Made the multiple feeds config changes "loudly" backwards-incompatible

CHANGELOG.md

@@ -11,6 +11,7 @@
 - Added support for generating multiple kinds of feeds at once
 - Changed config options named `generate_feed` to `generate_feeds` (both in config.toml and in section front-matter)
 - Changed config option `feed_filename: String` to `feed_filenames: Vec<String>`
+- The config file no longer allows arbitrary fields outside the `[extra]` section (front-matter is unaffected)
 
 ## 0.18.0 (2023-12-18)
 

components/config/src/config/languages.rs

@@ -5,22 +5,19 @@ use libs::unic_langid::LanguageIdentifier;
 use serde::{Deserialize, Serialize};
 
 use crate::config::search;
-use crate::config::single_or_vec;
 use crate::config::taxonomies;
 
 #[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(default)]
+#[serde(default, deny_unknown_fields)]
 pub struct LanguageOptions {
     /// Title of the site. Defaults to None
     pub title: Option<String>,
     /// Description of the site. Defaults to None
     pub description: Option<String>,
     /// Whether to generate feeds for that language, defaults to `false`
-    #[serde(alias = "generate_feed")]
     pub generate_feeds: bool,
     /// The filenames to use for feeds. Used to find the templates, too.
     /// Defaults to ["atom.xml"], with "rss.xml" also having a template provided out of the box.
-    #[serde(alias = "feed_filename", deserialize_with = "single_or_vec")]
     pub feed_filenames: Vec<String>,
     pub taxonomies: Vec<taxonomies::TaxonomyConfig>,
     /// Whether to generate search index for that language, defaults to `false`

components/config/src/config/mod.rs

@@ -10,8 +10,7 @@ use std::path::{Path, PathBuf};
 
 use libs::globset::GlobSet;
 use libs::toml::Value as Toml;
-use serde::de::DeserializeOwned;
-use serde::{Deserialize, Deserializer, Serialize};
+use serde::{Deserialize, Serialize};
 
 use crate::theme::Theme;
 use errors::{anyhow, bail, Result};
@@ -31,7 +30,7 @@ pub enum Mode {
 }
 
 #[derive(Clone, Debug, Deserialize)]
-#[serde(default)]
+#[serde(default, deny_unknown_fields)]
 pub struct Config {
     /// Base URL of the site, the only required config argument
     pub base_url: String,
@@ -51,13 +50,11 @@ pub struct Config {
     translations: HashMap<String, String>,
 
     /// Whether to generate feeds. Defaults to false.
-    #[serde(alias = "generate_feed")]
     pub generate_feeds: bool,
     /// The number of articles to include in the feed. Defaults to including all items.
     pub feed_limit: Option<usize>,
     /// The filenames to use for feeds. Used to find the templates, too.
     /// Defaults to ["atom.xml"], with "rss.xml" also having a template provided out of the box.
-    #[serde(alias = "feed_filename", deserialize_with = "single_or_vec")]
     pub feed_filenames: Vec<String>,
     /// If set, files from static/ will be hardlinked instead of copied to the output dir.
     pub hard_link_static: bool,
@@ -400,48 +397,6 @@ impl Default for Config {
     }
 }
 
-/// Used for deserializing values that can be either a single value or a vec of values
-pub(crate) fn single_or_vec<'de, T, D>(deserializer: D) -> Result<Vec<T>, D::Error>
-where
-    T: DeserializeOwned,
-    D: Deserializer<'de>,
-{
-    let v = SingleOrVec::deserialize(deserializer)?;
-    Ok(v.into())
-}
-
-#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
-#[serde(untagged)]
-pub(crate) enum SingleOrVec<T> {
-    Multiple(Vec<T>),
-    One(T),
-    None,
-}
-
-impl<T> From<SingleOrVec<T>> for Vec<T> {
-    fn from(x: SingleOrVec<T>) -> Vec<T> {
-        use SingleOrVec::*;
-
-        match x {
-            Multiple(v) => v,
-            One(v) => vec![v],
-            None => vec![],
-        }
-    }
-}
-
-impl<T> From<Vec<T>> for SingleOrVec<T> {
-    fn from(value: Vec<T>) -> Self {
-        Self::Multiple(value)
-    }
-}
-
-impl<T> Default for SingleOrVec<T> {
-    fn default() -> Self {
-        Self::None
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1025,15 +980,14 @@ author = "[email protected] (Some Person)"
     }
 
     #[test]
-    fn test_backwards_compatibility_for_feeds() {
+    #[should_panic]
+    fn test_backwards_incompatibility_for_feeds() {
         let config = r#"
 base_url = "example.com"
 generate_feed = true
 feed_filename = "test.xml"
         "#;
 
-        let config = Config::parse(config).unwrap();
-        assert_eq!(config.generate_feeds, true);
-        assert_eq!(config.feed_filenames, vec!["test.xml".to_owned()]);
+        Config::parse(config).unwrap();
     }
 }

components/config/src/lib.rs

@@ -2,7 +2,7 @@ mod config;
 pub mod highlighting;
 mod theme;
 
-use std::path::Path;
+use std::{marker::PhantomData, path::Path};
 
 pub use crate::config::{
     languages::LanguageOptions,
@@ -14,9 +14,35 @@ pub use crate::config::{
     Config,
 };
 use errors::Result;
+use serde::Deserialize;
 
 /// Get and parse the config.
 /// If it doesn't succeed, exit
 pub fn get_config(filename: &Path) -> Result<Config> {
     Config::from_file(filename)
 }
+
+/// This is used to print an error message for deprecated fields
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub struct Deprecated<T> {
+    _type: PhantomData<T>,
+}
+
+impl<T> Deprecated<T> {
+    pub fn new() -> Self {
+        Self { _type: PhantomData }
+    }
+}
+
+pub trait DeprecationReason {
+    const REASON: &'static str;
+}
+
+impl<'de, T: DeprecationReason> Deserialize<'de> for Deprecated<T> {
+    fn deserialize<D>(_deserializer: D) -> std::prelude::v1::Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        Err(serde::de::Error::custom(format!("Failed to parse a deprecated option: {}", T::REASON)))
+    }
+}

components/content/src/front_matter/section.rs

@@ -1,6 +1,7 @@
 use libs::tera::{Map, Value};
 use serde::{Deserialize, Serialize};
 
+use config::{Deprecated, DeprecationReason};
 use errors::Result;
 use utils::de::fix_toml_dates;
 use utils::types::InsertAnchor;
@@ -67,13 +68,23 @@ pub struct SectionFrontMatter {
     /// redirect to this
     #[serde(skip_serializing)]
     pub aliases: Vec<String>,
+    /// Deprecated
+    #[serde(skip_serializing)]
+    pub generate_feed: Deprecated<DeprecatedGenerateFeed>,
     /// Whether to generate a feed for the current section
-    #[serde(skip_serializing, alias = "generate_feed")]
+    #[serde(skip_serializing)]
     pub generate_feeds: bool,
     /// Any extra parameter present in the front matter
     pub extra: Map<String, Value>,
 }
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub struct DeprecatedGenerateFeed {}
+
+impl DeprecationReason for DeprecatedGenerateFeed {
+    const REASON: &'static str = "generate_feed is deprecated, please use generate_feeds instead";
+}
+
 impl SectionFrontMatter {
     pub fn parse(raw: &RawFrontMatter) -> Result<SectionFrontMatter> {
         let mut f: SectionFrontMatter = raw.deserialize()?;
@@ -113,6 +124,7 @@ impl Default for SectionFrontMatter {
             transparent: false,
             page_template: None,
             aliases: Vec::new(),
+            generate_feed: Deprecated::new(),
             generate_feeds: false,
             extra: Map::new(),
             draft: false,