Fix fallback to syntax highlighting theme (closes #1309) (#1312)

* Highlight fallback from extra syntaxes to the theme (close #1309)

* Warning when codeblock language is unknown and cannot be highlighted

* page/section path in codeblock language missing warning

Co-authored-by: southerntofu <southerntofu@thunix.net>

components/config/src/highlighting.rs

@@ -16,29 +16,34 @@ lazy_static! {
         from_binary(include_bytes!("../../../sublime/themes/all.themedump"));
 }
 
+pub enum HighlightSource {
+    Theme,
+    Extra,
+    Plain,
+    NotFound,
+}
+
 /// Returns the highlighter and whether it was found in the extra or not
-pub fn get_highlighter(language: Option<&str>, config: &Config) -> (HighlightLines<'static>, bool) {
+pub fn get_highlighter(language: Option<&str>, config: &Config) -> (HighlightLines<'static>, HighlightSource) {
     let theme = &THEME_SET.themes[config.highlight_theme()];
-    let mut in_extra = false;
 
     if let Some(ref lang) = language {
-        let syntax = if let Some(ref extra) = config.markdown.extra_syntax_set {
+        if let Some(ref extra_syntaxes) = config.markdown.extra_syntax_set {
-            let s = extra.find_syntax_by_token(lang);
+            if let Some(syntax) = extra_syntaxes.find_syntax_by_token(lang) {
-            if s.is_some() {
+                return (HighlightLines::new(syntax, theme), HighlightSource::Extra);
-                in_extra = true;
+            }
         }
-            s
-        } else {
         // The JS syntax hangs a lot... the TS syntax is probably better anyway.
         // https://github.com/getzola/zola/issues/1241
         // https://github.com/getzola/zola/issues/1211
         // https://github.com/getzola/zola/issues/1174
         let hacked_lang = if *lang == "js" || *lang == "javascript" { "ts" } else { lang };
-            SYNTAX_SET.find_syntax_by_token(hacked_lang)
+        if let Some(syntax) = SYNTAX_SET.find_syntax_by_token(hacked_lang) {
-        }
+            (HighlightLines::new(syntax, theme), HighlightSource::Theme)
-        .unwrap_or_else(|| SYNTAX_SET.find_syntax_plain_text());
-        (HighlightLines::new(syntax, theme), in_extra)
         } else {
-        (HighlightLines::new(SYNTAX_SET.find_syntax_plain_text(), theme), false)
+            (HighlightLines::new(SYNTAX_SET.find_syntax_plain_text(), theme), HighlightSource::NotFound)
+        }
+    } else {
+        (HighlightLines::new(SYNTAX_SET.find_syntax_plain_text(), theme), HighlightSource::Plain)
     }
 }

components/rendering/src/markdown.rs

@@ -242,6 +242,7 @@ pub fn markdown_to_html(content: &str, context: &RenderContext) -> Result<Render
                                     fence_info,
                                     &context.config,
                                     IncludeBackground::IfDifferent(color),
+                                    context.tera_context.get("page").or(context.tera_context.get("section")).map(|x| x.as_object().unwrap().get("relative_path").unwrap().as_str().unwrap())
                                 ));
                             }
                         };

components/rendering/src/markdown/codeblock.rs

@@ -1,4 +1,4 @@
-use config::highlighting::{get_highlighter, SYNTAX_SET, THEME_SET};
+use config::highlighting::{get_highlighter, HighlightSource, SYNTAX_SET, THEME_SET};
 use config::Config;
 use std::cmp::min;
 use std::collections::HashSet;
@@ -22,16 +22,27 @@ pub struct CodeBlock<'config> {
 }
 
 impl<'config> CodeBlock<'config> {
-    pub fn new(fence_info: &str, config: &'config Config, background: IncludeBackground) -> Self {
+    pub fn new(fence_info: &str, config: &'config Config, background: IncludeBackground, path: Option<&'config str>) -> Self {
         let fence_info = FenceSettings::new(fence_info);
         let theme = &THEME_SET.themes[config.highlight_theme()];
-        let (highlighter, in_extra) = get_highlighter(fence_info.language, config);
+        let (highlighter, highlight_source) = get_highlighter(fence_info.language, config);
+        let extra_syntax_set = match highlight_source {
+            HighlightSource::Extra => config.markdown.extra_syntax_set.as_ref(),
+            HighlightSource::NotFound => {
+                // Language was not found, so it exists (safe unwrap)
+                let lang = fence_info.language.unwrap();
+                if let Some(path) = path {
+                    eprintln!("Warning: Highlight language {} not found in {}", lang, path);
+                } else {
+                    eprintln!("Warning: Highlight language {} not found", lang);
+                }
+                None
+            },
+            _ => None,
+        };
         Self {
             highlighter,
-            extra_syntax_set: match in_extra {
+            extra_syntax_set,
-                true => config.markdown.extra_syntax_set.as_ref(),
-                false => None,
-            },
             background,
             theme,