[SourceKit][CodeFormat] When indent to siblings, respect tuple elements' names. rdar://24251847

Author: nkcsgexi

test/SourceKit/CodeFormat/indent-sibling2.swift

@@ -0,0 +1,23 @@
+func foo(foo: Int, bar: Int, baz: Int, buzz: Int) -> Int {
+    return foo + bar + baz + buzz
+}
+
+foo(0,
+  bar: 1,
+      baz: 2,
+          buzz: 3)
+
+// RUN: %sourcekitd-test -req=format -line=6 -length=1 %s >%t.response
+// RUN: %sourcekitd-test -req=format -line=7 -length=1 %s >>%t.response
+// RUN: %sourcekitd-test -req=format -line=8 -length=1 %s >>%t.response
+// RUN: %sourcekitd-test -req=format -line=9 -length=1 %s >>%t.response
+// RUN: FileCheck --strict-whitespace %s <%t.response
+
+//                        "foo(0,"
+// CHECK: key.sourcetext: "    bar: 1,"
+
+//                        "  bar: 1,"
+// CHECK: key.sourcetext: "  baz: 2,"
+
+//                        "      baz: 2,"
+// CHECK: key.sourcetext: "      buzz: 3)"

tools/SourceKit/lib/SwiftLang/SwiftEditor.cpp

@@ -1894,8 +1894,11 @@ class FormatWalker: public ide::SourceEntityWalker {
         // Trailing closures are not considered siblings to other args.
         unsigned EndAdjust = TE->hasTrailingClosure() ? 1 : 0;
         for (unsigned I = 0, N = TE->getNumElements() - EndAdjust; I < N; I ++) {
-          addPair(TE->getElement(I)->getEndLoc(),
-                  FindAlignLoc(TE->getElement(I)->getStartLoc()), tok::comma);
+          auto EleStart = TE->getElementNameLoc(I);
+          if (EleStart.isInvalid()) {
+            EleStart = TE->getElement(I)->getStartLoc();
+          }
+          addPair(TE->getElement(I)->getEndLoc(), EleStart, tok::comma);
         }
       }