Add reserved namespace bindings.

This adds xml and xmlns namespace bindings. These are defined at
https://www.w3.org/TR/xml-names11/#xmlReserved.

.github/workflows/rust.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: dtolnay/rust-toolchain@1.52.0
+    - uses: dtolnay/rust-toolchain@1.53.0
     - run: cargo check
 
   minimal-versions:

Cargo.toml

@@ -10,7 +10,7 @@ repository = "https://github.com/tafia/quick-xml"
 keywords = ["xml", "serde", "parser", "writer", "html"]
 categories = ["asynchronous", "encoding", "parsing", "parser-implementations"]
 license = "MIT"
-rust-version = "1.52"
+rust-version = "1.53"
 include = ["src/*", "LICENSE-MIT.md", "README.md"]
 
 [dependencies]

Changelog.md

@@ -12,10 +12,16 @@
 
 ### New Features
 
+- [#541]: Deserialize specially named `$text` enum variant in [externally tagged]
+  enums from textual content
+- [#545]: Resolve well-known namespaces (xml and xmlns) to their approrpriate URIs.
+  Also, enforce namespace constraints related to these well-known namespaces.
+
 ### Bug Fixes
 
 ### Misc Changes
 
+- [#541]: Updated MSRV to 1.53 due to https://doc.rust-lang.org/edition-guide/rust-2021/IntoIterator-for-arrays.html
 
 ## 0.30.0 -- 2023-07-23
 

src/errors.rs

@@ -9,6 +9,12 @@ use std::str::Utf8Error;
 use std::string::FromUtf8Error;
 use std::sync::Arc;
 
+#[derive(Clone, Debug)]
+pub struct ReservedNamespaceError {
+    pub prefix: String,
+    pub name: String,
+}
+
 /// The error type used by this crate.
 #[derive(Clone, Debug)]
 pub enum Error {
@@ -45,6 +51,8 @@ pub enum Error {
     InvalidAttr(AttrError),
     /// Escape error
     EscapeError(EscapeError),
+    /// Error for when a reserved namespace is set incorrectly
+    ReservedNamespaceError(ReservedNamespaceError),
     /// Specified namespace prefix is unknown, cannot resolve namespace for it
     UnknownPrefix(Vec<u8>),
 }
@@ -120,7 +128,10 @@ impl fmt::Display for Error {
                 f.write_str("Unknown namespace prefix '")?;
                 write_byte_string(f, prefix)?;
                 f.write_str("'")
-            }
+            },
+            Error::ReservedNamespaceError(e) => write!(
+                f, "The namespace prefix `{}` with name `{}` is invalid.", e.prefix, e.name
+            ),
         }
     }
 }