XXX simplify

Author: phip1611

multiboot2/src/boot_loader_name.rs

@@ -43,15 +43,6 @@ impl Debug for BootLoaderNameTag {
     }
 }
 
-impl crate::TagTrait for BootLoaderNameTag {
-    fn dst_size(base_tag: &Tag) -> usize {
-        // The size of the sized portion of the bootloader name tag.
-        let tag_base_size = 8;
-        assert!(base_tag.size >= 8);
-        base_tag.size as usize - tag_base_size
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use crate::{BootLoaderNameTag, Tag, TagType};

multiboot2/src/command_line.rs

@@ -50,15 +50,6 @@ impl Debug for CommandLineTag {
     }
 }
 
-impl TagTrait for CommandLineTag {
-    fn dst_size(base_tag: &Tag) -> usize {
-        // The size of the sized portion of the command line tag.
-        let tag_base_size = 8;
-        assert!(base_tag.size >= 8);
-        base_tag.size as usize - tag_base_size
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use crate::{CommandLineTag, Tag, TagType};

multiboot2/src/lib.rs

@@ -340,14 +340,14 @@ impl BootInformation {
     /// }
     ///
     /// // This implementation is only necessary for tags that are DSTs.
-    /// impl TagTrait for CustomTag {
+    /// /*impl TagTrait for CustomTag {
     ///     fn dst_size(base_tag: &Tag) -> usize {
     ///         // The size of the sized portion of the custom tag.
     ///         let tag_base_size = 8; // id + size is 8 byte in size
     ///         assert!(base_tag.size >= 8);
     ///         base_tag.size as usize - tag_base_size
     ///     }
-    /// }
+    /// }*/
     ///
     /// impl CustomTag {
     ///     fn name(&self) -> Result<&str, Utf8Error> {
@@ -533,6 +533,19 @@ impl<T: Pointee<Metadata = ()>> TagTrait for T {
     }
 }
 
+// All sized tags automatically have a Pointee implementation where
+// Pointee::Metadata is (). Hence, the TagTrait is implemented automatically for
+// all tags that are sized.
+impl<T: Pointee<Metadata = usize>> TagTrait for T {
+    #[allow(clippy::unused_unit)]
+    fn dst_size(base_tag: &Tag) -> Self::Metadata {
+        // The size of the sized portion of the command line tag.
+        let tag_base_size = 8;
+        assert!(base_tag.size >= 8);
+        base_tag.size as usize - tag_base_size
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1618,14 +1631,14 @@ mod tests {
             }
         }
 
-        impl TagTrait for CustomTag {
+        /*impl TagTrait for CustomTag {
             fn dst_size(base_tag: &Tag) -> usize {
                 // The size of the sized portion of the command line tag.
                 let tag_base_size = 8;
                 assert!(base_tag.size >= 8);
                 base_tag.size as usize - tag_base_size
             }
-        }
+        }*/
 
         #[repr(C, align(8))]
         struct AlignedBytes([u8; 32]);

multiboot2/src/module.rs

@@ -44,15 +44,6 @@ impl ModuleTag {
     }
 }
 
-impl crate::TagTrait for ModuleTag {
-    fn dst_size(base_tag: &Tag) -> usize {
-        // The size of the sized portion of the module tag.
-        let tag_base_size = 16;
-        assert!(base_tag.size >= 8);
-        base_tag.size as usize - tag_base_size
-    }
-}
-
 impl Debug for ModuleTag {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         f.debug_struct("ModuleTag")