1 files changed, 726 insertions, 0 deletions
diff --git a/library/core/tests/fmt/builders.rs b/library/core/tests/fmt/builders.rs
new file mode 100644
index 000000000..487ce46be
--- /dev/null
+++ b/library/core/tests/fmt/builders.rs
@@ -0,0 +1,726 @@
+mod debug_struct {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo").finish()
+            }
+        }
+
+        assert_eq!("Foo", format!("{Foo:?}"));
+        assert_eq!("Foo", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo").field("bar", &true).finish()
+            }
+        }
+
+        assert_eq!("Foo { bar: true }", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo {
+    bar: true,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        assert_eq!("Foo { bar: true, baz: 10/20 }", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo {
+    bar: true,
+    baz: 10/20,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Bar").field("foo", &Foo).field("hello", &"world").finish()
+            }
+        }
+
+        assert_eq!(
+            "Bar { foo: Foo { bar: true, baz: 10/20 }, hello: \"world\" }",
+            format!("{Bar:?}")
+        );
+        assert_eq!(
+            "Bar {
+    foo: Foo {
+        bar: true,
+        baz: 10/20,
+    },
+    hello: \"world\",
+}",
+            format!("{Bar:#?}")
+        );
+    }
+
+    #[test]
+    fn test_only_non_exhaustive() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo").finish_non_exhaustive()
+            }
+        }
+
+        assert_eq!("Foo { .. }", format!("{Foo:?}"));
+        assert_eq!("Foo { .. }", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_multiple_and_non_exhaustive() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish_non_exhaustive()
+            }
+        }
+
+        assert_eq!("Foo { bar: true, baz: 10/20, .. }", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo {
+    bar: true,
+    baz: 10/20,
+    ..
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested_non_exhaustive() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish_non_exhaustive()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Bar")
+                    .field("foo", &Foo)
+                    .field("hello", &"world")
+                    .finish_non_exhaustive()
+            }
+        }
+
+        assert_eq!(
+            "Bar { foo: Foo { bar: true, baz: 10/20, .. }, hello: \"world\", .. }",
+            format!("{Bar:?}")
+        );
+        assert_eq!(
+            "Bar {
+    foo: Foo {
+        bar: true,
+        baz: 10/20,
+        ..
+    },
+    hello: \"world\",
+    ..
+}",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+mod debug_tuple {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").finish()
+            }
+        }
+
+        assert_eq!("Foo", format!("{Foo:?}"));
+        assert_eq!("Foo", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").field(&true).finish()
+            }
+        }
+
+        assert_eq!("Foo(true)", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo(
+    true,
+)",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").field(&true).field(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        assert_eq!("Foo(true, 10/20)", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo(
+    true,
+    10/20,
+)",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").field(&true).field(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Bar").field(&Foo).field(&"world").finish()
+            }
+        }
+
+        assert_eq!("Bar(Foo(true, 10/20), \"world\")", format!("{Bar:?}"));
+        assert_eq!(
+            "Bar(
+    Foo(
+        true,
+        10/20,
+    ),
+    \"world\",
+)",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+mod debug_map {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().finish()
+            }
+        }
+
+        assert_eq!("{}", format!("{Foo:?}"));
+        assert_eq!("{}", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Entry;
+
+        impl fmt::Debug for Entry {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().entry(&"bar", &true).finish()
+            }
+        }
+
+        struct KeyValue;
+
+        impl fmt::Debug for KeyValue {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().key(&"bar").value(&true).finish()
+            }
+        }
+
+        assert_eq!(format!("{Entry:?}"), format!("{KeyValue:?}"));
+        assert_eq!(format!("{Entry:#?}"), format!("{KeyValue:#?}"));
+
+        assert_eq!("{\"bar\": true}", format!("{Entry:?}"));
+        assert_eq!(
+            "{
+    \"bar\": true,
+}",
+            format!("{Entry:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Entry;
+
+        impl fmt::Debug for Entry {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map()
+                    .entry(&"bar", &true)
+                    .entry(&10, &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        struct KeyValue;
+
+        impl fmt::Debug for KeyValue {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map()
+                    .key(&"bar")
+                    .value(&true)
+                    .key(&10)
+                    .value(&format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        assert_eq!(format!("{Entry:?}"), format!("{KeyValue:?}"));
+        assert_eq!(format!("{Entry:#?}"), format!("{KeyValue:#?}"));
+
+        assert_eq!("{\"bar\": true, 10: 10/20}", format!("{Entry:?}"));
+        assert_eq!(
+            "{
+    \"bar\": true,
+    10: 10/20,
+}",
+            format!("{Entry:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map()
+                    .entry(&"bar", &true)
+                    .entry(&10, &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().entry(&"foo", &Foo).entry(&Foo, &"world").finish()
+            }
+        }
+
+        assert_eq!(
+            "{\"foo\": {\"bar\": true, 10: 10/20}, \
+                    {\"bar\": true, 10: 10/20}: \"world\"}",
+            format!("{Bar:?}")
+        );
+        assert_eq!(
+            "{
+    \"foo\": {
+        \"bar\": true,
+        10: 10/20,
+    },
+    {
+        \"bar\": true,
+        10: 10/20,
+    }: \"world\",
+}",
+            format!("{Bar:#?}")
+        );
+    }
+
+    #[test]
+    fn test_entry_err() {
+        // Ensure errors in a map entry don't trigger panics (#65231)
+        use std::fmt::Write;
+
+        struct ErrorFmt;
+
+        impl fmt::Debug for ErrorFmt {
+            fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
+                Err(fmt::Error)
+            }
+        }
+
+        struct KeyValue<K, V>(usize, K, V);
+
+        impl<K, V> fmt::Debug for KeyValue<K, V>
+        where
+            K: fmt::Debug,
+            V: fmt::Debug,
+        {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                let mut map = fmt.debug_map();
+
+                for _ in 0..self.0 {
+                    map.entry(&self.1, &self.2);
+                }
+
+                map.finish()
+            }
+        }
+
+        let mut buf = String::new();
+
+        assert!(write!(&mut buf, "{:?}", KeyValue(1, ErrorFmt, "bar")).is_err());
+        assert!(write!(&mut buf, "{:?}", KeyValue(1, "foo", ErrorFmt)).is_err());
+
+        assert!(write!(&mut buf, "{:?}", KeyValue(2, ErrorFmt, "bar")).is_err());
+        assert!(write!(&mut buf, "{:?}", KeyValue(2, "foo", ErrorFmt)).is_err());
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_key_when_entry_is_incomplete() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().key(&"bar").key(&"invalid").finish()
+            }
+        }
+
+        format!("{Foo:?}");
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_finish_incomplete_entry() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().key(&"bar").finish()
+            }
+        }
+
+        format!("{Foo:?}");
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_value_before_key() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().value(&"invalid").key(&"bar").finish()
+            }
+        }
+
+        format!("{Foo:?}");
+    }
+}
+
+mod debug_set {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().finish()
+            }
+        }
+
+        assert_eq!("{}", format!("{Foo:?}"));
+        assert_eq!("{}", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&true).finish()
+            }
+        }
+
+        assert_eq!("{true}", format!("{Foo:?}"));
+        assert_eq!(
+            "{
+    true,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        assert_eq!("{true, 10/20}", format!("{Foo:?}"));
+        assert_eq!(
+            "{
+    true,
+    10/20,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&Foo).entry(&"world").finish()
+            }
+        }
+
+        assert_eq!("{{true, 10/20}, \"world\"}", format!("{Bar:?}"));
+        assert_eq!(
+            "{
+    {
+        true,
+        10/20,
+    },
+    \"world\",
+}",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+mod debug_list {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().finish()
+            }
+        }
+
+        assert_eq!("[]", format!("{Foo:?}"));
+        assert_eq!("[]", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&true).finish()
+            }
+        }
+
+        assert_eq!("[true]", format!("{Foo:?}"));
+        assert_eq!(
+            "[
+    true,
+]",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        assert_eq!("[true, 10/20]", format!("{Foo:?}"));
+        assert_eq!(
+            "[
+    true,
+    10/20,
+]",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&Foo).entry(&"world").finish()
+            }
+        }
+
+        assert_eq!("[[true, 10/20], \"world\"]", format!("{Bar:?}"));
+        assert_eq!(
+            "[
+    [
+        true,
+        10/20,
+    ],
+    \"world\",
+]",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+#[test]
+fn test_formatting_parameters_are_forwarded() {
+    use std::collections::{BTreeMap, BTreeSet};
+    #[derive(Debug)]
+    #[allow(dead_code)]
+    struct Foo {
+        bar: u32,
+        baz: u32,
+    }
+    let struct_ = Foo { bar: 1024, baz: 7 };
+    let tuple = (1024, 7);
+    let list = [1024, 7];
+    let mut map = BTreeMap::new();
+    map.insert("bar", 1024);
+    map.insert("baz", 7);
+    let mut set = BTreeSet::new();
+    set.insert(1024);
+    set.insert(7);
+
+    assert_eq!(format!("{struct_:03?}"), "Foo { bar: 1024, baz: 007 }");
+    assert_eq!(format!("{tuple:03?}"), "(1024, 007)");
+    assert_eq!(format!("{list:03?}"), "[1024, 007]");
+    assert_eq!(format!("{map:03?}"), r#"{"bar": 1024, "baz": 007}"#);
+    assert_eq!(format!("{set:03?}"), "{007, 1024}");
+    assert_eq!(
+        format!("{struct_:#03?}"),
+        "
+Foo {
+    bar: 1024,
+    baz: 007,
+}
+    "
+        .trim()
+    );
+    assert_eq!(
+        format!("{tuple:#03?}"),
+        "
+(
+    1024,
+    007,
+)
+    "
+        .trim()
+    );
+    assert_eq!(
+        format!("{list:#03?}"),
+        "
+[
+    1024,
+    007,
+]
+    "
+        .trim()
+    );
+    assert_eq!(
+        format!("{map:#03?}"),
+        r#"
+{
+    "bar": 1024,
+    "baz": 007,
+}
+    "#
+        .trim()
+    );
+    assert_eq!(
+        format!("{set:#03?}"),
+        "
+{
+    007,
+    1024,
+}
+    "
+        .trim()
+    );
+}