Bug 2024601 - patch 6 - Also support env(), and add a couple tests for it. r=firefox-style-system-reviewers,dshin

jfkthame · jfkthame · commit 87de35f53311 · 2026-04-01T09:37:28.000Z
Differential Revision: https://phabricator.services.mozilla.com/D290988
diff --git a/servo/components/style/properties/mod.rs b/servo/components/style/properties/mod.rs
@@ -734,6 +734,15 @@ impl ShorthandId {
     }
 }
 
+/// Return the names of arbitrary substitution functions that are enabled.
+pub fn enabled_arbitrary_substitution_functions() -> &'static [&'static str] {
+    if static_prefs::pref!("layout.css.attr.enabled") {
+        &["var", "env", "attr"]
+    } else {
+        &["var", "env"]
+    }
+}
+
 fn parse_non_custom_property_declaration_value_into<'i>(
     declarations: &mut SourcePropertyDeclaration,
     context: &ParserContext,
@@ -765,13 +774,7 @@ fn parse_non_custom_property_declaration_value_into<'i>(
     };
 
     input.reset(&start);
-    input.look_for_arbitrary_substitution_functions(
-        if static_prefs::pref!("layout.css.attr.enabled") {
-            &["var", "env", "attr"]
-        } else {
-            &["var", "env"]
-        },
-    );
+    input.look_for_arbitrary_substitution_functions(enabled_arbitrary_substitution_functions());
 
     let err = match parse_entirely_into(declarations, input) {
         Ok(()) => {
diff --git a/servo/components/style/queries/feature_expression.rs b/servo/components/style/queries/feature_expression.rs
@@ -14,7 +14,7 @@ use crate::custom_properties::{
 use crate::derives::*;
 use crate::dom::AttributeTracker;
 use crate::parser::{Parse, ParserContext};
-use crate::properties::CSSWideKeyword;
+use crate::properties::{self, CSSWideKeyword};
 use crate::properties_and_values::value::{ComputedValueComponent as Component, ValueInner};
 use crate::selector_map::PrecomputedHashSet;
 use crate::str::{starts_with_ignore_ascii_case, string_as_ascii_lowercase};
@@ -810,9 +810,9 @@ impl QueryExpressionValue {
                     )
                 };
 
-            if name.eq_ignore_ascii_case("var")
-                || (static_prefs::pref!("layout.css.attr.enabled")
-                    && name.eq_ignore_ascii_case("attr"))
+            if properties::enabled_arbitrary_substitution_functions()
+                .iter()
+                .any(|n| n.eq_ignore_ascii_case(name))
             {
                 return Ok(Self::Function(Box::new(parse_func(input)?)));
             }
diff --git a/testing/web-platform/tests/css/css-conditional/container-queries/at-container-style-parsing.html b/testing/web-platform/tests/css/css-conditional/container-queries/at-container-style-parsing.html
@@ -44,6 +44,7 @@
   test_cq_condition_known('style(var(--p) < calc(100 + 200))');
   test_cq_condition_known('style(attr(data-foo type(<number>)) < var(--p) < var(--q))');
   test_cq_condition_known('style(--foo < initial)');
+  test_cq_condition_known('style(10px <= env(safe-area-inset-top) < 20px)');
 
   test_cq_condition_unknown('style(--foo: bar;)');
   test_cq_condition_unknown('style(style(--foo: bar))');
diff --git a/testing/web-platform/tests/css/css-conditional/container-queries/query-evaluation-style.html b/testing/web-platform/tests/css/css-conditional/container-queries/query-evaluation-style.html
@@ -271,4 +271,7 @@
     [['--x', '3'], ['--y', '3'], ['--z', '1']],
     true);
 
+  // test queries with env(), assuming "safe area" insets will never be negative.
+  test_query('style(0px <= env(safe-area-inset-top))', true);
+  test_query('style(0px > env(safe-area-inset-bottom))', false);
 </script>
