fix corner cases in `join_vars` (#3790)

fixes #3789
fixes #3791

1 files changed, 19 insertions, 7 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 2491757f..70ac9b8f 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -2330,7 +2330,7 @@ merge(Compressor.prototype, {
             statements.length = n;
         }
 
-        function join_assigns(defn, body) {
+        function join_assigns(defn, body, keep) {
             var exprs;
             if (body instanceof AST_Assign) {
                 exprs = [ body ];
@@ -2352,14 +2352,14 @@ merge(Compressor.prototype, {
             if (defn instanceof AST_Definitions) {
                 var def = defn.definitions[defn.definitions.length - 1];
                 if (trim_assigns(def.name, def.value, exprs)) trimmed = true;
-                if (join_var_assign(defn.definitions, exprs)) trimmed = true;
+                if (join_var_assign(defn.definitions, exprs, keep || 0)) trimmed = true;
             }
             return trimmed && exprs;
         }
 
-        function join_var_assign(definitions, exprs) {
+        function join_var_assign(definitions, exprs, keep) {
             var trimmed = false;
-            while (exprs.length) {
+            while (exprs.length > keep) {
                 var expr = exprs[0];
                 if (!(expr instanceof AST_Assign)) break;
                 if (expr.operator != "=") break;
@@ -2367,7 +2367,9 @@ merge(Compressor.prototype, {
                 if (!(lhs instanceof AST_SymbolRef)) break;
                 if (is_undeclared_ref(lhs)) break;
                 var def = lhs.definition();
-                if (def.scope !== definitions[0].name.scope) break;
+                if (def.scope !== lhs.scope) break;
+                if (def.orig.length > def.eliminated + 1) break;
+                if (def.orig[0].TYPE != "SymbolVar") break;
                 var name = make_node(AST_SymbolVar, lhs, lhs);
                 definitions.push(make_node(AST_VarDef, expr, {
                     name: name,
@@ -2478,7 +2480,7 @@ merge(Compressor.prototype, {
 
             function join_assigns_expr(value) {
                 statements[++j] = stat;
-                var exprs = join_assigns(prev, value);
+                var exprs = join_assigns(prev, value, 1);
                 if (!exprs) return value;
                 CHANGED = true;
                 var tail = value.tail_node();
@@ -6045,11 +6047,21 @@ merge(Compressor.prototype, {
 
         function can_inject_symbols() {
             var catches = Object.create(null);
+            var child;
+            scope = compressor.self();
             do {
+                child = scope;
                 scope = compressor.parent(++level);
                 if (scope instanceof AST_Catch) {
                     catches[scope.argname.name] = true;
-                } else if (scope instanceof AST_IterationStatement) {
+                } else if (scope instanceof AST_DWLoop) {
+                    in_loop = [];
+                } else if (scope instanceof AST_For) {
+                    if (scope.init === child) continue;
+                    in_loop = [];
+                } else if (scope instanceof AST_ForIn) {
+                    if (scope.init === child) continue;
+                    if (scope.object === child) continue;
                     in_loop = [];
                 } else if (scope instanceof AST_SymbolRef) {
                     if (scope.fixed_value() instanceof AST_Scope) return false;