fix corner cases in `collapse_vars` (#4249)

fixes #4248

3 files changed, 90 insertions, 0 deletions

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index dea01b60..edf4795a 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -8577,3 +8577,28 @@ issue_4242: {
     }
     expect_stdout: "undefined"
 }
+
+issue_4248: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 0;
+        try {
+            a = 1;
+            b[1];
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = 0;
+        try {
+            a = 1;
+            b[1];
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "1"
+}
diff --git a/test/compress/const.js b/test/compress/const.js
index 2f88975e..896e8c38 100644
--- a/test/compress/const.js
+++ b/test/compress/const.js
@@ -1104,3 +1104,34 @@ issue_4245: {
     }
     expect_stdout: true
 }
+
+issue_4248: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        try {
+            (function() {
+                a = "PASS";
+                b[a];
+                const b = 0;
+            })();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "FAIL";
+        try {
+            (function() {
+                a = "PASS";
+                b[a];
+                const b = 0;
+            })();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+}
diff --git a/test/compress/let.js b/test/compress/let.js
index deb48120..9a6fc944 100644
--- a/test/compress/let.js
+++ b/test/compress/let.js
@@ -916,3 +916,37 @@ issue_4245: {
     expect_stdout: ReferenceError("a is not defined")
     node_version: ">=4"
 }
+
+issue_4248: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        try {
+            (function() {
+                "use strict";
+                a = "PASS";
+                b[a];
+                let b;
+            })();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "FAIL";
+        try {
+            (function() {
+                "use strict";
+                a = "PASS";
+                b[a];
+                let b;
+            })();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}