Add regression tests for unconditional_recursion

Author: GuillaumeGomez

tests/ui/unconditional_recursion.rs

@@ -158,6 +158,52 @@ struct S5;
 impl_partial_eq!(S5);
 //~^ ERROR: function cannot return without recursing
 
+struct S6 {
+    field: String,
+}
+
+impl PartialEq for S6 {
+    fn eq(&self, other: &Self) -> bool {
+        let mine = &self.field;
+        let theirs = &other.field;
+        mine == theirs // Should not warn!
+    }
+}
+
+struct S7<'a> {
+    field: &'a S7<'a>,
+}
+
+impl<'a> PartialEq for S7<'a> {
+    fn eq(&self, other: &Self) -> bool {
+        //~^ ERROR: function cannot return without recursing
+        let mine = &self.field;
+        let theirs = &other.field;
+        mine == theirs
+    }
+}
+
+struct S8 {
+    num: i32,
+    field: Option<Box<S8>>,
+}
+
+impl PartialEq for S8 {
+    fn eq(&self, other: &Self) -> bool {
+        if self.num != other.num {
+            return false;
+        }
+
+        let (this, other) = match (self.field.as_deref(), other.field.as_deref()) {
+            (Some(x1), Some(x2)) => (x1, x2),
+            (None, None) => return true,
+            _ => return false,
+        };
+
+        this == other
+    }
+}
+
 fn main() {
     // test code goes here
 }

tests/ui/unconditional_recursion.stderr

@@ -54,6 +54,34 @@ note: recursive call site
 LL |         self == other
    |         ^^^^^^^^^^^^^
 
+error: function cannot return without recursing
+  --> $DIR/unconditional_recursion.rs:28:5
+   |
+LL | /     fn ne(&self, other: &Self) -> bool {
+LL | |         self != &Foo2::B // no error here
+LL | |     }
+   | |_____^
+   |
+note: recursive call site
+  --> $DIR/unconditional_recursion.rs:29:9
+   |
+LL |         self != &Foo2::B // no error here
+   |         ^^^^^^^^^^^^^^^^
+
+error: function cannot return without recursing
+  --> $DIR/unconditional_recursion.rs:31:5
+   |
+LL | /     fn eq(&self, other: &Self) -> bool {
+LL | |         self == &Foo2::B // no error here
+LL | |     }
+   | |_____^
+   |
+note: recursive call site
+  --> $DIR/unconditional_recursion.rs:32:9
+   |
+LL |         self == &Foo2::B // no error here
+   |         ^^^^^^^^^^^^^^^^
+
 error: function cannot return without recursing
   --> $DIR/unconditional_recursion.rs:42:5
    |
@@ -247,5 +275,22 @@ LL | impl_partial_eq!(S5);
    | -------------------- in this macro invocation
    = note: this error originates in the macro `impl_partial_eq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 19 previous errors
+error: function cannot return without recursing
+  --> $DIR/unconditional_recursion.rs:178:5
+   |
+LL | /     fn eq(&self, other: &Self) -> bool {
+LL | |
+LL | |         let mine = &self.field;
+LL | |         let theirs = &other.field;
+LL | |         mine == theirs
+LL | |     }
+   | |_____^
+   |
+note: recursive call site
+  --> $DIR/unconditional_recursion.rs:182:9
+   |
+LL |         mine == theirs
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 22 previous errors