Correct identification of in/instanceof identifiers (#20019)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

changelog_unreleased/javascript/20019.md

@@ -0,0 +1,22 @@
+#### Avoid unnecessary semicolons before private members named `#in` or `#instanceof` (#20019 by @cellison-figma)
+
+<!-- prettier-ignore -->
+```js
+// Input
+class Graph {
+  #nodes = {};
+  #in = {};
+}
+
+// Prettier stable (--parser oxc --no-semi)
+class Graph {
+  #nodes = {};
+  #in = {}
+}
+
+// Prettier main (--parser oxc --no-semi)
+class Graph {
+  #nodes = {}
+  #in = {}
+}
+```

src/language-js/print/class-body.js

@@ -256,8 +256,8 @@ function shouldPrintSemicolonAfterClassProperty(
     return false;
   }
 
-  if (!nextNode.computed) {
-    const name = nextNode.key?.name;
+  if (!nextNode.computed && nextNode.key?.type === "Identifier") {
+    const { name } = nextNode.key;
     if (name === "in" || name === "instanceof") {
       return true;
     }

tests/format/js/no-semi/__snapshots__/format.test.js.snap

@@ -2104,12 +2104,26 @@ class C {
   ["method"]() {}
 }
 
+class PrivateKeywordFields {
+  a = {};
+  #in = {};
+  b = {};
+  #instanceof = {};
+}
+
 =====================================output=====================================
 class C {
   #field = "value";
   ["method"]() {}
 }
 
+class PrivateKeywordFields {
+  a = {}
+  #in = {}
+  b = {}
+  #instanceof = {}
+}
+
 ================================================================================
 `;
 
@@ -2123,12 +2137,26 @@ class C {
   ["method"]() {}
 }
 
+class PrivateKeywordFields {
+  a = {};
+  #in = {};
+  b = {};
+  #instanceof = {};
+}
+
 =====================================output=====================================
 class C {
   #field = "value";
   ["method"]() {}
 }
 
+class PrivateKeywordFields {
+  a = {};
+  #in = {};
+  b = {};
+  #instanceof = {};
+}
+
 ================================================================================
 `;
 

tests/format/js/no-semi/private-field.js

@@ -2,3 +2,10 @@ class C {
   #field = 'value';
   ["method"]() {}
 }
+
+class PrivateKeywordFields {
+  a = {};
+  #in = {};
+  b = {};
+  #instanceof = {};
+}