[CS] NFC: Remove CTP_CalleeResult

This has been unused since the removal of CSDiag.

include/swift/Sema/ConstraintLocator.h

@@ -61,7 +61,6 @@ enum ContextualTypePurpose : uint8_t {
   /// 'foo(a : @autoclosure () -> Int = 42)'.
   CTP_AutoclosureDefaultParameter,
 
-  CTP_CalleeResult,     ///< Constraint is placed on the result of a callee.
   CTP_CallArgument,     ///< Call to function or operator requires type.
   CTP_ClosureResult,    ///< Closure result expects a specific type.
   CTP_ArrayElement,     ///< ArrayExpr wants elements to have a specific type.

lib/Sema/CSApply.cpp

@@ -9606,7 +9606,6 @@ ExprWalker::rewriteTarget(SyntacticElementTarget target) {
     case CTP_EnumCaseRawValue:
     case CTP_DefaultParameter:
     case CTP_AutoclosureDefaultParameter:
-    case CTP_CalleeResult:
     case CTP_CallArgument:
     case CTP_ClosureResult:
     case CTP_ArrayElement:

lib/Sema/CSDiagnostics.cpp

@@ -867,7 +867,6 @@ GenericArgumentsMismatchFailure::getDiagnosticFor(
   case CTP_Unused:
   case CTP_CannotFail:
   case CTP_YieldByReference:
-  case CTP_CalleeResult:
   case CTP_EnumCaseRawValue:
   case CTP_ExprPattern:
   case CTP_SingleValueStmtBranch:
@@ -2954,9 +2953,6 @@ getContextualNilDiagnostic(ContextualTypePurpose CTP) {
   case CTP_CannotFail:
     llvm_unreachable("These contextual type purposes cannot fail with a "
                      "conversion type specified!");
-  case CTP_CalleeResult:
-    llvm_unreachable("CTP_CalleeResult does not actually install a "
-                     "contextual type");
   case CTP_Initialization:
     return diag::cannot_convert_initializer_value_nil;
 
@@ -3758,7 +3754,6 @@ ContextualFailure::getDiagnosticFor(ContextualTypePurpose context,
   case CTP_Unused:
   case CTP_CannotFail:
   case CTP_YieldByReference:
-  case CTP_CalleeResult:
   case CTP_ExprPattern:
     break;
   }

lib/Sema/CSSimplify.cpp

@@ -16696,7 +16696,6 @@ void ConstraintSystem::addContextualConversionConstraint(
 
   case CTP_ArrayElement:
   case CTP_AssignSource:
-  case CTP_CalleeResult:
   case CTP_CannotFail:
   case CTP_Condition:
   case CTP_Unused:

lib/Sema/SyntacticElementTarget.cpp

@@ -263,7 +263,6 @@ bool SyntacticElementTarget::contextualTypeIsOnlyAHint() const {
   case CTP_EnumCaseRawValue:
   case CTP_DefaultParameter:
   case CTP_AutoclosureDefaultParameter:
-  case CTP_CalleeResult:
   case CTP_CallArgument:
   case CTP_ClosureResult:
   case CTP_ArrayElement:

test/Migrator/Inputs/substring_to_string_conversion.swift

@@ -28,7 +28,7 @@ do {
   func foo(x: String = ss) {}
 }
 
-// CTP_CalleeResult
+// CTP_Initialization
 do {
   func getSubstring() -> Substring { return ss }
   let gottenString : String = getSubstring()

test/Migrator/substring_to_string_conversion.swift.expected

@@ -28,7 +28,7 @@ do {
   func foo(x: String = String(ss)) {}
 }
 
-// CTP_CalleeResult
+// CTP_Initialization
 do {
   func getSubstring() -> Substring { return ss }
   let gottenString : String = String(getSubstring())

test/Sema/substring_to_string_conversion_swift4.swift

@@ -30,7 +30,7 @@ do {
   func foo(x: String = ss) {} // expected-error {{default argument value of type 'Substring' cannot be converted to type 'String'}} {{24-24=String(}} {{26-26=)}}
 }
 
-// CTP_CalleeResult
+// CTP_Initialization
 do {
   func getSubstring() -> Substring { return ss }
   let gottenString : String = getSubstring() // expected-error {{cannot convert value of type 'Substring' to specified type 'String'}} {{31-31=String(}} {{45-45=)}}