Fix #931: Create arrow functions in maybe_assign so that they can be used in assignments

lib/parse.js

@@ -1032,7 +1032,12 @@ function parse($TEXT, options) {
     var arrow_function = function(args) {
         expect_token("arrow", "=>");
 
-        var argnames = args.as_params(croak);
+        var argnames;
+        if (typeof args.length === 'number') {
+            argnames = args;
+        } else {
+            argnames = args.as_params(croak);
+        }
 
         var body = is("punc", "{") ?
             _function_body(true) :
@@ -1789,6 +1794,12 @@ function parse($TEXT, options) {
     var maybe_assign = function(no_in) {
         var start = S.token;
 
+        if (start.value == "(" && peek().value == ")") {
+            next();
+            next();
+            return arrow_function([]);
+        }
+
         var left = maybe_conditional(no_in);
         var val = S.token.value;
 
@@ -1805,6 +1816,14 @@ function parse($TEXT, options) {
             }
             croak("Invalid assignment");
         }
+        if (is("arrow")) {
+            left = new AST_SymbolFunarg({
+                name: left.name,
+                start: left.start,
+                end: left.end,
+            });
+            return arrow_function([left])
+        }
         return left;
     };
 

test/compress/harmony.js

@@ -36,6 +36,17 @@ regression_arrow_functions_and_hoist: {
     expect_exact: "a=>b;"
 }
 
+regression_assign_arrow_functions: {
+    input: {
+        oninstall = e => false;
+        oninstall = () => false;
+    }
+    expect: {
+        oninstall=e=>false;
+        oninstall=()=>false;
+    }
+}
+
 computed_property_names: {
     input: {
         obj({ ["x" + "x"]: 6 });