Display nicer error messages in the parser (display tokens and not internal names)

Changelog.md

@@ -4,6 +4,7 @@ Features:
  * Build System: Update internal dependency of jsoncpp to 1.8.4, which introduces more strictness and reduces memory usage.
  * Code Generator: Use native shift instructions on target Constantinople.
  * Optimizer: Remove unnecessary masking of the result of known short instructions (``ADDRESS``, ``CALLER``, ``ORIGIN`` and ``COINBASE``).
+ * Parser: Display nicer error messages by showing the actual tokens and not internal names.
  * Type Checker: Deprecate the ``years`` unit denomination and raise a warning for it (or an error as experimental 0.5.0 feature).
  * Type Checker: Make literals (without explicit type casting) an error for tight packing as experimental 0.5.0 feature.
 

libsolidity/parsing/ParserBase.cpp

@@ -71,10 +71,10 @@ void ParserBase::expectToken(Token::Value _value, bool _advance)
 		if (Token::isReservedKeyword(tok))
 		{
 			fatalParserError(
-				string("Expected token ") +
+				string("Expected '") +
-				string(Token::name(_value)) +
+				string(Token::toString(_value)) +
-				string(" got reserved keyword '") +
+				string("' but got reserved keyword '") +
-				string(Token::name(tok)) +
+				string(Token::toString(tok)) +
 				string("'")
 			);
 		}
@@ -82,19 +82,19 @@ void ParserBase::expectToken(Token::Value _value, bool _advance)
 		{
 			ElementaryTypeNameToken elemTypeName = m_scanner->currentElementaryTypeNameToken();
 			fatalParserError(
-				string("Expected token ") +
+				string("Expected '") +
-				string(Token::name(_value)) +
+				string(Token::toString(_value)) +
-				string(" got '") +
+				string("' but got '") +
 				elemTypeName.toString() +
 				string("'")
 			);
 		}
 		else
 			fatalParserError(
-				string("Expected token ") +
+				string("Expected '") +
-				string(Token::name(_value)) +
+				string(Token::toString(_value)) +
-				string(" got '") +
+				string("' but got '") +
-				string(Token::name(m_scanner->currentToken())) +
+				string(Token::toString(m_scanner->currentToken())) +
 				string("'")
 			);
 	}