handle function/variable name collisions correctly (#3451)

fixes #3439

lib/compress.js

@@ -1293,6 +1293,7 @@ merge(Compressor.prototype, {
                     return lhs instanceof AST_PropAccess && lhs.equivalent_to(node.expression);
                 }
                 if (node instanceof AST_Debugger) return true;
+                if (node instanceof AST_Defun) return funarg && lhs.name === node.name.name;
                 if (node instanceof AST_IterationStatement) return !(node instanceof AST_For);
                 if (node instanceof AST_LoopControl) return true;
                 if (node instanceof AST_Try) return true;
@@ -5226,25 +5227,26 @@ merge(Compressor.prototype, {
             return return_value(stat);
         }
 
-        function var_exists(catches, name) {
-            return catches[name] || identifier_atom[name] || scope.var_names()[name];
+        function var_exists(defined, name) {
+            return defined[name] || identifier_atom[name] || scope.var_names()[name];
         }
 
-        function can_inject_args(catches, safe_to_inject) {
+        function can_inject_args(catches, used, safe_to_inject) {
             for (var i = 0; i < fn.argnames.length; i++) {
                 var arg = fn.argnames[i];
                 if (arg.__unused) continue;
                 if (!safe_to_inject || var_exists(catches, arg.name)) return false;
+                used[arg.name] = true;
                 if (in_loop) in_loop.push(arg.definition());
             }
             return true;
         }
 
-        function can_inject_vars(catches, safe_to_inject) {
+        function can_inject_vars(catches, used, safe_to_inject) {
             for (var i = 0; i < fn.body.length; i++) {
                 var stat = fn.body[i];
                 if (stat instanceof AST_Defun) {
-                    if (!safe_to_inject || var_exists(catches, stat.name.name)) return false;
+                    if (!safe_to_inject || var_exists(used, stat.name.name)) return false;
                     continue;
                 }
                 if (!(stat instanceof AST_Var)) continue;
@@ -5273,8 +5275,9 @@ merge(Compressor.prototype, {
             var safe_to_inject = (!(scope instanceof AST_Toplevel) || compressor.toplevel.vars)
                 && (exp !== fn || fn.parent_scope === compressor.find_parent(AST_Scope));
             var inline = compressor.option("inline");
-            if (!can_inject_vars(catches, inline >= 3 && safe_to_inject)) return false;
-            if (!can_inject_args(catches, inline >= 2 && safe_to_inject)) return false;
+            var used = Object.create(catches);
+            if (!can_inject_args(catches, used, inline >= 2 && safe_to_inject)) return false;
+            if (!can_inject_vars(catches, used, inline >= 3 && safe_to_inject)) return false;
             return !in_loop || in_loop.length == 0 || !is_reachable(fn, in_loop);
         }
 

test/compress/collapse_vars.js

@@ -6197,3 +6197,43 @@ Infinity_assignment: {
     }
     expect_stdout: true
 }
+
+issue_3439_1: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function(a) {
+            function a() {}
+            return a;
+        }(42));
+    }
+    expect: {
+        console.log(typeof function(a) {
+            function a() {}
+            return a;
+        }(42));
+    }
+    expect_stdout: "function"
+}
+
+issue_3439_2: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function() {
+            var a = 42;
+            function a() {}
+            return a;
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            return 42;
+        }());
+    }
+    expect_stdout: "number"
+}

test/compress/functions.js

@@ -3149,6 +3149,27 @@ issue_3402: {
     ]
 }
 
+issue_3439: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log(typeof function() {
+            return function(a) {
+                function a() {}
+                return a;
+            }(42);
+        }());
+    }
+    expect: {
+        console.log(typeof function(a) {
+            function a() {}
+            return a;
+        }(42));
+    }
+    expect_stdout: "function"
+}
+
 issue_3444: {
     options = {
         inline: true,