Change error from directive to keyword.

Changelog.md

@@ -1,16 +1,10 @@
+### 0.9.0 (unreleased)
+
+Breaking changes:
+ * `error` is now a keyword that can only be used for defining errors.
+
 ### 0.8.5 (unreleased)
 
-Language Features:
- * Allowing conversion from ``bytes`` and ``bytes`` slices to ``bytes1``/.../``bytes32``.
- * Yul: Add ``verbatim`` builtin function to inject arbitrary bytecode.
-
-
-Compiler Features:
- * Yul Optimizer: Evaluate ``keccak256(a, c)``, when the value at memory location ``a`` is known at compile time and ``c`` is a constant ``<= 32``.
-
-
-Bugfixes:
-
 
 ### 0.8.4 (2021-04-21)
 

docs/090-breaking-changes.rst

@@ -0,0 +1,28 @@
+********************************
+Solidity v0.8.0 Breaking Changes
+********************************
+
+This section highlights the main breaking changes introduced in Solidity
+version 0.9.0.
+For the full list check
+`the release changelog <https://github.com/ethereum/solidity/releases/tag/v0.9.0>`_.
+
+Silent Changes of the Semantics
+===============================
+
+...
+
+New Restrictions
+================
+
+- `error` is now a keyword and cannot be used as identifier anymore.
+
+Interface Changes
+=================
+
+...
+
+How to update your code
+=======================
+
+...

docs/grammar/SolidityLexer.g4

@@ -29,7 +29,7 @@ Do: 'do';
 Else: 'else';
 Emit: 'emit';
 Enum: 'enum';
-Error: 'error'; // not a real keyword
+Error: 'error';
 Revert: 'revert'; // not a real keyword
 Event: 'event';
 External: 'external';

docs/grammar/SolidityParser.g4

@@ -13,6 +13,7 @@ sourceUnit: (
 	pragmaDirective
 	| importDirective
 	| contractDefinition
+	| errorDefinition
 	| interfaceDefinition
 	| libraryDefinition
 	| functionDefinition
@@ -379,9 +380,9 @@ tupleExpression: LParen (expression? ( Comma expression?)* ) RParen;
 inlineArrayExpression: LBrack (expression ( Comma expression)* ) RBrack;
 
 /**
- * Besides regular non-keyword Identifiers, some keywords like 'from' and 'error' can also be used as identifiers.
+ * Besides regular non-keyword Identifiers, some keywords like 'from' can also be used as identifiers.
  */
-identifier: Identifier | From | Error | Revert;
+identifier: Identifier | From | Revert;
 
 literal: stringLiteral | numberLiteral | booleanLiteral | hexStringLiteral | unicodeStringLiteral;
 booleanLiteral: True | False;

docs/index.rst

@@ -28,8 +28,8 @@ a 0.x version number `to indicate this fast pace of change <https://semver.org/#
 
 .. warning::
 
-  Solidity recently released the 0.8.x version that introduced a lot of breaking
-  changes. Make sure you read :doc:`the full list <080-breaking-changes>`.
+  Solidity recently released the 0.9.x version that introduced a lot of breaking
+  changes. Make sure you read :doc:`the full list <090-breaking-changes>`.
 
 Ideas for improving Solidity or this documentation are always welcome,
 read our :doc:`contributors guide <contributing>` for more details.
@@ -155,6 +155,7 @@ Contents
    060-breaking-changes.rst
    070-breaking-changes.rst
    080-breaking-changes.rst
+   090-breaking-changes.rst
    natspec-format.rst
    security-considerations.rst
    smtchecker.rst
@@ -165,4 +166,4 @@ Contents
    bugs.rst
    contributing.rst
    brand-guide.rst
-   language-influences.rst
+   language-influences.rst

liblangutil/Token.h

@@ -158,6 +158,7 @@ namespace solidity::langutil
 	K(Else, "else", 0)                                                 \
 	K(Enum, "enum", 0)                                                 \
 	K(Emit, "emit", 0)                                                 \
+	K(Error, "error", 0)                                               \
 	K(Event, "event", 0)                                               \
 	K(External, "external", 0)                                         \
 	K(Fallback, "fallback", 0)                                         \

libsolidity/parsing/Parser.cpp

@@ -111,17 +111,12 @@ ASTPointer<SourceUnit> Parser::parse(shared_ptr<Scanner> const& _scanner)
 			case Token::Function:
 				nodes.push_back(parseFunctionDefinition(true));
 				break;
+			case Token::Error:
+				nodes.push_back(parseErrorDefinition());
+				break;
 			default:
-				if (
-					// Workaround because `error` is not a keyword.
-					m_scanner->currentToken() == Token::Identifier &&
-					currentLiteral() == "error" &&
-					m_scanner->peekNextToken() == Token::Identifier &&
-					m_scanner->peekNextNextToken() == Token::LParen
-				)
-					nodes.push_back(parseErrorDefinition());
 				// Constant variable.
-				else if (variableDeclarationStart() && m_scanner->peekNextToken() != Token::EOS)
+				if (variableDeclarationStart() && m_scanner->peekNextToken() != Token::EOS)
 				{
 					VarDeclParserOptions options;
 					options.kind = VarDeclKind::FileLevel;
@@ -359,13 +354,7 @@ ASTPointer<ContractDefinition> Parser::parseContractDefinition()
 				subNodes.push_back(parseStructDefinition());
 			else if (currentTokenValue == Token::Enum)
 				subNodes.push_back(parseEnumDefinition());
-			else if (
-				// Workaround because `error` is not a keyword.
-				currentTokenValue == Token::Identifier &&
-				currentLiteral() == "error" &&
-				m_scanner->peekNextToken() == Token::Identifier &&
-				m_scanner->peekNextNextToken() == Token::LParen
-			)
+			else if (currentTokenValue == Token::Error)
 				subNodes.push_back(parseErrorDefinition());
 			else if (variableDeclarationStart())
 			{
@@ -936,7 +925,7 @@ ASTPointer<ErrorDefinition> Parser::parseErrorDefinition()
 	ASTNodeFactory nodeFactory(*this);
 	ASTPointer<StructuredDocumentation> documentation = parseStructuredDocumentation();
 
-	solAssert(*expectIdentifierToken() == "error", "");
+	expectToken(Token::Error);
 	auto&& [name, nameLocation] = expectIdentifierWithLocation();
 
 	ASTPointer<ParameterList> parameters = parseParameterList({});

test/libsolidity/semanticTests/errors/weird_name.sol

@@ -1,11 +0,0 @@
-error error(uint a);
-contract C {
-    function f() public pure {
-        revert error(2);
-    }
-}
-// ====
-// compileViaYul: also
-// compileToEwasm: also
-// ----
-// f() -> FAILURE, hex"b48fb6cf", hex"0000000000000000000000000000000000000000000000000000000000000002"

test/libsolidity/semanticTests/reverts/error_struct.sol

@@ -1,18 +0,0 @@
-struct error { uint error; }
-contract C {
-	error test();
-	error _struct;
-	function f() public {
-		revert test();
-	}
-	function g(uint x) public returns (uint) {
-		_struct.error = x;
-		return _struct.error;
-	}
-}
-// ====
-// compileViaYul: also
-// compileToEwasm: also
-// ----
-// f() -> FAILURE, hex"f8a8fd6d"
-// g(uint256): 7 -> 7

test/libsolidity/syntaxTests/errors/struct_named_error.sol

@@ -1,6 +1,6 @@
-// Test that the parser workaround is not breaking.
 struct error {uint a;}
 contract C {
     error x;
 }
 // ----
+// ParserError 2314: (7-12): Expected identifier but got 'error'

test/libsolidity/syntaxTests/errors/weird_name.sol

@@ -0,0 +1,8 @@
+error error(uint a);
+contract C {
+    function f() public pure {
+        revert error(2);
+    }
+}
+// ----
+// ParserError 2314: (6-11): Expected identifier but got 'error'

test/libsolidity/syntaxTests/unusedVariables/try_catch.sol

@@ -4,7 +4,7 @@ contract test {
 
         } catch Error(string memory message) {
 
-        } catch (bytes memory error) {
+        } catch (bytes memory _error) {
 
         }
     }
@@ -15,4 +15,4 @@ contract test {
 // Warning 5667: (49-55): Unused function parameter. Remove or comment out the variable name to silence this warning.
 // Warning 5667: (89-95): Unused try/catch parameter. Remove or comment out the variable name to silence this warning.
 // Warning 5667: (122-143): Unused try/catch parameter. Remove or comment out the variable name to silence this warning.
-// Warning 5667: (165-183): Unused try/catch parameter. Remove or comment out the variable name to silence this warning.
+// Warning 5667: (165-184): Unused try/catch parameter. Remove or comment out the variable name to silence this warning.