Add changelog entry and test cases.

Changelog.md

@@ -19,6 +19,7 @@ Features:
  * General: Introduce new constructor syntax using the ``constructor`` keyword as experimental 0.5.0 feature.
  * Inheritance: Error when using empty parentheses for base class constructors that require arguments as experimental 0.5.0 feature.
  * Inheritance: Error when using no parentheses in modifier-style constructor calls as experimental 0.5.0 feature.
+ * Type System: Allow access to constants via contract name.
 
 Bugfixes:
  * Code Generator: Allow ``block.blockhash`` without being called.

test/libsolidity/SolidityEndToEndTest.cpp

@@ -7173,6 +7173,24 @@ BOOST_AUTO_TEST_CASE(cross_contract_types)
 	ABI_CHECK(callContractFunction("f()"), encodeArgs(u256(3)));
 }
 
+BOOST_AUTO_TEST_CASE(cross_contract_constants)
+{
+	char const* sourceCode = R"(
+		contract C {
+			uint constant a = 33 * b + 4;
+			uint constant b = 44;
+		}
+		contract Test {
+			uint constant b = 66;
+			function f() returns (uint r) {
+				r = C.a;
+			}
+		}
+	)";
+	compileAndRun(sourceCode, 0, "Test");
+	ABI_CHECK(callContractFunction("f()"), encodeArgs(u256(1456)));
+}
+
 BOOST_AUTO_TEST_CASE(simple_throw)
 {
 	char const* sourceCode = R"(

test/libsolidity/syntaxTests/constants/access_through_contract_name.sol

@@ -0,0 +1,8 @@
+contract A {
+    uint constant a = 0x1;
+}
+contract C {
+    function f() public pure returns (uint) {
+        return A.a;
+    }
+}

test/libsolidity/syntaxTests/constants/cross_contract_base.sol

@@ -0,0 +1,10 @@
+contract A {
+    uint constant c = 0;
+}
+contract B is A {
+}
+contract C {
+    uint constant c = B.c;
+}
+// ----
+// TypeError: (95-98): Member "c" not found or not visible after argument-dependent lookup in type(contract B)

test/libsolidity/syntaxTests/constants/cross_contract_cyclic_dependency.sol

@@ -0,0 +1,8 @@
+contract A {
+    uint constant c = B.c;
+}
+contract B {
+    uint constant c = A.c;
+}
+// ----
+// Some Error: This should fail with some error!

test/libsolidity/syntaxTests/constants/cross_contract_super.sol

@@ -0,0 +1,10 @@
+contract A {
+    uint constant c = 0;
+}
+contract B is A {
+}
+contract C {
+    uint constant c = B.super.c;
+}
+// ----
+// TypeError: (95-102): Member "super" not found or not visible after argument-dependent lookup in type(contract B)

test/libsolidity/syntaxTests/constants/cross_contract_this.sol

@@ -0,0 +1,8 @@
+contract A {
+    uint constant c = 0;
+}
+contract C {
+    uint constant c = A.this.c;
+}
+// ----
+// TypeError: (75-81): Member "this" not found or not visible after argument-dependent lookup in type(contract A)

test/libsolidity/syntaxTests/constants/no_non_constant_access_through_contract_name.sol

@@ -0,0 +1,10 @@
+contract A {
+    uint a = 0x1;
+}
+contract C {
+    function f() public pure returns (uint) {
+        return A.a;
+    }
+}
+// ----
+// TypeError: (107-110): Member "a" not found or not visible after argument-dependent lookup in type(contract A)