Adjust antlr grammar

docs/grammar/SolidityLexer.g4

@@ -85,6 +85,7 @@ SignedIntegerType:
 Storage: 'storage';
 String: 'string';
 Struct: 'struct';
+Transient: 'transient';
 True: 'true';
 Try: 'try';
 Type: 'type';

docs/grammar/SolidityParser.g4

@@ -165,7 +165,7 @@ locals[
 	boolean overrideSpecifierSet = false,
 ]
 :
-	Function (identifier | Fallback | Receive)
+	Function (identifier | Fallback | Receive | Transient)
 	LParen (arguments=parameterList)? RParen
 	(
 		{!$visibilitySet}? visibility {$visibilitySet = true;}
@@ -273,7 +273,10 @@ locals [boolean constantnessSet = false, boolean visibilitySet = false, boolean
 		| {!$overrideSpecifierSet}? overrideSpecifier {$overrideSpecifierSet = true;}
 		| {!$constantnessSet}? Immutable {$constantnessSet = true;}
 	)*
-	name=identifier
+	(
+		location=Transient name=identifier
+		| name=identifier
+	)
 	(Assign initialValue=expression)?
 	Semicolon;
 
@@ -364,7 +367,14 @@ locals [boolean visibilitySet = false, boolean mutabilitySet = false]
 /**
  * The declaration of a single variable.
  */
-variableDeclaration: type=typeName location=dataLocation? name=identifier;
+variableDeclaration
+:
+	type=typeName
+	(
+		Tlocation=Transient name=identifier?
+		| location=dataLocation? name=identifier
+	);
+
 dataLocation: Memory | Storage | Calldata;
 
 /**
@@ -419,7 +429,7 @@ inlineArrayExpression: LBrack (expression ( Comma expression)* ) RBrack;
 /**
  * Besides regular non-keyword Identifiers, some keywords like 'from' and 'error' can also be used as identifiers.
  */
-identifier: Identifier | From | Error | Revert | Global;
+identifier: Identifier | From | Error | Revert | Global | Transient;
 
 literal: stringLiteral | numberLiteral | booleanLiteral | hexStringLiteral | unicodeStringLiteral;
 
@@ -497,7 +507,7 @@ tryStatement: Try expression (Returns LParen returnParameters=parameterList RPar
  */
 catchClause: Catch (identifier? LParen (arguments=parameterList) RParen)? block;
 
-returnStatement: Return expression? Semicolon;
+returnStatement: Return (expression | Transient)? Semicolon;
 /**
  * An emit statement. The contained expression needs to refer to an event.
  */