Fix crash when serializing ObjCIvarDecl.

[yiding]

Summary

r198432 refactors ObjCIvarDecl such that it no longer serializes
BackingIvarReferencedInAccessor. However, it failed to remove
the field in the corresponding record abbrev. This causes assertion to
trip, or stack overflow/crash when asserts are disabled.

This was discovered when I attempted to use clang_saveTranslationUnit
and received a stack overflow.

[akyrtzi]

Could you also add a test case ? See tests that invoke ‘c-index-test -write-pch …’, this calls clang_saveTranslationUnit.

Other than that LGTM, thank you!

[yiding]

add a test

[akyrtzi]

In r211438, thanks!

lib/Serialization/ASTWriterDecl.cpp

void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // InnerStartLoc
   Abv->Add(BitCodeAbbrevOp(0));                       // hasExtInfo
   // FieldDecl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isMutable
   Abv->Add(BitCodeAbbrevOp(0));                       //getBitWidth
   // ObjC Ivar
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getAccessControl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // getSynthesize
-  // getBackingIvarReferencedInAccessor
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
   // Type Source Info
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // TypeLoc
   DeclObjCIvarAbbrev = Stream.EmitAbbrev(Abv);
 
   // Abbreviation for DECL_ENUM
   Abv = new BitCodeAbbrev();

test/Index/index-pch-objc.m

+// RUN: c-index-test -write-pch %t.pch %s
+// RUN: env LIBCLANG_NOTHREADS=1 c-index-test -index-tu %t.pch | FileCheck %s
+
+@interface SomeClass
+@property (retain) id foo;
+@end
+@implementation SomeClass
+@end
+
+// CHECK: [indexDeclaration]: kind: objc-ivar | name: _foo