[Omit needless words] Don't split subscript accessors.

Author: DougGregor

lib/ClangImporter/ClangImporter.cpp

@@ -2319,7 +2319,7 @@ auto ClangImporter::Implementation::importFullName(
 
   // Omit needless words.
   StringScratchSpace omitNeedlessWordsScratch;
-  if (OmitNeedlessWords) {
+  if (OmitNeedlessWords && !result.IsSubscriptAccessor) {
     // Check whether the module in which the declaration resides has a
     // module prefix. If so, strip that prefix off when present.
     if (D->getDeclContext()->getRedeclContext()->isFileContext() &&

test/IDE/Inputs/custom-modules/OmitNeedlessWords.h

@@ -15,4 +15,5 @@
 -(nullable Class)typeOfNamedString:(nonnull NSString *)string;
 -(nullable Class)typeOfTypeNamed:(nonnull NSString *)string;
 -(void)appendWithContentsOfString:(nonnull NSString *)string;
+-(nonnull id)objectAtIndexedSubscript:(NSUInteger)idx;
 @end

test/IDE/print_omit_needless_words.swift

@@ -287,5 +287,9 @@
 // Look for preposition prior to "of".
 // CHECK-OMIT-NEEDLESS-WORDS: func append(contentsOf _: String)
 
+// Leave subscripts alone
+// CHECK-OMIT-NEEDLESS-WORDS: subscript (_: UInt) -> AnyObject { get }
+// CHECK-OMIT-NEEDLESS-WORDS: func objectAtIndexedSubscript(_: UInt) -> AnyObject
+
 // Don't drop the 'error'.
 // CHECK-ERRORS: func tryAndReturnError(_: ()) throws