From c2e471e3ad37a5c02f91179781c85d0e5177dfff Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Mon, 29 May 2017 18:08:08 +0800
Subject: [PATCH] fix `if_return` on block-scoped variables (#2021)

fixes #1317
---
 lib/compress.js            |  4 ++-
 test/compress/if_return.js | 58 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/lib/compress.js b/lib/compress.js
index 2582550bf79..de6a476a38d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1068,7 +1068,9 @@ merge(Compressor.prototype, {
             }
 
             function can_merge_flow(ab) {
-                if (!ab) return false;
+                if (!ab || !all(ret, function(stat) {
+                    return !(stat instanceof AST_Const || stat instanceof AST_Let);
+                })) return false;
                 var lct = ab instanceof AST_LoopControl ? compressor.loopcontrol_target(ab) : null;
                 return ab instanceof AST_Return && in_lambda && is_return_void(ab.value)
                     || ab instanceof AST_Continue && self === loop_body(lct)
diff --git a/test/compress/if_return.js b/test/compress/if_return.js
index 72b69e709f9..bc958e68721 100644
--- a/test/compress/if_return.js
+++ b/test/compress/if_return.js
@@ -326,3 +326,61 @@ issue_512: {
         }
     }
 }
+
+issue_1317: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        !function(a) {
+            if (a) return;
+            let b = 1;
+            function g() {
+                return b;
+            }
+            console.log(g());
+        }();
+    }
+    expect: {
+        !function(a) {
+            if (a) return;
+            let b = 1;
+            function g() {
+                return b;
+            }
+            console.log(g());
+        }();
+    }
+    expect_stdout: "1"
+    node_version: ">=6"
+}
+
+issue_1317_strict: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        "use strict";
+        !function(a) {
+            if (a) return;
+            let b = 1;
+            function g() {
+                return b;
+            }
+            console.log(g());
+        }();
+    }
+    expect: {
+        "use strict";
+        !function(a) {
+            if (a) return;
+            let b = 1;
+            function g() {
+                return b;
+            }
+            console.log(g());
+        }();
+    }
+    expect_stdout: "1"
+    node_version: ">=4"
+}