From 9b8054ae11cdcbfb94974c55b492b553b0e8bc1d Mon Sep 17 00:00:00 2001
From: Dylan Conway <35280289+dylan-conway@users.noreply.github.com>
Date: Fri, 16 Jun 2023 21:11:57 -0700
Subject: don't remove const if referenced before declaration (#3337)

---
 src/js_parser.zig                    |  6 +++---
 test/bundler/esbuild/default.test.ts | 42 ++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/src/js_parser.zig b/src/js_parser.zig
index a64e32114..5a9bca91a 100644
--- a/src/js_parser.zig
+++ b/src/js_parser.zig
@@ -5798,8 +5798,7 @@ fn NewParser_(
 
             if (p.options.features.inlining) {
                 if (p.const_values.get(ref)) |replacement| {
-                    // TODO:
-                    // p.ignoreUsage(ref);
+                    p.ignoreUsage(ref);
                     return replacement;
                 }
             }
@@ -20427,7 +20426,8 @@ fn NewParser_(
                                     var end: usize = 0;
                                     for (decls) |decl| {
                                         if (decl.binding.data == .b_identifier) {
-                                            if (p.const_values.contains(decl.binding.data.b_identifier.ref)) {
+                                            const symbol = p.symbols.items[decl.binding.data.b_identifier.ref.innerIndex()];
+                                            if (p.const_values.contains(decl.binding.data.b_identifier.ref) and symbol.use_count_estimate == 0) {
                                                 continue;
                                             }
                                         }
diff --git a/test/bundler/esbuild/default.test.ts b/test/bundler/esbuild/default.test.ts
index 215276139..0d1775606 100644
--- a/test/bundler/esbuild/default.test.ts
+++ b/test/bundler/esbuild/default.test.ts
@@ -6520,4 +6520,46 @@ describe("bundler", () => {
       `,
     },
   });
+  itBundled("default/ConstDeclNotRemovedIfReferencedBeforeDecl", {
+    files: {
+      "/entry.js": `
+        {
+          const foo = () => {
+            return data;
+          }
+          const data = 123;
+
+          console.log(foo());
+        }
+      `,
+    },
+    minifySyntax: true,
+    run: {
+      stdout: "123",
+    },
+    onAfterBundle(api) {
+      api.expectFile("/out.js").toContain("data = 123");
+    },
+  });
+  itBundled("default/ConstDeclRemovedIfReferencedBeforeAllUses", {
+    files: {
+      "/entry.js": `
+        {
+          const data = 123;
+          const foo = () => {
+            return data;
+          }
+
+          console.log(foo());
+        }
+      `,
+    },
+    minifySyntax: true,
+    run: {
+      stdout: "123",
+    },
+    onAfterBundle(api) {
+      api.expectFile("/out.js").not.toContain("data = 123");
+    },
+  });
 });
-- 
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