From 7107aa22b2219ff11b645178e32d3905ad99da7d Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Sun, 31 Dec 2023 11:01:47 +0100
Subject: [PATCH] Add regression tests for `unconditional_recursion`

---
 tests/ui/unconditional_recursion.rs     | 58 ++++++++++++++++++++++---
 tests/ui/unconditional_recursion.stderr | 53 ++++++++++++++++++++--
 2 files changed, 101 insertions(+), 10 deletions(-)

diff --git a/tests/ui/unconditional_recursion.rs b/tests/ui/unconditional_recursion.rs
index 36fb7e08d64..19cd553b375 100644
--- a/tests/ui/unconditional_recursion.rs
+++ b/tests/ui/unconditional_recursion.rs
@@ -158,18 +158,64 @@ struct S5;
 impl_partial_eq!(S5);
 //~^ ERROR: function cannot return without recursing
 
-struct S6;
+struct S6 {
+    field: String,
+}
 
-impl std::string::ToString for S6 {
+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
+    }
+}
+
+struct S9;
+
+impl std::string::ToString for S9 {
     fn to_string(&self) -> String {
         //~^ ERROR: function cannot return without recursing
         self.to_string()
     }
 }
 
-struct S7;
+struct S10;
 
-impl std::string::ToString for S7 {
+impl std::string::ToString for S10 {
     fn to_string(&self) -> String {
         //~^ ERROR: function cannot return without recursing
         let x = self;
@@ -177,9 +223,9 @@ impl std::string::ToString for S7 {
     }
 }
 
-struct S8;
+struct S11;
 
-impl std::string::ToString for S8 {
+impl std::string::ToString for S11 {
     fn to_string(&self) -> String {
         //~^ ERROR: function cannot return without recursing
         (self as &Self).to_string()
diff --git a/tests/ui/unconditional_recursion.stderr b/tests/ui/unconditional_recursion.stderr
index 040cc4a85a4..364dd572819 100644
--- a/tests/ui/unconditional_recursion.stderr
+++ b/tests/ui/unconditional_recursion.stderr
@@ -23,7 +23,7 @@ LL |         self.eq(other)
    = help: a `loop` may express intention better if this is on purpose
 
 error: function cannot return without recursing
-  --> $DIR/unconditional_recursion.rs:164:5
+  --> $DIR/unconditional_recursion.rs:210:5
    |
 LL |     fn to_string(&self) -> String {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
@@ -34,7 +34,7 @@ LL |         self.to_string()
    = help: a `loop` may express intention better if this is on purpose
 
 error: function cannot return without recursing
-  --> $DIR/unconditional_recursion.rs:173:5
+  --> $DIR/unconditional_recursion.rs:219:5
    |
 LL |     fn to_string(&self) -> String {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
@@ -45,7 +45,7 @@ LL |         x.to_string()
    = help: a `loop` may express intention better if this is on purpose
 
 error: function cannot return without recursing
-  --> $DIR/unconditional_recursion.rs:183:5
+  --> $DIR/unconditional_recursion.rs:229:5
    |
 LL |     fn to_string(&self) -> String {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
@@ -87,6 +87,34 @@ 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
    |
@@ -280,5 +308,22 @@ 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 22 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 25 previous errors