Merge pull request #69331 from xedin/dont-favor-vars-with-no-direct-bindings

[CSBindings] Don't priorize variables without direct bindings over di…

Author: xedin

lib/Sema/CSBindings.cpp

@@ -1080,6 +1080,10 @@ bool BindingSet::favoredOverDisjunction(Constraint *disjunction) const {
     return boundType->lookThroughAllOptionalTypes()->is<TypeVariableType>();
   }
 
+  // Don't prioritize type variables that don't have any direct bindings.
+  if (Bindings.empty())
+    return false;
+
   return !involvesTypeVariables();
 }
 

test/Constraints/casts.swift

@@ -349,8 +349,8 @@ func test_compatibility_coercions(_ arr: [Int], _ optArr: [Int]?, _ dict: [Strin
   _  = [i: stringAnyDict] as [String: Any] // expected-error {{cannot convert value of type 'Int' to expected dictionary key type 'String'}}
 
   // These are currently not peepholed.
-  _ = [i].self as Magic as [String] // expected-warning {{coercion from '[Int]' to '[String]' may fail; use 'as?' or 'as!' instead}}
-  _ = (try [i]) as Magic as [String] // expected-warning {{coercion from '[Int]' to '[String]' may fail; use 'as?' or 'as!' instead}}
+  _ = [i].self as Magic as [String] // expected-error {{cannot convert value of type 'Int' to expected element type 'String'}}
+  _ = (try [i]) as Magic as [String] // expected-error {{cannot convert value of type 'Int' to expected element type 'String'}}
   // expected-warning@-1 {{no calls to throwing functions occur within 'try' expression}}
 
   // These are wrong, but make sure we don't warn about the value cast always succeeding.
@@ -750,4 +750,4 @@ do {
     _ = a is Issue68825 // expected-error {{cannot find type 'Issue68825' in scope}}
     _ = a is String // OK
   }
-}
+}

test/SILGen/collection_downcast.swift

@@ -297,15 +297,4 @@ func testCollectionCompatibilityCoercions(_ arr: [Int], _ optArr: [Any]?, _ set:
   // CHECK: [[CAST_FN:%.+]] = function_ref @$ss17_dictionaryUpCastySDyq0_q1_GSDyxq_GSHRzSHR0_r2_lF : $@convention(thin) <τ_0_0, τ_0_1, τ_0_2, τ_0_3 where τ_0_0 : Hashable, τ_0_2 : Hashable> (@guaranteed Dictionary<τ_0_0, τ_0_1>) -> @owned Dictionary<τ_0_2, τ_0_3>
   // CHECK: apply [[CAST_FN]]<String, Int, Int, String>([[DICT]]) : $@convention(thin) <τ_0_0, τ_0_1, τ_0_2, τ_0_3 where τ_0_0 : Hashable, τ_0_2 : Hashable> (@guaranteed Dictionary<τ_0_0, τ_0_1>) -> @owned Dictionary<τ_0_2, τ_0_3>
   _ = promote(promote(promote(dict))) as [Int: String]
-
-  typealias Magic<T> = T
-
-  // These are currently not peepholed.
-  // CHECK: [[CAST_FN:%.+]] = function_ref @$ss15_arrayForceCastySayq_GSayxGr0_lF : $@convention(thin) <τ_0_0, τ_0_1> (@guaranteed Array<τ_0_0>) -> @owned Array<τ_0_1>
-  // CHECK: apply [[CAST_FN]]<Int, String>
-  [i].self as Magic as [String]
-
-  // CHECK: [[CAST_FN:%.+]] = function_ref @$ss15_arrayForceCastySayq_GSayxGr0_lF : $@convention(thin) <τ_0_0, τ_0_1> (@guaranteed Array<τ_0_0>) -> @owned Array<τ_0_1>
-  // CHECK: apply [[CAST_FN]]<Int, String>
-  (try [i]) as Magic as [String]
 }