate_parser_tests(Mode::Overwrite)?;
-        generate_assists_tests(Mode::Overwrite)?;
-        generate_assists_docs(Mode::Overwrite)?;
-        generate_feature_docs(Mode::Overwrite)?;
-        generate_diagnostic_docs(Mode::Overwrite)?;
-        Ok(())
-    }
+#[allow(unused)]
+fn used() {
+    generate_parser_tests();
+    generate_assists_tests();
+    generate_syntax();
+    generate_lint_completions();
 }
 
-/// A helper to update file on disk if it has changed.
-/// With verify = false,
-fn update(path: &Path, contents: &str, mode: Mode) -> Result<()> {
-    match read_file(path) {
-        Ok(old_contents) if normalize(&old_contents) == normalize(contents) => {
-            return Ok(());
+/// Checks that the `file` has the specified `contents`. If that is not the
+/// case, updates the file and then fails the test.
+pub(crate) fn ensure_file_contents(file: &Path, contents: &str) -> Result<()> {
+    match std::fs::read_to_string(file) {
+        Ok(old_contents) if normalize_newlines(&old_contents) == normalize_newlines(contents) => {
+            return Ok(())
         }
         _ => (),
     }
-    if mode == Mode::Verify {
-        anyhow::bail!("`{}` is not up-to-date", path.display());
+    let display_path = file.strip_prefix(&project_root()).unwrap_or(file);
+    eprintln!(
+        "\n\x1b[31;1merror\x1b[0m: {} was not up-to-date, updating\n",
+        display_path.display()
+    );
+    if std::env::var("CI").is_ok() {
+        eprintln!("    NOTE: run `cargo test` locally and commit the updated files\n");
     }
-    eprintln!("updating {}", path.display());
-    write_file(path, contents)?;
-    return Ok(());
-
-    fn normalize(s: &str) -> String {
-        s.replace("\r\n", "\n")
+    if let Some(parent) = file.parent() {
+        let _ = std::fs::create_dir_all(parent);
     }
+    std::fs::write(file, contents).unwrap();
+    anyhow::bail!("some file were not up to date")
+}
+
+fn normalize_newlines(s: &str) -> String {
+    s.replace("\r\n", "\n")
 }
 
 const PREAMBLE: &str = "Generated file, do not edit by hand, see `xtask/src/codegen`";
diff --git a/xtask/src/codegen/gen_assists_docs.rs b/xtask/src/codegen/gen_assists_docs.rs
index c469b388d..158680993 100644
--- a/xtask/src/codegen/gen_assists_docs.rs
+++ b/xtask/src/codegen/gen_assists_docs.rs
@@ -2,22 +2,25 @@
 
 use std::{fmt, path::Path};
 
+use xshell::write_file;
+
 use crate::{
-    codegen::{self, extract_comment_blocks_with_empty_lines, reformat, Location, Mode, PREAMBLE},
+    codegen::{self, extract_comment_blocks_with_empty_lines, reformat, Location, PREAMBLE},
     project_root, rust_files_in, Result,
 };
 
-pub(crate) fn generate_assists_tests(mode: Mode) -> Result<()> {
+pub(crate) fn generate_assists_tests() -> Result<()> {
     let assists = Assist::collect()?;
-    generate_tests(&assists, mode)
+    generate_tests(&assists)
 }
 
-pub(crate) fn generate_assists_docs(mode: Mode) -> Result<()> {
+pub(crate) fn generate_assists_docs() -> Result<()> {
     let assists = Assist::collect()?;
     let contents = assists.into_iter().map(|it| it.to_string()).collect::<Vec<_>>().join("\n\n");
     let contents = format!("//{}\n{}\n", PREAMBLE, contents.trim());
     let dst = project_root().join("docs/user/generated_assists.adoc");
-    codegen::update(&dst, &contents, mode)
+    write_file(dst, &contents)?;
+    Ok(())
 }
 
 #[derive(Debug)]
@@ -111,7 +114,7 @@ impl fmt::Display for Assist {
     }
 }
 
-fn generate_tests(assists: &[Assist], mode: Mode) -> Result<()> {
+fn generate_tests(assists: &[Assist]) -> Result<()> {
     let mut buf = String::from("use super::check_doc_test;\n");
 
     for assist in assists.iter() {
@@ -135,7 +138,10 @@ r#####"
         buf.push_str(&test)
     }
     let buf = reformat(&buf)?;
-    codegen::update(&project_root().join("crates/ide_assists/src/tests/generated.rs"), &buf, mode)
+    codegen::ensure_file_contents(
+        &project_root().join("crates/ide_assists/src/tests/generated.rs"),
+        &buf,
+    )
 }
 
 fn hide_hash_comments(text: &str) -> String {
diff --git a/xtask/src/codegen/gen_diagnostic_docs.rs b/xtask/src/codegen/gen_diagnostic_docs.rs
index a2561817b..9cf4d0a88 100644
--- a/xtask/src/codegen/gen_diagnostic_docs.rs
+++ b/xtask/src/codegen/gen_diagnostic_docs.rs
@@ -2,18 +2,20 @@
 
 use std::{fmt, path::PathBuf};
 
+use xshell::write_file;
+
 use crate::{
-    codegen::{self, extract_comment_blocks_with_empty_lines, Location, Mode, PREAMBLE},
+    codegen::{extract_comment_blocks_with_empty_lines, Location, PREAMBLE},
     project_root, rust_files, Result,
 };
 
-pub(crate) fn generate_diagnostic_docs(mode: Mode) -> Result<()> {
+pub(crate) fn generate_diagnostic_docs() -> Result<()> {
     let diagnostics = Diagnostic::collect()?;
     let contents =
         diagnostics.into_iter().map(|it| it.to_string()).collect::<Vec<_>>().join("\n\n");
     let contents = format!("//{}\n{}\n", PREAMBLE, contents.trim());
     let dst = project_root().join("docs/user/generated_diagnostic.adoc");
-    codegen::update(&dst, &contents, mode)?;
+    write_file(&dst, &contents)?;
     Ok(())
 }
 
diff --git a/xtask/src/codegen/gen_feature_docs.rs b/xtask/src/codegen/gen_feature_docs.rs
index cad7ff477..c373d7d70 100644
--- a/xtask/src/codegen/gen_feature_docs.rs
+++ b/xtask/src/codegen/gen_feature_docs.rs
@@ -2,17 +2,19 @@
 
 use std::{fmt, path::PathBuf};
 
+use xshell::write_file;
+
 use crate::{
-    codegen::{self, extract_comment_blocks_with_empty_lines, Location, Mode, PREAMBLE},
+    codegen::{extract_comment_blocks_with_empty_lines, Location, PREAMBLE},
     project_root, rust_files, Result,
 };
 
-pub(crate) fn generate_feature_docs(mode: Mode) -> Result<()> {
+pub(crate) fn generate_feature_docs() -> Result<()> {
     let features = Feature::collect()?;
     let contents = features.into_iter().map(|it| it.to_string()).collect::<Vec<_>>().join("\n\n");
     let contents = format!("//{}\n{}\n", PREAMBLE, contents.trim());
     let dst = project_root().join("docs/user/generated_features.adoc");
-    codegen::update(&dst, &contents, mode)?;
+    write_file(&dst, &contents)?;
     Ok(())
 }
 
diff --git a/xtask/src/codegen/gen_lint_completions.rs b/xtask/src/codegen/gen_lint_completions.rs
index b1c057037..24dbc6a39 100644
--- a/xtask/src/codegen/gen_lint_completions.rs
+++ b/xtask/src/codegen/gen_lint_completions.rs
@@ -5,13 +5,10 @@ use std::path::{Path, PathBuf};
 use walkdir::WalkDir;
 use xshell::{cmd, read_file};
 
-use crate::{
-    codegen::{project_root, reformat, update, Mode, Result},
-    run_rustfmt,
-};
+use crate::codegen::{ensure_file_contents, project_root, reformat, Result};
 
-pub(crate) fn generate_lint_completions(mode: Mode) -> Result<()> {
-    if !Path::new("./target/rust").exists() {
+pub(crate) fn generate_lint_completions() -> Result<()> {
+    if !project_root().join("./target/rust").exists() {
         cmd!("git clone --depth=1 https://github.com/rust-lang/rust ./target/rust").run()?;
     }
 
@@ -25,8 +22,7 @@ pub(crate) fn generate_lint_completions(mode: Mode) -> Result<()> {
 
     let destination =
         project_root().join("crates/ide_completion/src/generated_lint_completions.rs");
-    update(destination.as_path(), &contents, mode)?;
-    run_rustfmt(mode)?;
+    ensure_file_contents(destination.as_path(), &contents)?;
 
     Ok(())
 }
diff --git a/xtask/src/codegen/gen_parser_tests.rs b/xtask/src/codegen/gen_parser_tests.rs
index cb8939063..096590653 100644
--- a/xtask/src/codegen/gen_parser_tests.rs
+++ b/xtask/src/codegen/gen_parser_tests.rs
@@ -8,13 +8,13 @@ use std::{
 };
 
 use crate::{
-    codegen::{extract_comment_blocks, update, Mode},
+    codegen::{ensure_file_contents, extract_comment_blocks},
     project_root, Result,
 };
 
-pub(crate) fn generate_parser_tests(mode: Mode) -> Result<()> {
+pub(crate) fn generate_parser_tests() -> Result<()> {
     let tests = tests_from_dir(&project_root().join(Path::new("crates/parser/src/grammar")))?;
-    fn install_tests(tests: &HashMap<String, Test>, into: &str, mode: Mode) -> Result<()> {
+    fn install_tests(tests: &HashMap<String, Test>, into: &str) -> Result<()> {
         let tests_dir = project_root().join(into);
         if !tests_dir.is_dir() {
             fs::create_dir_all(&tests_dir)?;
@@ -35,12 +35,12 @@ pub(crate) fn generate_parser_tests(mode: Mode) -> Result<()> {
                     tests_dir.join(file_name)
                 }
             };
-            update(&path, &test.text, mode)?;
+            ensure_file_contents(&path, &test.text)?;
         }
         Ok(())
     }
-    install_tests(&tests.ok, "crates/syntax/test_data/parser/inline/ok", mode)?;
-    install_tests(&tests.err, "crates/syntax/test_data/parser/inline/err", mode)
+    install_tests(&tests.ok, "crates/syntax/test_data/parser/inline/ok")?;
+    install_tests(&tests.err, "crates/syntax/test_data/parser/inline/err")
 }
 
 #[derive(Debug)]
diff --git a/xtask/src/codegen/gen_syntax.rs b/xtask/src/codegen/gen_syntax.rs
index 191bc0e9d..80f26e8f5 100644
--- a/xtask/src/codegen/gen_syntax.rs
+++ b/xtask/src/codegen/gen_syntax.rs
@@ -14,25 +14,25 @@ use ungrammar::{rust_grammar, Grammar, Rule};
 
 use crate::{
     ast_src::{AstEnumSrc, AstNodeSrc, AstSrc, Cardinality, Field, KindsSrc, KINDS_SRC},
-    codegen::{reformat, update, Mode},
+    codegen::{ensure_file_contents, reformat},
     project_root, Result,
 };
 
-pub(crate) fn generate_syntax(mode: Mode) -> Result<()> {
+pub(crate) fn generate_syntax() -> Result<()> {
     let grammar = rust_grammar();
     let ast = lower(&grammar);
 
     let syntax_kinds_file = project_root().join("crates/parser/src/syntax_kind/generated.rs");
     let syntax_kinds = generate_syntax_kinds(KINDS_SRC)?;
-    update(syntax_kinds_file.as_path(), &syntax_kinds, mode)?;
+    ensure_file_contents(syntax_kinds_file.as_path(), &syntax_kinds)?;
 
     let ast_tokens_file = project_root().join("crates/syntax/src/ast/generated/tokens.rs");
     let contents = generate_tokens(&ast)?;
-    update(ast_tokens_file.as_path(), &contents, mode)?;
+    ensure_file_contents(ast_tokens_file.as_path(), &contents)?;
 
     let ast_nodes_file = project_root().join("crates/syntax/src/ast/generated/nodes.rs");
     let contents = generate_nodes(KINDS_SRC, &ast)?;
-    update(ast_nodes_file.as_path(), &contents, mode)?;
+    ensure_file_contents(ast_nodes_file.as_path(), &contents)?;
 
     Ok(())
 }
diff --git a/xtask/src/flags.rs b/xtask/src/flags.rs
index 5710fbdb5..48d1ad45e 100644
--- a/xtask/src/flags.rs
+++ b/xtask/src/flags.rs
@@ -1,6 +1,10 @@
 #![allow(unreachable_pub)]
 
-xflags::args_parser! {
+use crate::install::{ClientOpt, Malloc, ServerOpt};
+
+xflags::xflags! {
+    src "./src/flags.rs"
+
     /// Run custom build command.
     cmd xtask {
         default cmd help {
@@ -23,10 +27,6 @@ xflags::args_parser! {
             optional --jemalloc
         }
 
-        cmd codegen {
-            optional --features
-        }
-
         cmd lint {}
         cmd fuzz-tests {}
         cmd pre-cache {}
@@ -53,7 +53,7 @@ xflags::args_parser! {
 
 // generated start
 // The following code is generated by `xflags` macro.
-// Run `env XFLAGS_DUMP= cargo build` to regenerate.
+// Run `env UPDATE_XFLAGS=1 cargo build` to regenerate.
 #[derive(Debug)]
 pub struct Xtask {
     pub subcommand: XtaskCmd,
@@ -63,7 +63,6 @@ pub struct Xtask {
 pub enum XtaskCmd {
     Help(Help),
     Install(Install),
-    Codegen(Codegen),
     Lint(Lint),
     FuzzTests(FuzzTests),
     PreCache(PreCache),
@@ -89,18 +88,13 @@ pub struct Install {
 }
 
 #[derive(Debug)]
-pub struct Codegen {
-    pub features: bool,
-}
-
-#[derive(Debug)]
-pub struct Lint {}
+pub struct Lint;
 
 #[derive(Debug)]
-pub struct FuzzTests {}
+pub struct FuzzTests;
 
 #[derive(Debug)]
-pub struct PreCache {}
+pub struct PreCache;
 
 #[derive(Debug)]
 pub struct Release {
@@ -129,11 +123,32 @@ pub struct Bb {
 }
 
 impl Xtask {
-    pub const HELP: &'static str = Self::_HELP;
+    pub const HELP: &'static str = Self::HELP_;
 
     pub fn from_env() -> xflags::Result<Self> {
-        let mut p = xflags::rt::Parser::new_from_env();
-        Self::_parse(&mut p)
+        Self::from_env_()
     }
 }
 // generated end
+
+impl Install {
+    pub(crate) fn server(&self) -> Option<ServerOpt> {
+        if self.client && !self.server {
+            return None;
+        }
+        let malloc = if self.mimalloc {
+            Malloc::Mimalloc
+        } else if self.jemalloc {
+            Malloc::Jemalloc
+        } else {
+            Malloc::System
+        };
+        Some(ServerOpt { malloc })
+    }
+    pub(crate) fn client(&self) -> Option<ClientOpt> {
+        if !self.client && self.server {
+            return None;
+        }
+        Some(ClientOpt { code_bin: self.code_bin.clone() })
+    }
+}
diff --git a/xtask/src/install.rs b/xtask/src/install.rs
index ea2194248..177028b08 100644
--- a/xtask/src/install.rs
+++ b/xtask/src/install.rs
@@ -5,60 +5,32 @@ use std::{env, path::PathBuf, str};
 use anyhow::{bail, format_err, Context, Result};
 use xshell::{cmd, pushd};
 
+use crate::flags;
+
 // Latest stable, feel free to send a PR if this lags behind.
 const REQUIRED_RUST_VERSION: u32 = 50;
 
-pub(crate) struct InstallCmd {
-    pub(crate) client: Option<ClientOpt>,
-    pub(crate) server: Option<ServerOpt>,
-}
-
-#[derive(Clone, Copy)]
-pub(crate) enum ClientOpt {
-    VsCode,
-    VsCodeExploration,
-    VsCodeInsiders,
-    VsCodium,
-    VsCodeOss,
-    Any,
-}
-
-impl ClientOpt {
-    pub(crate) const fn as_cmds(&self) -> &'static [&'static str] {
-        match self {
-            ClientOpt::VsCode => &["code"],
-            ClientOpt::VsCodeExploration => &["code-exploration"],
-            ClientOpt::VsCodeInsiders => &["code-insiders"],
-            ClientOpt::VsCodium => &["codium"],
-            ClientOpt::VsCodeOss => &["code-oss"],
-            ClientOpt::Any => &["code", "code-exploration", "code-insiders", "codium", "code-oss"],
+impl flags::Install {
+    pub(crate) fn run(self) -> Result<()> {
+        if cfg!(target_os = "macos") {
+            fix_path_for_mac().context("Fix path for mac")?
+        }
+        if let Some(server) = self.server() {
+            install_server(server).context("install server")?;
+        }
+        if let Some(client) = self.client() {
+            install_client(client).context("install client")?;
         }
+        Ok(())
     }
 }
 
-impl Default for ClientOpt {
-    fn default() -> Self {
-        ClientOpt::Any
-    }
+#[derive(Clone)]
+pub(crate) struct ClientOpt {
+    pub(crate) code_bin: Option<String>,
 }
 
-impl std::str::FromStr for ClientOpt {
-    type Err = anyhow::Error;
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        [
-            ClientOpt::VsCode,
-            ClientOpt::VsCodeExploration,
-            ClientOpt::VsCodeInsiders,
-            ClientOpt::VsCodium,
-            ClientOpt::VsCodeOss,
-        ]
-        .iter()
-        .copied()
-        .find(|c| [s] == c.as_cmds())
-        .ok_or_else(|| anyhow::format_err!("no such client"))
-    }
-}
+const VS_CODES: &[&str] = &["code", "code-exploration", "code-insiders", "codium", "code-oss"];
 
 pub(crate) struct ServerOpt {
     pub(crate) malloc: Malloc,
@@ -70,21 +42,6 @@ pub(crate) enum Malloc {
     Jemalloc,
 }
 
-impl InstallCmd {
-    pub(crate) fn run(self) -> Result<()> {
-        if cfg!(target_os = "macos") {
-            fix_path_for_mac().context("Fix path for mac")?
-        }
-        if let Some(server) = self.server {
-            install_server(server).context("install server")?;
-        }
-        if let Some(client) = self.client {
-            install_client(client).context("install client")?;
-        }
-        Ok(())
-    }
-}
-
 fn fix_path_for_mac() -> Result<()> {
     let mut vscode_path: Vec<PathBuf> = {
         const COMMON_APP_PATH: &str =
@@ -121,21 +78,12 @@ fn fix_path_for_mac() -> Result<()> {
 fn install_client(client_opt: ClientOpt) -> Result<()> {
     let _dir = pushd("./editors/code");
 
-    let find_code = |f: fn(&str) -> bool| -> Result<&'static str> {
-        client_opt.as_cmds().iter().copied().find(|bin| f(bin)).ok_or_else(|| {
-            format_err!("Can't execute `code --version`. Perhaps it is not in $PATH?")
-        })
-    };
-
-    let installed_extensions = if cfg!(unix) {
+    // Package extension.
+    if cfg!(unix) {
         cmd!("npm --version").run().context("`npm` is required to build the VS Code plugin")?;
         cmd!("npm ci").run()?;
 
         cmd!("npm run package --scripts-prepend-node-path").run()?;
-
-        let code = find_code(|bin| cmd!("{bin} --version").read().is_ok())?;
-        cmd!("{code} --install-extension rust-analyzer.vsix --force").run()?;
-        cmd!("{code} --list-extensions").read()?
     } else {
         cmd!("cmd.exe /c npm --version")
             .run()
@@ -143,8 +91,36 @@ fn install_client(client_opt: ClientOpt) -> Result<()> {
         cmd!("cmd.exe /c npm ci").run()?;
 
         cmd!("cmd.exe /c npm run package").run()?;
+    };
+
+    // Find the appropriate VS Code binary.
+    let lifetime_extender;
+    let candidates: &[&str] = match client_opt.code_bin.as_deref() {
+        Some(it) => {
+            lifetime_extender = [it];
+            &lifetime_extender[..]
+        }
+        None => VS_CODES,
+    };
+    let code = candidates
+        .iter()
+        .copied()
+        .find(|&bin| {
+            if cfg!(unix) {
+                cmd!("{bin} --version").read().is_ok()
+            } else {
+                cmd!("cmd.exe /c {bin}.cmd --version").read().is_ok()
+            }
+        })
+        .ok_or_else(|| {
+            format_err!("Can't execute `{} --version`. Perhaps it is not in $PATH?", candidates[0])
+        })?;
 
-        let code = find_code(|bin| cmd!("cmd.exe /c {bin}.cmd --version").read().is_ok())?;
+    // Install & verify.
+    let installed_extensions = if cfg!(unix) {
+        cmd!("{code} --install-extension rust-analyzer.vsix --force").run()?;
+        cmd!("{code} --list-extensions").read()?
+    } else {
         cmd!("cmd.exe /c {code}.cmd --install-extension rust-analyzer.vsix --force").run()?;
         cmd!("cmd.exe /c {code}.cmd --list-extensions").read()?
     };
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index e419db7a7..35cc7c108 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -28,11 +28,7 @@ use std::{
 use walkdir::{DirEntry, WalkDir};
 use xshell::{cmd, cp, pushd, pushenv};
 
-use crate::{
-    codegen::Mode,
-    dist::DistCmd,
-    install::{InstallCmd, Malloc, ServerOpt},
-};
+use crate::dist::DistCmd;
 
 fn main() -> Result<()> {
     let _d = pushd(project_root())?;
@@ -43,32 +39,7 @@ fn main() -> Result<()> {
             println!("{}", flags::Xtask::HELP);
             return Ok(());
         }
-        flags::XtaskCmd::Install(flags) => {
-            if flags.server && flags.client {
-                eprintln!(
-                    "error: The argument `--server` cannot be used with `--client`\n\n\
-                     For more information try --help"
-                );
-                return Ok(());
-            }
-
-            let malloc = if flags.mimalloc {
-                Malloc::Mimalloc
-            } else if flags.jemalloc {
-                Malloc::Jemalloc
-            } else {
-                Malloc::System
-            };
-
-            let client_bin = flags.code_bin.map(|it| it.parse()).transpose()?;
-
-            InstallCmd {
-                client: if flags.server { None } else { client_bin },
-                server: if flags.client { None } else { Some(ServerOpt { malloc }) },
-            }
-            .run()
-        }
-        flags::XtaskCmd::Codegen(cmd) => cmd.run(),
+        flags::XtaskCmd::Install(cmd) => cmd.run(),
         flags::XtaskCmd::Lint(_) => run_clippy(),
         flags::XtaskCmd::FuzzTests(_) => run_fuzzer(),
         flags::XtaskCmd::PreCache(cmd) => cmd.run(),
@@ -113,18 +84,6 @@ fn rust_files_in(path: &Path) -> impl Iterator<Item = PathBuf> {
     files_in(path, "rs")
 }
 
-fn run_rustfmt(mode: Mode) -> Result<()> {
-    let _dir = pushd(project_root())?;
-    let _e = pushenv("RUSTUP_TOOLCHAIN", "stable");
-    ensure_rustfmt()?;
-    let check = match mode {
-        Mode::Overwrite => &[][..],
-        Mode::Verify => &["--", "--check"],
-    };
-    cmd!("cargo fmt {check...}").run()?;
-    Ok(())
-}
-
 fn ensure_rustfmt() -> Result<()> {
     let out = cmd!("rustfmt --version").read()?;
     if !out.contains("stable") {
diff --git a/xtask/src/release.rs b/xtask/src/release.rs
index d8d86fd63..dde5d14ee 100644
--- a/xtask/src/release.rs
+++ b/xtask/src/release.rs
@@ -2,7 +2,7 @@ use std::fmt::Write;
 
 use xshell::{cmd, cp, pushd, read_dir, write_file};
 
-use crate::{codegen, date_iso, flags, is_release_tag, project_root, Mode, Result};
+use crate::{codegen, date_iso, flags, is_release_tag, project_root, Result};
 
 impl flags::Release {
     pub(crate) fn run(self) -> Result<()> {
@@ -12,8 +12,7 @@ impl flags::Release {
             cmd!("git reset --hard tags/nightly").run()?;
             cmd!("git push").run()?;
         }
-        codegen::generate_assists_docs(Mode::Overwrite)?;
-        codegen::generate_feature_docs(Mode::Overwrite)?;
+        codegen::docs()?;
 
         let website_root = project_root().join("../rust-analyzer.github.io");
         let changelog_dir = website_root.join("./thisweek/_posts");
diff --git a/xtask/src/tidy.rs b/xtask/src/tidy.rs
index 349ca14d0..1352d1218 100644
--- a/xtask/src/tidy.rs
+++ b/xtask/src/tidy.rs
@@ -3,48 +3,48 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use xshell::{cmd, read_file};
+use xshell::{cmd, pushd, pushenv, read_file};
 
-use crate::{
-    cargo_files,
-    codegen::{self, Mode},
-    project_root, run_rustfmt, rust_files,
-};
+use crate::{cargo_files, codegen, project_root, rust_files};
 
 #[test]
-fn generated_grammar_is_fresh() {
-    if let Err(error) = codegen::generate_syntax(Mode::Verify) {
-        panic!("{}. Please update it by running `cargo xtask codegen`", error);
-    }
+fn generate_grammar() {
+    codegen::generate_syntax().unwrap()
 }
 
 #[test]
-fn generated_tests_are_fresh() {
-    if let Err(error) = codegen::generate_parser_tests(Mode::Verify) {
-        panic!("{}. Please update tests by running `cargo xtask codegen`", error);
-    }
+fn generate_parser_tests() {
+    codegen::generate_parser_tests().unwrap()
 }
 
 #[test]
-fn generated_assists_are_fresh() {
-    if let Err(error) = codegen::generate_assists_tests(Mode::Verify) {
-        panic!("{}. Please update assists by running `cargo xtask codegen`", error);
-    }
+fn generate_assists_tests() {
+    codegen::generate_assists_tests().unwrap();
+}
+
+/// This clones rustc repo, and so is not worth to keep up-to-date. We update
+/// manually by un-ignoring the test from time to time.
+#[test]
+#[ignore]
+fn generate_lint_completions() {
+    codegen::generate_lint_completions().unwrap()
 }
 
 #[test]
 fn check_code_formatting() {
-    if let Err(error) = run_rustfmt(Mode::Verify) {
-        panic!("{}. Please format the code by running `cargo format`", error);
+    let _dir = pushd(project_root()).unwrap();
+    let _e = pushenv("RUSTUP_TOOLCHAIN", "stable");
+    crate::ensure_rustfmt().unwrap();
+    let res = cmd!("cargo fmt -- --check").run();
+    if !res.is_ok() {
+        let _ = cmd!("cargo fmt").run();
     }
+    res.unwrap()
 }
 
 #[test]
-fn smoke_test_docs_generation() {
-    // We don't commit docs to the repo, so we can just overwrite in tests.
-    codegen::generate_assists_docs(Mode::Overwrite).unwrap();
-    codegen::generate_feature_docs(Mode::Overwrite).unwrap();
-    codegen::generate_diagnostic_docs(Mode::Overwrite).unwrap();
+fn smoke_test_generate_documentation() {
+    codegen::docs().unwrap()
 }
 
 #[test]