From 32426d77ba3c10372d27de4774bae45bcd307a75 Mon Sep 17 00:00:00 2001
From: Dirkjan Ochtman <dirkjan@ochtman.nl>
Date: Wed, 23 Nov 2022 19:03:22 -0800
Subject: [PATCH] Report kind of missing value

---
 instant-xml-macros/src/de.rs   |  2 +-
 instant-xml/src/impls.rs       |  6 +++---
 instant-xml/src/lib.rs         |  6 +++---
 instant-xml/tests/de-direct.rs |  6 +++---
 instant-xml/tests/de-ns.rs     | 10 ++++++----
 5 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/instant-xml-macros/src/de.rs b/instant-xml-macros/src/de.rs
index a8e7cd5..17ec43d 100644
--- a/instant-xml-macros/src/de.rs
+++ b/instant-xml-macros/src/de.rs
@@ -127,7 +127,7 @@ fn deserialize_wrapped_enum(
 
                 let node = match deserializer.next() {
                     Some(result) => result?,
-                    None => return Err(Error::MissingValue),
+                    None => return Err(Error::MissingValue(&<Self as FromXml>::KIND)),
                 };
 
                 let data = match node {
diff --git a/instant-xml/src/impls.rs b/instant-xml/src/impls.rs
index b4fa659..20209ed 100644
--- a/instant-xml/src/impls.rs
+++ b/instant-xml/src/impls.rs
@@ -26,7 +26,7 @@ impl<'xml> FromXml<'xml> for bool {
     fn deserialize<'cx>(deserializer: &'cx mut Deserializer<'cx, 'xml>) -> Result<Self, Error> {
         FromXmlStr::<Self>::deserialize(deserializer)?
             .0
-            .ok_or(Error::MissingValue)
+            .ok_or(Error::MissingValue(&Kind::Scalar))
     }
 
     const KIND: Kind<'static> = Kind::Scalar;
@@ -72,7 +72,7 @@ macro_rules! from_xml_for_number {
             ) -> Result<Self, Error> {
                 FromXmlStr::<Self>::deserialize(deserializer)?
                     .0
-                    .ok_or(Error::MissingValue)
+                    .ok_or(Error::MissingValue(&Kind::Scalar))
             }
 
             const KIND: Kind<'static> = Kind::Scalar;
@@ -97,7 +97,7 @@ impl<'xml> FromXml<'xml> for char {
     fn deserialize<'cx>(deserializer: &'cx mut Deserializer<'cx, 'xml>) -> Result<Self, Error> {
         FromXmlStr::<Self>::deserialize(deserializer)?
             .0
-            .ok_or(Error::MissingValue)
+            .ok_or(Error::MissingValue(&Kind::Scalar))
     }
 
     const KIND: Kind<'static> = Kind::Scalar;
diff --git a/instant-xml/src/lib.rs b/instant-xml/src/lib.rs
index fd1cf2a..7579389 100644
--- a/instant-xml/src/lib.rs
+++ b/instant-xml/src/lib.rs
@@ -39,7 +39,7 @@ pub trait FromXml<'xml>: Sized {
     // If the missing field is of type `Option<T>` then treat is as `None`,
     // otherwise it is an error.
     fn missing_value() -> Result<Self, Error> {
-        Err(Error::MissingValue)
+        Err(Error::MissingValue(&Self::KIND))
     }
 
     const KIND: Kind<'static>;
@@ -95,7 +95,7 @@ pub enum Error {
     #[error("missing tag")]
     MissingTag,
     #[error("missing value")]
-    MissingValue,
+    MissingValue(&'static Kind<'static>),
     #[error("unexpected token: {0}")]
     UnexpectedToken(String),
     #[error("missing prefix")]
@@ -112,7 +112,7 @@ pub enum Error {
     DuplicateValue,
 }
 
-#[derive(Eq, PartialEq)]
+#[derive(Debug, Eq, PartialEq)]
 pub enum Kind<'a> {
     Scalar,
     Element(Id<'a>),
diff --git a/instant-xml/tests/de-direct.rs b/instant-xml/tests/de-direct.rs
index b15c882..1558712 100644
--- a/instant-xml/tests/de-direct.rs
+++ b/instant-xml/tests/de-direct.rs
@@ -1,6 +1,6 @@
 use similar_asserts::assert_eq;
 
-use instant_xml::{from_str, Error, FromXml};
+use instant_xml::{from_str, Error, FromXml, Kind};
 
 #[derive(Debug, Eq, PartialEq, FromXml)]
 #[xml(ns("URI"))]
@@ -24,12 +24,12 @@ fn direct_namespaces() {
         from_str(
             "<StructDirectNamespace xmlns=\"URI\"><flag xmlns=\"WRONG\">true</flag></StructDirectNamespace>"
         ),
-        Err::<StructDirectNamespace, _>(Error::MissingValue)
+        Err::<StructDirectNamespace, _>(Error::MissingValue(&Kind::Scalar))
     );
 
     // Wrong direct namespace - missing namespace
     assert_eq!(
         from_str("<StructDirectNamespace xmlns=\"URI\"><flag>true</flag></StructDirectNamespace>"),
-        Err::<StructDirectNamespace, _>(Error::MissingValue)
+        Err::<StructDirectNamespace, _>(Error::MissingValue(&Kind::Scalar))
     );
 }
diff --git a/instant-xml/tests/de-ns.rs b/instant-xml/tests/de-ns.rs
index 2caec63..2458f0b 100644
--- a/instant-xml/tests/de-ns.rs
+++ b/instant-xml/tests/de-ns.rs
@@ -1,6 +1,6 @@
 use similar_asserts::assert_eq;
 
-use instant_xml::{from_str, Error, FromXml};
+use instant_xml::{from_str, Error, FromXml, Id, Kind};
 
 #[derive(Debug, Eq, PartialEq, FromXml)]
 struct NestedWrongNamespace {
@@ -71,7 +71,9 @@ fn default_namespaces() {
     // Wrong child namespace
     assert_eq!(
         from_str("<StructWithWrongNestedNamespace xmlns=\"URI\" xmlns:dar=\"BAZ\"><NestedWrongNamespace><flag>true</flag></NestedWrongNamespace></StructWithWrongNestedNamespace>"),
-        Err::<StructWithWrongNestedNamespace, _>(Error::MissingValue)
+        Err::<StructWithWrongNestedNamespace, _>(
+            Error::MissingValue(&Kind::Element(Id { ns: "", name: "NestedWrongNamespace" }))
+        )
     );
 }
 
@@ -111,7 +113,7 @@ fn other_namespaces() {
         from_str(
             "<NestedOtherNamespace xmlns=\"URI\" xmlns:bar=\"WRONG\"><bar:flag>true</bar:flag></NestedOtherNamespace>"
         ),
-        Err::<NestedOtherNamespace, _>(Error::MissingValue)
+        Err::<NestedOtherNamespace, _>(Error::MissingValue(&Kind::Scalar))
     );
 
     // Other namespace not-nested - missing parser prefix
@@ -119,7 +121,7 @@ fn other_namespaces() {
         from_str(
             "<NestedOtherNamespace xmlns=\"URI\" xmlns:bar=\"BAR\"><flag>true</flag></NestedOtherNamespace>"
         ),
-        Err::<NestedOtherNamespace, _>(Error::MissingValue)
+        Err::<NestedOtherNamespace, _>(Error::MissingValue(&Kind::Scalar))
     );
 
     // Correct child other namespace