From b2c7a52ea865f877bc0b57075fe1a88f83120546 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?St=C3=A9phane=20Campinas?= <stephane.campinas@gmail.com>
Date: Mon, 31 Jan 2022 23:45:30 +0100
Subject: [PATCH] Fix import_granularity option when the use tree has an alias

---
 src/imports.rs       |  6 ++++--
 tests/source/5131.rs | 33 +++++++++++++++++++++++++++++++++
 tests/target/5131.rs | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 2 deletions(-)
 create mode 100644 tests/source/5131.rs
 create mode 100644 tests/target/5131.rs

diff --git a/src/imports.rs b/src/imports.rs
index 40e0d06f99df..c60bec6d4a20 100644
--- a/src/imports.rs
+++ b/src/imports.rs
@@ -238,7 +238,8 @@ impl fmt::Display for UseSegment {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
             UseSegment::Glob => write!(f, "*"),
-            UseSegment::Ident(ref s, _) => write!(f, "{}", s),
+            UseSegment::Ident(ref s, Some(ref alias)) => write!(f, "{} as {}", s, alias),
+            UseSegment::Ident(ref s, None) => write!(f, "{}", s),
             UseSegment::Slf(..) => write!(f, "self"),
             UseSegment::Super(..) => write!(f, "super"),
             UseSegment::Crate(..) => write!(f, "crate"),
@@ -622,7 +623,8 @@ fn flatten(self) -> Vec<UseTree> {
     fn merge(&mut self, other: &UseTree, merge_by: SharedPrefix) {
         let mut prefix = 0;
         for (a, b) in self.path.iter().zip(other.path.iter()) {
-            if a.equal_except_alias(b) {
+            // only discard the alias at the root of the tree
+            if (prefix == 0 && a.equal_except_alias(b)) || a == b {
                 prefix += 1;
             } else {
                 break;
diff --git a/tests/source/5131.rs b/tests/source/5131.rs
new file mode 100644
index 000000000000..3e9139177c56
--- /dev/null
+++ b/tests/source/5131.rs
@@ -0,0 +1,33 @@
+// rustfmt-imports_granularity: Module
+
+#![allow(dead_code)]
+
+mod a {
+    pub mod b {
+        pub struct Data {
+            pub a: i32,
+        }
+    }
+
+    use crate::a::b::Data;
+    use crate::a::b::Data as Data2;
+
+    pub fn data(a: i32) -> Data {
+        Data { a }
+    }
+
+    pub fn data2(a: i32) -> Data2 {
+        Data2 { a }
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        pub fn test() {
+            data(1);
+            data2(1);
+        }
+    }
+}
diff --git a/tests/target/5131.rs b/tests/target/5131.rs
new file mode 100644
index 000000000000..763024d6fa49
--- /dev/null
+++ b/tests/target/5131.rs
@@ -0,0 +1,32 @@
+// rustfmt-imports_granularity: Module
+
+#![allow(dead_code)]
+
+mod a {
+    pub mod b {
+        pub struct Data {
+            pub a: i32,
+        }
+    }
+
+    use crate::a::b::{Data, Data as Data2};
+
+    pub fn data(a: i32) -> Data {
+        Data { a }
+    }
+
+    pub fn data2(a: i32) -> Data2 {
+        Data2 { a }
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        pub fn test() {
+            data(1);
+            data2(1);
+        }
+    }
+}