[CodeCompletion] Pre-remove argument labels from function types

Before checking type relation between candidate types and expected
types. In normal compilation, this removal is done in CSGen. However,
since code-completion directly uses Constraint System, we have to
manually remove argument labels before checking convertibility.

We can remove argument labels unconditionally because function types as
as value cannot have argument labels. (i.e. `let f: (a: Int) -> Int` is
illegal). That means, expected types shouldn't have any argument labels.

This fixes regression revealed in 5e75b1a
rdar://problem/41496748

Author: rintaro

lib/IDE/CodeCompletion.cpp

@@ -973,6 +973,7 @@ calculateTypeRelationForDecl(const Decl *D, Type ExpectedType,
         !IsImplicitlyCurriedInstanceMethod)
       funcType = funcType->getResult()->getAs<AnyFunctionType>();
     if (funcType) {
+      funcType = funcType->removeArgumentLabels(1)->castTo<AnyFunctionType>();
       auto relation = calculateTypeRelation(funcType, ExpectedType, DC);
       if (UseFuncResultType)
         relation =

test/IDE/complete_func_reference.swift

@@ -122,7 +122,7 @@ do {
 }
 
 // ANY_INT: Begin completions
-// ANY_INT-DAG: Decl{{.*}}:      anyToInt({#a: Any#})[#Int#]; name=anyToInt(a: Any)
+// ANY_INT_DAG: Decl{{.*}}/TypeRelation[Identical]: anyToInt(a:); name=anyToInt(a:)
 // ANY_INT-DAG: Decl{{.*}}/NotRecommended/TypeRelation[Invalid]: intToVoid({#a: Int#})[#Void#];
 // ANY_INT-DAG: Decl{{.*}}/NotRecommended/TypeRelation[Invalid]: anyToVoid({#a: Any#})[#Void#];
 // ANY_INT-DAG: Decl{{.*}}/NotRecommended/TypeRelation[Invalid]: voidToVoid()[#Void#];
@@ -135,7 +135,7 @@ do {
 // ANY_INT: End completions
 
 // ANY_INT_STATIC_CURRY: Begin completions
-// ANY_INT_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   anyToInt({#self: S0#})[#(a: Any) -> Int#]; name=anyToInt(S0)
+// ANY_INT_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Identical]: anyToInt({#self: S0#})[#(a: Any) -> Int#];
 // ANY_INT_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/NotRecommended/TypeRelation[Invalid]: voidToVoid({#self: S0#})[#() -> Void#];
 // ANY_INT_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/NotRecommended/TypeRelation[Invalid]: intToVoid({#self: S0#})[#(a: Int) -> Void#];
 // ANY_INT_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/NotRecommended/TypeRelation[Invalid]: anyToVoid({#self: S0#})[#(a: Any) -> Void#];
@@ -153,25 +153,25 @@ do {
 }
 
 // INT_ANY: Begin completions
-// INT_ANY-DAG: Decl{{.*}}:      intToAny({#a: Int#})[#Any#]; name=intToAny(a: Int)
-// INT_ANY-DAG: Decl{{.*}}:      intToInt({#a: Int#})[#Int#]; name=intToInt(a: Int)
-// INT_ANY-DAG: Decl{{.*}}:      intToVoid({#a: Int#})[#Void#]; name=intToVoid(a: Int)
-// INT_ANY-DAG: Decl{{.*}}:      anyToAny({#a: Any#})[#Any#]; name=anyToAny(a: Any)
-// INT_ANY-DAG: Decl{{.*}}:      anyToInt({#a: Any#})[#Int#]; name=anyToInt(a: Any)
-// INT_ANY-DAG: Decl{{.*}}:      anyToVoid({#a: Any#})[#Void#]; name=anyToVoid(a: Any)
+// INT_ANY-DAG: Decl{{.*}}/TypeRelation[Identical]: intToAny(a:);
+// INT_ANY-DAG: Decl{{.*}}/TypeRelation[Convertible]: intToInt(a:);
+// INT_ANY-DAG: Decl{{.*}}/TypeRelation[Convertible]: intToVoid(a:);
+// INT_ANY-DAG: Decl{{.*}}/TypeRelation[Convertible]: anyToAny(a:);
+// INT_ANY-DAG: Decl{{.*}}/TypeRelation[Convertible]: anyToInt(a:);
+// INT_ANY-DAG: Decl{{.*}}/TypeRelation[Convertible]: anyToVoid(a:);
 // INT_ANY-DAG: Decl{{.*}}/TypeRelation[Convertible]: returnsIntToInt()[#(Int) -> Int#];
 // INT_ANY-DAG: Decl{{.*}}/NotRecommended/TypeRelation[Invalid]: voidToVoid()[#Void#];
 // INT_ANY-DAG: Decl{{.*}}:      voidToInt()[#Int#];
 // INT_ANY-DAG: Decl{{.*}}:      voidToAny()[#Any#];
 // INT_ANY: End completions
 
 // INT_ANY_STATIC_CURRY: Begin completions
-// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   intToInt({#self: S0#})[#(a: Int) -> Int#]; name=intToInt(S0)
-// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/NotRecommended/TypeRelation[Invalid]: intToVoid({#self: S0#})[#(a: Int) -> Void#]; name=intToVoid(S0)
-// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   anyToAny({#self: S0#})[#(a: Any) -> Any#]; name=anyToAny(S0)
-// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/NotRecommended/TypeRelation[Invalid]: anyToVoid({#self: S0#})[#(a: Any) -> Void#]; name=anyToVoid(S0)
-// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   intToAny({#self: S0#})[#(a: Int) -> Any#]; name=intToAny(S0)
-// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   anyToInt({#self: S0#})[#(a: Any) -> Int#]; name=anyToInt(S0)
+// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Convertible]: intToInt({#self: S0#})[#(a: Int) -> Int#];
+// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Convertible]: intToVoid({#self: S0#})[#(a: Int) -> Void#];
+// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Convertible]: anyToAny({#self: S0#})[#(a: Any) -> Any#];
+// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Convertible]: anyToVoid({#self: S0#})[#(a: Any) -> Void#];
+// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Identical]: intToAny({#self: S0#})[#(a: Int) -> Any#];
+// INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Convertible]: anyToInt({#self: S0#})[#(a: Any) -> Int#];
 // INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal/TypeRelation[Convertible]: returnsIntToInt({#self: S0#})[#() -> (Int) -> Int#];
 // INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   voidToAny({#self: S0#})[#() -> Any#];
 // INT_ANY_STATIC_CURRY-DAG: Decl[InstanceMethod]/CurrNominal:   voidToInt({#self: S0#})[#() -> Int#];