More strict override check for data locations.

test/libsolidity/semanticTests/inheritance/dataLocation/external_public_calldata.sol

@@ -0,0 +1,18 @@
+abstract contract A {
+    function f(uint256[] calldata a) external virtual returns (uint256[] calldata);
+}
+
+contract B is A {
+    function f(uint256[] memory a) public override returns (uint256[] memory) {
+        return a;
+    }
+
+    function g(uint[] calldata x) public returns (uint256[] memory) {
+        return f(x);
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f(uint256[]): 0x20, 2, 9, 8 -> 0x20, 2, 9, 8
+// g(uint256[]): 0x20, 2, 9, 8 -> 0x20, 2, 9, 8

test/libsolidity/syntaxTests/inheritance/dataLocation/external_overriding_external.sol

@@ -0,0 +1,14 @@
+abstract contract A {
+    function f(uint256[1] memory a) external virtual returns (uint256);
+}
+contract B is A {
+    function f(uint256[1] calldata a) external pure virtual override returns (uint256) {
+        return a[0];
+    }
+}
+contract C is A, B {
+    function f(uint256[1] memory a) external pure override(B, A) returns (uint256) {
+        return a[0];
+    }
+}
+// ----

test/libsolidity/syntaxTests/inheritance/dataLocation/modifier_parameter_data_location_change_illegal_internal.sol

@@ -0,0 +1,13 @@
+abstract contract A {
+    modifier m(uint256[1] memory a) virtual;
+    function test(uint256[1] memory a) m(a) external {
+    }
+}
+
+contract B is A {
+    modifier m(uint256[1] calldata a) override {
+        _;
+    }
+}
+// ----
+// TypeError 1078: (153-214): Override changes modifier signature.

test/libsolidity/syntaxTests/inheritance/dataLocation/parameter_data_location_change_calldata_memory_illegal_public.sol

@@ -0,0 +1,11 @@
+abstract contract A {
+    function f(uint256[1] calldata a) public virtual returns (uint256);
+}
+
+contract B is A {
+    function f(uint256[1] memory a) public override returns (uint256) {
+        return a[0];
+    }
+}
+// ----
+// TypeError 7723: (119-213): Data locations of parameters have to be the same when overriding non-external functions, but they differ.

test/libsolidity/syntaxTests/inheritance/dataLocation/parameter_data_location_change_illegal_internal.sol

@@ -0,0 +1,16 @@
+abstract contract A {
+    function f(uint256[1] memory a) internal virtual returns (uint256);
+    function test() external returns (uint) {
+        uint[1] memory t;
+        t[0] = 7;
+        return f(t);
+    }
+}
+
+contract B is A {
+    function f(uint256[1] calldata a) internal override returns (uint256) {
+        return a[0];
+    }
+}
+// ----
+// TypeError 7723: (236-334): Data locations of parameters have to be the same when overriding non-external functions, but they differ.

test/libsolidity/syntaxTests/inheritance/dataLocation/parameter_data_location_change_illegal_public.sol

@@ -0,0 +1,16 @@
+abstract contract A {
+    function f(uint256[1] memory a) public virtual returns (uint256);
+    function test() external returns (uint) {
+        uint[1] memory t;
+        t[0] = 7;
+        return f(t);
+    }
+}
+
+contract B is A {
+    function f(uint256[1] calldata a) public override returns (uint256) {
+        return a[0];
+    }
+}
+// ----
+// TypeError 7723: (234-330): Data locations of parameters have to be the same when overriding non-external functions, but they differ.

test/libsolidity/syntaxTests/inheritance/dataLocation/return_type_data_location.sol

@@ -0,0 +1,7 @@
+abstract contract A {
+	function foo() external virtual view returns(uint[] calldata);
+}
+contract X is A {
+	function foo() public view override returns(uint[] memory) {  }
+}
+// ----

test/libsolidity/syntaxTests/inheritance/dataLocation/return_type_data_location_change_illegal.sol

@@ -0,0 +1,8 @@
+abstract contract A {
+	function foo() public virtual view returns(uint[] calldata);
+}
+contract X is A {
+	function foo() public view override returns(uint[] memory) {  }
+}
+// ----
+// TypeError 1443: (105-168): Data locations of return variables have to be the same when overriding non-external functions, but they differ.