flycheck: Fix label for source file

tools/rust_analyzer/bin/flycheck.rs

@@ -457,6 +457,23 @@ fn resolve_label_for(
     query_label_for(bazel, workspace, saved_file)
 }
 
+/// Produces the query string used by `query_label_for`
+fn query_string_for(workspace: &Utf8Path, saved_file: &Utf8Path) -> Result<String> {
+    let file_rel = saved_file
+        .strip_prefix(workspace)
+        .with_context(|| format!("saved file {saved_file} is not under workspace {workspace}"))?;
+    let package = find_owning_package(workspace, file_rel).with_context(|| {
+        format!("no BUILD.bazel found above {saved_file} — is this file part of a Bazel target?")
+    })?;
+
+    // Generate a label that preserves the package-relative file path.
+    let file_in_package = file_rel.strip_prefix(&package).with_context(|| {
+        format!("saved file {saved_file} is not under Bazel package //{package}")
+    })?;
+    let pattern = format!("//{package}:{file_in_package}");
+    Ok(format!("attr(srcs, {pattern:?}, //{package}:*)"))
+}
+
 /// `bazel query 'attr(srcs, "<file>", //<package>:*)'` scoped to the
 /// nearest `BUILD.bazel`. Returns the first match — if a file belongs
 /// to several targets, any is correct.
@@ -465,17 +482,7 @@ fn query_label_for(
     workspace: &Utf8Path,
     saved_file: &Utf8Path,
 ) -> Result<String> {
-    let file_rel = saved_file
-        .strip_prefix(workspace)
-        .with_context(|| format!("saved file {saved_file} is not under workspace {workspace}"))?;
-    let package = find_owning_package(workspace, file_rel).with_context(|| {
-        format!("no BUILD.bazel found above {saved_file} — is this file part of a Bazel target?")
-    })?;
-    let file_basename = file_rel
-        .file_name()
-        .with_context(|| format!("saved file {saved_file} has no file name"))?;
-    let pattern = format!("//{package}:{file_basename}");
-    let query = format!("attr(srcs, {pattern:?}, //{package}:*)");
+    let query = query_string_for(workspace, saved_file)?;
     let output = Command::new(bazel.as_str())
         .current_dir(workspace)
         .arg("query")
@@ -492,7 +499,7 @@ fn query_label_for(
         .lines()
         .find(|l| !l.is_empty())
         .map(str::to_owned)
-        .with_context(|| format!("bazel query returned no targets for {pattern}"))
+        .with_context(|| format!("bazel query {query:?} returned no targets"))
 }
 
 /// Walk up looking for `BUILD.bazel` or `BUILD`. Returns the
@@ -523,8 +530,49 @@ fn scopeguard(path: Utf8PathBuf) -> impl Drop {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use gen_rust_project_lib::make_workspace;
     use serde_json::json;
 
+    #[test]
+    fn find_owning_package_test() {
+        let pkg_path = "example/library";
+        let build_path = format!("{pkg_path}/BUILD.bazel");
+        let rust_src_path = format!("{pkg_path}/src/main.rs");
+        let workspace = make_workspace(
+            "find_owning_package_test",
+            &[
+                ("MODULE.bazel", ""),
+                (&build_path, "package()"),
+                (&rust_src_path, "fn main() {}"),
+            ],
+        );
+
+        assert_eq!(
+            find_owning_package(&workspace, &Utf8PathBuf::from(&rust_src_path)).unwrap(),
+            pkg_path
+        );
+    }
+
+    #[test]
+    fn query_test() {
+        let pkg_path = "example/library";
+        let build_path = format!("{pkg_path}/BUILD.bazel");
+        let rust_src_path = format!("{pkg_path}/src/main.rs");
+        let workspace = make_workspace(
+            "query_test",
+            &[
+                ("MODULE.bazel", ""),
+                (&build_path, "package()"),
+                (&rust_src_path, "fn main() {}"),
+            ],
+        );
+
+        assert_eq!(
+            query_string_for(&workspace, &workspace.join(&rust_src_path)).unwrap(),
+            r#"attr(srcs, "//example/library:src/main.rs", //example/library:*)"#
+        );
+    }
+
     #[test]
     fn relative_file_names_become_absolute() {
         let workspace = Utf8Path::new("/abs/ws");

tools/rust_analyzer/bin/setup.rs

@@ -1273,6 +1273,7 @@ fn generate_settings_json(ctx: &SetupCtx, launcher_dir: &Utf8Path) -> String {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use gen_rust_project_lib::make_workspace;
 
     fn dummy_toolchain() -> ToolchainBinaries {
         ToolchainBinaries {
@@ -1831,20 +1832,6 @@ mod tests {
     // `.code-workspace` support
     // -----------------------------------------------------------------
 
-    /// Build a workspace dir in $TMPDIR, populated with the listed
-    /// files. Returns the dir path; caller is responsible for cleanup
-    /// (use `remove_dir_all` in a `_guard`-style drop, or accept the
-    /// leak — TMPDIR gets cleaned eventually).
-    fn make_workspace(tag: &str, files: &[(&str, &str)]) -> Utf8PathBuf {
-        let tmp = std::env::temp_dir().join(format!("setup_{tag}_{}", std::process::id()));
-        let _ = std::fs::remove_dir_all(&tmp);
-        std::fs::create_dir_all(&tmp).unwrap();
-        for (name, content) in files {
-            std::fs::write(tmp.join(name), content).unwrap();
-        }
-        Utf8PathBuf::try_from(tmp).unwrap()
-    }
-
     #[test]
     fn merge_under_settings_key_preserves_top_level_keys() {
         let (ctx, _launcher_dir) = dummy_ctx();

tools/rust_analyzer/lib.rs

@@ -4,7 +4,7 @@ mod cache;
 mod rust_project;
 pub mod user_config;
 
-use std::{collections::BTreeMap, fs, process::Command};
+use std::{collections::BTreeMap, convert::TryFrom, fs, process::Command};
 
 use anyhow::{bail, Context};
 use camino::{Utf8Path, Utf8PathBuf};
@@ -553,6 +553,22 @@ pub struct ToolchainInfo {
     pub version: String,
 }
 
+/// Build a workspace dir in $TMPDIR, populated with the listed
+/// files. Returns the dir path; caller is responsible for cleanup
+/// (use `remove_dir_all` in a `_guard`-style drop, or accept the
+/// leak — TMPDIR gets cleaned eventually).
+pub fn make_workspace(tag: &str, files: &[(&str, &str)]) -> Utf8PathBuf {
+    let tmp = std::env::temp_dir().join(format!("setup_{tag}_{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&tmp);
+    std::fs::create_dir_all(&tmp).unwrap();
+    for (name, content) in files {
+        let abs_path = tmp.join(name);
+        std::fs::create_dir_all(abs_path.parent().unwrap()).unwrap();
+        std::fs::write(abs_path, content).unwrap();
+    }
+    Utf8PathBuf::try_from(tmp).unwrap()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;