Ensure fallback rules for logical properties are before nested rules

Fixes parcel-bundler#175

Also ensures that nested rules use a different compilation context from parents so that logical rules are not merged.

Author: devongovett

src/context.rs

@@ -50,6 +50,18 @@ impl<'i, 'o> PropertyHandlerContext<'i, 'o> {
     }
   }
 
+  pub fn child(&self, context: DeclarationContext) -> Self {
+    PropertyHandlerContext {
+      targets: self.targets,
+      is_important: false,
+      supports: Vec::new(),
+      ltr: Vec::new(),
+      rtl: Vec::new(),
+      context,
+      unused_symbols: self.unused_symbols
+    }
+  }
+
   pub fn should_compile_logical(&self, feature: Feature) -> bool {
     // Don't convert logical properties in style attributes because
     // our fallbacks rely on extra rules to define --ltr and --rtl.

src/lib.rs

@@ -9525,6 +9525,39 @@ mod tests {
         ..Browsers::default()
       },
     );
+
+    nesting_test_with_targets(
+      r#"
+      .foo {
+        padding-inline-start: 3px;
+
+        .bar {
+          padding-inline-start: 5px;
+        }
+      }
+      "#,
+      indoc! {r#"
+      .foo:not(:lang(ae, ar, arc, bcc, bqi, ckb, dv, fa, glk, he, ku, mzn, nqo, pnb, ps, sd, ug, ur, yi)) {
+        padding-left: 3px;
+      }
+
+      .foo:lang(ae, ar, arc, bcc, bqi, ckb, dv, fa, glk, he, ku, mzn, nqo, pnb, ps, sd, ug, ur, yi) {
+        padding-right: 3px;
+      }
+
+      .foo .bar:not(:lang(ae, ar, arc, bcc, bqi, ckb, dv, fa, glk, he, ku, mzn, nqo, pnb, ps, sd, ug, ur, yi)) {
+        padding-left: 5px;
+      }
+
+      .foo .bar:lang(ae, ar, arc, bcc, bqi, ckb, dv, fa, glk, he, ku, mzn, nqo, pnb, ps, sd, ug, ur, yi) {
+        padding-right: 5px;
+      }
+      "#},
+      Browsers {
+        safari: Some(12 << 16),
+        ..Browsers::default()
+      }.into(),
+    );
   }
 
   #[test]

src/rules/keyframes.rs

@@ -119,7 +119,7 @@ impl<'i> KeyframesRule<'i> {
     for keyframe in &mut self.keyframes {
       keyframe
         .declarations
-        .minify(context.handler, context.important_handler, context.handler_context)
+        .minify(context.handler, context.important_handler, &mut context.handler_context)
     }
 
     context.handler_context.context = DeclarationContext::None;

src/rules/mod.rs

@@ -59,7 +59,7 @@ use self::font_palette_values::FontPaletteValuesRule;
 use self::layer::{LayerBlockRule, LayerStatementRule};
 use self::property::PropertyRule;
 use crate::context::PropertyHandlerContext;
-use crate::declaration::DeclarationHandler;
+use crate::declaration::{DeclarationHandler, DeclarationBlock};
 use crate::dependencies::{Dependency, ImportDependency};
 use crate::error::{MinifyError, ParserError, PrinterError, PrinterErrorKind};
 use crate::parser::{
@@ -466,7 +466,7 @@ pub(crate) struct MinifyContext<'a, 'i> {
   pub targets: &'a Targets,
   pub handler: &'a mut DeclarationHandler<'i>,
   pub important_handler: &'a mut DeclarationHandler<'i>,
-  pub handler_context: &'a mut PropertyHandlerContext<'i, 'a>,
+  pub handler_context: PropertyHandlerContext<'i, 'a>,
   pub unused_symbols: &'a HashSet<String>,
   pub custom_media: Option<HashMap<CowArcStr<'i>, CustomMediaRule<'i>>>,
   pub css_modules: bool,
@@ -668,6 +668,24 @@ impl<'i, T: Clone> CssRuleList<'i, T> {
             .collect::<Vec<_>>();
 
           context.handler_context.reset();
+
+          // If the rule has nested rules, and we have extra rules to insert such as for logical properties,
+          // we need to split the rule in two so we can insert the extra rules in between the declarations from
+          // the main rule and the nested rules.
+          let nested_rule = if !style.rules.0.is_empty() && (!logical.is_empty() || !supports.is_empty() || !incompatible_rules.is_empty()) {
+            let mut rules =  CssRuleList(vec![]);
+            std::mem::swap(&mut style.rules, &mut rules);
+            Some(StyleRule {
+              selectors: style.selectors.clone(),
+              declarations: DeclarationBlock::default(),
+              rules,
+              vendor_prefix: style.vendor_prefix,
+              loc: style.loc
+            })
+          } else {
+            None
+          };
+
           if !merged && !style.is_empty() {
             let source_index = style.loc.source_index;
             let has_no_rules = style.rules.0.is_empty();
@@ -714,6 +732,11 @@ impl<'i, T: Clone> CssRuleList<'i, T> {
             }
             rules.extend(supports);
           }
+
+          if let Some(nested_rule) = nested_rule {
+            rules.push(CssRule::Style(nested_rule));
+          }
+
           continue;
         }
         CssRule::CounterStyle(counter_style) => {
@@ -777,7 +800,7 @@ fn merge_style_rules<'i, T>(
       .extend(style.declarations.important_declarations.drain(..));
     last_style_rule
       .declarations
-      .minify(context.handler, context.important_handler, context.handler_context);
+      .minify(context.handler, context.important_handler, &mut context.handler_context);
     return true;
   } else if style.declarations == last_style_rule.declarations
     && style.rules.0.is_empty()

src/rules/style.rs

@@ -71,11 +71,14 @@ impl<'i, T: Clone> StyleRule<'i, T> {
     context.handler_context.context = DeclarationContext::StyleRule;
     self
       .declarations
-      .minify(context.handler, context.important_handler, context.handler_context);
+      .minify(context.handler, context.important_handler, &mut context.handler_context);
     context.handler_context.context = DeclarationContext::None;
 
     if !self.rules.0.is_empty() {
+      let mut handler_context = context.handler_context.child(DeclarationContext::StyleRule);
+      std::mem::swap(&mut context.handler_context, &mut handler_context);
       self.rules.minify(context, unused)?;
+      context.handler_context = handler_context;
       if unused && self.rules.0.is_empty() {
         return Ok(true);
       }

src/stylesheet.rs

@@ -188,7 +188,7 @@ where
 
   /// Minify and transform the style sheet for the provided browser targets.
   pub fn minify(&mut self, options: MinifyOptions) -> Result<(), Error<MinifyErrorKind>> {
-    let mut context = PropertyHandlerContext::new(options.targets, &options.unused_symbols);
+    let context = PropertyHandlerContext::new(options.targets, &options.unused_symbols);
     let mut handler = DeclarationHandler::default();
     let mut important_handler = DeclarationHandler::default();
 
@@ -212,7 +212,7 @@ where
       targets: &options.targets,
       handler: &mut handler,
       important_handler: &mut important_handler,
-      handler_context: &mut context,
+      handler_context: context,
       unused_symbols: &options.unused_symbols,
       custom_media,
       css_modules: self.options.css_modules.is_some(),