From 56058b588c0a85bf2dca54f8a744b6d507a12e46 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 18 Aug 2021 12:29:33 -0700
Subject: [PATCH 01/12] Add an "impl_arbitrary" feature to enable implementing
 `Arbitrary`.

Fixes #248.
---
 Cargo.toml         |  2 ++
 src/lib.rs         | 24 ++++++++++++++++++++++++
 tests/arbitrary.rs | 17 +++++++++++++++++
 3 files changed, 43 insertions(+)
 create mode 100644 tests/arbitrary.rs

diff --git a/Cargo.toml b/Cargo.toml
index be9e05ad..2e2d86e2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,11 +29,13 @@ walkdir = "2.3"
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
+arbitrary = "1"
 
 [features]
 default = []
 example_generated = []
 rustc-dep-of-std = ["core", "compiler_builtins"]
+impl_arbitrary = []
 
 [package.metadata.docs.rs]
 features = ["example_generated"]
diff --git a/src/lib.rs b/src/lib.rs
index 935e432f..6cbc2a1a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -820,6 +820,8 @@ macro_rules! __impl_bitflags {
                 result
             }
         }
+
+        __impl_arbitrary_for_bitflags!($BitFlags);
     };
 
     // Every attribute that the user writes on a const is applied to the
@@ -931,6 +933,28 @@ macro_rules! __impl_bitflags {
     };
 }
 
+// When "arbitrary" is not enabled, emit code to implement the `Arbitrary` trait.
+#[cfg(feature = "impl_arbitrary")]
+#[macro_export(local_inner_macros)]
+#[doc(hidden)]
+macro_rules! __impl_arbitrary_for_bitflags {
+    ($BitFlags:ident) => {
+        impl<'a> arbitrary::Arbitrary<'a> for $BitFlags {
+            fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+                 Self::from_bits(u.arbitrary()?).ok_or_else(|| arbitrary::Error::IncorrectFormat)
+            }
+        }
+    };
+}
+
+// When "arbitrary" is not enabled, don't emit any code for it.
+#[cfg(not(feature = "impl_arbitrary"))]
+#[macro_export(local_inner_macros)]
+#[doc(hidden)]
+macro_rules! __impl_arbitrary_for_bitflags {
+    ($BitFlags:ident) => {};
+}
+
 #[cfg(feature = "example_generated")]
 pub mod example_generated;
 
diff --git a/tests/arbitrary.rs b/tests/arbitrary.rs
new file mode 100644
index 00000000..8544c316
--- /dev/null
+++ b/tests/arbitrary.rs
@@ -0,0 +1,17 @@
+#![cfg(feature = "impl_arbitrary")]
+
+use arbitrary::Arbitrary;
+
+bitflags::bitflags! {
+    struct Color: u32 {
+        const RED = 0x1;
+        const GREEN = 0x2;
+        const BLUE = 0x4;
+    }
+}
+
+#[test]
+fn test_arbitary() {
+    let mut unstructured = arbitrary::Unstructured::new(&[0_u8; 256]);
+    let _color = Color::arbitrary(&mut unstructured);
+}

From 66be4264436da3de5fdd9f22f2dfa356335b5275 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 18 Aug 2021 13:27:04 -0700
Subject: [PATCH 02/12] Update src/lib.rs

Co-authored-by: konsumlamm <44230978+konsumlamm@users.noreply.github.com>
---
 src/lib.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 6cbc2a1a..b28ff1b1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -933,9 +933,9 @@ macro_rules! __impl_bitflags {
     };
 }
 
-// When "arbitrary" is not enabled, emit code to implement the `Arbitrary` trait.
+// When "impl_arbitrary" is enabled, emit code to implement the `Arbitrary` trait.
 #[cfg(feature = "impl_arbitrary")]
-#[macro_export(local_inner_macros)]
+#[macro_export]
 #[doc(hidden)]
 macro_rules! __impl_arbitrary_for_bitflags {
     ($BitFlags:ident) => {
@@ -947,9 +947,9 @@ macro_rules! __impl_arbitrary_for_bitflags {
     };
 }
 
-// When "arbitrary" is not enabled, don't emit any code for it.
+// When "impl_arbitrary" is not enabled, don't emit any code for it.
 #[cfg(not(feature = "impl_arbitrary"))]
-#[macro_export(local_inner_macros)]
+#[macro_export]
 #[doc(hidden)]
 macro_rules! __impl_arbitrary_for_bitflags {
     ($BitFlags:ident) => {};

From ad754db3d26e3453c10837aca21fb31847014eac Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 18 Aug 2021 13:26:41 -0700
Subject: [PATCH 03/12] Test impl_arbitrary in CI.

This enables impl_arbitrary when example_generated is enabled.
---
 .github/workflows/rust.yml | 2 +-
 Cargo.toml                 | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index ffe0edad..7de62f2d 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -32,7 +32,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: test
-          args: --features example_generated
+          args: --features example_generated,impl_arbitrary
 
   embedded:
     name: Build (embedded)
diff --git a/Cargo.toml b/Cargo.toml
index 2e2d86e2..6e0cdc83 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,6 +21,7 @@ exclude = ["bors.toml"]
 [dependencies]
 core = { version = '1.0.0', optional = true, package = 'rustc-std-workspace-core' }
 compiler_builtins = { version = '0.1.2', optional = true }
+arbitrary = { version = "1", optional = true }
 
 [dev-dependencies]
 trybuild = "1.0"
@@ -33,7 +34,7 @@ arbitrary = "1"
 
 [features]
 default = []
-example_generated = []
+example_generated = ["impl_arbitrary", "arbitrary"]
 rustc-dep-of-std = ["core", "compiler_builtins"]
 impl_arbitrary = []
 

From dec18af1507dfa79d8e08c4827994bd377cbfbd2 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 18 Aug 2021 13:32:15 -0700
Subject: [PATCH 04/12] Document the "impl_arbitrary" feature in the README.md.

---
 README.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/README.md b/README.md
index 0da0f853..a2841c5f 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,11 @@ and this to your source code:
 use bitflags::bitflags;
 ```
 
+Enable the `impl_arbitrary` feature to enable implementations of the
+[`Arbitrary`] trait for the generated structures.
+
+[`Arbitrary`]: https://docs.rs/arbitrary/1.0.1/arbitrary/trait.Arbitrary.html
+
 ## Rust Version Support
 
 The minimum supported Rust version is 1.46 due to use of associated constants and const functions.

From d970ee0fc4e17436c5b2acd10f377ae7e6a00316 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 18 Aug 2021 13:46:07 -0700
Subject: [PATCH 05/12] Use absolute paths to `arbirary` symbols.

---
 src/lib.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index b28ff1b1..18e33848 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -939,9 +939,9 @@ macro_rules! __impl_bitflags {
 #[doc(hidden)]
 macro_rules! __impl_arbitrary_for_bitflags {
     ($BitFlags:ident) => {
-        impl<'a> arbitrary::Arbitrary<'a> for $BitFlags {
-            fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
-                 Self::from_bits(u.arbitrary()?).ok_or_else(|| arbitrary::Error::IncorrectFormat)
+        impl<'a> ::arbitrary::Arbitrary<'a> for $BitFlags {
+            fn arbitrary(u: &mut ::arbitrary::Unstructured<'a>) -> ::arbitrary::Result<Self> {
+                 Self::from_bits(u.arbitrary()?).ok_or_else(|| ::arbitrary::Error::IncorrectFormat)
             }
         }
     };

From fee72add6657b58001a1e97d81e92b32e4d63d52 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 18 Aug 2021 14:05:25 -0700
Subject: [PATCH 06/12] Depend on and re-export "arbitrary".

Drop the "impl_arbitrary" feature, now that we can just use "arbitrary".
---
 Cargo.toml                                   |  3 +--
 README.md                                    |  4 ++--
 src/lib.rs                                   | 22 +++++++++++++-------
 tests/arbitrary.rs                           |  2 +-
 tests/compile-pass/redefinition/arbitrary.rs | 20 ++++++++++++++++++
 5 files changed, 39 insertions(+), 12 deletions(-)
 create mode 100644 tests/compile-pass/redefinition/arbitrary.rs

diff --git a/Cargo.toml b/Cargo.toml
index 6e0cdc83..159b4c27 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -34,9 +34,8 @@ arbitrary = "1"
 
 [features]
 default = []
-example_generated = ["impl_arbitrary", "arbitrary"]
+example_generated = ["arbitrary"]
 rustc-dep-of-std = ["core", "compiler_builtins"]
-impl_arbitrary = []
 
 [package.metadata.docs.rs]
 features = ["example_generated"]
diff --git a/README.md b/README.md
index a2841c5f..e7f780c0 100644
--- a/README.md
+++ b/README.md
@@ -27,8 +27,8 @@ and this to your source code:
 use bitflags::bitflags;
 ```
 
-Enable the `impl_arbitrary` feature to enable implementations of the
-[`Arbitrary`] trait for the generated structures.
+Enable the `arbitrary` feature to enable implementations of the [`Arbitrary`]
+trait for the generated structures.
 
 [`Arbitrary`]: https://docs.rs/arbitrary/1.0.1/arbitrary/trait.Arbitrary.html
 
diff --git a/src/lib.rs b/src/lib.rs
index 18e33848..eb33bb5c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -933,28 +933,36 @@ macro_rules! __impl_bitflags {
     };
 }
 
-// When "impl_arbitrary" is enabled, emit code to implement the `Arbitrary` trait.
-#[cfg(feature = "impl_arbitrary")]
+// When "arbitrary" is enabled, emit code to implement the `Arbitrary` trait.
+#[cfg(feature = "arbitrary")]
 #[macro_export]
 #[doc(hidden)]
 macro_rules! __impl_arbitrary_for_bitflags {
     ($BitFlags:ident) => {
-        impl<'a> ::arbitrary::Arbitrary<'a> for $BitFlags {
-            fn arbitrary(u: &mut ::arbitrary::Unstructured<'a>) -> ::arbitrary::Result<Self> {
-                 Self::from_bits(u.arbitrary()?).ok_or_else(|| ::arbitrary::Error::IncorrectFormat)
+        impl<'a> $crate::_arbitrary::Arbitrary<'a> for $BitFlags {
+            fn arbitrary(
+                u: &mut $crate::_arbitrary::Unstructured<'a>
+            ) -> $crate::_arbitrary::Result<Self> {
+                 Self::from_bits(u.arbitrary()?).ok_or_else(|| $crate::_arbitrary::Error::IncorrectFormat)
             }
         }
     };
 }
 
-// When "impl_arbitrary" is not enabled, don't emit any code for it.
-#[cfg(not(feature = "impl_arbitrary"))]
+// When "arbitrary" is not enabled, don't emit any code for it.
+#[cfg(not(feature = "arbitrary"))]
 #[macro_export]
 #[doc(hidden)]
 macro_rules! __impl_arbitrary_for_bitflags {
     ($BitFlags:ident) => {};
 }
 
+// Re-export `arbitrary` so that our macro expansions can refer to it by a
+// known name.
+#[cfg(feature = "arbitrary")]
+#[doc(hidden)]
+pub extern crate arbitrary as _arbitrary;
+
 #[cfg(feature = "example_generated")]
 pub mod example_generated;
 
diff --git a/tests/arbitrary.rs b/tests/arbitrary.rs
index 8544c316..a3b2f694 100644
--- a/tests/arbitrary.rs
+++ b/tests/arbitrary.rs
@@ -1,4 +1,4 @@
-#![cfg(feature = "impl_arbitrary")]
+#![cfg(feature = "arbitrary")]
 
 use arbitrary::Arbitrary;
 
diff --git a/tests/compile-pass/redefinition/arbitrary.rs b/tests/compile-pass/redefinition/arbitrary.rs
new file mode 100644
index 00000000..a9ef6791
--- /dev/null
+++ b/tests/compile-pass/redefinition/arbitrary.rs
@@ -0,0 +1,20 @@
+use bitflags::bitflags;
+
+// Checks for possible errors caused by overriding names used by `bitflags!` internally.
+
+mod arbitrary {}
+mod _arbitrary {}
+
+bitflags! {
+    struct Test: u8 {
+        const A = 1;
+    }
+}
+
+fn main() {
+    #[cfg(feature = "arbitrary")]
+    {
+        let mut unstructured = arbitrary::Unstructured::new(&[0_u8; 256]);
+        let _test = Test::arbitrary(&mut unstructured);
+    }
+}

From 8efeb65118153decee03bf2caaceff2101418ee7 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Thu, 19 Aug 2021 13:09:13 -0700
Subject: [PATCH 07/12] Update Cargo.toml

Co-authored-by: konsumlamm <44230978+konsumlamm@users.noreply.github.com>
---
 Cargo.toml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 159b4c27..9762cd20 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -30,7 +30,6 @@ walkdir = "2.3"
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"
-arbitrary = "1"
 
 [features]
 default = []

From fc99c5e3066b5eaf4bfbf45e67bf190c5fe763d1 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Thu, 19 Aug 2021 13:09:34 -0700
Subject: [PATCH 08/12] Update .github/workflows/rust.yml

Co-authored-by: konsumlamm <44230978+konsumlamm@users.noreply.github.com>
---
 .github/workflows/rust.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 7de62f2d..ffe0edad 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -32,7 +32,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: test
-          args: --features example_generated,impl_arbitrary
+          args: --features example_generated
 
   embedded:
     name: Build (embedded)

From 230933b1e86149a001f26062abb70a78f878cc42 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Thu, 19 Aug 2021 13:40:15 -0700
Subject: [PATCH 09/12] Fix a typo.

---
 tests/arbitrary.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/arbitrary.rs b/tests/arbitrary.rs
index a3b2f694..a6b25e97 100644
--- a/tests/arbitrary.rs
+++ b/tests/arbitrary.rs
@@ -11,7 +11,7 @@ bitflags::bitflags! {
 }
 
 #[test]
-fn test_arbitary() {
+fn test_arbitrary() {
     let mut unstructured = arbitrary::Unstructured::new(&[0_u8; 256]);
     let _color = Color::arbitrary(&mut unstructured);
 }

From 411d15264efc3ba67ac778cb65660386eea2a2e0 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Thu, 19 Aug 2021 13:40:26 -0700
Subject: [PATCH 10/12] Move the compile-pass test into a toplevel test.

And make the other changes suggested by @konsumlamm.
---
 tests/arbitrary-redefinition.rs              | 23 ++++++++++++++++++++
 tests/compile-pass/redefinition/arbitrary.rs | 20 -----------------
 2 files changed, 23 insertions(+), 20 deletions(-)
 create mode 100644 tests/arbitrary-redefinition.rs
 delete mode 100644 tests/compile-pass/redefinition/arbitrary.rs

diff --git a/tests/arbitrary-redefinition.rs b/tests/arbitrary-redefinition.rs
new file mode 100644
index 00000000..0e961eeb
--- /dev/null
+++ b/tests/arbitrary-redefinition.rs
@@ -0,0 +1,23 @@
+#![cfg(feature = "arbitrary")]
+
+extern crate arbitrary as a;
+
+use a::Arbitrary;
+use bitflags::bitflags;
+
+// Checks for possible errors caused by overriding names used by `bitflags!` internally.
+
+mod arbitrary {}
+mod _arbitrary {}
+
+bitflags! {
+    struct Test: u8 {
+        const A = 1;
+    }
+}
+
+#[test]
+fn test_arbitrary_redefinition() {
+    let mut unstructured = a::Unstructured::new(&[0_u8; 256]);
+    let _test = Test::arbitrary(&mut unstructured);
+}
diff --git a/tests/compile-pass/redefinition/arbitrary.rs b/tests/compile-pass/redefinition/arbitrary.rs
deleted file mode 100644
index a9ef6791..00000000
--- a/tests/compile-pass/redefinition/arbitrary.rs
+++ /dev/null
@@ -1,20 +0,0 @@
-use bitflags::bitflags;
-
-// Checks for possible errors caused by overriding names used by `bitflags!` internally.
-
-mod arbitrary {}
-mod _arbitrary {}
-
-bitflags! {
-    struct Test: u8 {
-        const A = 1;
-    }
-}
-
-fn main() {
-    #[cfg(feature = "arbitrary")]
-    {
-        let mut unstructured = arbitrary::Unstructured::new(&[0_u8; 256]);
-        let _test = Test::arbitrary(&mut unstructured);
-    }
-}

From 1a1e3753af5f78912629159cf70f18caa487b5ee Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Tue, 24 Aug 2021 22:28:40 -0700
Subject: [PATCH 11/12] Avoid adding `arbitrary` to the `example_generated`
 feature.

Add it to the docs.rs enabled features instead, as suggested in the
PR comments.
---
 Cargo.toml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 9762cd20..fed83f2d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,8 +33,8 @@ serde_json = "1.0"
 
 [features]
 default = []
-example_generated = ["arbitrary"]
+example_generated = []
 rustc-dep-of-std = ["core", "compiler_builtins"]
 
 [package.metadata.docs.rs]
-features = ["example_generated"]
+features = ["example_generated", "arbitrary"]

From fab01fa629fdb63fa3f37dff905bf34705e34068 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Wed, 25 Aug 2021 09:29:55 -0700
Subject: [PATCH 12/12] Re-enable the arbitrary feature in CI.

---
 .github/workflows/rust.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index ffe0edad..3242d3ed 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -32,7 +32,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: test
-          args: --features example_generated
+          args: --features example_generated,arbitrary
 
   embedded:
     name: Build (embedded)