diff --git a/.cargo/config.toml b/.cargo/config.toml
index c3cfda85517..070560dfbc3 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -3,6 +3,7 @@ xtask = "run --package xtask --bin xtask --"
 tq = "test -- -q"
 qt = "tq"
 lint = "clippy --all-targets -- --cap-lints warn"
+codegen = "run --package xtask --bin xtask -- codegen"
 
 [target.x86_64-pc-windows-msvc]
 linker = "rust-lld"
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 5a8b18e3fe1..2d8946520d5 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -79,6 +79,9 @@ jobs:
         if: matrix.os == 'ubuntu-latest'
         run: sed -i '/\[profile.dev]/a opt-level=1' Cargo.toml
 
+      - name: Codegen checks (rust-analyzer)
+        run: cargo codegen --check
+
       - name: Compile (tests)
         run: cargo test --no-run --locked ${{ env.USE_SYSROOT_ABI }}
 
diff --git a/Cargo.lock b/Cargo.lock
index 607b831f01b..9b431d85a64 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -670,7 +670,6 @@ dependencies = [
  "ide-db",
  "itertools",
  "smallvec",
- "sourcegen",
  "stdx",
  "syntax",
  "test-fixture",
@@ -2494,6 +2493,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "flate2",
+ "stdx",
  "time",
  "write-json",
  "xflags",
diff --git a/crates/ide-assists/Cargo.toml b/crates/ide-assists/Cargo.toml
index e1375f9c3ee..a78129fc47e 100644
--- a/crates/ide-assists/Cargo.toml
+++ b/crates/ide-assists/Cargo.toml
@@ -32,7 +32,6 @@ expect-test = "1.4.0"
 # local deps
 test-utils.workspace = true
 test-fixture.workspace = true
-sourcegen.workspace = true
 
 [features]
 in-rust-tree = []
diff --git a/crates/ide-assists/src/tests.rs b/crates/ide-assists/src/tests.rs
index 9b6f7d018ee..32d69841020 100644
--- a/crates/ide-assists/src/tests.rs
+++ b/crates/ide-assists/src/tests.rs
@@ -1,6 +1,4 @@
 mod generated;
-#[cfg(not(feature = "in-rust-tree"))]
-mod sourcegen;
 
 use expect_test::expect;
 use hir::Semantics;
diff --git a/xtask/Cargo.toml b/xtask/Cargo.toml
index 863a63ac82e..5e758e0190c 100644
--- a/xtask/Cargo.toml
+++ b/xtask/Cargo.toml
@@ -14,7 +14,8 @@ xshell.workspace = true
 xflags = "0.3.0"
 time = { version = "0.3", default-features = false }
 zip = { version = "0.6", default-features = false, features = ["deflate", "time"] }
+stdx.workspace = true
 # Avoid adding more dependencies to this crate
 
 [lints]
-workspace = true
\ No newline at end of file
+workspace = true
diff --git a/xtask/src/codegen.rs b/xtask/src/codegen.rs
new file mode 100644
index 00000000000..e579660ac9b
--- /dev/null
+++ b/xtask/src/codegen.rs
@@ -0,0 +1,211 @@
+use std::{
+    fmt, fs, mem,
+    path::{Path, PathBuf},
+};
+
+use xshell::{cmd, Shell};
+
+use crate::{flags, project_root};
+
+pub(crate) mod assists_doc_tests;
+
+impl flags::Codegen {
+    pub(crate) fn run(self, _sh: &Shell) -> anyhow::Result<()> {
+        match self.codegen_type.unwrap_or_default() {
+            flags::CodegenType::All => {
+                assists_doc_tests::generate(self.check);
+            }
+            flags::CodegenType::AssistsDocTests => assists_doc_tests::generate(self.check),
+        }
+        Ok(())
+    }
+}
+
+fn list_rust_files(dir: &Path) -> Vec<PathBuf> {
+    let mut res = list_files(dir);
+    res.retain(|it| {
+        it.file_name().unwrap_or_default().to_str().unwrap_or_default().ends_with(".rs")
+    });
+    res
+}
+
+fn list_files(dir: &Path) -> Vec<PathBuf> {
+    let mut res = Vec::new();
+    let mut work = vec![dir.to_path_buf()];
+    while let Some(dir) = work.pop() {
+        for entry in dir.read_dir().unwrap() {
+            let entry = entry.unwrap();
+            let file_type = entry.file_type().unwrap();
+            let path = entry.path();
+            let is_hidden =
+                path.file_name().unwrap_or_default().to_str().unwrap_or_default().starts_with('.');
+            if !is_hidden {
+                if file_type.is_dir() {
+                    work.push(path);
+                } else if file_type.is_file() {
+                    res.push(path);
+                }
+            }
+        }
+    }
+    res
+}
+
+#[derive(Clone)]
+pub(crate) struct CommentBlock {
+    pub(crate) id: String,
+    pub(crate) line: usize,
+    pub(crate) contents: Vec<String>,
+    is_doc: bool,
+}
+
+impl CommentBlock {
+    fn extract(tag: &str, text: &str) -> Vec<CommentBlock> {
+        assert!(tag.starts_with(char::is_uppercase));
+
+        let tag = format!("{tag}:");
+        let mut blocks = CommentBlock::extract_untagged(text);
+        blocks.retain_mut(|block| {
+            let first = block.contents.remove(0);
+            let Some(id) = first.strip_prefix(&tag) else {
+                return false;
+            };
+
+            if block.is_doc {
+                panic!("Use plain (non-doc) comments with tags like {tag}:\n    {first}");
+            }
+
+            block.id = id.trim().to_owned();
+            true
+        });
+        blocks
+    }
+
+    fn extract_untagged(text: &str) -> Vec<CommentBlock> {
+        let mut res = Vec::new();
+
+        let lines = text.lines().map(str::trim_start);
+
+        let dummy_block =
+            CommentBlock { id: String::new(), line: 0, contents: Vec::new(), is_doc: false };
+        let mut block = dummy_block.clone();
+        for (line_num, line) in lines.enumerate() {
+            match line.strip_prefix("//") {
+                Some(mut contents) => {
+                    if let Some('/' | '!') = contents.chars().next() {
+                        contents = &contents[1..];
+                        block.is_doc = true;
+                    }
+                    if let Some(' ') = contents.chars().next() {
+                        contents = &contents[1..];
+                    }
+                    block.contents.push(contents.to_owned());
+                }
+                None => {
+                    if !block.contents.is_empty() {
+                        let block = mem::replace(&mut block, dummy_block.clone());
+                        res.push(block);
+                    }
+                    block.line = line_num + 2;
+                }
+            }
+        }
+        if !block.contents.is_empty() {
+            res.push(block);
+        }
+        res
+    }
+}
+
+#[derive(Debug)]
+pub(crate) struct Location {
+    pub(crate) file: PathBuf,
+    pub(crate) line: usize,
+}
+
+impl fmt::Display for Location {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let path = self.file.strip_prefix(project_root()).unwrap().display().to_string();
+        let path = path.replace('\\', "/");
+        let name = self.file.file_name().unwrap();
+        write!(
+            f,
+            "https://github.com/rust-lang/rust-analyzer/blob/master/{}#L{}[{}]",
+            path,
+            self.line,
+            name.to_str().unwrap()
+        )
+    }
+}
+
+fn ensure_rustfmt(sh: &Shell) {
+    let version = cmd!(sh, "rustup run stable rustfmt --version").read().unwrap_or_default();
+    if !version.contains("stable") {
+        panic!(
+            "Failed to run rustfmt from toolchain 'stable'. \
+                 Please run `rustup component add rustfmt --toolchain stable` to install it.",
+        );
+    }
+}
+
+fn reformat(text: String) -> String {
+    let sh = Shell::new().unwrap();
+    ensure_rustfmt(&sh);
+    let rustfmt_toml = project_root().join("rustfmt.toml");
+    let mut stdout = cmd!(
+        sh,
+        "rustup run stable rustfmt --config-path {rustfmt_toml} --config fn_single_line=true"
+    )
+    .stdin(text)
+    .read()
+    .unwrap();
+    if !stdout.ends_with('\n') {
+        stdout.push('\n');
+    }
+    stdout
+}
+
+fn add_preamble(generator: &'static str, mut text: String) -> String {
+    let preamble = format!("//! Generated by `{generator}`, do not edit by hand.\n\n");
+    text.insert_str(0, &preamble);
+    text
+}
+
+/// Checks that the `file` has the specified `contents`. If that is not the
+/// case, updates the file and then fails the test.
+#[allow(clippy::print_stderr)]
+fn ensure_file_contents(file: &Path, contents: &str, check: bool) {
+    if let Ok(old_contents) = fs::read_to_string(file) {
+        if normalize_newlines(&old_contents) == normalize_newlines(contents) {
+            // File is already up to date.
+            return;
+        }
+    }
+
+    let display_path = file.strip_prefix(project_root()).unwrap_or(file);
+    if check {
+        panic!(
+            "{} was not up-to-date{}",
+            file.display(),
+            if std::env::var("CI").is_ok() {
+                "\n    NOTE: run `cargo codegen` locally and commit the updated files\n"
+            } else {
+                ""
+            }
+        );
+    } else {
+        eprintln!(
+            "\n\x1b[31;1merror\x1b[0m: {} was not up-to-date, updating\n",
+            display_path.display()
+        );
+
+        if let Some(parent) = file.parent() {
+            let _ = fs::create_dir_all(parent);
+        }
+        fs::write(file, contents).unwrap();
+    }
+}
+
+fn normalize_newlines(s: &str) -> String {
+    s.replace("\r\n", "\n")
+}
diff --git a/crates/ide-assists/src/tests/sourcegen.rs b/xtask/src/codegen/assists_doc_tests.rs
similarity index 89%
rename from crates/ide-assists/src/tests/sourcegen.rs
rename to xtask/src/codegen/assists_doc_tests.rs
index 847cb1af51e..b2d89dde765 100644
--- a/crates/ide-assists/src/tests/sourcegen.rs
+++ b/xtask/src/codegen/assists_doc_tests.rs
@@ -3,10 +3,15 @@
 use std::{fmt, fs, path::Path};
 
 use stdx::format_to_acc;
-use test_utils::project_root;
 
-#[test]
-fn sourcegen_assists_docs() {
+use crate::{
+    codegen::{
+        add_preamble, ensure_file_contents, list_rust_files, reformat, CommentBlock, Location,
+    },
+    project_root,
+};
+
+pub(crate) fn generate(check: bool) {
     let assists = Assist::collect();
 
     {
@@ -40,10 +45,11 @@ fn doctest_{}() {{
                 buf.push_str(&test)
             }
         }
-        let buf = sourcegen::add_preamble("sourcegen_assists_docs", sourcegen::reformat(buf));
-        sourcegen::ensure_file_contents(
+        let buf = add_preamble("sourcegen_assists_docs", reformat(buf));
+        ensure_file_contents(
             &project_root().join("crates/ide-assists/src/tests/generated.rs"),
             &buf,
+            check,
         );
     }
 
@@ -52,7 +58,7 @@ fn doctest_{}() {{
         // git repo. Instead, `cargo xtask release` runs this test before making
         // a release.
 
-        let contents = sourcegen::add_preamble(
+        let contents = add_preamble(
             "sourcegen_assists_docs",
             assists.into_iter().map(|it| it.to_string()).collect::<Vec<_>>().join("\n\n"),
         );
@@ -71,7 +77,7 @@ struct Section {
 #[derive(Debug)]
 struct Assist {
     id: String,
-    location: sourcegen::Location,
+    location: Location,
     sections: Vec<Section>,
 }
 
@@ -80,7 +86,7 @@ fn collect() -> Vec<Assist> {
         let handlers_dir = project_root().join("crates/ide-assists/src/handlers");
 
         let mut res = Vec::new();
-        for path in sourcegen::list_rust_files(&handlers_dir) {
+        for path in list_rust_files(&handlers_dir) {
             collect_file(&mut res, path.as_path());
         }
         res.sort_by(|lhs, rhs| lhs.id.cmp(&rhs.id));
@@ -88,7 +94,7 @@ fn collect() -> Vec<Assist> {
 
         fn collect_file(acc: &mut Vec<Assist>, path: &Path) {
             let text = fs::read_to_string(path).unwrap();
-            let comment_blocks = sourcegen::CommentBlock::extract("Assist", &text);
+            let comment_blocks = CommentBlock::extract("Assist", &text);
 
             for block in comment_blocks {
                 let id = block.id;
@@ -97,7 +103,7 @@ fn collect_file(acc: &mut Vec<Assist>, path: &Path) {
                     "invalid assist id: {id:?}"
                 );
                 let mut lines = block.contents.iter().peekable();
-                let location = sourcegen::Location { file: path.to_path_buf(), line: block.line };
+                let location = Location { file: path.to_path_buf(), line: block.line };
                 let mut assist = Assist { id, location, sections: Vec::new() };
 
                 while lines.peek().is_some() {
diff --git a/xtask/src/flags.rs b/xtask/src/flags.rs
index e234090a07c..f5827170b65 100644
--- a/xtask/src/flags.rs
+++ b/xtask/src/flags.rs
@@ -52,6 +52,11 @@
         cmd bb {
             required suffix: String
         }
+
+        cmd codegen {
+            optional codegen_type: CodegenType
+            optional --check
+        }
     }
 }
 
@@ -73,8 +78,32 @@ pub enum XtaskCmd {
     PublishReleaseNotes(PublishReleaseNotes),
     Metrics(Metrics),
     Bb(Bb),
+    Codegen(Codegen),
 }
 
+#[derive(Debug)]
+pub struct Codegen {
+    pub check: bool,
+    pub codegen_type: Option<CodegenType>,
+}
+
+#[derive(Debug, Default)]
+pub enum CodegenType {
+    #[default]
+    All,
+    AssistsDocTests,
+}
+
+impl FromStr for CodegenType {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "all" => Ok(Self::All),
+            "assists-doc-tests" => Ok(Self::AssistsDocTests),
+            _ => Err("Invalid option".to_owned()),
+        }
+    }
+}
 #[derive(Debug)]
 pub struct Install {
     pub client: bool,
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index df4d9810e6f..9418675a348 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -13,6 +13,7 @@
 
 mod flags;
 
+mod codegen;
 mod dist;
 mod install;
 mod metrics;
@@ -20,10 +21,7 @@
 mod release;
 
 use anyhow::bail;
-use std::{
-    env,
-    path::{Path, PathBuf},
-};
+use std::{env, path::PathBuf};
 use xshell::{cmd, Shell};
 
 fn main() -> anyhow::Result<()> {
@@ -40,6 +38,7 @@ fn main() -> anyhow::Result<()> {
         flags::XtaskCmd::Dist(cmd) => cmd.run(sh),
         flags::XtaskCmd::PublishReleaseNotes(cmd) => cmd.run(sh),
         flags::XtaskCmd::Metrics(cmd) => cmd.run(sh),
+        flags::XtaskCmd::Codegen(cmd) => cmd.run(sh),
         flags::XtaskCmd::Bb(cmd) => {
             {
                 let _d = sh.push_dir("./crates/rust-analyzer");
@@ -54,14 +53,11 @@ fn main() -> anyhow::Result<()> {
     }
 }
 
+/// Returns the path to the root directory of `rust-analyzer` project.
 fn project_root() -> PathBuf {
-    Path::new(
-        &env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| env!("CARGO_MANIFEST_DIR").to_owned()),
-    )
-    .ancestors()
-    .nth(1)
-    .unwrap()
-    .to_path_buf()
+    let dir =
+        env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| env!("CARGO_MANIFEST_DIR").to_owned());
+    PathBuf::from(dir).parent().unwrap().to_owned()
 }
 
 fn run_fuzzer(sh: &Shell) -> anyhow::Result<()> {
diff --git a/xtask/src/release.rs b/xtask/src/release.rs
index 4a306914778..f99f9ecbc39 100644
--- a/xtask/src/release.rs
+++ b/xtask/src/release.rs
@@ -2,7 +2,7 @@
 
 use xshell::{cmd, Shell};
 
-use crate::{date_iso, flags, is_release_tag, project_root};
+use crate::{codegen, date_iso, flags, is_release_tag, project_root};
 
 impl flags::Release {
     pub(crate) fn run(self, sh: &Shell) -> anyhow::Result<()> {
@@ -23,8 +23,8 @@ pub(crate) fn run(self, sh: &Shell) -> anyhow::Result<()> {
         }
 
         // Generates bits of manual.adoc.
-        cmd!(sh, "cargo test -p ide-assists -p ide-diagnostics -p rust-analyzer -- sourcegen_")
-            .run()?;
+        cmd!(sh, "cargo test -p ide-diagnostics -p rust-analyzer -- sourcegen_").run()?;
+        codegen::assists_doc_tests::generate(false);
 
         let website_root = project_root().join("../rust-analyzer.github.io");
         {