fix corner case in if_return (#5596)

alexlamsl · web-flow · commit 8076d66ae583 · 2022-08-03T20:07:55.000+08:00
fixes #5595
diff --git a/lib/compress.js b/lib/compress.js
@@ -3452,15 +3452,16 @@ Compressor.prototype.compress = function(node) {
             var parent = compressor.parent();
             var self = compressor.self();
             var declare_only, jump, merge_jump;
-            var in_iife = in_lambda && parent && parent.TYPE == "Call" && parent.expression === self;
-            var chain_if_returns = in_lambda && compressor.option("conditionals") && compressor.option("sequences");
+            var in_tail = in_lambda && self instanceof AST_Block && self.body === statements;
+            var in_iife = in_tail && parent && parent.TYPE == "Call" && parent.expression === self;
+            var chain_if_returns = in_tail && compressor.option("conditionals") && compressor.option("sequences");
             var multiple_if_returns = has_multiple_if_returns(statements);
             for (var i = statements.length; --i >= 0;) {
                 var stat = statements[i];
                 var j = next_index(i);
                 var next = statements[j];
 
-                if (in_lambda && declare_only && !next && stat instanceof AST_Return
+                if (in_tail && declare_only && !next && stat instanceof AST_Return
                     && !(self instanceof AST_SwitchBranch)
                     && !(in_try && in_try.bfinally && in_async_generator(in_lambda))) {
                     var body = stat.value;
@@ -3563,7 +3564,7 @@ Compressor.prototype.compress = function(node) {
                     // if (foo()) return x; [ return ; ] ---> return foo() ? x : undefined;
                     // 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 (in_lambda && declare_only && !next && !stat.alternative && (in_bool
+                    if (in_tail && declare_only && !next && !stat.alternative && (in_bool
                         || value && multiple_if_returns
                         || value instanceof AST_Conditional && (is_undefined(value.consequent, compressor)
                             || is_undefined(value.alternative, compressor)))) {
@@ -3644,7 +3645,7 @@ Compressor.prototype.compress = function(node) {
             function can_drop_abort(ab) {
                 if (ab instanceof AST_Exit) {
                     if (merge_jump = match_return(ab)) return true;
-                    if (!in_lambda) return false;
+                    if (!in_tail) return false;
                     if (!(ab instanceof AST_Return)) return false;
                     var value = ab.value;
                     if (value && !is_undefined(value.tail_node())) return false;
@@ -3657,7 +3658,7 @@ Compressor.prototype.compress = function(node) {
                 if (!(ab instanceof AST_LoopControl)) return false;
                 if (jump && self instanceof AST_SwitchBranch) {
                     if (jump instanceof AST_Exit) {
-                        if (!in_lambda) return false;
+                        if (!in_tail) return false;
                         if (jump.value) return false;
                     } else if (compressor.loopcontrol_target(jump) !== parent) {
                         return false;
@@ -6162,7 +6163,8 @@ Compressor.prototype.compress = function(node) {
     function opt_arrow(self, compressor) {
         if (!compressor.option("arrows")) return self;
         drop_rest_farg(self, compressor);
-        var body = tighten_body(self.value ? [ self.first_statement() ] : self.body, compressor);
+        if (self.value) self.body = [ self.first_statement() ];
+        var body = tighten_body(self.body, compressor);
         switch (body.length) {
           case 1:
             var stat = body[0];
diff --git a/test/compress/if_return.js b/test/compress/if_return.js
@@ -2253,3 +2253,29 @@ issue_5592_2: {
         "baz",
     ]
 }
+
+issue_5595: {
+    options = {
+        conditionals: true,
+        if_return: true,
+    }
+    input: {
+        function f(a) {
+            if (a) {
+                var b;
+                if (b++)
+                    return "FAIL";
+            } else
+                return "PASS";
+        }
+        console.log(f());
+    }
+    expect: {
+        function f(a) {
+            var b;
+            return a ? b++ ? "FAIL" : void 0 : "PASS";
+        }
+        console.log(f());
+    }
+    expect_stdout: "PASS"
+}
