fix corner cases with duplicate name

lib/scope.js

@@ -318,6 +318,9 @@ AST_Scope.DEFMETHOD("def_variable", function(symbol, init){
     var def = this.variables.get(symbol.name);
     if (def) {
         def.orig.push(symbol);
+        if (def.init && (def.scope !== symbol.scope || def.init instanceof AST_Function)) {
+            def.init = init;
+        }
     } else {
         def = new SymbolDef(this, symbol, init);
         this.variables.set(symbol.name, def);

test/compress/reduce_vars.js

@@ -5237,3 +5237,42 @@ defun_catch_6: {
     }
     expect_stdout: "42"
 }
+
+duplicate_lambda_defun_name_1: {
+    options = {
+        reduce_vars: true,
+    }
+    input: {
+        console.log(function f(a) {
+            function f() {}
+            return f.length;
+        }());
+    }
+    expect: {
+        console.log(function f(a) {
+            function f() {}
+            return f.length;
+        }());
+    }
+    expect_stdout: "0"
+}
+
+duplicate_lambda_defun_name_2: {
+    options = {
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {
+            function f() {}
+            return f.length;
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            return function() {}.length;
+        }());
+    }
+    expect_stdout: "0"
+}

test/compress/typeof.js

@@ -138,3 +138,43 @@ typeof_defun_2: {
         "2",
     ]
 }
+
+duplicate_defun_arg_name: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        typeofs: true,
+    }
+    input: {
+        function long_name(long_name) {
+            return typeof long_name;
+        }
+        console.log(typeof long_name, long_name());
+    }
+    expect: {
+        function long_name(long_name) {
+            return typeof long_name;
+        }
+        console.log(typeof long_name, long_name());
+    }
+    expect_stdout: "function undefined"
+}
+
+duplicate_lambda_arg_name: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        typeofs: true,
+    }
+    input: {
+        console.log(function long_name(long_name) {
+            return typeof long_name;
+        }());
+    }
+    expect: {
+        console.log(function long_name(long_name) {
+            return typeof long_name;
+        }());
+    }
+    expect_stdout: "undefined"
+}