fix corner cases in `join_vars` (#3790)

fixes #3789
fixes #3791

2 files changed, 120 insertions, 1 deletions

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index a9167262..fd421a20 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -804,7 +804,7 @@ collapse_vars_assignment: {
         function log(x) { return console.log(x), x; }
         function f0(c) {
             var a = 3 / c;
-            return a;
+            return a = a;
         }
         function f1(c) {
             return 1 - 3 / c;
diff --git a/test/compress/join_vars.js b/test/compress/join_vars.js
index bfbebdef..9901c486 100644
--- a/test/compress/join_vars.js
+++ b/test/compress/join_vars.js
@@ -663,3 +663,122 @@ issue_3788: {
         "PASS",
     ]
 }
+
+issue_3789_1: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        try {
+            c;
+            console.log("FAIL");
+        } catch (e) {
+            console.log("PASS");
+        }
+        try {} catch (c) {
+            var a;
+            c = 0;
+        }
+    }
+    expect: {
+        try {
+            c;
+            console.log("FAIL");
+        } catch (e) {
+            console.log("PASS");
+        }
+        try {} catch (c) {
+            var a;
+            c = 0;
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_3789_2: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        try {
+            c;
+            console.log("FAIL");
+        } catch (e) {
+            console.log("PASS");
+        }
+        try {} catch (c) {
+            try {} catch (c) {
+                var a;
+                c = 0;
+            }
+        }
+    }
+    expect: {
+        try {
+            c;
+            console.log("FAIL");
+        } catch (e) {
+            console.log("PASS");
+        }
+        try {} catch (c) {
+            try {} catch (c) {
+                var a;
+                c = 0;
+            }
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_3791_1: {
+    options = {
+        collapse_vars: true,
+        join_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "PASS";
+        switch (a) {
+          case console:
+        }
+        var a = a;
+        console.log(a);
+    }
+    expect: {
+        var a;
+        switch (a = "PASS") {
+          case console:
+        }
+        var a = a;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_3791_2: {
+    options = {
+        collapse_vars: true,
+        join_vars: true,
+    }
+    input: {
+        function f(a) {
+            var b;
+            return b = a || g;
+            function g() {
+                return b;
+            }
+        }
+        console.log(typeof f()());
+    }
+    expect: {
+        function f(a) {
+            var b;
+            return b = a || g;
+            function g() {
+                return b;
+            }
+        }
+        console.log(typeof f()());
+    }
+    expect_stdout: "function"
+}