fix corner cases with `import` (#4709)

fixes #4708

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/compress.js b/lib/compress.js
index ba7ab4a0..fb6d16f9 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1127,6 +1127,9 @@ merge(Compressor.prototype, {
         def(AST_SymbolCatch, function() {
             this.definition().fixed = false;
         });
+        def(AST_SymbolImport, function() {
+            this.definition().fixed = false;
+        });
         def(AST_SymbolRef, function(tw, descend, compressor) {
             var d = this.definition();
             push_ref(d, this);
@@ -5836,6 +5839,14 @@ merge(Compressor.prototype, {
                     assignments.add(def.id, node);
                     return true;
                 }
+                if (node instanceof AST_SymbolImport) {
+                    var def = node.definition();
+                    if (!(def.id in in_use_ids) && (!drop_vars || !is_safe_lexical(def))) {
+                        in_use_ids[def.id] = true;
+                        in_use.push(def);
+                    }
+                    return true;
+                }
             } else if (node instanceof AST_This && scope instanceof AST_DefClass) {
                 var def = scope.name.definition();
                 if (!(def.id in in_use_ids)) {