Added syntax tests for constructors with function parameter

Changelog.md

@@ -12,6 +12,7 @@ Bugfixes:
  * Type Checker: Fix internal error when override specifier is not a contract.
  * SMTChecker: Fix missing type constraints on block and transaction variables in the deployment phase.
  * AST: Added ``referencedDeclaration`` for enum members.
+ * Code Generator: Fix internal error when functions are passed as parameters of other callables, when the function types can be implicitly converted, but not identical.
 
 
 AST Changes:

test/libsolidity/syntaxTests/constructor/constructor_function_parameter_disallowed_conversion.sol

@@ -0,0 +1,59 @@
+contract D {
+    constructor(function() external pure returns (uint) ) {
+    }
+}
+
+library L {
+    function f() public pure returns (uint) {
+        return 5;
+    }
+}
+
+contract C {
+    function f() public returns (uint r) {
+        // An assert used to fail if the function types are not exactly equal (pure, view) v/s
+        // default
+        // ok
+        new D(this.testPure);
+        // not okay
+        new D(this.testView);
+        // not okay
+        new D(this.testDefault);
+        // not okay
+        new D(this.testDifferentSignature);
+        // not okay
+        new D(gasleft);
+        // not okay
+        new D(L.f);
+        // not okay
+        new D(testInternalFunction);
+        // not okay
+        new D(this.testInternalFunction);
+    }
+
+    function testPure() public pure returns (uint) {
+    }
+
+    function testView() public view returns (uint) {
+        block.timestamp;
+    }
+
+    function testDefault() public returns (uint) {
+        selfdestruct(payable(address(this)));
+    }
+
+    function testDifferentSignature(uint a) public pure returns (uint) {
+    }
+
+    function testInternalFunction() internal pure returns (uint) {
+        return 10;
+    }
+}
+// ----
+// TypeError 9553: (415-428): Invalid type for argument in function call. Invalid implicit conversion from function () view external returns (uint256) to function () pure external returns (uint256) requested.
+// TypeError 9553: (465-481): Invalid type for argument in function call. Invalid implicit conversion from function () external returns (uint256) to function () pure external returns (uint256) requested.
+// TypeError 9553: (518-545): Invalid type for argument in function call. Invalid implicit conversion from function (uint256) pure external returns (uint256) to function () pure external returns (uint256) requested.
+// TypeError 9553: (582-589): Invalid type for argument in function call. Invalid implicit conversion from function () view returns (uint256) to function () pure external returns (uint256) requested. Special functions can not be converted to function types.
+// TypeError 9553: (626-629): Invalid type for argument in function call. Invalid implicit conversion from function () pure returns (uint256) to function () pure external returns (uint256) requested. Special functions can not be converted to function types.
+// TypeError 9553: (666-686): Invalid type for argument in function call. Invalid implicit conversion from function () pure returns (uint256) to function () pure external returns (uint256) requested. Special functions can not be converted to function types.
+// TypeError 9582: (723-748): Member "testInternalFunction" not found or not visible after argument-dependent lookup in contract C.

test/libsolidity/syntaxTests/functionTypes/function_parameter_allowed_conversions.sol

@@ -0,0 +1,83 @@
+contract D {
+    constructor(function() external returns (uint)) {
+    }
+}
+
+contract E {
+    function test(function() external returns(uint) f) public returns (uint) {
+        return f();
+    }
+}
+
+library L {
+    function test(function() external returns(uint) f) public returns (uint) {
+        return f();
+    }
+}
+
+contract C {
+    uint x;
+    // tests for usage as constructor parameter
+    function f() public {
+        // An assert used to fail in ABIFunction.cpp that the function types are not exactly equal
+        // that is pure or view v/s default even though they could be converted.
+        new D(this.testPure);
+        new D(this.testView);
+        new D(this.testDefault);
+    }
+
+    // tests for usage as contract function parameter
+    function g() public {
+        E e = E(address(0));
+
+        e.test(this.testPure);
+        e.test(this.testView);
+        e.test(this.testDefault);
+    }
+
+    // tests for usage as library function parameter
+    function h() public {
+        L.test(this.testPure);
+        L.test(this.testView);
+        L.test(this.testDefault);
+    }
+
+    // tests for usage as return parameter
+    function i() public view returns (function() external returns(uint)) {
+        uint value = block.number % 3;
+
+        if (value == 0) {
+            return this.testPure;
+        }
+        else if (value == 1) {
+            return this.testView;
+        }
+        else {
+            return this.testDefault;
+        }
+    }
+
+    modifier mod(function() external returns(uint) fun) {
+        if (fun() == 0) {
+            _;
+        }
+    }
+
+    // tests for usage as modifier parameter
+    function j(function() external pure returns(uint) fun) mod(fun) public {
+    }
+
+    function testPure() public pure returns (uint) {
+        return 0;
+    }
+
+    function testView() public view returns (uint) {
+        return x;
+    }
+
+    function testDefault() public returns (uint) {
+        x = 5;
+        return x;
+    }
+}
+// ----