Tests for suffixes making external calls

test/libsolidity/semanticTests/literalSuffixes/suffix_making_pure_external_call.sol

@@ -0,0 +1,37 @@
+function suffix(int32 x) pure suffix returns (int32) {
+    return loadNegator().negate(x);
+}
+
+interface INegator {
+    function negate(int32) external pure returns (int32);
+}
+
+contract Negator is INegator {
+    function negate(int32 x) external pure override returns (int32) {
+        return -x;
+    }
+}
+
+function storeNegator(INegator negator) pure {
+    assembly {
+        // this test would also work without assembly if we could hard-code an address here.
+        mstore(0, negator)
+    }
+}
+
+function loadNegator() pure returns (INegator negator) {
+    assembly {
+        negator := mload(0)
+    }
+}
+
+contract C {
+    function testSuffix() public returns (int32) {
+        storeNegator(new Negator());
+
+        return 10 suffix;
+    }
+}
+// ----
+// testSuffix() -> -10
+// gas legacy: 131793

test/libsolidity/semanticTests/literalSuffixes/suffix_making_view_external_call.sol

@@ -0,0 +1,41 @@
+function suffix(int32 x) pure suffix returns (int32) {
+    return loadNegator().negate(x);
+}
+
+interface INegatorPure {
+    function negate(int32) external pure returns (int32);
+}
+
+interface INegatorView {
+    function negate(int32) external view returns (int32);
+}
+
+contract Negator is INegatorView {
+    function negate(int32 x) external view override returns (int32) {
+        return -x;
+    }
+}
+
+function storeNegator(INegatorView negator) pure {
+    assembly {
+        // this test would also work without assembly if we could hard-code an address here.
+        mstore(0, negator)
+    }
+}
+
+function loadNegator() pure returns (INegatorPure negator) {
+    assembly {
+        negator := mload(0)
+    }
+}
+
+contract C {
+    function testSuffix() public returns (int32) {
+        storeNegator(new Negator());
+
+        return 10 suffix;
+    }
+}
+// ----
+// testSuffix() -> -10
+// gas legacy: 131793