Tests for shadowing a builtin

test/libsolidity/semanticTests/literalSuffixes/keccak256_suffix.sol

@@ -0,0 +1,30 @@
+==== Source: builtin.sol ====
+function builtinKeccak(bytes memory input) pure returns (bytes32) {
+    return keccak256(input);
+}
+==== Source: suffix.sol ====
+import {builtinKeccak} from "builtin.sol";
+
+function keccak256(bytes memory input) pure suffix returns (bytes32) {
+    // NOTE: A call to keccak256() here would not call the built-in
+    // and would instead result in infinite recursion.
+    return builtinKeccak(input);
+}
+
+contract C {
+    function testBuiltin() public pure returns (bytes32) {
+        return builtinKeccak("solidity");
+    }
+
+    function testSuffix() public pure returns (bytes32) {
+        return "solidity" keccak256;
+    }
+
+    function testSuffixFunctionCall() public pure returns (bytes32) {
+        return keccak256("solidity");
+    }
+}
+// ----
+// testBuiltin() -> 0xa477d97b122e6356d32a064f9ee824230d42d04c7d66d8e7d125a091a42b0b25
+// testSuffix() -> 0xa477d97b122e6356d32a064f9ee824230d42d04c7d66d8e7d125a091a42b0b25
+// testSuffixFunctionCall() -> 0xa477d97b122e6356d32a064f9ee824230d42d04c7d66d8e7d125a091a42b0b25

test/libsolidity/syntaxTests/literalSuffixes/usableAsSuffix/suffix_function_shadowing_builtin.sol

@@ -0,0 +1 @@
+function keccak256(bytes memory input) pure suffix returns (bytes32) {}