From cee93d946d798a4076ab5df5f32c5687608defe8 Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Fri, 5 May 2017 16:46:26 +0100
Subject: Support parsing let statements without a value

---
 libsolidity/inlineasm/AsmAnalysis.cpp | 16 +++++++++++-----
 libsolidity/inlineasm/AsmParser.cpp   | 13 +++++++++----
 libsolidity/inlineasm/AsmPrinter.cpp  |  7 +++++--
 test/libjulia/Parser.cpp              |  5 +++++
 test/libsolidity/InlineAssembly.cpp   |  5 +++++
 5 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/libsolidity/inlineasm/AsmAnalysis.cpp b/libsolidity/inlineasm/AsmAnalysis.cpp
index 7e00ffae..d8aca725 100644
--- a/libsolidity/inlineasm/AsmAnalysis.cpp
+++ b/libsolidity/inlineasm/AsmAnalysis.cpp
@@ -174,14 +174,20 @@ bool AsmAnalyzer::operator()(assembly::Assignment const& _assignment)
 
 bool AsmAnalyzer::operator()(assembly::VariableDeclaration const& _varDecl)
 {
+	bool success = true;
 	int const expectedItems = _varDecl.variables.size();
-	int const stackHeight = m_stackHeight;
-	bool success = boost::apply_visitor(*this, *_varDecl.value);
-	if ((m_stackHeight - stackHeight) != expectedItems)
+	if (_varDecl.value)
 	{
-		m_errorReporter.declarationError(_varDecl.location, "Variable count mismatch.");
-		return false;
+		int const stackHeight = m_stackHeight;
+		success = boost::apply_visitor(*this, *_varDecl.value);
+		if ((m_stackHeight - stackHeight) != expectedItems)
+		{
+			m_errorReporter.declarationError(_varDecl.location, "Variable count mismatch.");
+			return false;
+		}
 	}
+	else
+		m_stackHeight += expectedItems;
 
 	for (auto const& variable: _varDecl.variables)
 	{
diff --git a/libsolidity/inlineasm/AsmParser.cpp b/libsolidity/inlineasm/AsmParser.cpp
index d282a30d..133f70b1 100644
--- a/libsolidity/inlineasm/AsmParser.cpp
+++ b/libsolidity/inlineasm/AsmParser.cpp
@@ -347,10 +347,15 @@ assembly::VariableDeclaration Parser::parseVariableDeclaration()
 		else
 			break;
 	}
-	expectToken(Token::Colon);
-	expectToken(Token::Assign);
-	varDecl.value.reset(new Statement(parseExpression()));
-	varDecl.location.end = locationOf(*varDecl.value).end;
+	if (currentToken() == Token::Colon)
+	{
+		expectToken(Token::Colon);
+		expectToken(Token::Assign);
+		varDecl.value.reset(new Statement(parseExpression()));
+		varDecl.location.end = locationOf(*varDecl.value).end;
+	}
+	else
+		varDecl.location.end = varDecl.variables.back().location.end;
 	return varDecl;
 }
 
diff --git a/libsolidity/inlineasm/AsmPrinter.cpp b/libsolidity/inlineasm/AsmPrinter.cpp
index 062ff453..4f96a3e9 100644
--- a/libsolidity/inlineasm/AsmPrinter.cpp
+++ b/libsolidity/inlineasm/AsmPrinter.cpp
@@ -128,8 +128,11 @@ string AsmPrinter::operator()(assembly::VariableDeclaration const& _variableDecl
 		),
 		", "
 	);
-	out += " := ";
-	out += boost::apply_visitor(*this, *_variableDeclaration.value);
+	if (_variableDeclaration.value)
+	{
+		out += " := ";
+		out += boost::apply_visitor(*this, *_variableDeclaration.value);
+	}
 	return out;
 }
 
diff --git a/test/libjulia/Parser.cpp b/test/libjulia/Parser.cpp
index fa7c45ed..f6db828a 100644
--- a/test/libjulia/Parser.cpp
+++ b/test/libjulia/Parser.cpp
@@ -131,6 +131,11 @@ BOOST_AUTO_TEST_CASE(vardecl_bool)
 	BOOST_CHECK(successParse("{ let x:bool := false:bool }"));
 }
 
+BOOST_AUTO_TEST_CASE(vardecl_empty)
+{
+	BOOST_CHECK(successParse("{ let x }"));
+}
+
 BOOST_AUTO_TEST_CASE(assignment)
 {
 	BOOST_CHECK(successParse("{ let x:u256 := 2:u256 let y:u256 := x }"));
diff --git a/test/libsolidity/InlineAssembly.cpp b/test/libsolidity/InlineAssembly.cpp
index 5197f649..4bf4eb48 100644
--- a/test/libsolidity/InlineAssembly.cpp
+++ b/test/libsolidity/InlineAssembly.cpp
@@ -195,6 +195,11 @@ BOOST_AUTO_TEST_CASE(vardecl_bool)
 	CHECK_PARSE_ERROR("{ let x := false }", ParserError, "True and false are not valid literals.");
 }
 
+BOOST_AUTO_TEST_CASE(vardecl_empty)
+{
+	BOOST_CHECK(successParse("{ let x }"));
+}
+
 BOOST_AUTO_TEST_CASE(assignment)
 {
 	BOOST_CHECK(successParse("{ let x := 2 7 8 add =: x }"));
-- 
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