From 995f5a29aa9c147d129ea3b55d4ab1b4be38ae51 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nicol=C3=B2=20Ribaudo?= <nribaudo@igalia.com>
Date: Mon, 5 Aug 2024 14:35:54 +0200
Subject: [PATCH] Update the Babel plugin to remove empty static blocks

This commit updates the Babel plugin to:
- apply the same flattening logic that we already
  have for blocks, to flatten blocks nested inside
  class static blocks
- remove class static blocks when, after flattening
  all the blocks they contain, they are empty.

Before this commit, the transform output was the
same as the input.
---
 .../babel-plugin-pdfjs-preprocessor.mjs       |  6 +++++-
 .../fixtures_babel/staticblock-expected.js    |  8 ++++++++
 .../builder/fixtures_babel/staticblock.js     | 20 +++++++++++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 external/builder/fixtures_babel/staticblock-expected.js
 create mode 100644 external/builder/fixtures_babel/staticblock.js

diff --git a/external/builder/babel-plugin-pdfjs-preprocessor.mjs b/external/builder/babel-plugin-pdfjs-preprocessor.mjs
index 8c5254e7374c8..8f8be7a724e75 100644
--- a/external/builder/babel-plugin-pdfjs-preprocessor.mjs
+++ b/external/builder/babel-plugin-pdfjs-preprocessor.mjs
@@ -184,7 +184,7 @@ function babelPluginPDFJSPreprocessor(babel, ctx) {
           path.replaceWith(t.importExpression(source));
         }
       },
-      BlockStatement: {
+      "BlockStatement|StaticBlock": {
         // Visit node in post-order so that recursive flattening
         // of blocks works correctly.
         exit(path) {
@@ -215,6 +215,10 @@ function babelPluginPDFJSPreprocessor(babel, ctx) {
             }
             subExpressionIndex++;
           }
+
+          if (node.type === "StaticBlock" && node.body.length === 0) {
+            path.remove();
+          }
         },
       },
       Function: {
diff --git a/external/builder/fixtures_babel/staticblock-expected.js b/external/builder/fixtures_babel/staticblock-expected.js
new file mode 100644
index 0000000000000..7edf5a8d902ba
--- /dev/null
+++ b/external/builder/fixtures_babel/staticblock-expected.js
@@ -0,0 +1,8 @@
+class A {
+  static {
+    foo();
+  }
+  static {
+    var a = 0;
+  }
+}
diff --git a/external/builder/fixtures_babel/staticblock.js b/external/builder/fixtures_babel/staticblock.js
new file mode 100644
index 0000000000000..161a5d7058886
--- /dev/null
+++ b/external/builder/fixtures_babel/staticblock.js
@@ -0,0 +1,20 @@
+class A {
+  static {}
+  static {
+    { foo() }
+  }
+  static {
+    {;}
+  }
+  static {
+    if (PDFJSDev.test('TRUE')) {
+      var a = 0;
+    }
+  }
+
+  static {
+    if (PDFJSDev.test('FALSE')) {
+      var a = 1;
+    }
+  }
+}