From 56fe3a6ab93116438ea52634e891c71b995d7c3f Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Wed, 24 May 2017 13:13:05 +0100
Subject: [PATCH] Better error messages during parsing functional instructions

---
 Changelog.md                        | 4 ++++
 libsolidity/inlineasm/AsmParser.cpp | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/Changelog.md b/Changelog.md
index 2073c0a4efdb..5ba712f53496 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,9 @@
 ### 0.4.12 (unreleased)
+
+Features:
  * AST: export all attributes to Json format
+ * Inline Assembly: Present proper error message when not supplying enough arguments to a functional
+   instruction.
 
 Bugfixes:
  * Unused variable warnings no longer issued for variables used inside inline assembly
diff --git a/libsolidity/inlineasm/AsmParser.cpp b/libsolidity/inlineasm/AsmParser.cpp
index 85ae94241f19..519bfa2eb83f 100644
--- a/libsolidity/inlineasm/AsmParser.cpp
+++ b/libsolidity/inlineasm/AsmParser.cpp
@@ -321,6 +321,15 @@ assembly::Statement Parser::parseCall(assembly::Statement&& _instruction)
 		unsigned args = unsigned(instrInfo.args);
 		for (unsigned i = 0; i < args; ++i)
 		{
+			/// check for premature closing parentheses
+			if (m_scanner->currentToken() == Token::RParen)
+				fatalParserError(string(
+					"Expected " +
+					boost::lexical_cast<string>(args) +
+					" arguments, but received " +
+					boost::lexical_cast<string>(i)
+				));
+
 			ret.arguments.emplace_back(parseExpression());
 			if (i != args - 1)
 			{