Add support for Unicode identifiers in GDScript

This is using an adapted version of UAX#31 to not rely on the ICU
database (which isn't available in builds without TextServerAdvanced).
It allows most characters used in diverse scripts but not everything.

doc/classes/ProjectSettings.xml

@@ -384,6 +384,9 @@
 		<member name="debug/gdscript/warnings/assert_always_true" type="int" setter="" getter="" default="1">
 			When set to [code]warn[/code] or [code]error[/code], produces a warning or an error respectively when an [code]assert[/code] call always evaluates to true.
 		</member>
+		<member name="debug/gdscript/warnings/confusable_identifier" type="int" setter="" getter="" default="1">
+			When set to [code]warn[/code] or [code]error[/code], produces a warning or an error respectively when an indentifier contains characters that can be confused with something else, like when mixing different alphabets.
+		</member>
 		<member name="debug/gdscript/warnings/constant_used_as_function" type="int" setter="" getter="" default="1">
 			When set to [code]warn[/code] or [code]error[/code], produces a warning or an error respectively when a constant is used as a function.
 		</member>

modules/gdscript/gdscript_parser.cpp

@@ -41,6 +41,7 @@
 #include "core/os/os.h"
 #include "core/string/string_builder.h"
 #include "gdscript_warning.h"
+#include "servers/text_server.h"
 #endif // DEBUG_ENABLED
 
 #ifdef TOOLS_ENABLED
@@ -186,24 +187,6 @@ void GDScriptParser::push_error(const String &p_message, const Node *p_origin) {
 }
 
 #ifdef DEBUG_ENABLED
-void GDScriptParser::push_warning(const Node *p_source, GDScriptWarning::Code p_code, const String &p_symbol1, const String &p_symbol2, const String &p_symbol3, const String &p_symbol4) {
-	ERR_FAIL_COND(p_source == nullptr);
-	Vector<String> symbols;
-	if (!p_symbol1.is_empty()) {
-		symbols.push_back(p_symbol1);
-	}
-	if (!p_symbol2.is_empty()) {
-		symbols.push_back(p_symbol2);
-	}
-	if (!p_symbol3.is_empty()) {
-		symbols.push_back(p_symbol3);
-	}
-	if (!p_symbol4.is_empty()) {
-		symbols.push_back(p_symbol4);
-	}
-	push_warning(p_source, p_code, symbols);
-}
-
 void GDScriptParser::push_warning(const Node *p_source, GDScriptWarning::Code p_code, const Vector<String> &p_symbols) {
 	ERR_FAIL_COND(p_source == nullptr);
 	if (is_ignoring_warnings) {
@@ -2251,7 +2234,14 @@ GDScriptParser::ExpressionNode *GDScriptParser::parse_expression(bool p_can_assi
 }
 
 GDScriptParser::IdentifierNode *GDScriptParser::parse_identifier() {
-	return static_cast<IdentifierNode *>(parse_identifier(nullptr, false));
+	IdentifierNode *identifier = static_cast<IdentifierNode *>(parse_identifier(nullptr, false));
+#ifdef DEBUG_ENABLED
+	// Check for spoofing here (if available in TextServer) since this isn't called inside expressions. This is only relevant for declarations.
+	if (identifier && TS->has_feature(TextServer::FEATURE_UNICODE_SECURITY) && TS->spoof_check(identifier->name.operator String())) {
+		push_warning(identifier, GDScriptWarning::CONFUSABLE_IDENTIFIER, identifier->name.operator String());
+	}
+#endif
+	return identifier;
 }
 
 GDScriptParser::ExpressionNode *GDScriptParser::parse_identifier(ExpressionNode *p_previous_operand, bool p_can_assign) {

modules/gdscript/gdscript_parser.h

@@ -1361,8 +1361,11 @@ private:
 	void clear();
 	void push_error(const String &p_message, const Node *p_origin = nullptr);
 #ifdef DEBUG_ENABLED
-	void push_warning(const Node *p_source, GDScriptWarning::Code p_code, const String &p_symbol1 = String(), const String &p_symbol2 = String(), const String &p_symbol3 = String(), const String &p_symbol4 = String());
 	void push_warning(const Node *p_source, GDScriptWarning::Code p_code, const Vector<String> &p_symbols);
+	template <typename... Symbols>
+	void push_warning(const Node *p_source, GDScriptWarning::Code p_code, const Symbols &...p_symbols) {
+		push_warning(p_source, p_code, Vector<String>{ p_symbols... });
+	}
 #endif
 
 	void make_completion_context(CompletionType p_type, Node *p_node, int p_argument = -1, bool p_force = false);

modules/gdscript/gdscript_tokenizer.cpp

@@ -31,10 +31,14 @@
 #include "gdscript_tokenizer.h"
 
 #include "core/error/error_macros.h"
+#include "core/string/char_utils.h"
 
 #ifdef TOOLS_ENABLED
 #include "editor/editor_settings.h"
 #endif
+#ifdef DEBUG_ENABLED
+#include "servers/text_server.h"
+#endif
 
 static const char *token_names[] = {
 	"Empty", // EMPTY,
@@ -435,10 +439,12 @@ GDScriptTokenizer::Token GDScriptTokenizer::check_vcs_marker(char32_t p_test, To
 }
 
 GDScriptTokenizer::Token GDScriptTokenizer::annotation() {
-	if (!is_ascii_identifier_char(_peek())) {
+	if (is_unicode_identifier_start(_peek())) {
+		_advance(); // Consume start character.
+	} else {
 		push_error("Expected annotation identifier after \"@\".");
 	}
-	while (is_ascii_identifier_char(_peek())) {
+	while (is_unicode_identifier_continue(_peek())) {
 		// Consume all identifier characters.
 		_advance();
 	}
@@ -447,7 +453,6 @@ GDScriptTokenizer::Token GDScriptTokenizer::annotation() {
 	return annotation;
 }
 
-GDScriptTokenizer::Token GDScriptTokenizer::potential_identifier() {
 #define KEYWORDS(KEYWORD_GROUP, KEYWORD)     \
 	KEYWORD_GROUP('a')                       \
 	KEYWORD("as", Token::AS)                 \
@@ -512,8 +517,21 @@ GDScriptTokenizer::Token GDScriptTokenizer::potential_identifier() {
 #define MIN_KEYWORD_LENGTH 2
 #define MAX_KEYWORD_LENGTH 10
 
-	// Consume all alphanumeric characters.
-	while (is_ascii_identifier_char(_peek())) {
+#ifdef DEBUG_ENABLED
+void GDScriptTokenizer::make_keyword_list() {
+#define KEYWORD_LINE(keyword, token_type) keyword,
+#define KEYWORD_GROUP_IGNORE(group)
+	keyword_list = {
+		KEYWORDS(KEYWORD_GROUP_IGNORE, KEYWORD_LINE)
+	};
+#undef KEYWORD_LINE
+#undef KEYWORD_GROUP_IGNORE
+}
+#endif // DEBUG_ENABLED
+
+GDScriptTokenizer::Token GDScriptTokenizer::potential_identifier() {
+	// Consume all identifier characters.
+	while (is_unicode_identifier_continue(_peek())) {
 		_advance();
 	}
 
@@ -565,15 +583,28 @@ GDScriptTokenizer::Token GDScriptTokenizer::potential_identifier() {
 	}
 
 	// Not a keyword, so must be an identifier.
-	return make_identifier(name);
+	Token id = make_identifier(name);
+
+#ifdef DEBUG_ENABLED
+	// Additional checks for identifiers but only in debug and if it's available in TextServer.
+	if (TS->has_feature(TextServer::FEATURE_UNICODE_SECURITY)) {
+		int64_t confusable = TS->is_confusable(name, keyword_list);
+		if (confusable >= 0) {
+			push_error(vformat(R"(Identifier "%s" is visually similar to the GDScript keyword "%s" and thus not allowed.)", name, keyword_list[confusable]));
+		}
+	}
+#endif // DEBUG_ENABLED
+
+	return id;
 
-#undef KEYWORDS
-#undef MIN_KEYWORD_LENGTH
-#undef MAX_KEYWORD_LENGTH
 #undef KEYWORD_GROUP_CASE
 #undef KEYWORD
 }
 
+#undef MAX_KEYWORD_LENGTH
+#undef MIN_KEYWORD_LENGTH
+#undef KEYWORDS
+
 void GDScriptTokenizer::newline(bool p_make_token) {
 	// Don't overwrite previous newline, nor create if we want a line continuation.
 	if (p_make_token && !pending_newline && !line_continuation) {
@@ -720,7 +751,7 @@ GDScriptTokenizer::Token GDScriptTokenizer::number() {
 		error.rightmost_column = column + 1;
 		push_error(error);
 		has_error = true;
-	} else if (is_ascii_identifier_char(_peek())) {
+	} else if (is_unicode_identifier_start(_peek()) || is_unicode_identifier_continue(_peek())) {
 		// Letter at the end of the number.
 		push_error("Invalid numeric notation.");
 	}
@@ -1311,7 +1342,7 @@ GDScriptTokenizer::Token GDScriptTokenizer::scan() {
 
 	if (is_digit(c)) {
 		return number();
-	} else if (is_ascii_identifier_char(c)) {
+	} else if (is_unicode_identifier_start(c)) {
 		return potential_identifier();
 	}
 
@@ -1504,7 +1535,11 @@ GDScriptTokenizer::Token GDScriptTokenizer::scan() {
 			}
 
 		default:
-			return make_error(vformat(R"(Unknown character "%s".)", String(&c, 1)));
+			if (is_whitespace(c)) {
+				return make_error(vformat(R"(Invalid white space character "\\u%X".)", static_cast<int32_t>(c)));
+			} else {
+				return make_error(vformat(R"(Unknown character "%s".)", String(&c, 1)));
+			}
 	}
 }
 
@@ -1514,4 +1549,7 @@ GDScriptTokenizer::GDScriptTokenizer() {
 		tab_size = EditorSettings::get_singleton()->get_setting("text_editor/behavior/indent/size");
 	}
 #endif // TOOLS_ENABLED
+#ifdef DEBUG_ENABLED
+	make_keyword_list();
+#endif // DEBUG_ENABLED
 }

modules/gdscript/gdscript_tokenizer.h

@@ -224,6 +224,9 @@ private:
 	char32_t indent_char = '\0';
 	int position = 0;
 	int length = 0;
+#ifdef DEBUG_ENABLED
+	Vector<String> keyword_list;
+#endif // DEBUG_ENABLED
 
 #ifdef TOOLS_ENABLED
 	HashMap<int, CommentData> comments;
@@ -239,6 +242,10 @@ private:
 	void _skip_whitespace();
 	void check_indent();
 
+#ifdef DEBUG_ENABLED
+	void make_keyword_list();
+#endif // DEBUG_ENABLED
+
 	Token make_error(const String &p_message);
 	void push_error(const String &p_message);
 	void push_error(const Token &p_error);

modules/gdscript/gdscript_warning.cpp

@@ -155,6 +155,10 @@ String GDScriptWarning::get_message() const {
 			CHECK_SYMBOLS(2);
 			return vformat(R"(The function '%s()' is a static function but was called from an instance. Instead, it should be directly called from the type: '%s.%s()'.)", symbols[0], symbols[1], symbols[0]);
 		}
+		case CONFUSABLE_IDENTIFIER: {
+			CHECK_SYMBOLS(1);
+			return vformat(R"(The identifier "%s" has misleading characters and might be confused with something else.)", symbols[0]);
+		}
 		case WARNING_MAX:
 			break; // Can't happen, but silences warning
 	}
@@ -219,6 +223,7 @@ String GDScriptWarning::get_name_from_code(Code p_code) {
 		"SHADOWED_GLOBAL_IDENTIFIER",
 		"INT_ASSIGNED_TO_ENUM",
 		"STATIC_CALLED_ON_INSTANCE",
+		"CONFUSABLE_IDENTIFIER",
 	};
 
 	static_assert((sizeof(names) / sizeof(*names)) == WARNING_MAX, "Amount of warning types don't match the amount of warning names.");

modules/gdscript/gdscript_warning.h

@@ -78,6 +78,7 @@ public:
 		SHADOWED_GLOBAL_IDENTIFIER, // A global class or function has the same name as variable.
 		INT_ASSIGNED_TO_ENUM, // An integer value was assigned to an enum-typed variable without casting.
 		STATIC_CALLED_ON_INSTANCE, // A static method was called on an instance of a class instead of on the class itself.
+		CONFUSABLE_IDENTIFIER, // The identifier contains misleading characters that can be confused. E.g. "usеr" (has Cyrillic "е" instead of Latin "e").
 		WARNING_MAX,
 	};
 

modules/gdscript/tests/scripts/analyzer/warnings/lambda_unused_arg.out

@@ -2,4 +2,4 @@ GDTEST_OK
 >> WARNING
 >> Line: 2
 >> UNUSED_PARAMETER
->>
+>> The parameter 'unused' is never used in the function ''. If this is intended, prefix it with an underscore: '_unused'

modules/gdscript/tests/scripts/parser/errors/identifier_similar_to_keyword.gd

@@ -0,0 +1,3 @@
+func test():
+	var аs # Using Cyrillic "а".
+	print(аs)

modules/gdscript/tests/scripts/parser/errors/identifier_similar_to_keyword.out

@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Identifier "аs" is visually similar to the GDScript keyword "as" and thus not allowed.

modules/gdscript/tests/scripts/parser/features/unicode_identifiers.gd

@@ -0,0 +1,35 @@
+const π = PI
+var ㄥ = π
+
+func test():
+	var փորձարկում = "test"
+	prints("փորձարկում", փորձարկում)
+	var امتحان = "test"
+	prints("امتحان", امتحان)
+	var পরীক্ষা = "test"
+	prints("পরীক্ষা", পরীক্ষা)
+	var тест = "test"
+	prints("тест", тест)
+	var जाँच = "test"
+	prints("जाँच", जाँच)
+	var 기준 = "test"
+	prints("기준", 기준)
+	var 测试 = "test"
+	prints("测试", 测试)
+	var テスト = "test"
+	prints("テスト", テスト)
+	var 試験 = "test"
+	prints("試験", 試験)
+	var പരീക്ഷ = "test"
+	prints("പരീക്ഷ", പരീക്ഷ)
+	var ทดสอบ = "test"
+	prints("ทดสอบ", ทดสอบ)
+	var δοκιμή = "test"
+	prints("δοκιμή", δοκιμή)
+
+	const d = 1.1
+	_process(d)
+	print(is_equal_approx(ㄥ, PI + (d * PI)))
+
+func _process(Δ: float) -> void:
+	ㄥ += Δ * π

modules/gdscript/tests/scripts/parser/features/unicode_identifiers.out

@@ -0,0 +1,14 @@
+GDTEST_OK
+փորձարկում test
+امتحان test
+পরীক্ষা test
+тест test
+जाँच test
+기준 test
+测试 test
+テスト test
+試験 test
+പരീക്ഷ test
+ทดสอบ test
+δοκιμή test
+true

modules/gdscript/tests/scripts/parser/warnings/confusable_identifier.gd

@@ -0,0 +1,5 @@
+func test():
+	var port = 0 # Only latin characters.
+	var pοrt = 1 # The "ο" is Greek omicron.
+
+	prints(port, pοrt)

modules/gdscript/tests/scripts/parser/warnings/confusable_identifier.out

@@ -0,0 +1,6 @@
+GDTEST_OK
+>> WARNING
+>> Line: 3
+>> CONFUSABLE_IDENTIFIER
+>> The identifier "pοrt" has misleading characters and might be confused with something else.
+0 1