Merge pull request #16288 from nathawes/rdar38153332-code-completion-hits-unreachable-in-matchtypes-4.2

Author: swift-ci

lib/IDE/CodeCompletion.cpp

@@ -939,10 +939,15 @@ static CodeCompletionResult::ExpectedTypeRelation calculateTypeRelation(
       Ty->is<ErrorType>() ||
       ExpectedTy->is<ErrorType>())
     return CodeCompletionResult::ExpectedTypeRelation::Unrelated;
-  if (Ty->isEqual(ExpectedTy))
-    return CodeCompletionResult::ExpectedTypeRelation::Identical;
-  if (isConvertibleTo(Ty, ExpectedTy, *DC))
-    return CodeCompletionResult::ExpectedTypeRelation::Convertible;
+
+  // Equality/Conversion of GenericTypeParameterType won't account for
+  // requirements – ignore them
+  if (!Ty->hasTypeParameter() && !ExpectedTy->hasTypeParameter()) {
+    if (Ty->isEqual(ExpectedTy))
+      return CodeCompletionResult::ExpectedTypeRelation::Identical;
+    if (isConvertibleTo(Ty, ExpectedTy, *DC))
+      return CodeCompletionResult::ExpectedTypeRelation::Convertible;
+  }
   if (auto FT = Ty->getAs<AnyFunctionType>()) {
     if (FT->getResult()->isVoid())
       return CodeCompletionResult::ExpectedTypeRelation::Invalid;

test/IDE/complete_call_arg.swift

@@ -45,6 +45,8 @@
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=BOUND_IUO | %FileCheck %s -check-prefix=MEMBEROF_IUO
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=FORCED_IUO | %FileCheck %s -check-prefix=MEMBEROF_IUO
 
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=GENERIC_TO_GENERIC | %FileCheck %s -check-prefix=GENERIC_TO_GENERIC
+
 var i1 = 1
 var i2 = 2
 var oi1 : Int?
@@ -373,6 +375,14 @@ struct TestBoundGeneric1 {
 // BOUND_GENERIC_1: Decl[InstanceVar]/CurrNominal:      y[#[Int]#];
 }
 
+func whereConvertible<T>(lhs: T, rhs: T) where T: Collection {
+  _ = zip(lhs, #^GENERIC_TO_GENERIC^#)
+}
+// GENERIC_TO_GENERIC: Begin completions
+// GENERIC_TO_GENERIC: Decl[LocalVar]/Local: lhs[#Collection#]; name=lhs
+// GENERIC_TO_GENERIC: Decl[LocalVar]/Local: rhs[#Collection#]; name=rhs
+// GENERIC_TO_GENERIC: End completions
+
 func emptyOverload() {}
 func emptyOverload(foo foo: Int) {}
 emptyOverload(foo: #^EMPTY_OVERLOAD_1^#)