fix corner case in inline (#5306)

fixes #5305

lib/compress.js

@@ -1869,22 +1869,26 @@ Compressor.prototype.compress = function(node) {
                 if (handle_if_return(statements, compressor)) changed = 3;
                 if (!changed && last_changed == 3) break;
             }
-            if (compressor.option("inline") >= 4) {
+            if (compressor.option("awaits") && compressor.option("side_effects")) {
-                if (inline_iife(statements, compressor)) changed = 4;
+                if (trim_awaits(statements, compressor)) changed = 4;
                 if (!changed && last_changed == 4) break;
             }
-            if (compressor.sequences_limit > 0) {
+            if (compressor.option("inline") >= 4) {
-                if (sequencesize(statements, compressor)) changed = 5;
+                if (inline_iife(statements, compressor)) changed = 5;
                 if (!changed && last_changed == 5) break;
-                if (sequencesize_2(statements, compressor)) changed = 6;
-                if (!changed && last_changed == 6) break;
             }
-            if (compressor.option("join_vars")) {
+            if (compressor.sequences_limit > 0) {
-                if (join_consecutive_vars(statements)) changed = 7;
+                if (sequencesize(statements, compressor)) changed = 6;
+                if (!changed && last_changed == 6) break;
+                if (sequencesize_2(statements, compressor)) changed = 7;
                 if (!changed && last_changed == 7) break;
             }
+            if (compressor.option("join_vars")) {
+                if (join_consecutive_vars(statements)) changed = 8;
+                if (!changed && last_changed == 8) break;
+            }
             if (compressor.option("collapse_vars")) {
-                if (collapse(statements, compressor)) changed = 8;
+                if (collapse(statements, compressor)) changed = 9;
             }
         } while (changed && max_iter-- > 0);
         return statements;
@@ -3524,6 +3528,27 @@ Compressor.prototype.compress = function(node) {
             return statements.length != len;
         }
 
+        function trim_awaits(statements, compressor) {
+            if (!in_lambda || in_try && in_try.bfinally) return;
+            var changed = false;
+            for (var index = statements.length; --index >= 0;) {
+                var stat = statements[index];
+                if (!(stat instanceof AST_SimpleStatement)) break;
+                var node = stat.body;
+                if (!(node instanceof AST_Await)) break;
+                var exp = node.expression;
+                if (!is_primitive(compressor, exp)) break;
+                changed = true;
+                exp = exp.drop_side_effect_free(compressor, true);
+                if (exp) {
+                    stat.body = exp;
+                    break;
+                }
+            }
+            statements.length = index + 1;
+            return changed;
+        }
+
         function inline_iife(statements, compressor) {
             var changed = false;
             var index = statements.length - 1;
@@ -12987,6 +13012,14 @@ Compressor.prototype.compress = function(node) {
             var self = this;
             var inlined = sync(self.expression).try_inline(compressor, scope, no_return, in_loop);
             if (!inlined) return;
+            if (!no_return) scan_local_returns(inlined, function(node) {
+                node.in_bool = false;
+                var value = node.value;
+                if (value instanceof AST_Await) return;
+                node.value = make_node(AST_Await, self, {
+                    expression: value || make_node(AST_Undefined, node).transform(compressor),
+                });
+            });
             return aborts(inlined) ? inlined : make_node(AST_BlockStatement, self, {
                 body: [ inlined, make_node(AST_SimpleStatement, self, {
                     body: make_node(AST_Await, self, { expression: make_node(AST_Number, self, { value: 0 })}),

test/compress/awaits.js

@@ -496,6 +496,7 @@ inline_block_await: {
         awaits: true,
         if_return: true,
         inline: true,
+        side_effects: true,
     }
     input: {
         console.log("foo");
@@ -567,6 +568,7 @@ inline_block_await_async_return: {
         awaits: true,
         if_return: true,
         inline: true,
+        side_effects: true,
     }
     input: {
         console.log("foo");
@@ -2855,3 +2857,105 @@ issue_5298: {
     expect_stdout: "PASS"
     node_version: ">=8"
 }
+
+issue_5305_1: {
+    options = {
+        inline: true,
+    }
+    input: {
+        var a = "PASS";
+        (async function() {
+            try {
+                return await function() {
+                    while (!console);
+                }();
+            } finally {
+                a = "FAIL";
+            }
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (async function() {
+            try {
+                while (!console);
+                return await void 0;
+            } finally {
+                a = "FAIL";
+            }
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5305_2: {
+    options = {
+        inline: true,
+    }
+    input: {
+        var a = "PASS";
+        (async function() {
+            try {
+                throw null;
+            } catch (e) {
+                return await function() {
+                    while (!console);
+                }();
+            } finally {
+                a = "FAIL";
+            }
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (async function() {
+            try {
+                throw null;
+            } catch (e) {
+                while (!console);
+                return await void 0;
+            } finally {
+                a = "FAIL";
+            }
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5305_3: {
+    options = {
+        awaits: true,
+        inline: true,
+        side_effects: true,
+    }
+    input: {
+        var a = "PASS";
+        (async function() {
+            try {
+                await function() {
+                    while (!console);
+                }();
+            } catch (e) {
+                a = "FAIL";
+            }
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        try {
+            while (!console);
+        } catch (e) {
+            a = "FAIL";
+        }
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}