From 1a6a74d3a13de562bfa7d465f413894597f08810 Mon Sep 17 00:00:00 2001
From: GrayJack <gr41.j4ck@gmail.com>
Date: Tue, 19 Nov 2024 06:13:28 -0300
Subject: [PATCH] feat: Make generating const function with mutable reference
 behind a feature flag

Turns out it was just stabilized, and will be on Rust 1.83.0
---
 Cargo.toml                      |  3 ++-
 bitflags-attr-macros/Cargo.toml |  2 ++
 bitflags-attr-macros/src/lib.rs | 12 +++++++++---
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 8a911da..4db8ca3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,7 +38,8 @@ default = []
 serde = ["bitflags-attr-macros/serde"]
 # Allows to use custom types as parameter for the bitflags macro
 custom-types = ["bitflags-attr-macros/custom-types"]
-
+# Generate as const functions some functions that take `&mut` (Only stable on rust 1.83.0: release date: 28 November, 2024)
+const-mut-ref = ["bitflags-attr-macros/const-mut-ref"]
 
 [workspace]
 members = ["bitflags-attr-macros"]
diff --git a/bitflags-attr-macros/Cargo.toml b/bitflags-attr-macros/Cargo.toml
index 5e3f5cf..10fb59c 100644
--- a/bitflags-attr-macros/Cargo.toml
+++ b/bitflags-attr-macros/Cargo.toml
@@ -32,3 +32,5 @@ default = []
 serde = []
 # Allows to use custom types as parameter for the bitflags macro
 custom-types = []
+# Generate as const functions some functions that take `&mut` (Only stable on rust 1.83.0: release date: 28 November, 2024)
+const-mut-ref = []
diff --git a/bitflags-attr-macros/src/lib.rs b/bitflags-attr-macros/src/lib.rs
index ddb23cf..8f71c63 100644
--- a/bitflags-attr-macros/src/lib.rs
+++ b/bitflags-attr-macros/src/lib.rs
@@ -133,6 +133,12 @@ fn bitflag_impl(attr: TokenStream, item: TokenStream) -> Result<TokenStream> {
         Ident::new(&ty_name, span)
     };
 
+    let const_mut = if cfg!(feature = "const-mut-ref") {
+        quote!(mut)
+    } else {
+        quote!()
+    };
+
     let number_flags = item.variants.len();
 
     let mut all_flags = Vec::with_capacity(number_flags);
@@ -607,20 +613,20 @@ fn bitflag_impl(attr: TokenStream, item: TokenStream) -> Result<TokenStream> {
             /// Set the flags in `other` in the value.
             #[inline]
             #[doc(alias = "insert")]
-            pub const fn set(&mut self, other: Self) {
+            pub #const_mut fn set(&mut self, other: Self) {
                 self.0 = self.or(other).0
             }
 
             /// Unset the flags in `other` in the value.
             #[inline]
             #[doc(alias = "remove")]
-            pub const fn unset(&mut self, other: Self) {
+            pub #const_mut fn unset(&mut self, other: Self) {
                 self.0 = self.difference(other).0
             }
 
             /// Toggle the flags in `other` in the value.
             #[inline]
-            pub const fn toggle(&mut self, other: Self) {
+            pub #const_mut fn toggle(&mut self, other: Self) {
                 self.0 = self.xor(other).0
             }
         }