WIP: Add an exported macro to impl From for all errors

When we use this crate downstream and wish to create a custom error enum
with a variant to hold the general purpose error type we need all the
`From` impls implemented.

Is this too much magic?

Author: tcharding

src/error.rs

@@ -13,6 +13,57 @@ use crate::key::error::{
 };
 use crate::{schnorr, MessageLengthError};
 
+/// Implements `From<E> for $error` for all the specific errors in this crate.
+///
+/// Requires `$error` to be a an enum with a variant `Secp256k1`.
+#[macro_export]
+macro_rules! impl_from_for_all_crate_errors_for {
+    ($error:ty) => {
+        $crate::impl_from_for_all_crate_errors_for!($error, Secp256k1);
+    };
+    ($error:ty, $variant:ident) => {
+        impl From<$crate::Error> for $error {
+            fn from(e: $crate::Error) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::NotEnoughMemoryError> for $error {
+            fn from(e: $crate::NotEnoughMemoryError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::MessageLengthError> for $error {
+            fn from(e: $crate::MessageLengthError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::schnorr::SignatureError> for $error {
+            fn from(e: $crate::schnorr::SignatureError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::ecdsa::SignatureError> for $error {
+            fn from(e: $crate::ecdsa::SignatureError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::RecoveryIdError> for $error {
+            fn from(e: $crate::RecoveryIdError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::SecretKeyError> for $error {
+            fn from(e: $crate::SecretKeyError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::PublicKeyError> for $error {
+            fn from(e: $crate::PublicKeyError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::PublicKeySumError> for $error {
+            fn from(e: $crate::PublicKeySumError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::TweakError> for $error {
+            fn from(e: $crate::TweakError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::ParityValueError> for $error {
+            fn from(e: $crate::ParityValueError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::XOnlyTweakError> for $error {
+            fn from(e: $crate::XOnlyTweakError) -> Self { Self::$variant(e.into()) }
+        }
+        impl From<$crate::SharedSecretError> for $error {
+            fn from(e: $crate::SharedSecretError) -> Self { Self::$variant(e.into()) }
+        }
+    };
+}
+
 /// This is a general purpose error type that can be used to wrap all the errors in this crate.
 ///
 /// Every error types in this crate can be converted (using `?`) to this type. We also support