From 082e7b6a9ea5f4651bed0b2ab037dbba05af26eb Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Mon, 16 Oct 2017 13:28:44 +0200
Subject: [PATCH] Allow ``gas`` in view functions.

---
 Changelog.md                         | 1 +
 libevmasm/SemanticInformation.cpp    | 2 +-
 test/libsolidity/ViewPureChecker.cpp | 7 +++++--
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/Changelog.md b/Changelog.md
index d78dbbba8..ac27ca7fb 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -19,6 +19,7 @@ Bugfixes:
    (such as ``balance``, ``transfer``, etc.)
  * Type Checker: Prevent duplicate event declarations.
  * Type Checker: Do not mark event parameters as shadowing state variables.
+ * Type Checker: Allow ``gas`` in view functions.
 
 ### 0.4.17 (2017-09-21)
 
diff --git a/libevmasm/SemanticInformation.cpp b/libevmasm/SemanticInformation.cpp
index 83cfe2c6d..61a6ccda4 100644
--- a/libevmasm/SemanticInformation.cpp
+++ b/libevmasm/SemanticInformation.cpp
@@ -198,6 +198,7 @@ bool SemanticInformation::invalidInPureFunctions(Instruction _instruction)
 	case Instruction::ORIGIN:
 	case Instruction::CALLER:
 	case Instruction::CALLVALUE:
+	case Instruction::GAS:
 	case Instruction::GASPRICE:
 	case Instruction::EXTCODESIZE:
 	case Instruction::EXTCODECOPY:
@@ -223,7 +224,6 @@ bool SemanticInformation::invalidInViewFunctions(Instruction _instruction)
 	case Instruction::SSTORE:
 	case Instruction::JUMP:
 	case Instruction::JUMPI:
-	case Instruction::GAS:
 	case Instruction::LOG0:
 	case Instruction::LOG1:
 	case Instruction::LOG2:
diff --git a/test/libsolidity/ViewPureChecker.cpp b/test/libsolidity/ViewPureChecker.cpp
index 802415196..6353ae8a8 100644
--- a/test/libsolidity/ViewPureChecker.cpp
+++ b/test/libsolidity/ViewPureChecker.cpp
@@ -349,7 +349,7 @@ BOOST_AUTO_TEST_CASE(assembly)
 				assembly { x := 7 }
 			}
 			function g() view public {
-				assembly { for {} 1 { pop(sload(0)) } { } }
+				assembly { for {} 1 { pop(sload(0)) } { } pop(gas) }
 			}
 			function h() view public {
 				assembly { function g() { pop(blockhash(20)) } }
@@ -357,6 +357,9 @@ BOOST_AUTO_TEST_CASE(assembly)
 			function j() public {
 				assembly { pop(call(0, 1, 2, 3, 4, 5, 6)) }
 			}
+			function k() public {
+				assembly { pop(call(gas, 1, 2, 3, 4, 5, 6)) }
+			}
 		}
 	)";
 	CHECK_SUCCESS_NO_WARNINGS(text);
@@ -367,7 +370,7 @@ BOOST_AUTO_TEST_CASE(assembly_staticcall)
 	string text = R"(
 		contract C {
 			function i() view public {
-				assembly { pop(staticcall(0, 1, 2, 3, 4, 5)) }
+				assembly { pop(staticcall(gas, 1, 2, 3, 4, 5)) }
 			}
 		}
 	)";