fix corner cases in dead_code & if_return (#5525)

fixes #5521
fixes #5522
fixes #5523
fixes #5524

Author: alexlamsl

lib/compress.js

@@ -1953,7 +1953,7 @@ Compressor.prototype.compress = function(node) {
         function last_of(compressor, predicate) {
             var block = compressor.self(), level = 0;
             do {
-                if (block instanceof AST_Catch || block instanceof AST_Finally) {
+                if (block instanceof AST_Catch) {
                     block = compressor.parent(level++);
                 } else if (block instanceof AST_LabeledStatement) {
                     block = block.body;
@@ -1968,7 +1968,6 @@ Compressor.prototype.compress = function(node) {
             } while (stat
                 && (block instanceof AST_BlockStatement
                     || block instanceof AST_Catch
-                    || block instanceof AST_Finally
                     || block instanceof AST_Scope
                     || block instanceof AST_Try)
                 && is_last_statement(block.body, stat));
@@ -3690,7 +3689,7 @@ Compressor.prototype.compress = function(node) {
         function eliminate_dead_code(statements, compressor) {
             var has_quit;
             var self = compressor.self();
-            if (self instanceof AST_Catch || self instanceof AST_Finally) {
+            if (self instanceof AST_Catch) {
                 self = compressor.parent();
             } else if (self instanceof AST_LabeledStatement) {
                 self = self.body;

test/compress/if_return.js

@@ -963,3 +963,57 @@ issue_4374: {
     }
     expect_stdout: "0"
 }
+
+issue_5521: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        console.log(function() {
+            if (console)
+                try {
+                    return "FAIL";
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            if (console)
+                try {
+                    return "FAIL";
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_5523: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        console.log(function() {
+            if (console)
+                try {
+                    FAIL;
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            if (console)
+                try {
+                    FAIL;
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect_stdout: "undefined"
+}

test/compress/labels.js

@@ -230,7 +230,6 @@ labels_12: {
         conditionals: true,
         dead_code: true,
         if_return: true,
-        unused: true,
     }
     input: {
         L: try {
@@ -246,13 +245,14 @@ labels_12: {
         }
     }
     expect: {
-        try {
+        L: try {
             if (!console.log("foo"))
                 throw "bar";
         } catch (e) {
             console.log(e);
         } finally {
-            console.log("baz")
+            if (console.log("baz"))
+                break L;
         }
     }
     expect_stdout: [
@@ -381,3 +381,53 @@ issue_4466_2_toplevel_v8: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5522: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(function() {
+            L: try {
+                return "FAIL";
+            } finally {
+                break L;
+            }
+            return "PASS";
+        }());
+    }
+    expect: {
+        console.log(function() {
+            L: try {
+                return "FAIL";
+            } finally {
+                break L;
+            }
+            return "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5524: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        L: try {
+            FAIL;
+        } finally {
+            break L;
+        }
+        console.log("PASS");
+    }
+    expect: {
+        L: try {
+            FAIL;
+        } finally {
+            break L;
+        }
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}