diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2b645e82b8e..8b3760d1ec3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2796,6 +2796,7 @@ Released 2018-09-13
[`missing_safety_doc`]: https://rust-lang.github.io/rust-clippy/master/index.html#missing_safety_doc
[`mistyped_literal_suffixes`]: https://rust-lang.github.io/rust-clippy/master/index.html#mistyped_literal_suffixes
[`mixed_case_hex_literals`]: https://rust-lang.github.io/rust-clippy/master/index.html#mixed_case_hex_literals
+[`mod_module_files`]: https://rust-lang.github.io/rust-clippy/master/index.html#mod_module_files
[`module_inception`]: https://rust-lang.github.io/rust-clippy/master/index.html#module_inception
[`module_name_repetitions`]: https://rust-lang.github.io/rust-clippy/master/index.html#module_name_repetitions
[`modulo_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#modulo_arithmetic
@@ -2906,6 +2907,7 @@ Released 2018-09-13
[`search_is_some`]: https://rust-lang.github.io/rust-clippy/master/index.html#search_is_some
[`self_assignment`]: https://rust-lang.github.io/rust-clippy/master/index.html#self_assignment
[`self_named_constructors`]: https://rust-lang.github.io/rust-clippy/master/index.html#self_named_constructors
+[`self_named_module_files`]: https://rust-lang.github.io/rust-clippy/master/index.html#self_named_module_files
[`semicolon_if_nothing_returned`]: https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned
[`serde_api_misuse`]: https://rust-lang.github.io/rust-clippy/master/index.html#serde_api_misuse
[`shadow_reuse`]: https://rust-lang.github.io/rust-clippy/master/index.html#shadow_reuse
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 30c684dc744..be97776187f 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -275,6 +275,7 @@ mod missing_const_for_fn;
mod missing_doc;
mod missing_enforced_import_rename;
mod missing_inline;
+mod module_style;
mod modulo_arithmetic;
mod multiple_crate_versions;
mod mut_key;
@@ -829,6 +830,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
missing_doc::MISSING_DOCS_IN_PRIVATE_ITEMS,
missing_enforced_import_rename::MISSING_ENFORCED_IMPORT_RENAMES,
missing_inline::MISSING_INLINE_IN_PUBLIC_ITEMS,
+ module_style::MOD_MODULE_FILES,
+ module_style::SELF_NAMED_MODULE_FILES,
modulo_arithmetic::MODULO_ARITHMETIC,
multiple_crate_versions::MULTIPLE_CRATE_VERSIONS,
mut_key::MUTABLE_KEY_TYPE,
@@ -1038,6 +1041,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(missing_doc::MISSING_DOCS_IN_PRIVATE_ITEMS),
LintId::of(missing_enforced_import_rename::MISSING_ENFORCED_IMPORT_RENAMES),
LintId::of(missing_inline::MISSING_INLINE_IN_PUBLIC_ITEMS),
+ LintId::of(module_style::MOD_MODULE_FILES),
+ LintId::of(module_style::SELF_NAMED_MODULE_FILES),
LintId::of(modulo_arithmetic::MODULO_ARITHMETIC),
LintId::of(panic_in_result_fn::PANIC_IN_RESULT_FN),
LintId::of(panic_unimplemented::PANIC),
@@ -2111,6 +2116,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| box manual_map::ManualMap);
store.register_late_pass(move || box if_then_some_else_none::IfThenSomeElseNone::new(msrv));
store.register_early_pass(|| box bool_assert_comparison::BoolAssertComparison);
+ store.register_early_pass(move || box module_style::ModStyle);
store.register_late_pass(|| box unused_async::UnusedAsync);
let disallowed_types = conf.disallowed_types.iter().cloned().collect::<FxHashSet<_>>();
store.register_late_pass(move || box disallowed_type::DisallowedType::new(&disallowed_types));
diff --git a/clippy_lints/src/module_style.rs b/clippy_lints/src/module_style.rs
new file mode 100644
index 00000000000..73e93cf5a3e
--- /dev/null
+++ b/clippy_lints/src/module_style.rs
@@ -0,0 +1,178 @@
+use std::{
+ ffi::OsString,
+ path::{Component, Path},
+};
+
+use rustc_ast::ast;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_lint::{EarlyContext, EarlyLintPass, Level, LintContext};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{FileName, RealFileName, SourceFile, Span, SyntaxContext};
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks that module layout uses only self named module files, bans mod.rs files.
+ ///
+ /// ### Why is this bad?
+ /// Having multiple module layout styles in a project can be confusing.
+ ///
+ /// ### Example
+ /// ```text
+ /// src/
+ /// stuff/
+ /// stuff_files.rs
+ /// mod.rs
+ /// lib.rs
+ /// ```
+ /// Use instead:
+ /// ```text
+ /// src/
+ /// stuff/
+ /// stuff_files.rs
+ /// stuff.rs
+ /// lib.rs
+ /// ```
+ pub MOD_MODULE_FILES,
+ restriction,
+ "checks that module layout is consistent"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks that module layout uses only mod.rs files.
+ ///
+ /// ### Why is this bad?
+ /// Having multiple module layout styles in a project can be confusing.
+ ///
+ /// ### Example
+ /// ```text
+ /// src/
+ /// stuff/
+ /// stuff_files.rs
+ /// stuff.rs
+ /// lib.rs
+ /// ```
+ /// Use instead:
+ /// ```text
+ /// src/
+ /// stuff/
+ /// stuff_files.rs
+ /// mod.rs
+ /// lib.rs
+ /// ```
+
+ pub SELF_NAMED_MODULE_FILES,
+ restriction,
+ "checks that module layout is consistent"
+}
+
+pub struct ModStyle;
+
+impl_lint_pass!(ModStyle => [MOD_MODULE_FILES, SELF_NAMED_MODULE_FILES]);
+
+impl EarlyLintPass for ModStyle {
+ fn check_crate(&mut self, cx: &EarlyContext<'_>, _: &ast::Crate) {
+ if cx.builder.lint_level(MOD_MODULE_FILES).0 == Level::Allow
+ && cx.builder.lint_level(SELF_NAMED_MODULE_FILES).0 == Level::Allow
+ {
+ return;
+ }
+
+ let files = cx.sess.source_map().files();
+
+ let trim_to_src = if let RealFileName::LocalPath(p) = &cx.sess.working_dir {
+ p.to_string_lossy()
+ } else {
+ return;
+ };
+
+ // `folder_segments` is all unique folder path segments `path/to/foo.rs` gives
+ // `[path, to]` but not foo
+ let mut folder_segments = FxHashSet::default();
+ // `mod_folders` is all the unique folder names that contain a mod.rs file
+ let mut mod_folders = FxHashSet::default();
+ // `file_map` maps file names to the full path including the file name
+ // `{ foo => path/to/foo.rs, .. }
+ let mut file_map = FxHashMap::default();
+ for file in files.iter() {
+ match &file.name {
+ FileName::Real(RealFileName::LocalPath(lp))
+ if lp.to_string_lossy().starts_with(trim_to_src.as_ref()) =>
+ {
+ let p = lp.to_string_lossy();
+ let path = Path::new(p.trim_start_matches(trim_to_src.as_ref()));
+ if let Some(stem) = path.file_stem() {
+ file_map.insert(stem.to_os_string(), (file, path.to_owned()));
+ }
+ process_paths_for_mod_files(path, &mut folder_segments, &mut mod_folders);
+ check_self_named_mod_exists(cx, path, file);
+ }
+ _ => {},
+ }
+ }
+
+ for folder in &folder_segments {
+ if !mod_folders.contains(folder) {
+ if let Some((file, path)) = file_map.get(folder) {
+ let mut correct = path.clone();
+ correct.pop();
+ correct.push(folder);
+ correct.push("mod.rs");
+ cx.struct_span_lint(
+ SELF_NAMED_MODULE_FILES,
+ Span::new(file.start_pos, file.start_pos, SyntaxContext::root()),
+ |build| {
+ let mut lint =
+ build.build(&format!("`mod.rs` files are required, found `{}`", path.display()));
+ lint.help(&format!("move `{}` to `{}`", path.display(), correct.display(),));
+ lint.emit();
+ },
+ );
+ }
+ }
+ }
+ }
+}
+
+/// For each `path` we add each folder component to `folder_segments` and if the file name
+/// is `mod.rs` we add it's parent folder to `mod_folders`.
+fn process_paths_for_mod_files(
+ path: &Path,
+ folder_segments: &mut FxHashSet<OsString>,
+ mod_folders: &mut FxHashSet<OsString>,
+) {
+ let mut comp = path.components().rev().peekable();
+ let _ = comp.next();
+ if path.ends_with("mod.rs") {
+ mod_folders.insert(comp.peek().map(|c| c.as_os_str().to_owned()).unwrap_or_default());
+ }
+ let folders = comp
+ .filter_map(|c| {
+ if let Component::Normal(s) = c {
+ Some(s.to_os_string())
+ } else {
+ None
+ }
+ })
+ .collect::<Vec<_>>();
+ folder_segments.extend(folders);
+}
+
+/// Checks every path for the presence of `mod.rs` files and emits the lint if found.
+fn check_self_named_mod_exists(cx: &EarlyContext<'_>, path: &Path, file: &SourceFile) {
+ if path.ends_with("mod.rs") {
+ let mut mod_file = path.to_path_buf();
+ mod_file.pop();
+ mod_file.set_extension("rs");
+
+ cx.struct_span_lint(
+ MOD_MODULE_FILES,
+ Span::new(file.start_pos, file.start_pos, SyntaxContext::root()),
+ |build| {
+ let mut lint = build.build(&format!("`mod.rs` files are not allowed, found `{}`", path.display()));
+ lint.help(&format!("move `{}` to `{}`", path.display(), mod_file.display(),));
+ lint.emit();
+ },
+ );
+ }
+}
diff --git a/tests/ui-cargo/module_style/fail_mod/Cargo.toml b/tests/ui-cargo/module_style/fail_mod/Cargo.toml
new file mode 100644
index 00000000000..27b61c09fb4
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "fail"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/tests/ui-cargo/module_style/fail_mod/src/bad/inner.rs b/tests/ui-cargo/module_style/fail_mod/src/bad/inner.rs
new file mode 100644
index 00000000000..91cd540a28f
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/src/bad/inner.rs
@@ -0,0 +1 @@
+pub mod stuff;
diff --git a/tests/ui-cargo/module_style/fail_mod/src/bad/inner/stuff.rs b/tests/ui-cargo/module_style/fail_mod/src/bad/inner/stuff.rs
new file mode 100644
index 00000000000..7713fa9d35c
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/src/bad/inner/stuff.rs
@@ -0,0 +1,3 @@
+pub mod most;
+
+pub struct Inner;
diff --git a/tests/ui-cargo/module_style/fail_mod/src/bad/inner/stuff/most.rs b/tests/ui-cargo/module_style/fail_mod/src/bad/inner/stuff/most.rs
new file mode 100644
index 00000000000..5a5eaf9670f
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/src/bad/inner/stuff/most.rs
@@ -0,0 +1 @@
+pub struct Snarks;
diff --git a/tests/ui-cargo/module_style/fail_mod/src/bad/mod.rs b/tests/ui-cargo/module_style/fail_mod/src/bad/mod.rs
new file mode 100644
index 00000000000..a12734db7cb
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/src/bad/mod.rs
@@ -0,0 +1,3 @@
+pub mod inner;
+
+pub struct Thing;
diff --git a/tests/ui-cargo/module_style/fail_mod/src/main.rs b/tests/ui-cargo/module_style/fail_mod/src/main.rs
new file mode 100644
index 00000000000..3e985d4e904
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/src/main.rs
@@ -0,0 +1,9 @@
+#![warn(clippy::self_named_module_files)]
+
+mod bad;
+
+fn main() {
+ let _ = bad::Thing;
+ let _ = bad::inner::stuff::Inner;
+ let _ = bad::inner::stuff::most::Snarks;
+}
diff --git a/tests/ui-cargo/module_style/fail_mod/src/main.stderr b/tests/ui-cargo/module_style/fail_mod/src/main.stderr
new file mode 100644
index 00000000000..af4c298b310
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_mod/src/main.stderr
@@ -0,0 +1,19 @@
+error: `mod.rs` files are required, found `/bad/inner.rs`
+ --> $DIR/bad/inner.rs:1:1
+ |
+LL | pub mod stuff;
+ | ^
+ |
+ = note: `-D clippy::self-named-module-files` implied by `-D warnings`
+ = help: move `/bad/inner.rs` to `/bad/inner/mod.rs`
+
+error: `mod.rs` files are required, found `/bad/inner/stuff.rs`
+ --> $DIR/bad/inner/stuff.rs:1:1
+ |
+LL | pub mod most;
+ | ^
+ |
+ = help: move `/bad/inner/stuff.rs` to `/bad/inner/stuff/mod.rs`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui-cargo/module_style/fail_no_mod/Cargo.toml b/tests/ui-cargo/module_style/fail_no_mod/Cargo.toml
new file mode 100644
index 00000000000..27b61c09fb4
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_no_mod/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "fail"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/tests/ui-cargo/module_style/fail_no_mod/src/bad/mod.rs b/tests/ui-cargo/module_style/fail_no_mod/src/bad/mod.rs
new file mode 100644
index 00000000000..f19ab10d5fb
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_no_mod/src/bad/mod.rs
@@ -0,0 +1 @@
+pub struct Thing;
diff --git a/tests/ui-cargo/module_style/fail_no_mod/src/main.rs b/tests/ui-cargo/module_style/fail_no_mod/src/main.rs
new file mode 100644
index 00000000000..c6e9045b8dc
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_no_mod/src/main.rs
@@ -0,0 +1,7 @@
+#![warn(clippy::mod_module_files)]
+
+mod bad;
+
+fn main() {
+ let _ = bad::Thing;
+}
diff --git a/tests/ui-cargo/module_style/fail_no_mod/src/main.stderr b/tests/ui-cargo/module_style/fail_no_mod/src/main.stderr
new file mode 100644
index 00000000000..11e15db7fb9
--- /dev/null
+++ b/tests/ui-cargo/module_style/fail_no_mod/src/main.stderr
@@ -0,0 +1,11 @@
+error: `mod.rs` files are not allowed, found `/bad/mod.rs`
+ --> $DIR/bad/mod.rs:1:1
+ |
+LL | pub struct Thing;
+ | ^
+ |
+ = note: `-D clippy::mod-module-files` implied by `-D warnings`
+ = help: move `/bad/mod.rs` to `/bad.rs`
+
+error: aborting due to previous error
+
diff --git a/tests/ui-cargo/module_style/pass_mod/Cargo.toml b/tests/ui-cargo/module_style/pass_mod/Cargo.toml
new file mode 100644
index 00000000000..27b61c09fb4
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_mod/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "fail"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/tests/ui-cargo/module_style/pass_mod/src/bad/mod.rs b/tests/ui-cargo/module_style/pass_mod/src/bad/mod.rs
new file mode 100644
index 00000000000..f19ab10d5fb
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_mod/src/bad/mod.rs
@@ -0,0 +1 @@
+pub struct Thing;
diff --git a/tests/ui-cargo/module_style/pass_mod/src/main.rs b/tests/ui-cargo/module_style/pass_mod/src/main.rs
new file mode 100644
index 00000000000..9e08715fc05
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_mod/src/main.rs
@@ -0,0 +1,10 @@
+#![warn(clippy::self_named_module_files)]
+
+mod bad;
+mod more;
+
+fn main() {
+ let _ = bad::Thing;
+ let _ = more::foo::Foo;
+ let _ = more::inner::Inner;
+}
diff --git a/tests/ui-cargo/module_style/pass_mod/src/more/foo.rs b/tests/ui-cargo/module_style/pass_mod/src/more/foo.rs
new file mode 100644
index 00000000000..4a835673a59
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_mod/src/more/foo.rs
@@ -0,0 +1 @@
+pub struct Foo;
diff --git a/tests/ui-cargo/module_style/pass_mod/src/more/inner/mod.rs b/tests/ui-cargo/module_style/pass_mod/src/more/inner/mod.rs
new file mode 100644
index 00000000000..aa84f78cc2c
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_mod/src/more/inner/mod.rs
@@ -0,0 +1 @@
+pub struct Inner;
diff --git a/tests/ui-cargo/module_style/pass_mod/src/more/mod.rs b/tests/ui-cargo/module_style/pass_mod/src/more/mod.rs
new file mode 100644
index 00000000000..d79569f78ff
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_mod/src/more/mod.rs
@@ -0,0 +1,2 @@
+pub mod foo;
+pub mod inner;
diff --git a/tests/ui-cargo/module_style/pass_no_mod/Cargo.toml b/tests/ui-cargo/module_style/pass_no_mod/Cargo.toml
new file mode 100644
index 00000000000..3c0896dd2cd
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_no_mod/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "pass"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/tests/ui-cargo/module_style/pass_no_mod/src/good.rs b/tests/ui-cargo/module_style/pass_no_mod/src/good.rs
new file mode 100644
index 00000000000..f19ab10d5fb
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_no_mod/src/good.rs
@@ -0,0 +1 @@
+pub struct Thing;
diff --git a/tests/ui-cargo/module_style/pass_no_mod/src/main.rs b/tests/ui-cargo/module_style/pass_no_mod/src/main.rs
new file mode 100644
index 00000000000..50211a340b9
--- /dev/null
+++ b/tests/ui-cargo/module_style/pass_no_mod/src/main.rs
@@ -0,0 +1,7 @@
+#![warn(clippy::mod_module_files)]
+
+mod good;
+
+fn main() {
+ let _ = good::Thing;
+}