fix(solidjs#66): signals as refs

playground/src/App.tsx

@@ -2,6 +2,7 @@ import { createSignal, onCleanup, onMount } from 'solid-js';
 
 export function App() {
   const [count, setCount] = createSignal(0);
+  const [, setEl] = createSignal<HTMLElement>();
 
   function increment() {
     setCount(c => c + 1);
@@ -19,7 +20,7 @@ export function App() {
 
   return (
     <>
-      <h1>Count: {count()}</h1>
+      <h1 ref={setEl}>Count: {count()}</h1>
       <button type="button" onClick={increment}>
         Increment
       </button>

src/babel/core/transform-jsx.ts

@@ -77,6 +77,10 @@ function extractJSXExpressionFromRef(
       let replacement: t.Expression;
       if (unwrappedIdentifier) {
         const arg = expr.scope.generateUidIdentifier('arg');
+        const binding = expr.scope.getBinding(unwrappedIdentifier.name);
+        const cannotAssignKind = ['const', 'module'];
+        const isConst = binding && cannotAssignKind.includes(binding.kind);
+
         replacement = t.arrowFunctionExpression(
           [arg],
           t.blockStatement([
@@ -91,11 +95,17 @@ function extractJSXExpressionFromRef(
                   t.callExpression(unwrappedIdentifier, [arg]),
                 ),
               ]),
-              t.blockStatement([
-                t.expressionStatement(
-                  t.assignmentExpression('=', unwrappedIdentifier, arg),
-                ),
-              ]),
+              // fix the new usage of `ref` attribute,
+              // if use `Signals as refs`, the `else` branch will throw an errow with `Cannot assign to "setter" because it is a constant` message
+              // issue: https://github.com/solidjs/solid-refresh/issues/66
+              // docs: https://docs.solidjs.com/concepts/refs#signals-as-refs
+              isConst
+                ? null
+                : t.blockStatement([
+                    t.expressionStatement(
+                      t.assignmentExpression('=', unwrappedIdentifier, arg),
+                    ),
+                  ]),
             ),
           ]),
         );

tests/client/__snapshots__/esm.test.ts.snap

@@ -1130,6 +1130,116 @@ if (import.meta.hot) {
 }"
 `;
 
+exports[`esm (client, non-hydratable) > fix build > refs > should work with a function 1`] = `
+"import { template as _$template } from "solid-js/web";
+import { createComponent as _$createComponent } from "solid-js/web";
+import { use as _$use } from "solid-js/web";
+var _tmpl$ = /*#__PURE__*/_$template(\`<div>Comp\`);
+import { $$component as _$$component } from "solid-refresh";
+import { $$refresh as _$$refresh } from "solid-refresh";
+import { $$registry as _$$registry } from "solid-refresh";
+const _REGISTRY = _$$registry();
+const Comp_1 = _$$component(_REGISTRY, "Comp_1", _props => /*@refresh jsx-skip*/(() => {
+  var _el$ = _tmpl$();
+  var _ref$ = _props.v0;
+  typeof _ref$ === "function" ? _$use(_ref$, _el$) : _props.v0 = _el$;
+  return _el$;
+})(), {
+  location: "example.jsx:4:19",
+  signature: "6f76290"
+});
+const Comp = _$$component(_REGISTRY, "Comp", () => {
+  let el;
+  return /*@refresh jsx-skip*/_$createComponent(Comp_1, {
+    v0: _el => el = _el
+  });
+}, {
+  location: "example.jsx:2:23",
+  signature: "726057ca"
+});
+if (import.meta.hot) {
+  _$$refresh("esm", import.meta.hot, _REGISTRY);
+}"
+`;
+
+exports[`esm (client, non-hydratable) > fix build > refs > should work with a mutable variable 1`] = `
+"import { template as _$template } from "solid-js/web";
+import { createComponent as _$createComponent } from "solid-js/web";
+import { use as _$use } from "solid-js/web";
+var _tmpl$ = /*#__PURE__*/_$template(\`<div>Comp\`);
+import { $$component as _$$component } from "solid-refresh";
+import { $$refresh as _$$refresh } from "solid-refresh";
+import { $$registry as _$$registry } from "solid-refresh";
+const _REGISTRY = _$$registry();
+const Comp_1 = _$$component(_REGISTRY, "Comp_1", _props => /*@refresh jsx-skip*/(() => {
+  var _el$ = _tmpl$();
+  var _ref$ = _props.v0;
+  typeof _ref$ === "function" ? _$use(_ref$, _el$) : _props.v0 = _el$;
+  return _el$;
+})(), {
+  location: "example.jsx:4:19",
+  signature: "6f76290"
+});
+const Comp = _$$component(_REGISTRY, "Comp", () => {
+  let el;
+  return /*@refresh jsx-skip*/_$createComponent(Comp_1, {
+    v0: _arg => {
+      if (typeof el === "function") {
+        el(_arg);
+      } else {
+        el = _arg;
+      }
+    }
+  });
+}, {
+  location: "example.jsx:2:23",
+  signature: "d3db0f89"
+});
+if (import.meta.hot) {
+  _$$refresh("esm", import.meta.hot, _REGISTRY);
+}"
+`;
+
+exports[`esm (client, non-hydratable) > fix build > signals as refs > should work 1`] = `
+"import { template as _$template } from "solid-js/web";
+import { createComponent as _$createComponent } from "solid-js/web";
+import { use as _$use } from "solid-js/web";
+var _tmpl$ = /*#__PURE__*/_$template(\`<div>Comp\`);
+import { $$component as _$$component } from "solid-refresh";
+import { $$refresh as _$$refresh } from "solid-refresh";
+import { $$registry as _$$registry } from "solid-refresh";
+import { createSignal } from 'solid-js';
+const _REGISTRY = _$$registry();
+const Comp_1 = _$$component(_REGISTRY, "Comp_1", _props => /*@refresh jsx-skip*/(() => {
+  var _el$ = _tmpl$();
+  var _ref$ = _props.v0;
+  typeof _ref$ === "function" ? _$use(_ref$, _el$) : _props.v0 = _el$;
+  return _el$;
+})(), {
+  location: "example.jsx:6:19",
+  signature: "6f76290"
+});
+const Comp = _$$component(_REGISTRY, "Comp", () => {
+  const [el, setEl] = createSignal();
+  return /*@refresh jsx-skip*/_$createComponent(Comp_1, {
+    v0: _arg => {
+      if (typeof setEl === "function") {
+        setEl(_arg);
+      }
+    }
+  });
+}, {
+  location: "example.jsx:4:23",
+  signature: "57db44c6",
+  dependencies: () => ({
+    createSignal
+  })
+});
+if (import.meta.hot) {
+  _$$refresh("esm", import.meta.hot, _REGISTRY);
+}"
+`;
+
 exports[`esm (client, non-hydratable) > fix render > @refresh reload > should work 1`] = `
 "import { createComponent as _$createComponent } from "solid-js/web";
 import { $$decline as _$$decline } from "solid-refresh";

tests/client/esm.test.ts

@@ -810,4 +810,57 @@ describe('esm (client, non-hydratable)', () => {
       });
     });
   });
+  describe('fix build', () => {
+    describe('refs', () => {
+      it('should work with a mutable variable', async () => {
+        expect(
+          await transform(
+            `
+          const Comp = () => {
+            let el;
+            return <div ref={el}>Comp</div>;
+          }
+        `,
+            'esm',
+            'client',
+            false,
+          ),
+        ).toMatchSnapshot();
+      });
+      it('should work with a function', async () => {
+        expect(
+          await transform(
+            `
+          const Comp = () => {
+            let el;
+            return <div ref={(_el) => el = _el}>Comp</div>;
+          }
+        `,
+            'esm',
+            'client',
+            false,
+          ),
+        ).toMatchSnapshot();
+      });
+    });
+    describe('signals as refs', () => {
+      it('should work', async () => {
+        expect(
+          await transform(
+            `
+          import { createSignal } from 'solid-js';
+          
+          const Comp = () => {
+            const [el, setEl] = createSignal();
+            return <div ref={setEl}>Comp</div>;
+          }
+        `,
+            'esm',
+            'client',
+            false,
+          ),
+        ).toMatchSnapshot();
+      });
+    });
+  });
 });