ObjC Module: try to make objc module deterministic.

Make sure that comparing selectors in DeclarationName does its job.
rdar://problem/28988750


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@287244 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/DeclarationName.cpp

@@ -95,12 +95,18 @@ int DeclarationName::compare(DeclarationName LHS, DeclarationName RHS) {
   case DeclarationName::ObjCMultiArgSelector: {
     Selector LHSSelector = LHS.getObjCSelector();
     Selector RHSSelector = RHS.getObjCSelector();
+    // getNumArgs for ZeroArgSelector returns 0, but we still need to compare.
+    if (LHS.getNameKind() == DeclarationName::ObjCZeroArgSelector &&
+        RHS.getNameKind() == DeclarationName::ObjCZeroArgSelector) {
+      return LHSSelector.getAsIdentifierInfo()->getName().compare(
+             RHSSelector.getAsIdentifierInfo()->getName());
+    }
     unsigned LN = LHSSelector.getNumArgs(), RN = RHSSelector.getNumArgs();
     for (unsigned I = 0, N = std::min(LN, RN); I != N; ++I) {
       switch (LHSSelector.getNameForSlot(I).compare(
                                                RHSSelector.getNameForSlot(I))) {
-      case -1: return true;
-      case 1: return false;
+      case -1: return -1;
+      case 1: return 1;
       default: break;
       }
     }

test/Modules/stress-objc.m

@@ -0,0 +1,22 @@
+// RUN: cd %S
+
+// RUN: %clang_cc1 -emit-pch -x objective-c-header %s -o %t_c00.pch -fno-pch-timestamp
+// RUN: %clang_cc1 -emit-pch -x objective-c-header %s -o %t_c00_1.pch -fno-pch-timestamp
+// RUN: diff %t_c00.pch %t_c00_1.pch
+
+// RUN: %clang_cc1 -emit-pch -x objective-c-header %s -o %t_c00_2.pch -fno-pch-timestamp
+// RUN: diff %t_c00.pch %t_c00_2.pch
+
+// RUN: %clang_cc1 -emit-pch -x objective-c-header %s -o %t_c00_3.pch -fno-pch-timestamp
+// RUN: diff %t_c00.pch %t_c00_3.pch
+
+// RUN: %clang_cc1 -emit-pch -x objective-c-header %s -o %t_c00_4.pch -fno-pch-timestamp
+// RUN: diff %t_c00.pch %t_c00_4.pch
+
+// RUN: %clang_cc1 -emit-pch -x objective-c-header %s -o %t_c00_5.pch -fno-pch-timestamp
+// RUN: diff %t_c00.pch %t_c00_5.pch
+
+@protocol NSObject
+- (void)doesNotRecognizeSelector:(SEL)aSelector;
+- (id)forwardingTargetForSelector:(SEL)aSelector;
+@end