From ca35ca839582d74f045a4a1eb9e1a82e29f0e032 Mon Sep 17 00:00:00 2001
From: Taylor Cramer <cramertj@google.com>
Date: Thu, 18 Oct 2018 17:11:51 -0700
Subject: [PATCH] Fix ordering of nested modules in non-mod.rs mods

Flatten relative offset into directory path before adding inline
(mod x { ... }) module names to the current directory path.

Fix #55094
---
 src/libsyntax/parse/parser.rs                         | 11 +++++++++++
 .../non_modrs_mods_and_inline_mods.rs                 |  5 +++++
 src/test/ui/non_modrs_mods_and_inline_mods/x.rs       |  5 +++++
 .../ui/non_modrs_mods_and_inline_mods/x/y/z/mod.rs    |  1 +
 4 files changed, 22 insertions(+)
 create mode 100644 src/test/ui/non_modrs_mods_and_inline_mods/non_modrs_mods_and_inline_mods.rs
 create mode 100644 src/test/ui/non_modrs_mods_and_inline_mods/x.rs
 create mode 100644 src/test/ui/non_modrs_mods_and_inline_mods/x/y/z/mod.rs

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index c7089a295fc..6c90b2d2acb 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -6426,6 +6426,17 @@ fn push_directory(&mut self, id: Ident, attrs: &[Attribute]) {
             self.directory.path.to_mut().push(&path.as_str());
             self.directory.ownership = DirectoryOwnership::Owned { relative: None };
         } else {
+            // We have to push on the current module name in the case of relative
+            // paths in order to ensure that any additional module paths from inline
+            // `mod x { ... }` come after the relative extension.
+            //
+            // For example, a `mod z { ... }` inside `x/y.rs` should set the current
+            // directory path to `/x/y/z`, not `/x/z` with a relative offset of `y`.
+            if let DirectoryOwnership::Owned { relative } = &mut self.directory.ownership {
+                if let Some(ident) = relative.take() { // remove the relative offset
+                    self.directory.path.to_mut().push(ident.as_str());
+                }
+            }
             self.directory.path.to_mut().push(&id.as_str());
         }
     }
diff --git a/src/test/ui/non_modrs_mods_and_inline_mods/non_modrs_mods_and_inline_mods.rs b/src/test/ui/non_modrs_mods_and_inline_mods/non_modrs_mods_and_inline_mods.rs
new file mode 100644
index 00000000000..25a9c2ed98e
--- /dev/null
+++ b/src/test/ui/non_modrs_mods_and_inline_mods/non_modrs_mods_and_inline_mods.rs
@@ -0,0 +1,5 @@
+// compile-pass
+
+mod x;
+
+fn main() {}
diff --git a/src/test/ui/non_modrs_mods_and_inline_mods/x.rs b/src/test/ui/non_modrs_mods_and_inline_mods/x.rs
new file mode 100644
index 00000000000..a39a7c6d9b3
--- /dev/null
+++ b/src/test/ui/non_modrs_mods_and_inline_mods/x.rs
@@ -0,0 +1,5 @@
+// ignore-test: not a test
+
+pub mod y {
+    pub mod z;
+}
diff --git a/src/test/ui/non_modrs_mods_and_inline_mods/x/y/z/mod.rs b/src/test/ui/non_modrs_mods_and_inline_mods/x/y/z/mod.rs
new file mode 100644
index 00000000000..e8442a47f2c
--- /dev/null
+++ b/src/test/ui/non_modrs_mods_and_inline_mods/x/y/z/mod.rs
@@ -0,0 +1 @@
+// ignore-test: not a test