feat: allow manually defining the project's manifest path

src/cargo.rs

@@ -8,8 +8,12 @@ use color_eyre::{
 use serde::Deserialize;
 
 /// Locate the root directory of the project under the current working directory.
-pub fn project_dir() -> Result<Utf8PathBuf> {
-    let manifest_path = cargo_locate_project().wrap_err("failed to locate project")?;
+pub fn project_dir(manifest_path: Option<&Utf8Path>) -> Result<Utf8PathBuf> {
+    let manifest_path = match manifest_path {
+        Some(path) => path.to_owned(),
+        None => cargo_locate_project().wrap_err("failed to locate project")?,
+    };
+
     cargo_metadata(&manifest_path)
         .map(|meta| meta.workspace_root)
         .wrap_err("failed to load project metadata")
@@ -21,8 +25,12 @@ pub fn project_dir() -> Result<Utf8PathBuf> {
 /// our own `target/llvm-cov-pretty` folder that holds the report files.
 ///
 /// This will only work if the current working directory contains a Rust project.
-pub fn output_dir() -> Result<Utf8PathBuf> {
-    let manifest_path = cargo_locate_project().wrap_err("failed to locate project")?;
+pub fn output_dir(manifest_path: Option<&Utf8Path>) -> Result<Utf8PathBuf> {
+    let manifest_path = match manifest_path {
+        Some(path) => path.to_owned(),
+        None => cargo_locate_project().wrap_err("failed to locate project")?,
+    };
+
     cargo_metadata(&manifest_path)
         .map(|meta| meta.target_directory.join(env!("CARGO_PKG_NAME")))
         .wrap_err("failed to load project metadata")
@@ -131,12 +139,12 @@ pub fn check_version() -> Result<()> {
 mod tests {
     #[test]
     fn project_dir() {
-        super::project_dir().unwrap();
+        super::project_dir(None).unwrap();
     }
 
     #[test]
     fn output_dir() {
-        super::output_dir().unwrap();
+        super::output_dir(None).unwrap();
     }
 
     #[test]

src/cli.rs

@@ -24,6 +24,9 @@ pub struct Cli {
     /// The highlighting theme to use, if not disabled.
     #[arg(long, default_value_t = Theme::OneHalf)]
     pub theme: Theme,
+    /// Location of the project's Cargo.toml, in case the default detection isn't sufficient.
+    #[arg(long)]
+    pub manifest_path: Option<Utf8PathBuf>,
     /// Input coverage file encoded as JSON, or STDIN if omitted.
     pub input: Option<Utf8PathBuf>,
     #[command(subcommand)]

src/main.rs

@@ -60,8 +60,10 @@ fn main() -> Result<()> {
             .wrap_err("failed parsing report data from STDIN")?
     };
 
-    let project_dir = cargo::project_dir().wrap_err("failed to locate project directory")?;
-    let output_dir = cargo::output_dir().wrap_err("failed to locate output directory")?;
+    let project_dir = cargo::project_dir(cli.manifest_path.as_deref())
+        .wrap_err("failed to locate project directory")?;
+    let output_dir = cargo::output_dir(cli.manifest_path.as_deref())
+        .wrap_err("failed to locate output directory")?;
 
     let files = collect_project_files(&project_dir)?;
     let mut files = merge_file_info(files, &export.files);
@@ -189,10 +191,7 @@ fn segments_to_ranges(
 
 fn merge_function_info(files: &mut Vec<FileInfo>, functions: &[schema::Function]) {
     files.par_iter_mut().for_each(|file| {
-        for function in functions
-            .iter()
-            .filter(|f| f.filenames[0] == file.path)
-        {
+        for function in functions.iter().filter(|f| f.filenames[0] == file.path) {
             for region in &function.regions {
                 if region.execution_count > 0 {
                     file.called