Add number truncation before back-end translation (#3162)

* Add number-truncation before backend translation

* Round instead of truncate (conform to testcases)

* Add test-case for plural rounding-to-one corner-case

* Move rounding into generated translation code

* Change unit test to test generated function

* Round any number in generation, ignore (int vs float)

(it seems that that type distinction is frequently inaccurate)

* Update formatting

rslib/i18n/src/lib.rs

@@ -22,13 +22,46 @@ type FluentBundle<T> = FluentBundleOrig<T, intl_memoizer::concurrent::IntlLangMe
 
 pub use fluent::fluent_args as tr_args;
 
-pub trait Number: Into<FluentNumber> {}
-impl Number for i32 {}
-impl Number for i64 {}
-impl Number for u32 {}
-impl Number for f32 {}
-impl Number for u64 {}
-impl Number for usize {}
+pub trait Number: Into<FluentNumber> {
+    fn round(self) -> Self;
+}
+impl Number for i32 {
+    #[inline]
+    fn round(self) -> Self {
+        self
+    }
+}
+impl Number for i64 {
+    #[inline]
+    fn round(self) -> Self {
+        self
+    }
+}
+impl Number for u32 {
+    #[inline]
+    fn round(self) -> Self {
+        self
+    }
+}
+impl Number for f32 {
+    // round to 2 decimal places
+    #[inline]
+    fn round(self) -> Self {
+        (self * 100.0).round() / 100.0
+    }
+}
+impl Number for u64 {
+    #[inline]
+    fn round(self) -> Self {
+        self
+    }
+}
+impl Number for usize {
+    #[inline]
+    fn round(self) -> Self {
+        self
+    }
+}
 
 fn remapped_lang_name(lang: &LanguageIdentifier) -> &str {
     let region = lang.region.as_ref().map(|v| v.as_str());
@@ -446,6 +479,14 @@ mod test {
         assert!(want_comma_as_decimal_separator(&[langid!("pl-PL")]));
     }
 
+    #[test]
+    fn decimal_rounding() {
+        let tr = I18n::new(&["en"]);
+
+        assert_eq!(tr.browsing_cards_deleted(1.001), "1 card deleted.");
+        assert_eq!(tr.browsing_cards_deleted(1.01), "1.01 cards deleted.");
+    }
+
     #[test]
     fn i18n() {
         // English template

rslib/i18n/write_strings.rs

@@ -97,7 +97,7 @@ fn build_vars(translation: &Translation) -> String {
             let rust_name = v.name.to_snake_case();
             let trailer = match v.kind {
                 VariableKind::Any => "",
-                VariableKind::Int | VariableKind::Float => ".into()",
+                VariableKind::Int | VariableKind::Float => ".round().into()",
                 VariableKind::String => ".into()",
             };
             writeln!(