From d3df2f985d478a96332c728f7065285e812e7158 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Tue, 25 Jul 2017 22:07:21 +0800
Subject: [PATCH] extend `collapse_vars` to `let` and `const` (#2252)

fixes #2250
---
 lib/ast.js                     |  2 +-
 lib/compress.js                |  1 +
 lib/scope.js                   |  2 +-
 test/compress/collapse_vars.js | 68 ++++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/lib/ast.js b/lib/ast.js
index d2be08a8..ab4b2897 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -697,7 +697,7 @@ var AST_Export = DEFNODE("Export", "exported_definition exported_value is_defaul
 var AST_VarDef = DEFNODE("VarDef", "name value", {
     $documentation: "A variable declaration; only appears in a AST_Definitions node",
     $propdoc: {
-        name: "[AST_SymbolVar|AST_SymbolConst|AST_Destructuring] name of the variable",
+        name: "[AST_Destructuring|AST_SymbolConst|AST_SymbolLet|AST_SymbolVar] name of the variable",
         value: "[AST_Node?] initializer, or null of there's no initializer"
     },
     _walk: function(visitor) {
diff --git a/lib/compress.js b/lib/compress.js
index 78e48c96..a6aef068 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -302,6 +302,7 @@ merge(Compressor.prototype, {
             if (reduce_vars) {
                 if (node instanceof AST_Toplevel) node.globals.each(reset_def);
                 if (node instanceof AST_Scope) node.variables.each(reset_def);
+                if (node.block_scope) node.block_scope.variables.each(reset_def);
                 if (node instanceof AST_SymbolRef) {
                     var d = node.definition();
                     d.references.push(node);
diff --git a/lib/scope.js b/lib/scope.js
index 1beeaa64..e7e6283e 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -116,7 +116,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
     var tw = new TreeWalker(function(node, descend){
         if (node.is_block_scope()) {
             var save_scope = scope;
-            scope = new AST_Scope(node);
+            node.block_scope = scope = new AST_Scope(node);
             scope.init_scope_vars(save_scope);
             if (!(node instanceof AST_Scope)) {
                 scope.uses_with = save_scope.uses_with;
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 5b64c6a3..3316042e 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -2548,3 +2548,71 @@ duplicate_argname: {
     }
     expect_stdout: "PASS"
 }
+
+issue_2250_1: {
+    options = {
+        collapse_vars: true,
+        conditionals: true,
+        reduce_vars: true,
+    }
+    input: {
+        function f(x) {
+            if (x) {
+                const a = foo();
+                x(a);
+            }
+        }
+        function g(x) {
+            if (x) {
+                let a = foo();
+                x(a);
+            }
+        }
+        function h(x) {
+            if (x) {
+                var a = foo();
+                x(a);
+            }
+        }
+    }
+    expect: {
+        function f(x) {
+            x && x(foo());
+        }
+        function g(x) {
+            x && x(foo());
+        }
+        function h(x) {
+            x && x(foo());
+        }
+    }
+}
+
+issue_2250_2: {
+    options = {
+        collapse_vars: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        {
+            const foo = function(){};
+            foo(bar());
+        }
+        {
+            let foo = function(){};
+            foo(bar());
+        }
+        {
+            var foo = function(){};
+            foo(bar());
+        }
+    }
+    expect: {
+        bar();
+        bar();
+        bar();
+    }
+}