Parse: Improve MemberImportVisibility diags for appendLiteral(_:) calls.

Ensure compiler generated calls to `appendLiteral(_:)` have source locations for
diagnostics.

Partially resolves rdar://144535697.

Author: tshortli

lib/Parse/ParseExpr.cpp

@@ -1972,7 +1972,7 @@ parseStringSegments(SmallVectorImpl<Lexer::StringSegment> &Segments,
         new (Context) UnresolvedDotExpr(InterpolationVarRef,
                                         /*dotloc=*/SourceLoc(),
                                         appendLiteral,
-                                        /*nameloc=*/DeclNameLoc(), 
+                                        /*nameloc=*/DeclNameLoc(TokenLoc),
                                         /*Implicit=*/true);
       auto *ArgList = ArgumentList::forImplicitUnlabeled(Context, {Literal});
       auto AppendLiteralCall =

test/NameLookup/members_transitive_compiler_protocols.swift

@@ -9,12 +9,17 @@
 //--- main.swift
 
 import Swift
-// expected-note 2 {{add import of module 'lib'}}
+// expected-note 6 {{add import of module 'lib'}}
 
 for _ in makeSequence() { }
 // expected-error@-1 {{instance method 'makeIterator()' is not available due to missing import of defining module 'lib'}}
 // expected-error@-2 {{instance method 'next()' is not available due to missing import of defining module 'lib'}}
 
+takesMessage("\(1)")
+// expected-error@-1 {{initializer 'init(stringInterpolation:)' is not available due to missing import of defining module 'lib'}}
+// expected-error@-2 {{instance method 'appendInterpolation' is not available due to missing import of defining module 'lib'}}
+// expected-error@-3 2 {{instance method 'appendLiteral' is not available due to missing import of defining module 'lib'}}
+
 //--- other.swift
 
 import lib
@@ -23,6 +28,8 @@ func makeSequence() -> EmptySequence {
   return MySequence()
 }
 
+func takesMessage(_ x: Message) { }
+
 //--- lib.swift
 
 public struct EmptySequence: Sequence {
@@ -33,3 +40,14 @@ public struct EmptySequence: Sequence {
   public func makeIterator() -> Iterator { Iterator() }
   public init() { }
 }
+
+public struct MessageInterpolation: StringInterpolationProtocol {
+  public init(literalCapacity: Int, interpolationCount: Int) { }
+  public mutating func appendInterpolation(_ value: @autoclosure () -> Int) { }
+  public mutating func appendLiteral(_ literal: String) { }
+}
+
+public struct Message: ExpressibleByStringInterpolation {
+  public init(stringInterpolation: MessageInterpolation) { }
+  public init(stringLiteral: String) { }
+}