enhance if_return (#5588)

fixes #5587

Author: alexlamsl

lib/compress.js

@@ -3567,7 +3567,7 @@ Compressor.prototype.compress = function(node) {
                             continue;
                         }
                         // if (foo()) return bar() ? x : void 0; ---> return foo() && bar() ? x : void 0;
-                        // if (foo()) return bar() ? void 0 : x; ---> return foo() || bar() ? void 0 : x;
+                        // if (foo()) return bar() ? void 0 : x; ---> return !foo() || bar() ? void 0 : x;
                         var or;
                         if (value instanceof AST_Conditional
                             && ((or = is_undefined(value.consequent, compressor))
@@ -3577,7 +3577,7 @@ Compressor.prototype.compress = function(node) {
                             ret.value = value.clone();
                             ret.value.condition = make_node(AST_Binary, stat, {
                                 operator: or ? "||" : "&&",
-                                left: stat.condition,
+                                left: or ? stat.condition.negate(compressor) : stat.condition,
                                 right: value.condition,
                             });
                             statements.splice(i, 1, ret.transform(compressor));

test/compress/if_return.js

@@ -254,7 +254,7 @@ if_return_cond_void_2: {
     }
     expect: {
         function f(a) {
-            return a || console.log("foo") ? void 0 : console.log("bar");
+            return !a || console.log("foo") ? void 0 : console.log("bar");
         }
         f();
         f(42);
@@ -1827,3 +1827,47 @@ issue_5586: {
         "baz",
     ]
 }
+
+issue_5587_1: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        function f(a) {
+            if (console)
+                return a ? void 0 : console.log("PASS");
+        }
+        f();
+        f(42);
+    }
+    expect: {
+        function f(a) {
+            return !console || a ? void 0 : console.log("PASS");
+        }
+        f();
+        f(42);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5587_2: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        function f(a) {
+            if (console)
+                return a ? console.log("PASS") : void 0;
+        }
+        f();
+        f(42);
+    }
+    expect: {
+        function f(a) {
+            return console && a ? console.log("PASS") : void 0;
+        }
+        f();
+        f(42);
+    }
+    expect_stdout: "PASS"
+}