From 433aebb7c91acf6d364acd76f6018dc1b4f847af Mon Sep 17 00:00:00 2001
From: Wei-Ning Huang <w@dexon.org>
Date: Thu, 18 Oct 2018 11:38:05 +0800
Subject: Add opcode RAND support

DEXON has a built-in on chain random oracle that allow one to retrieve a
random variable. Add `rand` solidity variable is introduced to load the
random variable onto the stack.
---
 libsolidity/analysis/GlobalContext.cpp   | 1 +
 libsolidity/analysis/ViewPureChecker.cpp | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

(limited to 'libsolidity/analysis')

diff --git a/libsolidity/analysis/GlobalContext.cpp b/libsolidity/analysis/GlobalContext.cpp
index 756bb540..347cf943 100644
--- a/libsolidity/analysis/GlobalContext.cpp
+++ b/libsolidity/analysis/GlobalContext.cpp
@@ -51,6 +51,7 @@ m_magicVariables(vector<shared_ptr<MagicVariableDeclaration const>>{
 	make_shared<MagicVariableDeclaration>("msg", make_shared<MagicType>(MagicType::Kind::Message)),
 	make_shared<MagicVariableDeclaration>("mulmod", make_shared<FunctionType>(strings{"uint256", "uint256", "uint256"}, strings{"uint256"}, FunctionType::Kind::MulMod, false, StateMutability::Pure)),
 	make_shared<MagicVariableDeclaration>("now", make_shared<IntegerType>(256)),
+	make_shared<MagicVariableDeclaration>("rand", make_shared<IntegerType>(256)),
 	make_shared<MagicVariableDeclaration>("require", make_shared<FunctionType>(strings{"bool"}, strings{}, FunctionType::Kind::Require, false, StateMutability::Pure)),
 	make_shared<MagicVariableDeclaration>("require", make_shared<FunctionType>(strings{"bool", "string memory"}, strings{}, FunctionType::Kind::Require, false, StateMutability::Pure)),
 	make_shared<MagicVariableDeclaration>("revert", make_shared<FunctionType>(strings(), strings(), FunctionType::Kind::Revert, false, StateMutability::Pure)),
diff --git a/libsolidity/analysis/ViewPureChecker.cpp b/libsolidity/analysis/ViewPureChecker.cpp
index d9843012..610ba617 100644
--- a/libsolidity/analysis/ViewPureChecker.cpp
+++ b/libsolidity/analysis/ViewPureChecker.cpp
@@ -210,7 +210,7 @@ void ViewPureChecker::endVisit(Identifier const& _identifier)
 				mutability = StateMutability::View;
 			break;
 		case Type::Category::Integer:
-			solAssert(_identifier.name() == "now", "");
+			solAssert(_identifier.name() == "now" || _identifier.name() == "rand", "");
 			mutability = StateMutability::View;
 			break;
 		default:
-- 
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