From 1d407e761e72601fa607f884e0f53ced8ae4b94d Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Fri, 12 May 2017 04:51:44 +0800
Subject: fix invalid transform on `const` (#1919)

- preserve (re)assignment to `const` for runtime error
- suppress `cascade` on `const`, as runtime behaviour is ill-defined
---
 test/compress/collapse_vars.js | 46 ++++++++++++++++++++++++++++++++++++++++++
 test/compress/drop-unused.js   | 25 +++++++++++++++++++++++
 test/compress/sequences.js     | 24 ++++++++++++++++++++++
 3 files changed, 95 insertions(+)

(limited to 'test')

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 4215cebe..0d578d7d 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -2186,3 +2186,49 @@ compound_assignment: {
     }
     expect_stdout: "4"
 }
+
+reassign_const_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function f() {
+            const a = 1;
+            a = 2;
+            return a;
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            const a = 1;
+            a = 2;
+            return a;
+        }
+        console.log(f());
+    }
+    expect_stdout: true
+}
+
+reassign_const_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function f() {
+            const a = 1;
+            ++a;
+            return a;
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            const a = 1;
+            ++a;
+            return a;
+        }
+        console.log(f());
+    }
+    expect_stdout: true
+}
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index ddf90bfa..96bd336c 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -1147,3 +1147,28 @@ var_catch_toplevel: {
         }();
     }
 }
+
+reassign_const: {
+    options = {
+        cascade: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            const a = 1;
+            a = 2;
+            return a;
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            const a = 1;
+            return a = 2, a;
+        }
+        console.log(f());
+    }
+    expect_stdout: true
+}
diff --git a/test/compress/sequences.js b/test/compress/sequences.js
index 10492565..9edf627e 100644
--- a/test/compress/sequences.js
+++ b/test/compress/sequences.js
@@ -710,3 +710,27 @@ issue_27: {
         })(jQuery);
     }
 }
+
+reassign_const: {
+    options = {
+        cascade: true,
+        sequences: true,
+        side_effects: true,
+    }
+    input: {
+        function f() {
+            const a = 1;
+            a++;
+            return a;
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            const a = 1;
+            return a++, a;
+        }
+        console.log(f());
+    }
+    expect_stdout: true
+}
-- 
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