exif: exif::TagType is only TryFrom<>

- This fixes a clippy warning about infaillible

Signed-off-by: Hubert Figuière <hub@figuiere.net>

3 files changed, 23 insertions, 18 deletions

diff --git a/src/tiff/entry.rs b/src/tiff/entry.rs
index b5b2319..d98915c 100644
--- a/src/tiff/entry.rs
+++ b/src/tiff/entry.rs
@@ -2,7 +2,7 @@
 /*
  * libopenraw - tiff/entry.rs
  *
- * Copyright (C) 2022-2023 Hubert Figuière
+ * Copyright (C) 2022-2024 Hubert Figuière
  *
  * This library is free software: you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -548,8 +548,8 @@ impl Entry {
                         .as_ref()
                         .map_or_else(|| array_to_str(e.data()), |d| array_to_str(d)),
                 ),
-                Err(_) => None,
-                _ => Some("VALUE".to_string()),
+                Ok(TagType::Invalid) => Some("INVALID".to_string()),
+                Err(n) => Some(n.to_string()),
             }
             .or_else(|| Some("ERROR".to_string()))
             .unwrap()
diff --git a/src/tiff/exif.rs b/src/tiff/exif.rs
index cad3cb2..ebff503 100644
--- a/src/tiff/exif.rs
+++ b/src/tiff/exif.rs
@@ -2,7 +2,7 @@
 /*
  * libopenraw - tiff/exif.rs
  *
- * Copyright (C) 2022-2023 Hubert Figuière
+ * Copyright (C) 2022-2024 Hubert Figuière
  *
  * This library is free software: you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -55,12 +55,14 @@ pub enum TagType {
     Invalid = 13,
 }
 
-impl std::convert::From<i16> for TagType {
-    fn from(value: i16) -> Self {
+impl std::convert::TryFrom<i16> for TagType {
+    type Error = i16;
+
+    fn try_from(value: i16) -> Result<Self, Self::Error> {
         if value <= 0 || value > 13 {
-            Self::Invalid
+            Err(value)
         } else {
-            unsafe { std::mem::transmute(value) }
+            Ok(unsafe { std::mem::transmute(value) })
         }
     }
 }
@@ -427,25 +429,27 @@ pub enum LightsourceValue {
 
 #[cfg(test)]
 mod test {
+    use std::convert::TryFrom;
+
     use byteorder::LittleEndian;
 
     use super::{ExifValue, Rational, SRational, TagType};
 
     #[test]
     fn test_tag_type_convert() {
-        let tag = TagType::from(1);
-        assert_eq!(tag, TagType::Byte);
+        let tag = TagType::try_from(1);
+        assert_eq!(tag, Ok(TagType::Byte));
 
-        let tag = TagType::from(4);
-        assert_eq!(tag, TagType::Long);
+        let tag = TagType::try_from(4);
+        assert_eq!(tag, Ok(TagType::Long));
 
         // Invalid value
-        let tag = TagType::from(-1);
-        assert_eq!(tag, TagType::Invalid);
+        let tag = TagType::try_from(-1);
+        assert_eq!(tag, Err(-1));
 
         // Invalid value
-        let tag = TagType::from(42);
-        assert_eq!(tag, TagType::Invalid);
+        let tag = TagType::try_from(42);
+        assert_eq!(tag, Err(42));
     }
 
     #[test]
diff --git a/src/tiff/iterator.rs b/src/tiff/iterator.rs
index 31a0667..29fa5e5 100644
--- a/src/tiff/iterator.rs
+++ b/src/tiff/iterator.rs
@@ -2,7 +2,7 @@
 /*
  * libopenraw - tiff/iterator.rs
  *
- * Copyright (C) 2023 Hubert Figuière
+ * Copyright (C) 2023-2024 Hubert Figuière
  *
  * This library is free software: you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -22,6 +22,7 @@
 //! The iterator over the ifd entries as `metadata::Value`
 
 use std::collections::btree_map;
+use std::convert::TryFrom;
 
 use crate::container::Endian;
 use crate::metadata::{Metadata, Value as MetadataValue};
@@ -70,7 +71,7 @@ impl<'a> std::iter::Iterator for Iterator<'a> {
 }
 
 fn from_entry(entry: &Entry, endian: Endian) -> MetadataValue {
-    match exif::TagType::from(entry.type_) {
+    match exif::TagType::try_from(entry.type_).unwrap_or(exif::TagType::Invalid) {
         exif::TagType::Ascii => {
             MetadataValue::String(utils::to_nul_terminated(&entry.string_value().unwrap()))
         }