tweak message, simplify logic

Author: Rich-Harris

packages/svelte/messages/client-warnings/warnings.md

@@ -22,4 +22,4 @@
 
 ## state_proxy_equality_mismatch
 
-> Detected an equality check between a $state proxy and a non-$state-proxy object for %method%. This equality check will always fail because the proxy has a different object identity. To ensure both operands are of the same kind for accurate results, consider using `$state.is(a, b)`.
+> Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results. Consider using `$state.is(a, b)` instead

packages/svelte/src/compiler/phases/3-transform/client/visitors/javascript-runes.js

@@ -456,38 +456,21 @@ export const javascript_visitors_runes = {
 		const operator = node.operator;
 
 		if (state.options.dev) {
-			if (operator === '===') {
+			if (operator === '===' || operator === '!==') {
 				return b.call(
 					'$.strict_equals',
 					/** @type {import('estree').Expression} */ (visit(node.left)),
-					/** @type {import('estree').Expression} */ (visit(node.right))
+					/** @type {import('estree').Expression} */ (visit(node.right)),
+					operator === '!==' && b.literal(false)
 				);
 			}
-			if (operator === '!==') {
-				return b.unary(
-					'!',
-					b.call(
-						'$.strict_equals',
-						/** @type {import('estree').Expression} */ (visit(node.left)),
-						/** @type {import('estree').Expression} */ (visit(node.right))
-					)
-				);
-			}
-			if (operator === '==') {
+
+			if (operator === '==' || operator === '!=') {
 				return b.call(
 					'$.equals',
 					/** @type {import('estree').Expression} */ (visit(node.left)),
-					/** @type {import('estree').Expression} */ (visit(node.right))
-				);
-			}
-			if (operator === '!=') {
-				return b.unary(
-					'!',
-					b.call(
-						'$.equals',
-						/** @type {import('estree').Expression} */ (visit(node.left)),
-						/** @type {import('estree').Expression} */ (visit(node.right))
-					)
+					/** @type {import('estree').Expression} */ (visit(node.right)),
+					operator === '!=' && b.literal(false)
 				);
 			}
 		}

packages/svelte/src/internal/client/dev/equality.js

@@ -12,7 +12,7 @@ export function init_array_prototype_warnings() {
 			const test = indexOf.call(get_proxied_value(this), get_proxied_value(item), from_index);
 
 			if (test !== -1) {
-				w.state_proxy_equality_mismatch('Array.indexOf');
+				w.state_proxy_equality_mismatch('array.indexOf(...)');
 
 				// eslint-disable-next-line no-console
 				console.trace();
@@ -29,7 +29,7 @@ export function init_array_prototype_warnings() {
 			const test = lastIndexOf.call(get_proxied_value(this), get_proxied_value(item), from_index);
 
 			if (test !== -1) {
-				w.state_proxy_equality_mismatch('Array.lastIndexOf');
+				w.state_proxy_equality_mismatch('array.lastIndexOf(...)');
 
 				// eslint-disable-next-line no-console
 				console.trace();
@@ -46,7 +46,7 @@ export function init_array_prototype_warnings() {
 			const test = includes.call(get_proxied_value(this), get_proxied_value(item), from_index);
 
 			if (test) {
-				w.state_proxy_equality_mismatch('Array.includes');
+				w.state_proxy_equality_mismatch('array.includes(...)');
 
 				// eslint-disable-next-line no-console
 				console.trace();
@@ -60,31 +60,33 @@ export function init_array_prototype_warnings() {
 /**
  * @param {any} a
  * @param {any} b
+ * @param {boolean} equal
  * @returns {boolean}
  */
-export function strict_equals(a, b) {
-	if (a !== b && get_proxied_value(a) === get_proxied_value(b)) {
-		w.state_proxy_equality_mismatch('=== operator');
+export function strict_equals(a, b, equal = true) {
+	if ((a === b) !== (get_proxied_value(a) === get_proxied_value(b))) {
+		w.state_proxy_equality_mismatch(equal ? '===' : '!==');
 
 		// eslint-disable-next-line no-console
 		console.trace();
 	}
 
-	return a === b;
+	return (a === b) === equal;
 }
 
 /**
  * @param {any} a
  * @param {any} b
+ * @param {boolean} equal
  * @returns {boolean}
  */
-export function equals(a, b) {
-	if (a != b && get_proxied_value(a) == get_proxied_value(b)) {
-		w.state_proxy_equality_mismatch('== operator');
+export function equals(a, b, equal = true) {
+	if ((a == b) !== (get_proxied_value(a) == get_proxied_value(b))) {
+		w.state_proxy_equality_mismatch(equal ? '==' : '!=');
 
 		// eslint-disable-next-line no-console
 		console.trace();
 	}
 
-	return a == b;
+	return (a == b) === equal;
 }

packages/svelte/src/internal/client/warnings.js

@@ -74,12 +74,12 @@ export function ownership_invalid_mutation(component, owner) {
 }
 
 /**
- * Detected an equality check between a $state proxy and a non-$state-proxy object for %method%. This equality check will always fail because the proxy has a different object identity. To ensure both operands are of the same kind for accurate results, consider using `$state.is(a, b)`.
- * @param {string} method
+ * Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results. Consider using `$state.is(a, b)` instead
+ * @param {string} operator
  */
-export function state_proxy_equality_mismatch(method) {
+export function state_proxy_equality_mismatch(operator) {
 	if (DEV) {
-		console.warn(`%c[svelte] ${"state_proxy_equality_mismatch"}\n%c${`Detected an equality check between a $state proxy and a non-$state-proxy object for ${method}. This equality check will always fail because the proxy has a different object identity. To ensure both operands are of the same kind for accurate results, consider using \`$state.is(a, b)\`.`}`, bold, normal);
+		console.warn(`%c[svelte] ${"state_proxy_equality_mismatch"}\n%c${`Reactive \`$state(...)\` proxies and the values they proxy have different identities. Because of this, comparisons with \`${operator}\` will produce unexpected results. Consider using \`$state.is(a, b)\` instead`}`, bold, normal);
 	} else {
 		// TODO print a link to the documentation
 		console.warn("state_proxy_equality_mismatch");