derive_where attribute macro instead of derive macro (#33)

* Code changes for migrating to attribute_macro

* documentation for attribute macro

* formatted

* Fixing tests

* Formatted

* Fixed test

* Remove empty lines

* Apply suggestions from code review

Co-authored-by: daxpedda <[email protected]>

* Apply suggestions

* fix removing item on error

* resort imports

* Use span of cleaned item

Co-authored-by: daxpedda <[email protected]>

Author: ModProg

README.md

@@ -12,11 +12,9 @@ generic type bounds.
 ## Usage
 
 The `derive_where` macro can be used just like std's `#[derive(...)]`
-statements, with the only caveat that it requires to derive `DeriveWhere`
-([#27]):
+statements:
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Clone, Debug)]
 struct Example<T>(PhantomData<T>);
 ```
@@ -34,7 +32,6 @@ specified. This example will restrict the implementation for `Example` to
 `T: Clone`:
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Clone; T)]
 struct Example<T, U>(T, PhantomData<U>);
 ```
@@ -45,7 +42,6 @@ bind implementation for `Example` to `T: Super`:
 ```rust
 trait Super: Clone {}
 
-#[derive(DeriveWhere)]
 #[derive_where(Clone; T: Super)]
 struct Example<T>(PhantomData<T>);
 ```
@@ -65,7 +61,6 @@ impl Trait for Impl {
 	type Type = i32;
 }
 
-#[derive(DeriveWhere)]
 #[derive_where(Clone; T::Type)]
 struct Example<T: Trait>(T::Type);
 ```
@@ -75,7 +70,6 @@ specific constrain. It is also possible to use multiple separate
 constrain specifications when required:
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Clone; T)]
 #[derive_where(Debug; U)]
 struct Example<T, U>(PhantomData<T>, PhantomData<U>);
@@ -87,7 +81,6 @@ Deriving [`Default`] on an enum is not possible in Rust at the moment.
 Derive-where allows this with a `default` attribute:
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Default)]
 enum Example<T> {
 	#[derive_where(default)]
@@ -102,7 +95,6 @@ that allow it, which are: [`Debug`], [`Hash`], [`Ord`](https://doc.rust-lang.org
 [`PartialEq`](https://doc.rust-lang.org/core/cmp/trait.PartialEq.html), [`Zeroize`] and [`ZeroizeOnDrop`].
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Debug, PartialEq; T)]
 struct Example<T>(#[derive_where(skip)] T);
 
@@ -113,14 +105,12 @@ assert_eq!(Example(42), Example(0));
 It is also possible to skip all fields in an item or variant if desired:
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Debug)]
 #[derive_where(skip_inner)]
 struct StructExample<T>(T);
 
 assert_eq!(format!("{:?}", StructExample(42)), "StructExample");
 
-#[derive(DeriveWhere)]
 #[derive_where(Debug)]
 enum EnumExample<T> {
 	#[derive_where(skip_inner)]
@@ -134,7 +124,6 @@ Selective skipping of fields for certain traits is also an option, both in
 `skip` and `skip_inner`:
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Debug, PartialEq)]
 #[derive_where(skip_inner(Debug))]
 struct Example<T>(i32, PhantomData<T>);
@@ -156,7 +145,6 @@ assert_ne!(
   This is to avoid ambiguity between another method also called `zeroize`.
 
 ```rust
-#[derive(DeriveWhere)]
 #[derive_where(Zeroize(crate = "zeroize_"))]
 struct Example(#[derive_where(Zeroize(fqs))] i32);
 
@@ -189,8 +177,7 @@ and can be implemented without [`Zeroize`], otherwise it only implements
 - `crate`: an item-level option which specifies a path to the `zeroize`
   crate in case of a re-export or rename.
 
-```
-#[derive(DeriveWhere)]
+```rust
 #[derive_where(ZeroizeOnDrop(crate = "zeroize_"))]
 struct Example(i32);
 
@@ -253,8 +240,8 @@ accompanied by a minor version bump. If MSRV is important to you, use
 
 [derivative](https://crates.io/crates/derivative)
 ([![Crates.io](https://img.shields.io/crates/v/derivative.svg)](https://crates.io/crates/derivative))
-is a great alternative with many options. Notably it has no `no_std`
-support.
+is a great alternative with many options. Notably it doesn't support `no_std`
+and requires an extra `#[derive(Derivative)]` to use.
 
 ## Changelog
 

ensure-no-std/src/lib.rs

@@ -5,9 +5,8 @@ extern crate zeroize_ as zeroize;
 
 use core::marker::PhantomData;
 
-use derive_where::DeriveWhere;
+use derive_where::derive_where;
 
-#[derive(DeriveWhere)]
 #[derive_where(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "zeroize", derive_where(Zeroize))]
 pub struct Test<T>(PhantomData<T>);

non-msrv-tests/tests/ui/default.rs

@@ -1,25 +1,21 @@
 use std::marker::PhantomData;
 
-use derive_where::DeriveWhere;
+use derive_where::derive_where;
 
-#[derive(DeriveWhere)]
 #[derive_where(Debug)]
 struct DefaultOnStruct<T>(#[derive_where(default)] PhantomData<T>);
 
-#[derive(DeriveWhere)]
 #[derive_where(Clone)]
 enum DefaultWithoutTrait<T> {
 	#[derive_where(default)]
 	A(PhantomData<T>),
 }
 
-#[derive(DeriveWhere)]
 #[derive_where(Default)]
 enum MissingDefault<T> {
 	A(PhantomData<T>),
 }
 
-#[derive(DeriveWhere)]
 #[derive_where(Default)]
 enum DuplicateDefaultSeparate<T> {
 	#[derive_where(default)]
@@ -28,14 +24,12 @@ enum DuplicateDefaultSeparate<T> {
 	B(PhantomData<T>),
 }
 
-#[derive(DeriveWhere)]
 #[derive_where(Default)]
 enum DuplicateDefaultSame<T> {
 	#[derive_where(default, default)]
 	A(PhantomData<T>),
 }
 
-#[derive(DeriveWhere)]
 #[derive_where(Default)]
 enum DuplicateDefaultSameSeparate<T> {
 	#[derive_where(default)]

non-msrv-tests/tests/ui/default.stderr

@@ -1,38 +1,37 @@
 error: unknown option
- --> tests/ui/default.rs:7:42
+ --> tests/ui/default.rs:6:42
   |
-7 | struct DefaultOnStruct<T>(#[derive_where(default)] PhantomData<T>);
+6 | struct DefaultOnStruct<T>(#[derive_where(default)] PhantomData<T>);
   |                                          ^^^^^^^
 
 error: `default` is only supported if `Default` is being implemented
-  --> tests/ui/default.rs:12:17
+  --> tests/ui/default.rs:10:17
    |
-12 |     #[derive_where(default)]
+10 |     #[derive_where(default)]
    |                    ^^^^^^^
 
 error: required `default` option on a variant if `Default` is being implemented
-  --> tests/ui/default.rs:17:1
+  --> tests/ui/default.rs:15:1
    |
-17 | / #[derive_where(Default)]
-18 | | enum MissingDefault<T> {
-19 | |     A(PhantomData<T>),
-20 | | }
+15 | / enum MissingDefault<T> {
+16 | |     A(PhantomData<T>),
+17 | | }
    | |_^
 
 error: multiple `default` options in enum
-  --> tests/ui/default.rs:27:17
+  --> tests/ui/default.rs:23:17
    |
-27 |     #[derive_where(default)]
+23 |     #[derive_where(default)]
    |                    ^^^^^^^
 
 error: duplicate `default` option
-  --> tests/ui/default.rs:34:26
+  --> tests/ui/default.rs:29:26
    |
-34 |     #[derive_where(default, default)]
+29 |     #[derive_where(default, default)]
    |                             ^^^^^^^
 
 error: duplicate `default` option
-  --> tests/ui/default.rs:42:17
+  --> tests/ui/default.rs:36:17
    |
-42 |     #[derive_where(default)]
+36 |     #[derive_where(default)]
    |                    ^^^^^^^

non-msrv-tests/tests/ui/item.rs

@@ -1,39 +1,28 @@
 use std::marker::PhantomData;
 
-use derive_where::DeriveWhere;
+use derive_where::derive_where;
 
-#[derive(DeriveWhere)]
-struct NoAttribute<T>(PhantomData<T>);
-
-#[derive(DeriveWhere)]
 #[derive_where]
 struct NoOption<T>(PhantomData<T>);
 
-#[derive(DeriveWhere)]
 #[derive_where()]
 struct EmptyAttribute<T>(PhantomData<T>);
 
-#[derive(DeriveWhere)]
 #[derive_where(Clone; T;)]
 struct SemiColonAtTheEnd<T, U>(T, PhantomData<U>);
 
-#[derive(DeriveWhere)]
 #[derive_where(Clone; T,,)]
 struct DoubleColonAtTheEnd<T, U>(T, PhantomData<U>);
 
-#[derive(derive_where::DeriveWhere)]
 #[derive_where(Clone; where)]
 struct InvalidGeneric<T>(PhantomData<T>);
 
-#[derive(derive_where::DeriveWhere)]
 #[derive_where(Clone Debug)]
 struct MissingCommaBetweenTraits<T>(PhantomData<T>);
 
-#[derive(derive_where::DeriveWhere)]
 #[derive_where(Clone; T U)]
 struct MissingCommaBetweenGenerics<T, U, V>(T, PhantomData<(U, V)>);
 
-#[derive(DeriveWhere)]
 #[derive_where("Clone")]
 struct InvalidTrait<T>(PhantomData<T>);
 

non-msrv-tests/tests/ui/item.stderr

@@ -1,53 +1,51 @@
-error: no traits found to implement, use `#[derive_where(..)` to specify some
- --> tests/ui/item.rs:6:1
+error: empty `derive_where` found
+ --> tests/ui/item.rs:5:1
   |
-6 | struct NoAttribute<T>(PhantomData<T>);
-  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: unexpected option syntax
- --> tests/ui/item.rs:9:3
+5 | #[derive_where]
+  | ^^^^^^^^^^^^^^^
   |
-9 | #[derive_where]
-  |   ^^^^^^^^^^^^
+  = note: this error originates in the attribute macro `derive_where` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: empty `derive_where` found
-  --> tests/ui/item.rs:13:3
-   |
-13 | #[derive_where()]
-   |   ^^^^^^^^^^^^^^
+ --> tests/ui/item.rs:8:1
+  |
+8 | #[derive_where()]
+  | ^^^^^^^^^^^^^^^^^
+  |
+  = note: this error originates in the attribute macro `derive_where` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: expected `,`
-  --> tests/ui/item.rs:17:24
+  --> tests/ui/item.rs:11:24
    |
-17 | #[derive_where(Clone; T;)]
+11 | #[derive_where(Clone; T;)]
    |                        ^
 
 error: expected type to bind to, expected one of: `for`, parentheses, `fn`, `unsafe`, `extern`, identifier, `::`, `<`, square brackets, `*`, `&`, `!`, `impl`, `_`, lifetime
-  --> tests/ui/item.rs:21:25
+  --> tests/ui/item.rs:14:25
    |
-21 | #[derive_where(Clone; T,,)]
+14 | #[derive_where(Clone; T,,)]
    |                         ^
 
 error: expected type to bind to, expected one of: `for`, parentheses, `fn`, `unsafe`, `extern`, identifier, `::`, `<`, square brackets, `*`, `&`, `!`, `impl`, `_`, lifetime
-  --> tests/ui/item.rs:25:23
+  --> tests/ui/item.rs:17:23
    |
-25 | #[derive_where(Clone; where)]
+17 | #[derive_where(Clone; where)]
    |                       ^^^^^
 
 error: expected `;` or `,
-  --> tests/ui/item.rs:29:22
+  --> tests/ui/item.rs:20:22
    |
-29 | #[derive_where(Clone Debug)]
+20 | #[derive_where(Clone Debug)]
    |                      ^^^^^
 
 error: expected `,`
-  --> tests/ui/item.rs:33:25
+  --> tests/ui/item.rs:23:25
    |
-33 | #[derive_where(Clone; T U)]
+23 | #[derive_where(Clone; T U)]
    |                         ^
 
 error: unexpected option syntax
-  --> tests/ui/item.rs:37:16
+  --> tests/ui/item.rs:26:16
    |
-37 | #[derive_where("Clone")]
+26 | #[derive_where("Clone")]
    |                ^^^^^^^

non-msrv-tests/tests/ui/item_option_syntax.rs

@@ -1,29 +1,19 @@
 use std::marker::PhantomData;
 
-use derive_where::DeriveWhere;
+use derive_where::derive_where;
 
-#[derive(DeriveWhere)]
-// Rust itself already fails to parse this and will provide a separate error message.
-#[derive_where = invalid]
-struct InvalidAttribute<T>(PhantomData<T>);
-
-#[derive(DeriveWhere)]
 #[derive_where = "invalid"]
 struct WrongAttributeSyntax<T>(PhantomData<T>);
 
-#[derive(DeriveWhere)]
 #[derive_where()]
 struct EmptyAttribute<T>(PhantomData<T>);
 
-#[derive(DeriveWhere)]
 #[derive_where(Debug = "option")]
 struct WrongOptionSyntax<T>(PhantomData<T>);
 
-#[derive(DeriveWhere)]
 #[derive_where(Debug())]
 struct EmptyOption<T>(PhantomData<T>);
 
-#[derive(derive_where::DeriveWhere)]
 #[derive_where(Debug(option))]
 struct UnsupportedOption<T>(PhantomData<T>);