Changelog entry and tests.

Changelog.md

@@ -1,6 +1,7 @@
 ### 0.5.1 (unreleased)
 
 Language Features:
+ * Allow public functions to override external functions.
 
 
 Compiler Features:

test/libsolidity/SolidityEndToEndTest.cpp

@@ -14062,6 +14062,21 @@ BOOST_AUTO_TEST_CASE(flipping_sign_tests)
 	ABI_CHECK(callContractFunction("f()"), encodeArgs(true));
 }
 
+BOOST_AUTO_TEST_CASE(external_public_override)
+{
+	char const* sourceCode = R"(
+		contract A {
+			function f() external returns (uint) { return 1; }
+		}
+		contract B is A {
+			function f() public returns (uint) { return 2; }
+			function g() public returns (uint) { return f(); }
+		}
+	)";
+	compileAndRun(sourceCode);
+	ABI_CHECK(callContractFunction("f()"), encodeArgs(2));
+	ABI_CHECK(callContractFunction("g()"), encodeArgs(2));
+}
 BOOST_AUTO_TEST_SUITE_END()
 
 }

test/libsolidity/syntaxTests/inheritance/override/external_turns_public_no_params.sol

@@ -0,0 +1,7 @@
+contract A {
+    function f() external pure {}
+}
+contract B is A {
+    function f() public pure {
+    }
+}

test/libsolidity/syntaxTests/inheritance/super_on_external.sol

@@ -0,0 +1,10 @@
+contract A {
+    function f() external pure {}
+}
+contract B is A {
+    function f() public pure {
+        super.f();
+    }
+}
+// ----
+// TypeError: (106-113): Member "f" not found or not visible after argument-dependent lookup in contract super B.

test/libsolidity/syntaxTests/nameAndTypeResolution/182_equal_overload.sol

@@ -4,4 +4,3 @@ contract C {
 }
 // ----
 // DeclarationError: (17-66): Function with same name and arguments defined twice.
-// TypeError: (17-66): Overriding function visibility differs.