[interop] expand std.pair tests after non-trivial record fix

Author: hyp

test/Interop/Cxx/stdlib/Inputs/std-pair.h

@@ -4,8 +4,22 @@
 
 using PairInts = std::pair<int, int>;
 
-// FIXME: return pair by value, but it causes IRGen crash atm.
-inline const PairInts &getIntPair() {
-    static PairInts value = { -5, 12 };
+inline const PairInts &getIntPairPointer() {
+    static PairInts value = { 4, 9 };
     return value;
 }
+
+inline PairInts getIntPair() {
+    return { -5, 12 };
+}
+
+struct StructInPair {
+    int x;
+    int y;
+};
+
+using PairStructInt = std::pair<StructInPair, int>;
+
+inline PairStructInt getPairStructInt(int x) {
+    return { { x * 2, -x}, x };
+}

test/Interop/Cxx/stdlib/use-std-pair.swift

@@ -12,12 +12,25 @@ import Cxx
 var StdPairTestSuite = TestSuite("StdPair")
 
 StdPairTestSuite.test("StdPair.elements") {
-  var pi = getIntPair().pointee
+  var pi = getIntPair()
   expectEqual(pi.first, -5)
   expectEqual(pi.second, 12)
   pi.first = 11
   expectEqual(pi.first, 11)
   expectEqual(pi.second, 12)
 }
 
+StdPairTestSuite.test("StdPair.ref.elements") {
+  let pi = getIntPairPointer().pointee
+  expectEqual(pi.first, 4)
+  expectEqual(pi.second, 9)
+}
+
+StdPairTestSuite.test("PairStructInt.elements") {
+  let pair = getPairStructInt(11)
+  expectEqual(pair.first.x, 22)
+  expectEqual(pair.first.y, -11)
+  expectEqual(pair.second, 11)
+}
+
 runAllTests()