From e7c77b37909aaca3259b4993b5141f3cada96bc2 Mon Sep 17 00:00:00 2001
From: Dylan Piercey <dpiercey@ebay.com>
Date: Fri, 8 Jul 2022 15:19:27 -0700
Subject: [PATCH] feat: allow missing default attribute for let tag

---
 .changeset/metal-boxes-wash.md                |  5 +++++
 .../node.compile.error.expected.txt           |  5 -----
 .../web.compile.error.expected.txt            |  5 -----
 .../node.render.expected.html                 |  3 +++
 .../web.render.expected.html                  |  3 +++
 src/__tests__/fixtures/let/index.test.ts      |  7 ++-----
 .../let/templates/error-no-default-attr.marko |  2 --
 .../let/templates/no-default-attr.marko       |  2 ++
 src/components/let/translate.ts               | 19 ++++++++-----------
 src/util/deep-freeze/transform.ts             |  7 ++++++-
 10 files changed, 29 insertions(+), 29 deletions(-)
 create mode 100644 .changeset/metal-boxes-wash.md
 delete mode 100644 src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/node.compile.error.expected.txt
 delete mode 100644 src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/web.compile.error.expected.txt
 create mode 100644 src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/node.render.expected.html
 create mode 100644 src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/web.render.expected.html
 delete mode 100644 src/__tests__/fixtures/let/templates/error-no-default-attr.marko
 create mode 100644 src/__tests__/fixtures/let/templates/no-default-attr.marko

diff --git a/.changeset/metal-boxes-wash.md b/.changeset/metal-boxes-wash.md
new file mode 100644
index 0000000..a682172
--- /dev/null
+++ b/.changeset/metal-boxes-wash.md
@@ -0,0 +1,5 @@
+---
+"@marko/tags-api-preview": patch
+---
+
+Allow missing default attribute for let tag.
diff --git a/src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/node.compile.error.expected.txt b/src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/node.compile.error.expected.txt
deleted file mode 100644
index 7f5f8dc..0000000
--- a/src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/node.compile.error.expected.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-src/__tests__/fixtures/let/templates/error-no-default-attr.marko(1,2): The <let> tag must be initialized with a value.
-> 1 | <let/count/>
-    |  ^^^
-  2 | <div>${count}</div>
-  3 |
\ No newline at end of file
diff --git a/src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/web.compile.error.expected.txt b/src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/web.compile.error.expected.txt
deleted file mode 100644
index 7f5f8dc..0000000
--- a/src/__tests__/fixtures/let/__snapshots__/let-error-no-default-attr/web.compile.error.expected.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-src/__tests__/fixtures/let/templates/error-no-default-attr.marko(1,2): The <let> tag must be initialized with a value.
-> 1 | <let/count/>
-    |  ^^^
-  2 | <div>${count}</div>
-  3 |
\ No newline at end of file
diff --git a/src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/node.render.expected.html b/src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/node.render.expected.html
new file mode 100644
index 0000000..9da8511
--- /dev/null
+++ b/src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/node.render.expected.html
@@ -0,0 +1,3 @@
+<div>
+  undefined
+</div>
\ No newline at end of file
diff --git a/src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/web.render.expected.html b/src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/web.render.expected.html
new file mode 100644
index 0000000..9da8511
--- /dev/null
+++ b/src/__tests__/fixtures/let/__snapshots__/let-no-default-attr/web.render.expected.html
@@ -0,0 +1,3 @@
+<div>
+  undefined
+</div>
\ No newline at end of file
diff --git a/src/__tests__/fixtures/let/index.test.ts b/src/__tests__/fixtures/let/index.test.ts
index 261c77e..c111fb9 100644
--- a/src/__tests__/fixtures/let/index.test.ts
+++ b/src/__tests__/fixtures/let/index.test.ts
@@ -125,6 +125,8 @@ describe(
   ])
 );
 
+describe("<let> no default attr", fixture("./templates/no-default-attr.marko"));
+
 describe("<let> error args", fixture("./templates/error-args.marko"));
 
 describe(
@@ -147,11 +149,6 @@ describe(
   fixture("./templates/error-extra-attr.marko")
 );
 
-describe(
-  "<let> error no default attr",
-  fixture("./templates/error-no-default-attr.marko")
-);
-
 describe(
   "<let> error no tag var",
   fixture("./templates/error-no-tag-var.marko")
diff --git a/src/__tests__/fixtures/let/templates/error-no-default-attr.marko b/src/__tests__/fixtures/let/templates/error-no-default-attr.marko
deleted file mode 100644
index 3780e76..0000000
--- a/src/__tests__/fixtures/let/templates/error-no-default-attr.marko
+++ /dev/null
@@ -1,2 +0,0 @@
-<let/count/>
-<div>${count}</div>
diff --git a/src/__tests__/fixtures/let/templates/no-default-attr.marko b/src/__tests__/fixtures/let/templates/no-default-attr.marko
new file mode 100644
index 0000000..fefd908
--- /dev/null
+++ b/src/__tests__/fixtures/let/templates/no-default-attr.marko
@@ -0,0 +1,2 @@
+<let/value/>
+<div>${typeof value}</div>
diff --git a/src/components/let/translate.ts b/src/components/let/translate.ts
index d6a3cb3..7ede042 100644
--- a/src/components/let/translate.ts
+++ b/src/components/let/translate.ts
@@ -7,7 +7,7 @@ export = function translate(tag: t.NodePath<t.MarkoTag>) {
   const { file } = tag.hub;
   const server = file.markoOpts.output === "html";
   const tagVar = tag.node.var as t.Identifier;
-  let defaultAttr!: t.NodePath<t.MarkoAttribute>;
+  let defaultAttr: t.NodePath<t.MarkoAttribute> | undefined;
   let changeAttr: t.NodePath<t.MarkoAttribute> | undefined;
   let errorMessage: string | undefined;
 
@@ -33,8 +33,6 @@ export = function translate(tag: t.NodePath<t.MarkoTag>) {
       ? "requires a tag variable"
       : !t.isIdentifier(tagVar)
       ? "tag variable cannot be destructured"
-      : !defaultAttr
-      ? "must be initialized with a value"
       : tag.node.body.body.length
       ? "does not support body content"
       : tag.node.body.params.length
@@ -48,13 +46,16 @@ export = function translate(tag: t.NodePath<t.MarkoTag>) {
   }
 
   file.path.scope.crawl();
+  const defaultValue = defaultAttr
+    ? defaultAttr.node.value
+    : t.unaryExpression("void", t.numericLiteral(0));
   const binding = tag.scope.getBinding(tagVar.name)!;
 
   if (server) {
     file.path.scope.crawl();
     tag.replaceWith(
       t.variableDeclaration("const", [
-        t.variableDeclarator(tagVar, deepFreeze(file, defaultAttr.node.value)),
+        t.variableDeclarator(tagVar, deepFreeze(file, defaultValue)),
       ])
     );
   } else {
@@ -67,7 +68,7 @@ export = function translate(tag: t.NodePath<t.MarkoTag>) {
       t.assignmentExpression(
         "=",
         t.memberExpression(meta.state, keyString, true),
-        deepFreeze(file, defaultAttr.node.value)
+        deepFreeze(file, defaultValue)
       )
     );
 
@@ -82,7 +83,7 @@ export = function translate(tag: t.NodePath<t.MarkoTag>) {
 
       if (t.isFunction(changeAttr.node.value)) {
         setFnId = changeFnId;
-        decls.push(t.variableDeclarator(tagVar, defaultAttr.node.value));
+        decls.push(t.variableDeclarator(tagVar, defaultValue));
       } else {
         setFnId = tag.scope.generateUidIdentifier(`${tagVar.name}Set`);
         decls.push(
@@ -102,11 +103,7 @@ export = function translate(tag: t.NodePath<t.MarkoTag>) {
           ),
           t.variableDeclarator(
             tagVar,
-            t.conditionalExpression(
-              changeFnId,
-              defaultAttr.node.value,
-              getStateExpr
-            )
+            t.conditionalExpression(changeFnId, defaultValue, getStateExpr)
           )
         );
       }
diff --git a/src/util/deep-freeze/transform.ts b/src/util/deep-freeze/transform.ts
index e51b9d0..7f4dbc2 100644
--- a/src/util/deep-freeze/transform.ts
+++ b/src/util/deep-freeze/transform.ts
@@ -2,7 +2,12 @@ import { types as t } from "@marko/compiler";
 import { importDefault } from "@marko/babel-utils";
 
 export default (file: t.BabelFile, value: t.Expression) => {
-  if (file.markoOpts.optimize || t.isLiteral(value)) {
+  if (
+    file.markoOpts.optimize ||
+    t.isLiteral(value) ||
+    t.isBinaryExpression(value) ||
+    t.isUnaryExpression(value)
+  ) {
     return value;
   }