JavaScript: capture the right side object of destructuring assignment…

… as anonymous class

The JavaScript parser captures a variable, to which an object is
assigned, with class kind.

Input:

  var x = { prop: "value" };

Tags output (x.js):

  prop	/tmp/x.js	/^var x = { prop: "value" };$/;"	p	class:x
  x	/tmp/x.js	/^var x = { prop: "value" };$/;"	c

In a statement of destructuring assignment, there is no variable to
which an object is assigned though an object exists at the right side.
The JavaScript parser cannot provide the scope name when capturing
a property in the object. That causes "null tag" warning.

Input (y.js):

  var {prop} = { prop: "value" };

Tags output of the original JavaScript parser:

  ctags: Warning: ignoring null tag in /tmp/y.js(line: 1)
  prop	/tmp/y.js	/^var {prop} = { prop: "value" };$/;"	p

This change introduces an anonymous class to capture the right side
object with class kind.

Tags output of the JavaScript parser with this change:

  AnonymousClass322d0fb80101	/tmp/y.js	/^var {prop} = { prop: "value" };$/;"	c
  prop	/tmp/y.js	/^var {prop} = { prop: "value" };$/;"	p	class:AnonymousClass322d0fb80101

About destructuring binding, see
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

Units/parser-javascript.r/js-empty-class-name.d/args.ctags

@@ -0,0 +1 @@
+--sort=no

Units/parser-javascript.r/js-empty-class-name.d/expected.tags

@@ -0,0 +1,2 @@
+prop	input.js	/^var {prop} = { prop: "value" };$/;"	p	class:AnonymousClass4ca5b60a0101
+AnonymousClass4ca5b60a0101	input.js	/^var {prop} = { prop: "value" };$/;"	c

Units/parser-javascript.r/js-empty-class-name.d/input.js

@@ -0,0 +1 @@
+var {prop} = { prop: "value" };

parsers/jscript.c

@@ -2225,9 +2225,12 @@ static bool parseStatement (tokenInfo *const token, bool is_inside_class)
 			 * Or checks if this is a hash variable.
 			 *     var z = {};
 			 */
+			bool anonClass = vStringIsEmpty (name->string);
+			if (anonClass)
+				anonGenerate (name->string, "AnonymousClass", JSTAG_CLASS);
 			has_methods = parseMethods(token, name, false);
 			if (has_methods)
-				makeJsTag (name, JSTAG_CLASS, NULL, NULL);
+				makeJsTagCommon (name, JSTAG_CLASS, NULL, NULL, anonClass);
 			else
 			{
 				/*