JavaScript: generate tags for empty properties with setting allowNullTag

In javascript it is legal to have e.g. {"": false}.  With the
original code the parser attempts to generate the tag for the empty
string which produces warning.

With setting allowNullTag member of tagEntryInfo, the parser can
generate such tags without producing warnings.

Actual tag emission is controlled by --extras=+{nulltag}.

This commit is based on the commit in universal-ctags#4153.

Co-Author: Masatake YAMATO <[email protected]>

Units/parser-javascript.r/js-extract-empty-property.d/args.ctags

@@ -0,0 +1,3 @@
+--sort=no
+--extras=+{nulltag}
+--fields=+{extras}

Units/parser-javascript.r/js-extract-empty-property.d/expected.tags

@@ -0,0 +1,2 @@
+	input.js	/^var variable = { "": "value" };$/;"	p	variable:variable	extras:nulltag
+variable	input.js	/^var variable = { "": "value" };$/;"	v

Units/parser-javascript.r/js-extract-empty-property.d/input.js

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

Units/parser-javascript.r/js-skip-empty-property.d/args.ctags

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

Units/parser-javascript.r/js-skip-empty-property.d/expected.tags

@@ -0,0 +1 @@
+variable	input.js	/^var variable = { "": "value" };$/;"	v

Units/parser-javascript.r/js-skip-empty-property.d/input.js

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

parsers/jscript.c

@@ -480,7 +480,7 @@ static int makeJsRefTagsForNameChain (char *name_chain, const tokenInfo *token,
 
 static int makeJsTagCommon (const tokenInfo *const token, const jsKind kind,
 							vString *const signature, vString *const inheritance,
-							bool anonymous)
+							bool anonymous, bool nulltag)
 {
 	int index = CORK_NIL;
 	const char *name = vStringValue (token->string);
@@ -550,6 +550,9 @@ static int makeJsTagCommon (const tokenInfo *const token, const jsKind kind,
 	if (anonymous)
 		markTagExtraBit (&e, XTAG_ANONYMOUS);
 
+	if (nulltag)
+		e.allowNullTag = 1;
+
 	index = makeTagEntry (&e);
 	/* We shold remove This condition. We should fix the callers passing
 	 * an empty name instead. makeTagEntry() returns CORK_NIL if the tag
@@ -563,13 +566,19 @@ static int makeJsTagCommon (const tokenInfo *const token, const jsKind kind,
 static int makeJsTag (const tokenInfo *const token, const jsKind kind,
 					   vString *const signature, vString *const inheritance)
 {
-	return makeJsTagCommon (token, kind, signature, inheritance, false);
+	return makeJsTagCommon (token, kind, signature, inheritance, false, false);
+}
+
+static int makeJsNullTag (const tokenInfo *const token, const jsKind kind,
+						  vString *const signature, vString *const inheritance)
+{
+	return makeJsTagCommon (token, kind, signature, inheritance, false, true);
 }
 
 static int makeClassTagCommon (tokenInfo *const token, vString *const signature,
 						  vString *const inheritance, bool anonymous)
 {
-	return makeJsTagCommon (token, JSTAG_CLASS, signature, inheritance, anonymous);
+	return makeJsTagCommon (token, JSTAG_CLASS, signature, inheritance, anonymous, false);
 }
 
 static int makeClassTag (tokenInfo *const token, vString *const signature,
@@ -582,7 +591,7 @@ static int makeFunctionTagCommon (tokenInfo *const token, vString *const signatu
 								  bool generator, bool anonymous)
 {
 	return makeJsTagCommon (token, generator ? JSTAG_GENERATOR : JSTAG_FUNCTION, signature, NULL,
-							anonymous);
+							anonymous, false);
 }
 
 static int makeFunctionTag (tokenInfo *const token, vString *const signature, bool generator)
@@ -1430,7 +1439,7 @@ static int parseMethodsInAnonymousObject (tokenInfo *const token)
 	anonGenerate (anon_object->string, "anonymousObject", JSTAG_VARIABLE);
 	anon_object->type = TOKEN_IDENTIFIER;
 
-	index = makeJsTagCommon (anon_object, JSTAG_VARIABLE, NULL, NULL, true);
+	index = makeJsTagCommon (anon_object, JSTAG_VARIABLE, NULL, NULL, true, false);
 	if (! parseMethods (token, index, false))
 	{
 		/* If no method is found, the anonymous object
@@ -2257,7 +2266,12 @@ static bool parseMethods (tokenInfo *const token, int class_index,
 					deleteToken (saved_token);
 
 					has_methods = true;
-					index_for_name = makeJsTag (name, JSTAG_PROPERTY, NULL, NULL);
+					/* property names can be empty strings such as { "": true },
+					 * use a special function for generating tags for those */
+					if (name->string->length == 0)
+						index_for_name =  makeJsNullTag (name, JSTAG_PROPERTY, NULL, NULL);
+					else
+						index_for_name = makeJsTag (name, JSTAG_PROPERTY, NULL, NULL);
 					if (p != CORK_NIL)
 						moveChildren (p, index_for_name);
 				}
@@ -2341,7 +2355,7 @@ static bool parseES6Class (tokenInfo *const token, const tokenInfo *target_name)
 	TRACE_PRINT("Emitting tag for class '%s'", vStringValue(target_name->string));
 
 	int r = makeJsTagCommon (target_name, JSTAG_CLASS, NULL, inheritance,
-							 (is_anonymous && (target_name == class_name)));
+							 (is_anonymous && (target_name == class_name)), false);
 
 	if (! is_anonymous && target_name != class_name)
 	{
@@ -2675,7 +2689,7 @@ static bool parseStatementRHS (tokenInfo *const name, tokenInfo *const token, st
 		if ( parseMethods(token, p, false) )
 		{
 			jsKind kind = state->foundThis || strchr (vStringValue(name->string), '.') != NULL ? JSTAG_PROPERTY : JSTAG_VARIABLE;
-			state->indexForName = makeJsTagCommon (name, kind, NULL, NULL, anon_object);
+			state->indexForName = makeJsTagCommon (name, kind, NULL, NULL, anon_object, false);
 			moveChildren (p, state->indexForName);
 		}
 		else if ( token->nestLevel == 0 && state->isGlobal )
@@ -2722,7 +2736,7 @@ static bool parseStatementRHS (tokenInfo *const name, tokenInfo *const token, st
 		 */
 		if ( ( token->nestLevel == 0 && state->isGlobal ) || kind == JSTAG_PROPERTY )
 		{
-			state->indexForName = makeJsTagCommon (name, kind, NULL, NULL, false);
+			state->indexForName = makeJsTagCommon (name, kind, NULL, NULL, false, false);
 		}
 	}
 	else if (isKeyword (token, KEYWORD_new))