Treat #[path] files as mod.rs files

Author: cramertj

Diff for: src/libsyntax/parse/parser.rs

@@ -5876,10 +5876,14 @@ impl<'a> Parser<'a> {
         if let Some(path) = Parser::submod_path_from_attr(outer_attrs, &self.directory.path) {
             return Ok(ModulePathSuccess {
                 directory_ownership: match path.file_name().and_then(|s| s.to_str()) {
-                    Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
-                    Some(_) => {
-                        DirectoryOwnership::Owned { relative: Some(id) }
-                    }
+                    // All `#[path]` files are treated as though they are a `mod.rs` file.
+                    // This means that `mod foo;` declarations inside `#[path]`-included
+                    // files are siblings,
+                    //
+                    // Note that this will produce weirdness when a file named `foo.rs` is
+                    // `#[path]` included and contains a `mod foo;` declaration.
+                    // If you encounter this, it's your own darn fault :P
+                    Some(_) => DirectoryOwnership::Owned { relative: None },
                     _ => DirectoryOwnership::UnownedViaMod(true),
                 },
                 path,

Diff for: src/test/compile-fail/directory_ownership/backcompat-warnings.rs

@@ -34,14 +34,5 @@ error: mod statements in non-mod.rs files are unstable (see issue #44660)
    = help: add #![feature(non_modrs_mods)] to the crate attributes to enable
    = help: on stable builds, rename this file to inner_foors_mod/mod.rs
 
-error: mod statements in non-mod.rs files are unstable (see issue #44660)
-  --> $DIR/some_crazy_attr_mod_dir/arbitrary_name.rs:11:9
-   |
-11 | pub mod inner_modrs_mod;
-   |         ^^^^^^^^^^^^^^^
-   |
-   = help: add #![feature(non_modrs_mods)] to the crate attributes to enable
-   = help: on stable builds, rename this file to attr_mod/mod.rs
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors