Merge pull request #4898 from DougGregor/tuple-casting

Runtime/standard library: fix tuple printing, reflection, and casting

Author: DougGregor

stdlib/public/core/OutputStream.swift

@@ -270,16 +270,24 @@ internal func _adHocPrint_unlocked<T, TargetStream : TextOutputStream>(
       case .tuple:
         target.write("(")
         var first = true
-        for (_, value) in mirror.children {
+        for (label, value) in mirror.children {
           if first {
             first = false
           } else {
             target.write(", ")
           }
+
+          if let label = label {
+            if !label.isEmpty && label[label.startIndex] != "." {
+              target.write(label)
+              target.write(": ")
+            }
+          }
+
           _debugPrint_unlocked(value, &target)
         }
         target.write(")")
-      case .`struct`:
+      case .struct:
         printTypeName(mirror.subjectType)
         target.write("(")
         var first = true
@@ -296,7 +304,7 @@ internal func _adHocPrint_unlocked<T, TargetStream : TextOutputStream>(
           }
         }
         target.write(")")
-      case .`enum`:
+      case .enum:
         if let cString = _getEnumCaseName(value),
             let caseName = String(validatingUTF8: cString) {
           // Write the qualified type name in debugPrint.

stdlib/public/runtime/Casting.cpp

@@ -2513,6 +2513,7 @@ static bool _dynamicCastTupleToTuple(OpaqueValue *destination,
   // Check that the elements line up.
   const char *sourceLabels = sourceType->Labels;
   const char *targetLabels = targetType->Labels;
+  bool anyTypeMismatches = false;
   for (unsigned i = 0, n = sourceType->NumElements; i != n; ++i) {
     // Check the label, if there is one.
     if (sourceLabels && targetLabels && sourceLabels != targetLabels) {
@@ -2533,13 +2534,74 @@ static bool _dynamicCastTupleToTuple(OpaqueValue *destination,
       targetLabels = targetSpace ? targetSpace + 1 : nullptr;
     }
 
-    // Make sure the types match exactly.
-    // FIXME: we should dynamically cast the elements themselves.
+    // If the types don't match exactly, make a note of it. We'll try to
+    // convert them in a second pass.
     if (sourceType->getElement(i).Type != targetType->getElement(i).Type)
-      return _fail(source, sourceType, targetType, flags);
+      anyTypeMismatches = true;
+  }
+
+  // If there were no type mismatches, the only difference was in the argument
+  // labels. We can directly map from the source to the destination type.
+  if (!anyTypeMismatches)
+    return _succeed(destination, source, targetType, flags);
+
+  // Determine how the individual elements will get casted.
+  // If both success and failure will destroy the source, then
+  // we can be destructively cast each element. Otherwise, we'll have to
+  // manually handle them.
+  const DynamicCastFlags alwaysDestroySourceFlags =
+    DynamicCastFlags::TakeOnSuccess | DynamicCastFlags::DestroyOnFailure;
+  bool alwaysDestroysSource =
+    (static_cast<DynamicCastFlags>(flags & alwaysDestroySourceFlags)
+       == alwaysDestroySourceFlags);
+  DynamicCastFlags elementFlags = flags;
+  if (!alwaysDestroysSource)
+    elementFlags = elementFlags - alwaysDestroySourceFlags;
+
+  // Local function to destroy the elements in the range [start, end).
+  auto destroyRange = [](const TupleTypeMetadata *type, OpaqueValue *value,
+                        unsigned start, unsigned end) {
+    assert(start <= end && "invalid range in destroyRange");
+    for (unsigned i = start; i != end; ++i) {
+      const auto &elt = type->getElement(i);
+      elt.Type->vw_destroy(elt.findIn(value));
+    }
+  };
+
+  // Cast each element.
+  for (unsigned i = 0, n = sourceType->NumElements; i != n; ++i) {
+    // Cast the element. If it succeeds, keep going.
+    const auto &sourceElt = sourceType->getElement(i);
+    const auto &targetElt = targetType->getElement(i);
+    if (swift_dynamicCast(targetElt.findIn(destination),
+                          sourceElt.findIn(source),
+                          sourceElt.Type, targetElt.Type, elementFlags))
+      continue;
+
+    // Casting failed, so clean up.
+
+    // Destroy all of the elements that got casted into the destination buffer.
+    destroyRange(targetType, destination, 0, i);
+
+    // If we're supposed to destroy on failure, destroy any elements from the
+    // source buffer that haven't been destroyed/taken from yet.
+    if (flags & DynamicCastFlags::DestroyOnFailure)
+      destroyRange(sourceType, source, alwaysDestroysSource ? i : 0, n);
+
+    // If an unconditional cast failed, complain.
+    if (flags & DynamicCastFlags::Unconditional)
+      swift_dynamicCastFailure(sourceType, targetType);
+    return false;
   }
 
-  return _succeed(destination, source, targetType, flags);
+  // Casting succeeded.
+
+  // If we were supposed to take on success from the source buffer but couldn't
+  // before, destroy the source buffer now.
+  if (!alwaysDestroysSource && (flags & DynamicCastFlags::TakeOnSuccess))
+    destroyRange(sourceType, source, 0, sourceType->NumElements);
+
+  return true;
 }
 
 /******************************************************************************/

stdlib/public/runtime/Reflection.mm

@@ -372,12 +372,30 @@ void swift_TupleMirror_subscript(String *outString,
 
   if (i < 0 || (size_t)i > Tuple->NumElements)
     swift::crash("Swift mirror subscript bounds check failure");
-  
-  // The name is the stringized element number '.0'.
-  char buf[32];
-  snprintf(buf, sizeof(buf), ".%zd", i);
-  new (outString) String(buf, strlen(buf));
-  
+
+  // Determine whether there is a label.
+  bool hasLabel = false;
+  if (const char *labels = Tuple->Labels) {
+    const char *space = strchr(labels, ' ');
+    for (intptr_t j = 0; j != i && space; ++j) {
+      labels = space + 1;
+      space = strchr(labels, ' ');
+    }
+
+    // If we have a label, create it.
+    if (labels && space && labels != space) {
+      new (outString) String(labels, space - labels);
+      hasLabel = true;
+    }
+  }
+
+  if (!hasLabel) {
+    // The name is the stringized element number '.0'.
+    char buf[32];
+    snprintf(buf, sizeof(buf), ".%zd", i);
+    new (outString) String(buf, strlen(buf));
+  }
+
   // Get a Mirror for the nth element.
   auto &elt = Tuple->getElement(i);
   auto bytes = reinterpret_cast<const char*>(value);

test/Interpreter/tuple_casts.swift

@@ -1,8 +1,12 @@
-// RUN: %target-run-simple-swift | %FileCheck %s
+// RUN: %target-run-simple-swift
 // RUN: %target-build-swift -O %s -o %t/a.out.optimized
-// RUN: %target-run %t/a.out.optimized | %FileCheck %s
+// RUN: %target-run %t/a.out.optimized
 // REQUIRES: executable_test
 
+import StdlibUnittest
+
+let tupleCastTests = TestSuite("Tuple casting")
+
 func anyToIntPoint(_ x: Any) -> (x: Int, y: Int) {
   return x as! (x: Int, y: Int)
 }
@@ -15,16 +19,126 @@ func anyToInt2(_ x: Any) -> (Int, Int) {
   return x as! (Int, Int)
 }
 
-// Labels can be added/removed.
-print("Label add/remove")          // CHECK: Label add/remove
-print(anyToIntPoint((x: 1, y: 2))) // CHECK-NEXT: (1, 2)
-print(anyToIntPoint((3, 4)))       // CHECK-NEXT: (3, 4)
-print(anyToIntPoint((x: 5, 6)))    // CHECK-NEXT: (5, 6)
-print(anyToInt2((1, 2)))           // CHECK-NEXT: (1, 2)
-print(anyToInt2((x: 3, y: 4)))     // CHECK-NEXT: (3, 4)
-print(anyToInt2((x: 5, 6)))        // CHECK-NEXT: (5, 6)
+func anyToPartlyLabeled(_ x: Any) -> (first: Int, Int, third: Int) {
+  return x as! (first: Int, Int, third: Int)
+}
+
+tupleCastTests.test("Adding/removing labels") {
+  expectEqual("(x: 1, y: 2)",
+              String(describing: anyToIntPoint((x: 1, y: 2))))
+  expectEqual("(x: 3, y: 4)",
+              String(describing: anyToIntPoint((3, 4))))
+  expectEqual("(x: 5, y: 6)",
+              String(describing: anyToIntPoint((x: 5, 6))))
+
+  expectEqual("(1, 2)", String(describing: anyToInt2((1, 2))))
+  expectEqual("(3, 4)", String(describing: anyToInt2((x: 3, y: 4))))
+  expectEqual("(5, 6)", String(describing: anyToInt2((x: 5, 6))))
+
+  expectEqual("(first: 1, 2, third: 3)",
+              String(describing: anyToPartlyLabeled((1, 2, 3))))
+}
+
+tupleCastTests.test("Incorrect labels conditional cast") {
+  expectNil(anyToIntPointOpt((x: 1, z: 2)))
+  expectEqual("Optional((x: 1, y: 2))",
+              String(describing: anyToIntPointOpt((x: 1, y: 2))))
+}
+
+tupleCastTests
+  .test("Incorrect labels forced cast")
+  .crashOutputMatches("Could not cast value of type '(x: Swift.Int, z: Swift.Int)'")
+  .code {
+  expectCrashLater()
+  _ = anyToIntPoint((x: 1, z: 2))
+}
+
+func castToThree<T, U, V>(_ x: Any, _: T.Type, _: U.Type, _: V.Type)
+    -> (t: T, u: U, v: V) {
+  return x as! (t: T, u: U, v: V)
+}
+
+func castToThreeOpt<T, U, V>(_ x: Any, _: T.Type, _: U.Type, _: V.Type)
+    -> (t: T, u: U, v: V)? {
+  return x as? (t: T, u: U, v: V)
+}
+
+class LifetimeA {
+  var tracked: LifetimeTracked
+
+  init(value: Int) { 
+    tracked = LifetimeTracked(value)
+  }
+}
+
+class LifetimeB : LifetimeA {
+}
+
+class LifetimeC : LifetimeA {
+}
+
+protocol P { }
+extension LifetimeA : P { }
+
+tupleCastTests.test("Elementwise tuple casts that succeed") {
+  let abc: (P, Any, P) = (LifetimeA(value: 1),
+                          LifetimeB(value: 2),
+                          LifetimeC(value: 3))
+
+  expectEqual(
+    "(t: main.LifetimeA, u: main.LifetimeB, v: main.LifetimeC)",
+    String(describing: castToThree(abc, LifetimeA.self, LifetimeA.self,
+                                   LifetimeA.self)))
+
+  expectEqual(
+    "(t: main.LifetimeA, u: main.LifetimeB, v: main.LifetimeC)",
+    String(describing: castToThree((LifetimeA(value: 1),
+                                    LifetimeB(value: 2),
+                                    LifetimeC(value: 3)) as (P, Any, P),
+                                   LifetimeA.self, LifetimeA.self,
+                                   LifetimeA.self)))
+}
+
+tupleCastTests.test("Elementwise tuple casts that conditionally fail") {
+  let abc: (P, Any, P) = (LifetimeA(value: 1),
+                          LifetimeB(value: 2),
+                          LifetimeC(value: 3))
+  expectNil(castToThreeOpt(abc, LifetimeA.self, LifetimeB.self, LifetimeB.self))
+  expectNil(castToThreeOpt(abc, LifetimeA.self, LifetimeC.self, LifetimeC.self))
+  expectNil(castToThreeOpt(abc, LifetimeC.self, LifetimeB.self, LifetimeC.self))
+}
+
+tupleCastTests
+  .test("Elementwise tuple casts that crash (1/3)")
+  .crashOutputMatches("Could not cast value of type 'main.LifetimeA'")
+  .code {
+  let abc: (P, Any, P) = (LifetimeA(value: 1),
+                          LifetimeB(value: 2),
+                          LifetimeC(value: 3))
+  expectCrashLater()
+  _ = castToThree(abc, LifetimeC.self, LifetimeB.self, LifetimeC.self)
+}
+
+tupleCastTests
+  .test("Elementwise tuple casts that crash (2/3)")
+  .crashOutputMatches("Could not cast value of type 'main.LifetimeB")
+  .code {
+  let abc: (P, Any, P) = (LifetimeA(value: 1),
+                          LifetimeB(value: 2),
+                          LifetimeC(value: 3))
+  expectCrashLater()
+  _ = castToThree(abc, LifetimeA.self, LifetimeC.self, LifetimeC.self)
+}
+
+tupleCastTests
+  .test("Elementwise tuple casts that crash (3/3)")
+  .crashOutputMatches("Could not cast value of type 'main.LifetimeC")
+  .code {
+  let abc: (P, Any, P) = (LifetimeA(value: 1),
+                          LifetimeB(value: 2),
+                          LifetimeC(value: 3))
+  expectCrashLater()
+  _ = castToThree(abc, LifetimeA.self, LifetimeB.self, LifetimeB.self)
+}
 
-// Labels cannot be wrong.
-print("Wrong labels")                 // CHECK: Wrong labels
-print(anyToIntPointOpt((x: 1, z: 2))) // CHECK-NEXT: nil
-print(anyToIntPointOpt((x: 1, y: 2))) // CHECK-NEXT: Optional((1, 2))
+runAllTests()

test/stdlib/DebuggerSupport.swift

@@ -78,7 +78,8 @@ StringForPrintObjectTests.test("Array") {
 
 StringForPrintObjectTests.test("Dictionary") {
   let printed = _DebuggerSupport.stringForPrintObject([1:2])
-  expectEqual(printed, "▿ 1 element\n  ▿ 0 : 2 elements\n    - .0 : 1\n    - .1 : 2\n")
+  expectEqual("▿ 1 element\n  ▿ 0 : 2 elements\n    - key : 1\n    - value : 2\n",
+              printed)
 }
 
 StringForPrintObjectTests.test("NilOptional") {

test/stdlib/Mirror.swift

@@ -653,10 +653,10 @@ mirrors.test("Addressing") {
   expectEqual(2, m0.descendant(1) as? Int)
   expectEqual(3, m0.descendant(2) as? Int)
 
-  let m1 = Mirror(reflecting: (a: ["one", "two", "three"], b: 4))
+  let m1 = Mirror(reflecting: (a: ["one", "two", "three"], 4))
   let ott0 = m1.descendant(0) as? [String]
   expectNotNil(ott0)
-  let ott1 = m1.descendant(".0") as? [String]
+  let ott1 = m1.descendant("a") as? [String]
   expectNotNil(ott1)
   if ott0 != nil && ott1 != nil {
     expectEqualSequence(ott0!, ott1!)
@@ -666,7 +666,7 @@ mirrors.test("Addressing") {
   expectEqual("one", m1.descendant(0, 0) as? String)
   expectEqual("two", m1.descendant(0, 1) as? String)
   expectEqual("three", m1.descendant(0, 2) as? String)
-  expectEqual("one", m1.descendant(".0", 0) as? String)
+  expectEqual("one", m1.descendant("a", 0) as? String)
 
   struct Zee : CustomReflectable {
     var customMirror: Mirror {
@@ -680,7 +680,7 @@ mirrors.test("Addressing") {
     (a: [], b: Zee())]
 
   let m = Mirror(reflecting: x)
-  let two = m.descendant(0, ".0", 1)
+  let two = m.descendant(0, "a", 1)
   expectEqual("two", two as? String)
   expectEqual(1, m.descendant(1, 1, "bark") as? Int)
   expectEqual(0, m.descendant(1, 1, "bite") as? Int)