From 46695fde17786bbbd80a7f5da14692ae9f2df624 Mon Sep 17 00:00:00 2001
From: Lilith River <lilith@imazen.io>
Date: Sun, 18 Jan 2026 22:42:14 -0700
Subject: [PATCH] fix: add deprecated compat shims for Gray_v08 and
 GrayAlpha_v08
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Adds backward-compatible methods for dependent crates during v0.8 → v1.0 migration:

Gray_v08:
- value() - reads .0 field
- value_mut() - mutable access to .0 field
- with_alpha() - creates GrayAlpha_v08

GrayAlpha_v08:
- value_mut() - mutable access to .0 field
- DerefMut impl - allows mutable .v/.a access

All methods marked #[deprecated] to encourage migration to Gray_v09/GrayA.

Tested with cargo-copter against 224 dependents: 95% pass rate.
Regressions are version conflicts that auto-resolve when 0.8.91 is stable.
---
 src/formats/gray.rs       | 27 +++++++++++++++++++++++++++
 src/formats/gray_alpha.rs | 22 ++++++++++++++++++++--
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/formats/gray.rs b/src/formats/gray.rs
index dbbbd151..79ead552 100644
--- a/src/formats/gray.rs
+++ b/src/formats/gray.rs
@@ -48,3 +48,30 @@ impl<T> core::ops::Deref for Gray_v08<T> {
         &self.0
     }
 }
+
+impl<T: Copy> Gray_v08<T> {
+    /// Reads the `.0` field
+    ///
+    /// This is a compatibility shim. Migrate to `Gray_v09` and use `.v` directly.
+    #[deprecated(since = "0.8.91", note = "Use Gray_v09 with .v field instead")]
+    pub fn value(self) -> T {
+        self.0
+    }
+
+    /// Exposes the `.0` field for writing
+    ///
+    /// This is a compatibility shim. Migrate to `Gray_v09` and use `.v` directly.
+    #[deprecated(since = "0.8.91", note = "Use Gray_v09 with .v field instead")]
+    pub fn value_mut(&mut self) -> &mut T {
+        &mut self.0
+    }
+
+    /// Add alpha component to this pixel
+    ///
+    /// This is a compatibility shim. Migrate to `Gray_v09` and use `GrayA` instead.
+    #[deprecated(since = "0.8.91", note = "Use Gray_v09::with_alpha() or GrayA instead")]
+    #[allow(deprecated)]
+    pub fn with_alpha(self, add_alpha_value: T) -> crate::formats::gray_alpha::GrayAlpha_v08<T> {
+        crate::formats::gray_alpha::GrayAlpha_v08(self.0, add_alpha_value)
+    }
+}
diff --git a/src/formats/gray_alpha.rs b/src/formats/gray_alpha.rs
index 37c1b068..7a25361a 100644
--- a/src/formats/gray_alpha.rs
+++ b/src/formats/gray_alpha.rs
@@ -1,5 +1,5 @@
 use crate::formats::gray_a::GrayA;
-use core::ops::Deref;
+use core::ops::{Deref, DerefMut};
 
 #[repr(C)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
@@ -34,13 +34,31 @@ impl<T, A> Deref for GrayAlpha_v08<T, A> {
     }
 }
 
+impl<T, A> DerefMut for GrayAlpha_v08<T, A> {
+    /// Compatibility shim - allows mutable access to `.v` and `.a` on the old `GrayAlpha` type.
+    ///
+    /// **Deprecated:** Migrate to `GrayA` instead of `GrayAlpha_v08`.
+    fn deref_mut(&mut self) -> &mut GrayA<T, A> {
+        unsafe { &mut *(self as *mut Self).cast::<GrayA<T, A>>() }
+    }
+}
+
 impl<T: Copy, A> GrayAlpha_v08<T, A> {
     /// Value - the brightness component. May be luma or luminance.
     ///
-    /// Backwards-compatible getter for `self.v`
+    /// This is a compatibility shim. Migrate to `GrayA` and use `.v` directly.
+    #[deprecated(since = "0.8.91", note = "Use GrayA with .v field instead")]
     pub fn value(&self) -> T {
         self.0
     }
+
+    /// Exposes the `.0` field for writing
+    ///
+    /// This is a compatibility shim. Migrate to `GrayA` and use `.v` directly.
+    #[deprecated(since = "0.8.91", note = "Use GrayA with .v field instead")]
+    pub fn value_mut(&mut self) -> &mut T {
+        &mut self.0
+    }
 }
 
 #[test]