Merge pull request #9366 from slavapestov/fix-two-diagnostics-crashers

Fix two diagnostics crashers

Author: slavapestov

lib/Sema/CSDiag.cpp

@@ -325,13 +325,17 @@ static DeclName getOverloadChoiceName(ArrayRef<OverloadChoice> choices) {
 
 /// Returns true if any diagnostics were emitted.
 static bool
-tryDiagnoseTrailingClosureAmbiguity(TypeChecker &tc, const Expr *expr,
+tryDiagnoseTrailingClosureAmbiguity(TypeChecker &tc,
+                                    const Expr *expr,
+                                    const Expr *anchor,
                                     ArrayRef<OverloadChoice> choices) {
   auto *callExpr = dyn_cast<CallExpr>(expr);
   if (!callExpr)
     return false;
   if (!callExpr->hasTrailingClosure())
     return false;
+  if (callExpr->getFn() != anchor)
+    return false;
 
   llvm::SmallMapVector<Identifier, const ValueDecl *, 8> choicesByLabel;
   for (const OverloadChoice &choice : choices) {
@@ -465,7 +469,7 @@ static bool diagnoseAmbiguity(ConstraintSystem &cs,
                                   : diag::ambiguous_decl_ref,
                 name);
 
-    if (tryDiagnoseTrailingClosureAmbiguity(tc, expr, overload.choices))
+    if (tryDiagnoseTrailingClosureAmbiguity(tc, expr, anchor, overload.choices))
       return true;
 
     // Emit candidates.  Use a SmallPtrSet to make sure only emit a particular

lib/Sema/CSGen.cpp

@@ -2672,8 +2672,12 @@ namespace {
       // Compute the type to which the source must be converted to allow
       // assignment to the destination.
       auto destTy = CS.computeAssignDestType(expr->getDest(), expr->getLoc());
-      if (!destTy || destTy->getRValueType()->is<UnresolvedType>())
+      if (!destTy)
         return Type();
+      if (destTy->getRValueType()->is<UnresolvedType>()) {
+        return CS.createTypeVariable(CS.getConstraintLocator(expr),
+                                     TVO_CanBindToLValue);
+      }
 
       // The source must be convertible to the destination.
       CS.addConstraint(ConstraintKind::Conversion,

test/Constraints/diagnostics.swift

@@ -931,3 +931,12 @@ let _ = (r29850459() ? r29850459_a : r29850459_b) + 42.0 // expected-error {{bin
 // expected-note@-1 {{overloads for '+' exist with these partially matching parameter lists: (Double, Double), (Int, Int), (Int, UnsafeMutablePointer<Pointee>), (Int, UnsafePointer<Pointee>)}}
 let _ = ((r29850459_flag || r29850459()) ? r29850459_a : r29850459_b) + 42.0 // expected-error {{binary operator '+' cannot be applied to operands of type 'Int' and 'Double'}}
 // expected-note@-1 {{overloads for '+' exist with these partially matching parameter lists: (Double, Double), (Int, Int), (Int, UnsafeMutablePointer<Pointee>), (Int, UnsafePointer<Pointee>)}}
+
+// Ambiguous overload inside a trailing closure
+
+func ambiguousCall() -> Int {} // expected-note {{found this candidate}}
+func ambiguousCall() -> Float {} // expected-note {{found this candidate}}
+
+func takesClosure(fn: () -> ()) {}
+
+takesClosure() { ambiguousCall() } // expected-error {{ambiguous use of 'ambiguousCall()'}}

test/Constraints/lvalues.swift

@@ -232,3 +232,13 @@ func r23331567(_ fn: (_ x: inout Int) -> Void) {
 }
 r23331567 { $0 += 1 }
 
+// <rdar://problem/30685195> Compiler crash with invalid assignment
+struct G<T> {
+  subscript(x: Int) -> T { get { } nonmutating set { } }
+  // expected-note@-1 {{'subscript' declared here}}
+}
+
+func wump<T>(to: T, _ body: (G<T>) -> ()) {}
+
+wump(to: 0, { $0[] = 0 })
+// expected-error@-1 {{missing argument for parameter #1 in call}}