feat: ignore selectors tested in @supports rules

Author: rviscomi

src/rules/require-baseline.js

@@ -124,6 +124,12 @@ class SupportsRule {
 	 */
 	#properties = new Map();
 
+	/**
+	 * The selectors supported by this rule.
+	 * @type {Set<string>}
+	 */
+	#selectors = new Set();
+
 	/**
 	 * Adds a property to the rule.
 	 * @param {string} property The name of the property.
@@ -219,6 +225,24 @@ class SupportsRule {
 
 		return supportedProperty.hasFunctions();
 	}
+
+	/**
+	 * Adds a selector to the rule.
+	 * @param {string} selector The name of the selector.
+	 * @returns {void}
+	 */
+	addSelector(selector) {
+		this.#selectors.add(selector);
+	}
+
+	/**
+	 * Determines if the rule supports a selector.
+	 * @param {string} selector The name of the selector.
+	 * @returns {boolean} `true` if the selector is supported, `false` if not.
+	 */
+	hasSelector(selector) {
+		return this.#selectors.has(selector);
+	}
 }
 
 /**
@@ -304,6 +328,15 @@ class SupportsRules {
 	hasPropertyFunctions(property) {
 		return this.#rules.some(rule => rule.hasFunctions(property));
 	}
+
+	/**
+	 * Determines if any rule supports a selector.
+	 * @param {string} selector The name of the selector.
+	 * @returns {boolean} `true` if any rule supports the selector, `false` if not.
+	 */
+	hasSelector(selector) {
+		return this.#rules.some(rule => rule.hasSelector(selector));
+	}
 }
 
 //-----------------------------------------------------------------------------
@@ -462,6 +495,16 @@ export default {
 
 						continue;
 					}
+
+					if (
+						conditionChild.type === "FeatureFunction" &&
+						conditionChild.feature === "selector"
+					) {
+						for (const selectorChild of conditionChild.value
+							.children) {
+							supportsRule.addSelector(selectorChild.name);
+						}
+					}
 				}
 			},
 
@@ -637,6 +680,11 @@ export default {
 						continue;
 					}
 
+					// if the selector has been tested in a @supports rule, don't check it
+					if (supportsRules.hasSelector(selector)) {
+						continue;
+					}
+
 					const selectorLevel = selectors.get(selector);
 
 					if (selectorLevel < baselineLevel) {

tests/rules/require-baseline.test.js

@@ -57,6 +57,9 @@ ruleTester.run("require-baseline", rule, {
 		`@supports (width: abs(20% - 100px)) {
 			a { width: abs(20% - 100px); }
 		}`,
+		`@supports selector(:has()) {
+				h1:has(+ h2) { color: red; }
+		}`,
 		"div { cursor: pointer; }",
 		{
 			code: `@property --foo {
@@ -356,6 +359,28 @@ ruleTester.run("require-baseline", rule, {
 				},
 			],
 		},
+		{
+			code: `@supports selector(:has()) {}
+
+			@supports (color: red) {
+				h1:has(+ h2) {
+					color: red;
+				}
+			}`,
+			errors: [
+				{
+					messageId: "notBaselineSelector",
+					data: {
+						selector: "has",
+						availability: "widely",
+					},
+					line: 4,
+					column: 7,
+					endLine: 4,
+					endColumn: 11,
+				},
+			],
+		},
 		{
 			code: "details::details-content { background-color: #a29bfe; }",
 			errors: [