From d52af53e04379adbdef6cdaef5d43e64c45d6a2a Mon Sep 17 00:00:00 2001
From: mcarton <cartonmartin+git@gmail.com>
Date: Tue, 25 Oct 2016 19:41:24 +0200
Subject: [PATCH] Search for `clippy.toml` recursively

---
 clippy_lints/src/lib.rs        | 16 ++++++----
 clippy_lints/src/utils/conf.rs | 54 +++++++++++++++++++++++++++-------
 2 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 4c97c5d465f..2b2ecac9cdb 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -136,17 +136,23 @@ mod reexport {
 
 #[cfg_attr(rustfmt, rustfmt_skip)]
 pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
-    let conf = match utils::conf::file(reg.args()) {
+    let conf = match utils::conf::file_from_args(reg.args()) {
         Ok(file_name) => {
             // if the user specified a file, it must exist, otherwise default to `clippy.toml` but
             // do not require the file to exist
-            let (file_name, must_exist) = if let Some(ref file_name) = file_name {
-                (&**file_name, true)
+            let file_name = if let Some(file_name) = file_name {
+                Some(file_name)
             } else {
-                ("clippy.toml", false)
+                match utils::conf::lookup_conf_file() {
+                    Ok(path) => path,
+                    Err(error) => {
+                        reg.sess.struct_err(&format!("error reading Clippy's configuration file: {}", error)).emit();
+                        None
+                    }
+                }
             };
 
-            let (conf, errors) = utils::conf::read(file_name, must_exist);
+            let (conf, errors) = utils::conf::read(file_name.as_ref().map(|p| p.as_ref()));
 
             // all conf errors are non-fatal, we just use the default conf in case of error
             for error in errors {
diff --git a/clippy_lints/src/utils/conf.rs b/clippy_lints/src/utils/conf.rs
index 59913fd7115..0dccaec8ed8 100644
--- a/clippy_lints/src/utils/conf.rs
+++ b/clippy_lints/src/utils/conf.rs
@@ -2,14 +2,13 @@
 
 #![deny(missing_docs_in_private_items)]
 
-use std::{fmt, fs, io};
+use std::{env, fmt, fs, io, path};
 use std::io::Read;
 use syntax::{ast, codemap};
-use syntax::parse::token;
 use toml;
 
 /// Get the configuration file from arguments.
-pub fn file(args: &[codemap::Spanned<ast::NestedMetaItemKind>]) -> Result<Option<token::InternedString>, (&'static str, codemap::Span)> {
+pub fn file_from_args(args: &[codemap::Spanned<ast::NestedMetaItemKind>]) -> Result<Option<path::PathBuf>, (&'static str, codemap::Span)> {
     for arg in args.iter().filter_map(|a| a.meta_item()) {
         match arg.node {
             ast::MetaItemKind::Word(ref name) |
@@ -21,7 +20,7 @@ pub fn file(args: &[codemap::Spanned<ast::NestedMetaItemKind>]) -> Result<Option
             ast::MetaItemKind::NameValue(ref name, ref value) => {
                 if name == &"conf_file" {
                     return if let ast::LitKind::Str(ref file, _) = value.node {
-                        Ok(Some(file.clone()))
+                        Ok(Some(file.to_string().into()))
                     } else {
                         Err(("`conf_file` value must be a string", value.span))
                     };
@@ -179,13 +178,51 @@ define_Conf! {
     ("enum-variant-name-threshold", enum_variant_name_threshold, 3 => u64),
 }
 
-/// Read the `toml` configuration file. The function will ignore “File not found” errors iif
-/// `!must_exist`, in which case, it will return the default configuration.
+/// Search for the configuration file.
+pub fn lookup_conf_file() -> io::Result<Option<path::PathBuf>> {
+    /// Possible filename to search for.
+    const CONFIG_FILE_NAMES: [&'static str; 2] = [".clippy.toml", "clippy.toml"];
+
+    let mut current = try!(env::current_dir());
+
+    loop {
+        for config_file_name in &CONFIG_FILE_NAMES {
+            let config_file = current.join(config_file_name);
+            match fs::metadata(&config_file) {
+                // Only return if it's a file to handle the unlikely situation of a directory named
+                // `clippy.toml`.
+                Ok(ref md) if md.is_file() => return Ok(Some(config_file)),
+                // Return the error if it's something other than `NotFound`; otherwise we didn't
+                // find the project file yet, and continue searching.
+                Err(e) => {
+                    if e.kind() != io::ErrorKind::NotFound {
+                        return Err(e);
+                    }
+                }
+                _ => (),
+            }
+        }
+
+        // If the current directory has no parent, we're done searching.
+        if !current.pop() {
+            return Ok(None);
+        }
+    }
+}
+
+/// Read the `toml` configuration file.
+///
 /// In case of error, the function tries to continue as much as possible.
-pub fn read(path: &str, must_exist: bool) -> (Conf, Vec<Error>) {
+pub fn read(path: Option<&path::Path>) -> (Conf, Vec<Error>) {
     let mut conf = Conf::default();
     let mut errors = Vec::new();
 
+    let path = if let Some(path) = path {
+        path
+    } else {
+        return (conf, errors);
+    };
+
     let file = match fs::File::open(path) {
         Ok(mut file) => {
             let mut buf = String::new();
@@ -197,9 +234,6 @@ pub fn read(path: &str, must_exist: bool) -> (Conf, Vec<Error>) {
 
             buf
         }
-        Err(ref err) if !must_exist && err.kind() == io::ErrorKind::NotFound => {
-            return (conf, errors);
-        }
         Err(err) => {
             errors.push(err.into());
             return (conf, errors);