Merge pull request #2963 from dtolnay/diagnosticpath

Override diagnostic::on_unimplemented message for all serde_core traits

Author: dtolnay

serde_core/src/de/mod.rs

@@ -158,6 +158,12 @@ macro_rules! declare_error_trait {
         /// type appropriate for a basic JSON data format.
         ///
         /// [example data format]: https://serde.rs/data-format.html
+        #[cfg_attr(
+            not(no_diagnostic_namespace),
+            diagnostic::on_unimplemented(
+                message = "the trait bound `{Self}: serde::de::Error` is not satisfied",
+            )
+        )]
         pub trait Error: Sized $(+ $($supertrait)::+)* {
             /// Raised when there is general error when deserializing a type.
             ///
@@ -471,6 +477,12 @@ impl<'a> fmt::Display for Unexpected<'a> {
 /// ));
 /// # }
 /// ```
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::Expected` is not satisfied",
+    )
+)]
 pub trait Expected {
     /// Format an explanation of what data was being expected. Same signature as
     /// the `Display` and `Debug` traits.
@@ -534,6 +546,9 @@ impl Display for dyn Expected + '_ {
 #[cfg_attr(
     not(no_diagnostic_namespace),
     diagnostic::on_unimplemented(
+        // Prevents `serde_core::de::Deserialize` appearing in the error message
+        // in projects with no direct dependency on serde_core.
+        message = "the trait bound `{Self}: serde::Deserialize<'de>` is not satisfied",
         note = "for local types consider adding `#[derive(serde::Deserialize)]` to your `{Self}` type",
         note = "for types from other crates check whether the crate offers a `serde` feature flag",
     )
@@ -610,6 +625,12 @@ pub trait Deserialize<'de>: Sized {
 /// lifetimes].
 ///
 /// [Understanding deserializer lifetimes]: https://serde.rs/lifetimes.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::DeserializeOwned` is not satisfied",
+    )
+)]
 pub trait DeserializeOwned: for<'de> Deserialize<'de> {}
 impl<T> DeserializeOwned for T where T: for<'de> Deserialize<'de> {}
 
@@ -775,6 +796,12 @@ impl<T> DeserializeOwned for T where T: for<'de> Deserialize<'de> {}
 /// #     Ok(())
 /// # }
 /// ```
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::DeserializeSeed<'de>` is not satisfied",
+    )
+)]
 pub trait DeserializeSeed<'de>: Sized {
     /// The type produced by using this seed.
     type Value;
@@ -911,6 +938,12 @@ where
 /// a basic JSON `Deserializer`.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::Deserializer<'de>` is not satisfied",
+    )
+)]
 pub trait Deserializer<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1267,6 +1300,12 @@ pub trait Deserializer<'de>: Sized {
 ///     }
 /// }
 /// ```
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::Visitor<'de>` is not satisfied",
+    )
+)]
 pub trait Visitor<'de>: Sized {
     /// The value produced by this visitor.
     type Value;
@@ -1693,6 +1732,12 @@ pub trait Visitor<'de>: Sized {
 /// implementation of `SeqAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::SeqAccess<'de>` is not satisfied",
+    )
+)]
 pub trait SeqAccess<'de> {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1775,6 +1820,12 @@ where
 /// implementation of `MapAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::MapAccess<'de>` is not satisfied",
+    )
+)]
 pub trait MapAccess<'de> {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -1967,6 +2018,12 @@ where
 /// implementation of `EnumAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::EnumAccess<'de>` is not satisfied",
+    )
+)]
 pub trait EnumAccess<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization.
@@ -2014,6 +2071,12 @@ pub trait EnumAccess<'de>: Sized {
 /// implementation of `VariantAccess` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::de::VariantAccess<'de>` is not satisfied",
+    )
+)]
 pub trait VariantAccess<'de>: Sized {
     /// The error type that can be returned if some error occurs during
     /// deserialization. Must match the error type of our `EnumAccess`.

serde_core/src/ser/mod.rs

@@ -139,6 +139,12 @@ macro_rules! declare_error_trait {
         /// type appropriate for a basic JSON data format.
         ///
         /// [example data format]: https://serde.rs/data-format.html
+        #[cfg_attr(
+            not(no_diagnostic_namespace),
+            diagnostic::on_unimplemented(
+                message = "the trait bound `{Self}: serde::ser::Error` is not satisfied",
+            )
+        )]
         pub trait Error: Sized $(+ $($supertrait)::+)* {
             /// Used when a [`Serialize`] implementation encounters any error
             /// while serializing a type.
@@ -218,6 +224,9 @@ declare_error_trait!(Error: Sized + Debug + Display);
 #[cfg_attr(
     not(no_diagnostic_namespace),
     diagnostic::on_unimplemented(
+        // Prevents `serde_core::ser::Serialize` appearing in the error message
+        // in projects with no direct dependency on serde_core.
+        message = "the trait bound `{Self}: serde::Serialize` is not satisfied",
         note = "for local types consider adding `#[derive(serde::Serialize)]` to your `{Self}` type",
         note = "for types from other crates check whether the crate offers a `serde` feature flag",
     )
@@ -337,6 +346,12 @@ pub trait Serialize {
 /// a basic JSON `Serializer`.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::Serializer` is not satisfied",
+    )
+)]
 pub trait Serializer: Sized {
     /// The output type produced by this `Serializer` during successful
     /// serialization. Most serializers that produce text or binary output
@@ -1494,6 +1509,12 @@ pub trait Serializer: Sized {
 /// implementation of `SerializeSeq` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeSeq` is not satisfied",
+    )
+)]
 pub trait SerializeSeq {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1594,6 +1615,12 @@ pub trait SerializeSeq {
 /// implementation of `SerializeTuple` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeTuple` is not satisfied",
+    )
+)]
 pub trait SerializeTuple {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1639,6 +1666,12 @@ pub trait SerializeTuple {
 /// implementation of `SerializeTupleStruct` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeTupleStruct` is not satisfied",
+    )
+)]
 pub trait SerializeTupleStruct {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1697,6 +1730,12 @@ pub trait SerializeTupleStruct {
 /// implementation of `SerializeTupleVariant` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeTupleVariant` is not satisfied",
+    )
+)]
 pub trait SerializeTupleVariant {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1763,6 +1802,12 @@ pub trait SerializeTupleVariant {
 /// implementation of `SerializeMap` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeMap` is not satisfied",
+    )
+)]
 pub trait SerializeMap {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1853,6 +1898,12 @@ pub trait SerializeMap {
 /// implementation of `SerializeStruct` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeStruct` is not satisfied",
+    )
+)]
 pub trait SerializeStruct {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;
@@ -1917,6 +1968,12 @@ pub trait SerializeStruct {
 /// implementation of `SerializeStructVariant` for a basic JSON data format.
 ///
 /// [example data format]: https://serde.rs/data-format.html
+#[cfg_attr(
+    not(no_diagnostic_namespace),
+    diagnostic::on_unimplemented(
+        message = "the trait bound `{Self}: serde::ser::SerializeStructVariant` is not satisfied",
+    )
+)]
 pub trait SerializeStructVariant {
     /// Must match the `Ok` type of our `Serializer`.
     type Ok;

test_suite/tests/ui/unimplemented/required_by_dependency.rs

@@ -0,0 +1,6 @@
+struct MyStruct;
+
+fn main() {
+    serde_test::assert_ser_tokens(&MyStruct, &[]);
+    serde_test::assert_de_tokens(&MyStruct, &[]);
+}

test_suite/tests/ui/unimplemented/required_by_dependency.stderr

@@ -0,0 +1,113 @@
+error[E0277]: the trait bound `MyStruct: serde::Serialize` is not satisfied
+ --> tests/ui/unimplemented/required_by_dependency.rs:4:35
+  |
+4 |     serde_test::assert_ser_tokens(&MyStruct, &[]);
+  |     ----------------------------- ^^^^^^^^^ unsatisfied trait bound
+  |     |
+  |     required by a bound introduced by this call
+  |
+help: the trait `serde_core::ser::Serialize` is not implemented for `MyStruct`
+ --> tests/ui/unimplemented/required_by_dependency.rs:1:1
+  |
+1 | struct MyStruct;
+  | ^^^^^^^^^^^^^^^
+  = note: for local types consider adding `#[derive(serde::Serialize)]` to your `MyStruct` type
+  = note: for types from other crates check whether the crate offers a `serde` feature flag
+  = help: the following other types implement trait `serde_core::ser::Serialize`:
+            &'a T
+            &'a mut T
+            ()
+            (T,)
+            (T0, T1)
+            (T0, T1, T2)
+            (T0, T1, T2, T3)
+            (T0, T1, T2, T3, T4)
+          and $N others
+note: required by a bound in `assert_ser_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_ser_tokens<T>(value: &T, tokens: &[Token])
+  |        ----------------- required by a bound in this function
+  | where
+  |     T: ?Sized + Serialize,
+  |                 ^^^^^^^^^ required by this bound in `assert_ser_tokens`
+
+error[E0277]: the trait bound `MyStruct: serde::Deserialize<'de>` is not satisfied
+ --> tests/ui/unimplemented/required_by_dependency.rs:5:34
+  |
+5 |     serde_test::assert_de_tokens(&MyStruct, &[]);
+  |     ---------------------------- ^^^^^^^^^ unsatisfied trait bound
+  |     |
+  |     required by a bound introduced by this call
+  |
+help: the trait `serde_core::de::Deserialize<'_>` is not implemented for `MyStruct`
+ --> tests/ui/unimplemented/required_by_dependency.rs:1:1
+  |
+1 | struct MyStruct;
+  | ^^^^^^^^^^^^^^^
+  = note: for local types consider adding `#[derive(serde::Deserialize)]` to your `MyStruct` type
+  = note: for types from other crates check whether the crate offers a `serde` feature flag
+  = help: the following other types implement trait `serde_core::de::Deserialize<'de>`:
+            &'a Path
+            &'a [u8]
+            &'a str
+            ()
+            (T,)
+            (T0, T1)
+            (T0, T1, T2)
+            (T0, T1, T2, T3)
+          and $N others
+note: required by a bound in `assert_de_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
+  |        ---------------- required by a bound in this function
+  | where
+  |     T: Deserialize<'de> + PartialEq + Debug,
+  |        ^^^^^^^^^^^^^^^^ required by this bound in `assert_de_tokens`
+
+error[E0277]: can't compare `MyStruct` with `MyStruct`
+ --> tests/ui/unimplemented/required_by_dependency.rs:5:34
+  |
+5 |     serde_test::assert_de_tokens(&MyStruct, &[]);
+  |     ---------------------------- ^^^^^^^^^ no implementation for `MyStruct == MyStruct`
+  |     |
+  |     required by a bound introduced by this call
+  |
+  = help: the trait `PartialEq` is not implemented for `MyStruct`
+note: required by a bound in `assert_de_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
+  |        ---------------- required by a bound in this function
+  | where
+  |     T: Deserialize<'de> + PartialEq + Debug,
+  |                           ^^^^^^^^^ required by this bound in `assert_de_tokens`
+help: consider annotating `MyStruct` with `#[derive(PartialEq)]`
+  |
+  1 + #[derive(PartialEq)]
+  2 | struct MyStruct;
+    |
+
+error[E0277]: `MyStruct` doesn't implement `Debug`
+ --> tests/ui/unimplemented/required_by_dependency.rs:5:34
+  |
+5 |     serde_test::assert_de_tokens(&MyStruct, &[]);
+  |     ---------------------------- ^^^^^^^^^ the trait `Debug` is not implemented for `MyStruct`
+  |     |
+  |     required by a bound introduced by this call
+  |
+  = note: add `#[derive(Debug)]` to `MyStruct` or manually `impl Debug for MyStruct`
+note: required by a bound in `assert_de_tokens`
+ --> $CARGO/serde_test-$VERSION/src/assert.rs
+  |
+  | pub fn assert_de_tokens<'de, T>(value: &T, tokens: &'de [Token])
+  |        ---------------- required by a bound in this function
+  | where
+  |     T: Deserialize<'de> + PartialEq + Debug,
+  |                                       ^^^^^ required by this bound in `assert_de_tokens`
+help: consider annotating `MyStruct` with `#[derive(Debug)]`
+  |
+  1 + #[derive(Debug)]
+  2 | struct MyStruct;
+    |