[Index] Skip adding call relations to deduction guides

Deduction guides have no name and we already skip adding occurrences to
them for that reason. Also skip adding any relations to them.

Resolves rdar://142421120.

Author: bnbarham

clang/lib/Index/IndexBody.cpp

@@ -130,6 +130,9 @@ class BodyIndexer : public RecursiveASTVisitor<BodyIndexer> {
 
   void addCallRole(SymbolRoleSet &Roles,
                    SmallVectorImpl<SymbolRelation> &Relations) {
+    if (isa<CXXDeductionGuideDecl>(ParentDC))
+      return;
+
     Roles |= (unsigned)SymbolRole::Call;
     if (auto *FD = dyn_cast<FunctionDecl>(ParentDC))
       Relations.emplace_back((unsigned)SymbolRole::RelationCalledBy, FD);

clang/test/Index/index-deduction-guide.cpp

@@ -0,0 +1,10 @@
+// RUN: c-index-test core -print-source-symbols -- %s -std=gnu++17 | FileCheck %s
+
+template<typename T>
+typename T::type declval() {}
+template <typename T> struct Test;
+template <typename C, typename T = decltype(declval<C>().d())> Test(C &) -> Test<T>;
+// CHECK: [[@LINE-1]]:45 | function/C | declval
+// CHECK-NOT: RelCall
+// CHECK: [[@LINE-3]]:77 | struct(Gen)/C++ | Test
+// CHECK: [[@LINE-4]]:64 | struct(Gen)/C++ | Test