[index] C++: Improve handling of typedefs as base names in C++ class declarations

Report the typedef as reference, and desugar it to report the underlying class as an
implicit 'base' reference.
Reporting the underlying base class for 'base' relations matches the ObjC handling and
leads to a simpler model.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@296975 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Index/IndexTypeSourceInfo.cpp b/lib/Index/IndexTypeSourceInfo.cpp
index cf32325..33848da 100644
--- a/lib/Index/IndexTypeSourceInfo.cpp
+++ b/lib/Index/IndexTypeSourceInfo.cpp
@@ -40,18 +40,30 @@
   
   bool shouldWalkTypesOfTypeLocs() const { return false; }
 
-  bool VisitTypedefTypeLoc(TypedefTypeLoc TL) {
-    return IndexCtx.handleReference(TL.getTypedefNameDecl(), TL.getNameLoc(),
-                                    Parent, ParentDC, SymbolRoleSet(),
-                                    Relations);
-  }
-
 #define TRY_TO(CALL_EXPR)                                                      \
   do {                                                                         \
     if (!CALL_EXPR)                                                            \
       return false;                                                            \
   } while (0)
 
+  bool VisitTypedefTypeLoc(TypedefTypeLoc TL) {
+    if (IsBase) {
+      SourceLocation Loc = TL.getNameLoc();
+      TRY_TO(IndexCtx.handleReference(TL.getTypedefNameDecl(), Loc,
+                                      Parent, ParentDC, SymbolRoleSet()));
+      if (auto *CD = TL.getType()->getAsCXXRecordDecl()) {
+        TRY_TO(IndexCtx.handleReference(CD, Loc, Parent, ParentDC,
+                                        (unsigned)SymbolRole::Implicit,
+                                        Relations));
+      }
+    } else {
+      TRY_TO(IndexCtx.handleReference(TL.getTypedefNameDecl(), TL.getNameLoc(),
+                                      Parent, ParentDC, SymbolRoleSet(),
+                                      Relations));
+    }
+    return true;
+  }
+
   bool traverseParamVarHelper(ParmVarDecl *D) {
     TRY_TO(TraverseNestedNameSpecifierLoc(D->getQualifierLoc()));
     if (D->getTypeSourceInfo())
diff --git a/test/Index/Core/index-source.cpp b/test/Index/Core/index-source.cpp
index 2a4c1ef..ab7c6f4 100644
--- a/test/Index/Core/index-source.cpp
+++ b/test/Index/Core/index-source.cpp
@@ -1,6 +1,6 @@
 // RUN: c-index-test core -print-source-symbols -- %s -std=c++14 -target x86_64-apple-macosx10.7 | FileCheck %s
 
-// CHECK: [[@LINE+1]]:7 | class/C++ | Cls | c:@S@Cls | <no-cgname> | Def | rel: 0
+// CHECK: [[@LINE+1]]:7 | class/C++ | Cls | [[Cls_USR:.*]] | <no-cgname> | Def | rel: 0
 class Cls {
   // CHECK: [[@LINE+2]]:3 | constructor/C++ | Cls | c:@S@Cls@F@Cls#I# | __ZN3ClsC1Ei | Decl,RelChild | rel: 1
   // CHECK-NEXT: RelChild | Cls | c:@S@Cls
@@ -11,6 +11,19 @@
   Cls(Cls &&);
 };
 
+// CHECK: [[@LINE+3]]:7 | class/C++ | SubCls1 | [[SubCls1_USR:.*]] | <no-cgname> | Def | rel: 0
+// CHECK: [[@LINE+2]]:24 | class/C++ | Cls | [[Cls_USR]] | <no-cgname> | Ref,RelBase,RelCont | rel: 1
+// CHECK-NEXT: RelBase,RelCont | SubCls1 | [[SubCls1_USR]]
+class SubCls1 : public Cls {};
+// CHECK: [[@LINE+1]]:13 | type-alias/C | ClsAlias | [[ClsAlias_USR:.*]] | <no-cgname> | Def | rel: 0
+typedef Cls ClsAlias;
+// CHECK: [[@LINE+5]]:7 | class/C++ | SubCls2 | [[SubCls2_USR:.*]] | <no-cgname> | Def | rel: 0
+// CHECK: [[@LINE+4]]:24 | type-alias/C | ClsAlias | [[ClsAlias_USR]] | <no-cgname> | Ref,RelCont | rel: 1
+// CHECK-NEXT: RelCont | SubCls2 | [[SubCls2_USR]]
+// CHECK: [[@LINE+2]]:24 | class/C++ | Cls | [[Cls_USR]] | <no-cgname> | Ref,Impl,RelBase,RelCont | rel: 1
+// CHECK-NEXT: RelBase,RelCont | SubCls2 | [[SubCls2_USR]]
+class SubCls2 : public ClsAlias {};
+
 template <typename TemplArg>
 class TemplCls {
 // CHECK: [[@LINE-1]]:7 | class(Gen)/C++ | TemplCls | c:@ST>1#T@TemplCls | <no-cgname> | Def | rel: 0