From fbcc5f4ee5bd629474047531f76beaa19c62972b Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Sun, 9 Jul 2017 00:10:22 +0100
Subject: [PATCH] Support experimental feature pragma

---
 libsolidity/analysis/SyntaxChecker.cpp | 32 ++++++++++++++++++++++----
 libsolidity/analysis/SyntaxChecker.h   |  2 ++
 libsolidity/ast/ASTAnnotations.h       |  2 ++
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/libsolidity/analysis/SyntaxChecker.cpp b/libsolidity/analysis/SyntaxChecker.cpp
index bde0e616e..04c4e2d83 100644
--- a/libsolidity/analysis/SyntaxChecker.cpp
+++ b/libsolidity/analysis/SyntaxChecker.cpp
@@ -33,9 +33,10 @@ bool SyntaxChecker::checkSyntax(ASTNode const& _astRoot)
 	return Error::containsOnlyWarnings(m_errorReporter.errors());
 }
 
-bool SyntaxChecker::visit(SourceUnit const&)
+bool SyntaxChecker::visit(SourceUnit const& _sourceUnit)
 {
 	m_versionPragmaFound = false;
+	m_sourceUnit = &_sourceUnit;
 	return true;
 }
 
@@ -57,15 +58,36 @@ void SyntaxChecker::endVisit(SourceUnit const& _sourceUnit)
 
 		m_errorReporter.warning(_sourceUnit.location(), errorString);
 	}
+	m_sourceUnit = nullptr;
 }
 
 bool SyntaxChecker::visit(PragmaDirective const& _pragma)
 {
 	solAssert(!_pragma.tokens().empty(), "");
 	solAssert(_pragma.tokens().size() == _pragma.literals().size(), "");
-	if (_pragma.tokens()[0] != Token::Identifier || _pragma.literals()[0] != "solidity")
-		m_errorReporter.syntaxError(_pragma.location(), "Unknown pragma \"" + _pragma.literals()[0] + "\"");
-	else
+	if (_pragma.tokens()[0] != Token::Identifier)
+		m_errorReporter.syntaxError(_pragma.location(), "Invalid pragma \"" + _pragma.literals()[0] + "\"");
+	else if (_pragma.literals()[0] == "experimental")
+	{
+		solAssert(m_sourceUnit, "");
+		vector<string> literals(_pragma.literals().begin() + 1, _pragma.literals().end());
+		if (literals.size() == 0)
+			m_errorReporter.syntaxError(
+				_pragma.location(),
+				"At least one experimental feature or the wildcard symbol \"*\" is required."
+			);
+		else
+			for (string const literal: literals)
+			{
+				if (literal.empty())
+					m_errorReporter.syntaxError(_pragma.location(), "Empty experimental feature name is invalid.");
+				else if (m_sourceUnit->annotation().experimentalFeatures.count(literal))
+					m_errorReporter.syntaxError(_pragma.location(), "Duplicate experimental feature name.");
+				else
+					m_sourceUnit->annotation().experimentalFeatures.insert(literal);
+			}
+	}
+	else if (_pragma.literals()[0] == "solidity")
 	{
 		vector<Token::Value> tokens(_pragma.tokens().begin() + 1, _pragma.tokens().end());
 		vector<string> literals(_pragma.literals().begin() + 1, _pragma.literals().end());
@@ -81,6 +103,8 @@ bool SyntaxChecker::visit(PragmaDirective const& _pragma)
 			);
 		m_versionPragmaFound = true;
 	}
+	else
+		m_errorReporter.syntaxError(_pragma.location(), "Unknown pragma \"" + _pragma.literals()[0] + "\"");
 	return true;
 }
 
diff --git a/libsolidity/analysis/SyntaxChecker.h b/libsolidity/analysis/SyntaxChecker.h
index fb5cc6d7a..fa34bab31 100644
--- a/libsolidity/analysis/SyntaxChecker.h
+++ b/libsolidity/analysis/SyntaxChecker.h
@@ -77,6 +77,8 @@ private:
 	bool m_versionPragmaFound = false;
 
 	int m_inLoopDepth = 0;
+
+	SourceUnit const* m_sourceUnit = nullptr;
 };
 
 }
diff --git a/libsolidity/ast/ASTAnnotations.h b/libsolidity/ast/ASTAnnotations.h
index f757f03c0..083ecfa48 100644
--- a/libsolidity/ast/ASTAnnotations.h
+++ b/libsolidity/ast/ASTAnnotations.h
@@ -61,6 +61,8 @@ struct SourceUnitAnnotation: ASTAnnotation
 	std::string path;
 	/// The exported symbols (all global symbols).
 	std::map<ASTString, std::vector<Declaration const*>> exportedSymbols;
+	/// Experimental feature pragmas.
+	std::set<ASTString> experimentalFeatures;
 };
 
 struct ImportAnnotation: ASTAnnotation