Sema: Disambiguate some more bidirectional conversions

lib/Sema/CSRanking.cpp

@@ -852,7 +852,7 @@ Comparison TypeChecker::compareDeclarations(DeclContext *dc,
   return decl1Better ? Comparison::Better : Comparison::Worse;
 }
 
-static Type getUnlabeledType(Type type, ASTContext &ctx) {
+static Type getStrippedType(Type type, ASTContext &ctx) {
   return type.transformRec([&](TypeBase *type) -> std::optional<Type> {
     if (auto *tupleType = dyn_cast<TupleType>(type)) {
       if (tupleType->getNumElements() == 1)
@@ -866,6 +866,31 @@ static Type getUnlabeledType(Type type, ASTContext &ctx) {
       return TupleType::get(elts, ctx);
     }
 
+    if (auto *funcType = dyn_cast<FunctionType>(type)) {
+      auto params = funcType->getParams();
+      SmallVector<AnyFunctionType::Param, 4> newParams;
+      for (auto param : params) {
+        auto newParam = param;
+        switch (param.getParameterFlags().getOwnershipSpecifier()) {
+        case ParamSpecifier::Borrowing:
+        case ParamSpecifier::Consuming: {
+          auto flags = param.getParameterFlags()
+                            .withOwnershipSpecifier(ParamSpecifier::Default);
+          newParams.push_back(param.withFlags(flags));
+          break;
+        }
+        default:
+          newParams.push_back(newParam);
+          break;
+        }
+      }
+      auto newExtInfo = funcType->getExtInfo().withRepresentation(
+          AnyFunctionType::Representation::Swift);
+      return FunctionType::get(newParams,
+                               funcType->getResult(),
+                               newExtInfo);
+    }
+
     return std::nullopt;
   });
 }
@@ -1060,8 +1085,14 @@ SolutionCompareResult ConstraintSystem::compareSolutions(
     // In this case solver would produce 2 solutions: one where `count`
     // is a property reference on `[Int]` and another one is tuple access
     // for a `count:` element.
-    if (choice1.isDecl() != choice2.isDecl())
+    if (choice1.isDecl() != choice2.isDecl()) {
+      if (cs.isDebugMode()) {
+        llvm::errs().indent(cs.solverState->getCurrentIndent())
+            << "- incomparable\n";
+      }
+
       return SolutionCompareResult::Incomparable;
+    }
 
     auto decl1 = choice1.getDecl();
     auto dc1 = decl1->getDeclContext();
@@ -1438,15 +1469,16 @@ SolutionCompareResult ConstraintSystem::compareSolutions(
       if (type2Better)
         ++score2;
 
-      // Prefer the unlabeled form of a type.
-      auto unlabeled1 = getUnlabeledType(type1, cs.getASTContext());
-      auto unlabeled2 = getUnlabeledType(type2, cs.getASTContext());
-      if (unlabeled1->isEqual(unlabeled2)) {
-        if (type1->isEqual(unlabeled1) && !types.Type1WasLabeled) {
+      // Prefer the "stripped" form of a type. See getStrippedType()
+      // for the definition.
+      auto stripped1 = getStrippedType(type1, cs.getASTContext());
+      auto stripped2 = getStrippedType(type2, cs.getASTContext());
+      if (stripped1->isEqual(stripped2)) {
+        if (type1->isEqual(stripped1) && !types.Type1WasLabeled) {
           ++score1;
           continue;
         }
-        if (type2->isEqual(unlabeled2) && !types.Type2WasLabeled) {
+        if (type2->isEqual(stripped2) && !types.Type2WasLabeled) {
           ++score2;
           continue;
         }
@@ -1527,13 +1559,39 @@ SolutionCompareResult ConstraintSystem::compareSolutions(
 
   // If the scores are different, we have a winner.
   if (score1 != score2) {
-    return score1 > score2? SolutionCompareResult::Better
-                          : SolutionCompareResult::Worse;
+    if (score1 > score2) {
+      if (cs.isDebugMode()) {
+        llvm::errs().indent(cs.solverState->getCurrentIndent())
+            << "- better\n";
+      }
+
+      return SolutionCompareResult::Better;
+    } else {
+      if (cs.isDebugMode()) {
+        llvm::errs().indent(cs.solverState->getCurrentIndent())
+            << "- worse\n";
+      }
+
+      return SolutionCompareResult::Worse;
+    }
   }
 
   // Neither system wins; report whether they were identical or not.
-  return identical? SolutionCompareResult::Identical
-                  : SolutionCompareResult::Incomparable;
+  if (identical) {
+    if (cs.isDebugMode()) {
+      llvm::errs().indent(cs.solverState->getCurrentIndent())
+          << "- identical\n";
+    }
+
+    return SolutionCompareResult::Identical;
+  } else {
+    if (cs.isDebugMode()) {
+      llvm::errs().indent(cs.solverState->getCurrentIndent())
+          << "- incomparable\n";
+    }
+
+    return SolutionCompareResult::Incomparable;
+  }
 }
 
 std::optional<unsigned>

test/Constraints/bidirectional_conversions.swift

@@ -1,8 +1,4 @@
 // RUN: %target-typecheck-verify-swift
-// REQUIRES: objc_interop
-
-import Foundation
-import CoreGraphics
 
 /////////////
 
@@ -20,26 +16,6 @@ func foo2(x: (Int, Int)?, y: (x: Int, y: Int)) -> G<(Int, Int)> {
   return g
 }
 
-func foo3(x: (@convention(block) () -> ())?, y: @escaping () -> ()) -> G<@convention(block) () -> ()> {
-  let g = G(t: x ?? y)
-  return g
-}
-
-func foo4(x: (() -> ())?, y: @escaping @convention(block) () -> ()) -> G<() -> ()> {
-  let g = G(t: x ?? y)
-  return g
-}
-
-func foo5(x: CGFloat?, y: Double) -> G<CGFloat> {
-  let g = G(t: x ?? y)
-  return g
-}
-
-func foo6(x: Double?, y: CGFloat) -> G<Double> {
-  let g = G(t: x ?? y)
-  return g
-}
-
 /////////////
 
 func id<T>(_: T) -> T {}
@@ -54,28 +30,6 @@ func bar2(x: (Int, Int)) {
   f(id(x))
 }
 
-func bar3(x: @escaping () -> ()) {
-  func f(_: @escaping @convention(block) () -> ()) {}
-  // FIXME
-  f(id(x))  // expected-error {{conflicting arguments to generic parameter 'T' ('@convention(block) () -> ()' vs. '() -> ()')}}
-}
-
-func bar4(x: @escaping @convention(block) () -> ()) {
-  func f(_: @escaping () -> ()) {}
-  // FIXME
-  f(id(x))  // expected-error {{conflicting arguments to generic parameter 'T' ('() -> ()' vs. '@convention(block) () -> ()')}}
-}
-
-func bar5(x: Double) {
-  func f(_: CGFloat) {}
-  f(id(x))
-}
-
-func bar6(x: CGFloat) {
-  func f(_: Double) {}
-  f(id(x))
-}
-
 /////////////
 
 func unwrap<T>(_: T?) -> T {}
@@ -90,23 +44,36 @@ func baz2(x: (Int, Int)?) {
   f(unwrap(x))
 }
 
-func baz3(x: (() -> ())?) {
-  func f(_: @escaping @convention(block) () -> ()) {}
-  f(unwrap(x))
+/////////////
+
+func borrowingFn(fn: @escaping (borrowing AnyObject) -> ()) -> (AnyObject) -> () {
+  return id(id(fn))
 }
 
-func baz4(x: (@convention(block) () -> ())?) {
-  func f(_: @escaping () -> ()) {}
-  f(unwrap(x))
+/////////////
+
+infix operator <+
+infix operator >+
+
+protocol P {
+  static func <+ (lhs: borrowing Self, rhs: borrowing Self)
+  static func >+ (lhs: borrowing Self, rhs: borrowing Self)
 }
 
-func baz5(x: Double?) {
-  func f(_: CGFloat) {}
-  f(unwrap(x))
+extension P {
+  static func >+ (lhs: borrowing Self, rhs: borrowing Self) {}
 }
 
-func baz6(x: CGFloat?) {
-  func f(_: Double) {}
-  f(unwrap(x))
+struct S: P {
+  static func <+ (lhs: Self, rhs: Self) {}
+}
+
+let _: (S, S) -> () = false ? (<+) : (>+)
+
+/////////////
+
+struct MyString: Comparable {
+  static func < (lhs: Self, rhs: Self) -> Bool { fatalError() }
 }
 
+let _: (MyString, MyString) -> Bool = false ? (<) : (>)

test/Constraints/bidirectional_conversions_objc.swift

@@ -0,0 +1,79 @@
+// RUN: %target-typecheck-verify-swift
+// REQUIRES: objc_interop
+
+import Foundation
+import CoreGraphics
+
+/////////////
+
+struct G<T> {
+  var t: T
+}
+
+func foo3(x: (@convention(block) () -> ())?, y: @escaping () -> ()) -> G<@convention(block) () -> ()> {
+  let g = G(t: x ?? y)
+  return g
+}
+
+func foo4(x: (() -> ())?, y: @escaping @convention(block) () -> ()) -> G<() -> ()> {
+  let g = G(t: x ?? y)
+  return g
+}
+
+func foo5(x: CGFloat?, y: Double) -> G<CGFloat> {
+  let g = G(t: x ?? y)
+  return g
+}
+
+func foo6(x: Double?, y: CGFloat) -> G<Double> {
+  let g = G(t: x ?? y)
+  return g
+}
+
+/////////////
+
+func id<T>(_: T) -> T {}
+
+func bar3(x: @escaping () -> ()) {
+  func f(_: @escaping @convention(block) () -> ()) {}
+  f(id(x))
+}
+
+func bar4(x: @escaping @convention(block) () -> ()) {
+  func f(_: @escaping () -> ()) {}
+  f(id(x))
+}
+
+func bar5(x: Double) {
+  func f(_: CGFloat) {}
+  f(id(x))
+}
+
+func bar6(x: CGFloat) {
+  func f(_: Double) {}
+  f(id(x))
+}
+
+/////////////
+
+func unwrap<T>(_: T?) -> T {}
+
+func baz3(x: (() -> ())?) {
+  func f(_: @escaping @convention(block) () -> ()) {}
+  f(unwrap(x))
+}
+
+func baz4(x: (@convention(block) () -> ())?) {
+  func f(_: @escaping () -> ()) {}
+  f(unwrap(x))
+}
+
+func baz5(x: Double?) {
+  func f(_: CGFloat) {}
+  f(unwrap(x))
+}
+
+func baz6(x: CGFloat?) {
+  func f(_: Double) {}
+  f(unwrap(x))
+}

test/expr/closure/closures.swift

@@ -551,7 +551,7 @@ do {
   let qux: () -> Void
 
   f(qux)
-  f(id(qux)) // expected-error {{conflicting arguments to generic parameter 'T' ('() -> Void' vs. '@convention(block) () -> Void')}}
+  f(id(qux))
 
   func forceUnwrap<T>(_: T?) -> T {}