fix corner case in `unused` (#3234)

fixes #3233

3 files changed, 36 insertions, 14 deletions

diff --git a/lib/compress.js b/lib/compress.js
index eded00c7..ad86dd84 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -450,8 +450,7 @@ merge(Compressor.prototype, {
                 return value instanceof AST_Node && def.fixed.parent_scope === scope;
             }
             return all(def.orig, function(sym) {
-                return !(sym instanceof AST_SymbolDefun
-                    || sym instanceof AST_SymbolLambda);
+                return !(sym instanceof AST_SymbolDefun || sym instanceof AST_SymbolLambda);
             });
         }
 
@@ -3329,13 +3328,14 @@ merge(Compressor.prototype, {
             } else if (node instanceof AST_Unary && node.write_only) {
                 sym = node.expression;
             }
-            if (/strict/.test(compressor.option("pure_getters"))) {
-                while (sym instanceof AST_PropAccess && !sym.expression.may_throw_on_access(compressor)) {
-                    if (sym instanceof AST_Sub) props.unshift(sym.property);
-                    sym = sym.expression;
-                }
+            if (!/strict/.test(compressor.option("pure_getters"))) return sym instanceof AST_SymbolRef && sym;
+            while (sym instanceof AST_PropAccess && !sym.expression.may_throw_on_access(compressor)) {
+                if (sym instanceof AST_Sub) props.unshift(sym.property);
+                sym = sym.expression;
             }
-            return sym;
+            return sym instanceof AST_SymbolRef && all(sym.definition().orig, function(sym) {
+                return !(sym instanceof AST_SymbolLambda);
+            }) && sym;
         };
         var in_use = [];
         var in_use_ids = Object.create(null); // avoid expensive linear scans of in_use
@@ -3430,7 +3430,7 @@ merge(Compressor.prototype, {
             var parent = tt.parent();
             if (drop_vars) {
                 var props = [], sym = assign_as_unused(node, props);
-                if (sym instanceof AST_SymbolRef) {
+                if (sym) {
                     var def = sym.definition();
                     var in_use = def.id in in_use_ids;
                     var value = null;
@@ -3629,8 +3629,7 @@ merge(Compressor.prototype, {
 
         function scan_ref_scoped(node, descend) {
             var node_def, props = [], sym = assign_as_unused(node, props);
-            if (sym instanceof AST_SymbolRef
-                && self.variables.get(sym.name) === (node_def = sym.definition())) {
+            if (sym && self.variables.get(sym.name) === (node_def = sym.definition())) {
                 props.forEach(function(prop) {
                     prop.walk(tw);
                 });
diff --git a/test/compress/drop-unused.js b/test/compress/drop-unused.js
index 9dc45e57..b75c3ac5 100644
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -1982,3 +1982,26 @@ issue_3192: {
         "foo bar",
     ]
 }
+
+issue_3233: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = function b() {
+            b.c = "PASS";
+        };
+        a();
+        console.log(a.c);
+    }
+    expect: {
+        var a = function b() {
+            b.c = "PASS";
+        };
+        a();
+        console.log(a.c);
+    }
+    expect_stdout: "PASS"
+}
diff --git a/test/mocha/cli.js b/test/mocha/cli.js
index 56f6b184..1e27f64e 100644
--- a/test/mocha/cli.js
+++ b/test/mocha/cli.js
@@ -651,7 +651,7 @@ describe("bin/uglifyjs", function() {
         });
     });
     it("Should work with explicit --no-rename", function(done) {
-        var command = uglifyjscmd + " test/input/rename/input.js -mc --no-rename";
+        var command = uglifyjscmd + " test/input/rename/input.js -mc passes=2 --no-rename";
         exec(command, function(err, stdout, stderr) {
             if (err) throw err;
             assert.strictEqual(stdout, "function f(n){return function(n){return n}(n)}\n");
@@ -659,7 +659,7 @@ describe("bin/uglifyjs", function() {
         });
     });
     it("Should work with implicit --rename", function(done) {
-        var command = uglifyjscmd + " test/input/rename/input.js -mc";
+        var command = uglifyjscmd + " test/input/rename/input.js -mc passes=2";
         exec(command, function(err, stdout, stderr) {
             if (err) throw err;
             assert.strictEqual(stdout, "function f(n){return n}\n");
@@ -667,7 +667,7 @@ describe("bin/uglifyjs", function() {
         });
     });
     it("Should work with implicit --no-rename", function(done) {
-        var command = uglifyjscmd + " test/input/rename/input.js -c";
+        var command = uglifyjscmd + " test/input/rename/input.js -c passes=2";
         exec(command, function(err, stdout, stderr) {
             if (err) throw err;
             assert.strictEqual(stdout, "function f(x){return function(x){return x}(x)}\n");