enforce interface-functions to be external-declared

- libsolidity: Enforce interface-functions must be external-declared.
- Changelog adapted to reflect changes wrt. functions in interfaces.
- test: Adjustments according to prior interface-function changes.
- tests: Adapting SolidityEndToEndTest to interface-function change.
- docs: Adapted documentation to interface-function change.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp
index bee83007..1427826e 100644
--- a/test/libsolidity/SolidityEndToEndTest.cpp
+++ b/test/libsolidity/SolidityEndToEndTest.cpp
@@ -11649,7 +11649,7 @@ BOOST_AUTO_TEST_CASE(interface_contract)
 	char const* sourceCode = R"(
 		interface I {
 			event A();
-			function f() public returns (bool);
+			function f() external returns (bool);
 			function() external payable;
 		}