From c153451c026fd363e11f8d3694a281c82f035445 Mon Sep 17 00:00:00 2001
From: Gabor Szabo <gabor@szabgab.com>
Date: Thu, 3 Apr 2025 22:06:17 +0300
Subject: [PATCH 1/2] Warn on invalid fields in the `[book]` section of
 `book.toml`

A step for #1595.

We might need to revise this if de decide to remove the `multilingual`
field as described in #2636
---
 src/config.rs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/config.rs b/src/config.rs
index 2ede0c2f92..9e446c3344 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -313,6 +313,7 @@ impl<'de> serde::Deserialize<'de> for Config {
         }
 
         warn_on_invalid_fields(&raw);
+        warn_on_invalid_fields_in_book_section(&raw);
 
         use serde::de::Error;
         let mut table = match raw {
@@ -389,6 +390,29 @@ fn warn_on_invalid_fields(table: &Value) {
     }
 }
 
+fn warn_on_invalid_fields_in_book_section(table: &Value) {
+    let valid_items = [
+        "title",
+        "authors",
+        "description",
+        "src",
+        "language",
+        "text-direction",
+        "multilingual",
+    ];
+    if let Some(book) = table.get("book") {
+        let table = book.as_table().expect("root.book must be a table");
+        for item in table.keys() {
+            if !valid_items.contains(&item.as_str()) {
+                warn!(
+                    "Invalid field {:?} in the [book] section of book.toml",
+                    &item
+                );
+            }
+        }
+    }
+}
+
 fn is_legacy_format(table: &Value) -> bool {
     let legacy_items = [
         "title",

From 1e581c3043b7bc8f5845da815a64fe10ccb5787b Mon Sep 17 00:00:00 2001
From: Gabor Szabo <gabor@szabgab.com>
Date: Wed, 9 Apr 2025 10:30:19 +0300
Subject: [PATCH 2/2] remove multilingual field as we have removed it elsewhere

---
 src/config.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/config.rs b/src/config.rs
index 9e446c3344..f628e96d80 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -398,7 +398,6 @@ fn warn_on_invalid_fields_in_book_section(table: &Value) {
         "src",
         "language",
         "text-direction",
-        "multilingual",
     ];
     if let Some(book) = table.get("book") {
         let table = book.as_table().expect("root.book must be a table");