From d49046938a22fc2fd75087bfdd68fc1f369e8a6c Mon Sep 17 00:00:00 2001
From: George Marques <george@gmarqu.es>
Date: Wed, 15 Sep 2021 11:08:59 -0300
Subject: [PATCH] GDScript: Show error on unary operators without argument

---
 modules/gdscript/gdscript_parser.cpp                 | 12 ++++++++++++
 .../errors/binary_complement_without_argument.gd     |  2 ++
 .../errors/binary_complement_without_argument.out    |  2 ++
 .../errors/boolean_negation_without_argument.gd      |  2 ++
 .../errors/boolean_negation_without_argument.out     |  2 ++
 .../boolean_negation_without_argument_using_bang.gd  |  2 ++
 .../boolean_negation_without_argument_using_bang.out |  2 ++
 .../parser/errors/mistaken_decrement_operator.gd     |  3 +++
 .../parser/errors/mistaken_decrement_operator.out    |  2 ++
 .../parser/errors/mistaken_increment_operator.gd     |  3 +++
 .../parser/errors/mistaken_increment_operator.out    |  2 ++
 11 files changed, 34 insertions(+)
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.gd
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.out
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.gd
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.out
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.gd
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.out
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.gd
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.out
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.gd
 create mode 100644 modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.out

diff --git a/modules/gdscript/gdscript_parser.cpp b/modules/gdscript/gdscript_parser.cpp
index 42c06d81615..c9ac0553920 100644
--- a/modules/gdscript/gdscript_parser.cpp
+++ b/modules/gdscript/gdscript_parser.cpp
@@ -2123,22 +2123,34 @@ GDScriptParser::ExpressionNode *GDScriptParser::parse_unary_operator(ExpressionN
 			operation->operation = UnaryOpNode::OP_NEGATIVE;
 			operation->variant_op = Variant::OP_NEGATE;
 			operation->operand = parse_precedence(PREC_SIGN, false);
+			if (operation->operand == nullptr) {
+				push_error(R"(Expected expression after "-" operator.)");
+			}
 			break;
 		case GDScriptTokenizer::Token::PLUS:
 			operation->operation = UnaryOpNode::OP_POSITIVE;
 			operation->variant_op = Variant::OP_POSITIVE;
 			operation->operand = parse_precedence(PREC_SIGN, false);
+			if (operation->operand == nullptr) {
+				push_error(R"(Expected expression after "+" operator.)");
+			}
 			break;
 		case GDScriptTokenizer::Token::TILDE:
 			operation->operation = UnaryOpNode::OP_COMPLEMENT;
 			operation->variant_op = Variant::OP_BIT_NEGATE;
 			operation->operand = parse_precedence(PREC_BIT_NOT, false);
+			if (operation->operand == nullptr) {
+				push_error(R"(Expected expression after "~" operator.)");
+			}
 			break;
 		case GDScriptTokenizer::Token::NOT:
 		case GDScriptTokenizer::Token::BANG:
 			operation->operation = UnaryOpNode::OP_LOGIC_NOT;
 			operation->variant_op = Variant::OP_NOT;
 			operation->operand = parse_precedence(PREC_LOGIC_NOT, false);
+			if (operation->operand == nullptr) {
+				push_error(vformat(R"(Expected expression after "%s" operator.)", op_type == GDScriptTokenizer::Token::NOT ? "not" : "!"));
+			}
 			break;
 		default:
 			return nullptr; // Unreachable.
diff --git a/modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.gd b/modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.gd
new file mode 100644
index 00000000000..b52a6defcbb
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.gd
@@ -0,0 +1,2 @@
+func test():
+	print(~)
diff --git a/modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.out b/modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.out
new file mode 100644
index 00000000000..ceabe42d3c8
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/binary_complement_without_argument.out
@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected expression after "~" operator.
diff --git a/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.gd b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.gd
new file mode 100644
index 00000000000..b3ea1ba1f65
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.gd
@@ -0,0 +1,2 @@
+func test():
+	print(not)
diff --git a/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.out b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.out
new file mode 100644
index 00000000000..6cf191ea98e
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument.out
@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected expression after "not" operator.
diff --git a/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.gd b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.gd
new file mode 100644
index 00000000000..8a330791937
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.gd
@@ -0,0 +1,2 @@
+func test():
+	print(!)
diff --git a/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.out b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.out
new file mode 100644
index 00000000000..87fcc5e2b08
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/boolean_negation_without_argument_using_bang.out
@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected expression after "!" operator.
diff --git a/modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.gd b/modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.gd
new file mode 100644
index 00000000000..193f8247029
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.gd
@@ -0,0 +1,3 @@
+func test():
+	var a = 0
+	print(a--)
diff --git a/modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.out b/modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.out
new file mode 100644
index 00000000000..b6b577a2779
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/mistaken_decrement_operator.out
@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected expression after "-" operator.
diff --git a/modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.gd b/modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.gd
new file mode 100644
index 00000000000..035d27638c5
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.gd
@@ -0,0 +1,3 @@
+func test():
+	var a = 0
+	print(a++)
diff --git a/modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.out b/modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.out
new file mode 100644
index 00000000000..24eb76593a1
--- /dev/null
+++ b/modules/gdscript/tests/scripts/parser/errors/mistaken_increment_operator.out
@@ -0,0 +1,2 @@
+GDTEST_PARSER_ERROR
+Expected expression after "+" operator.