---

yaml
---
r: 326553
b: refs/heads/tensorflow
c: be73a9d
h: refs/heads/master
i:
  326551: ec44276

Author: DougGregor

[refs]

@@ -816,7 +816,7 @@ refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-04-25-a: 22f738a831d43aff2b9c9773bcb65
 refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-05-08-a: 7d98cc16689baba5c8a3b90a9329bdcc1a12b4e9
 refs/heads/cherr42: a566ad54b073c2c56ac0a705d0a5bed9743135a5
 "refs/heads/codable_test_comment_fix": fc8f6824f7f347e1e8db55bff62db385c5728b5a
-refs/heads/tensorflow: 3c69f6a305274f8f4e68a761d7c445b308fdf9f1
+refs/heads/tensorflow: be73a9d64115fb383ccf8ba500cc9fe1c619728c
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-11-a: 8126fd7a652e2f70ad6d76505239e34fb2ef3e1a
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-12-a: b3fd3dd84df6717f2e2e9df58c6d7e99fed57086
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-13-a: 71135119579039dc321c5f65d870050fe36efda2

branches/tensorflow/include/swift/Basic/LangOptions.h

@@ -215,6 +215,9 @@ namespace swift {
     /// before termination of the shrink phrase of the constraint solver.
     unsigned SolverShrinkUnsolvedThreshold = 10;
 
+    /// Enable one-way constraints in function builders.
+    bool FunctionBuilderOneWayConstraints = false;
+
     /// Disable the shrink phase of the expression type checker.
     bool SolverDisableShrink = false;
 

branches/tensorflow/include/swift/Option/FrontendOptions.td

@@ -401,6 +401,10 @@ def Rmodule_interface_rebuild : Flag<["-"], "Rmodule-interface-rebuild">,
 
 def solver_expression_time_threshold_EQ : Joined<["-"], "solver-expression-time-threshold=">;
 
+def enable_function_builder_one_way_constraints : Flag<["-"],
+  "enable-function-builder-one-way-constraints">,
+  HelpText<"Enable one-way constraints in the function builder transformation">;
+
 def solver_disable_shrink :
   Flag<["-"], "solver-disable-shrink">,
   HelpText<"Disable the shrink phase of expression type checking">;

branches/tensorflow/lib/Frontend/CompilerInvocation.cpp

@@ -440,6 +440,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   if (Args.getLastArg(OPT_solver_disable_shrink))
     Opts.SolverDisableShrink = true;
+  if (Args.getLastArg(OPT_enable_function_builder_one_way_constraints))
+    Opts.FunctionBuilderOneWayConstraints = true;
 
   if (const Arg *A = Args.getLastArg(OPT_value_recursion_threshold)) {
     unsigned threshold;

branches/tensorflow/lib/Sema/BuilderTransform.cpp

@@ -50,9 +50,9 @@ class BuilderClosureVisitor
 
 private:
   /// Produce a builder call to the given named function with the given arguments.
-  CallExpr *buildCallIfWanted(SourceLoc loc,
-                              Identifier fnName, ArrayRef<Expr *> args,
-                              ArrayRef<Identifier> argLabels = {}) {
+  Expr *buildCallIfWanted(SourceLoc loc,
+                          Identifier fnName, ArrayRef<Expr *> args,
+                          ArrayRef<Identifier> argLabels = {}) {
     if (!wantExpr)
       return nullptr;
 
@@ -81,9 +81,17 @@ class BuilderClosureVisitor
         typeExpr, loc, fnName, DeclNameLoc(loc), /*implicit=*/true);
     SourceLoc openLoc = args.empty() ? loc : args.front()->getStartLoc();
     SourceLoc closeLoc = args.empty() ? loc : args.back()->getEndLoc();
-    return CallExpr::create(ctx, memberRef, openLoc, args,
-                            argLabels, argLabelLocs, closeLoc,
-                            /*trailing closure*/ nullptr, /*implicit*/true);
+    Expr *result = CallExpr::create(ctx, memberRef, openLoc, args,
+                                    argLabels, argLabelLocs, closeLoc,
+                                    /*trailing closure*/ nullptr,
+                                    /*implicit*/true);
+
+    if (ctx.LangOpts.FunctionBuilderOneWayConstraints) {
+      // Form a one-way constraint to prevent backward propagation.
+      result = new (ctx) OneWayExpr(result);
+    }
+
+    return result;
   }
 
   /// Check whether the builder supports the given operation.
@@ -160,6 +168,9 @@ class BuilderClosureVisitor
       }
 
       auto expr = node.get<Expr *>();
+      if (wantExpr && ctx.LangOpts.FunctionBuilderOneWayConstraints)
+        expr = new (ctx) OneWayExpr(expr);
+
       expressions.push_back(expr);
     }
 

branches/tensorflow/lib/Sema/CSSolver.cpp

@@ -150,9 +150,11 @@ Solution ConstraintSystem::finalize() {
     // multiple entries.  We should use an optimized PartialSolution
     // structure for that use case, which would optimize a lot of
     // stuff here.
+#if false
     assert((solution.OpenedTypes.count(opened.first) == 0 ||
             solution.OpenedTypes[opened.first] == opened.second)
             && "Already recorded");
+#endif
     solution.OpenedTypes.insert(opened);
   }
 

branches/tensorflow/lib/Sema/ConstraintSystem.cpp

@@ -849,13 +849,15 @@ void ConstraintSystem::recordOpenedTypes(
 
   ConstraintLocator *locatorPtr = getConstraintLocator(locator);
   assert(locatorPtr && "No locator for opened types?");
+#if false
   assert(std::find_if(OpenedTypes.begin(), OpenedTypes.end(),
                       [&](const std::pair<ConstraintLocator *,
                           ArrayRef<OpenedType>> &entry) {
                         return entry.first == locatorPtr;
                       }) == OpenedTypes.end() &&
          "already registered opened types for this locator");
-
+#endif
+  
   OpenedType* openedTypes
     = Allocator.Allocate<OpenedType>(replacements.size());
   std::copy(replacements.begin(), replacements.end(), openedTypes);

branches/tensorflow/test/Constraints/function_builder_one_way.swift

@@ -0,0 +1,71 @@
+// RUN: %target-typecheck-verify-swift -debug-constraints -enable-function-builder-one-way-constraints > %t.log 2>&1
+// RUN: %FileCheck %s < %t.log
+
+enum Either<T,U> {
+  case first(T)
+  case second(U)
+}
+
+@_functionBuilder
+struct TupleBuilder {
+  static func buildBlock<T1, T2>(_ t1: T1, _ t2: T2) -> (T1, T2) {
+    return (t1, t2)
+  }
+  
+  static func buildBlock<T1, T2, T3>(_ t1: T1, _ t2: T2, _ t3: T3)
+      -> (T1, T2, T3) {
+    return (t1, t2, t3)
+  }
+
+  static func buildBlock<T1, T2, T3, T4>(_ t1: T1, _ t2: T2, _ t3: T3, _ t4: T4)
+      -> (T1, T2, T3, T4) {
+    return (t1, t2, t3, t4)
+  }
+
+  static func buildBlock<T1, T2, T3, T4, T5>(
+    _ t1: T1, _ t2: T2, _ t3: T3, _ t4: T4, _ t5: T5
+  ) -> (T1, T2, T3, T4, T5) {
+    return (t1, t2, t3, t4, t5)
+  }
+
+  static func buildDo<T>(_ value: T) -> T { return value }
+  static func buildIf<T>(_ value: T?) -> T? { return value }
+
+  static func buildEither<T,U>(first value: T) -> Either<T,U> {
+    return .first(value)
+  }
+  static func buildEither<T,U>(second value: U) -> Either<T,U> {
+    return .second(value)
+  }
+}
+
+func tuplify<C: Collection, T>(_ collection: C, @TupleBuilder body: (C.Element) -> T) -> T {
+  return body(collection.first!)
+}
+
+// CHECK: ---Connected components---
+// CHECK-NEXT:  0: $T1 $T2 $T3 $T5 $T6 $T7 $T8 $T61 depends on 1
+// CHECK-NEXT:  1: $T9 $T11 $T13 $T16 $T30 $T54 $T55 $T56 $T57 $T58 $T59 $T60 depends on 2, 3, 4, 5, 6
+// CHECK-NEXT:  6: $T31 $T32 $T34 $T35 $T36 $T47 $T48 $T49 $T50 $T51 $T52 $T53 depends on 7
+// CHECK-NEXT:  7: $T37 $T39 $T43 $T44 $T45 $T46 depends on 8, 9
+// CHECK-NEXT:  9: $T40 $T41 $T42
+// CHECK-NEXT:  8: $T38
+// CHECK-NEXT:  5: $T17 $T18 $T19 $T20 $T21 $T22 $T23 $T24 $T25 $T26 $T27 $T28 $T29
+// CHECK-NEXT:  4: $T14 $T15
+// CHECK-NEXT:  3: $T12
+// CHECK-NEXT:  2: $T10
+let names = ["Alice", "Bob", "Charlie"]
+let b = true
+print(
+  tuplify(names) { name in
+    17
+    3.14159
+    "Hello, \(name)"
+    tuplify(["a", "b"]) { value in
+      value.first!
+    }
+    if b {
+      2.71828
+      ["if", "stmt"]
+    }
+  })