Index: clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
+++ clang-tools-extra/clang-tidy/modernize/UseDefaultMemberInitCheck.cpp
@@ -60,6 +60,47 @@
   case Type::STK_IntegralComplex:
     return getValueOfValueInit(
         InitType->getAs<ComplexType>()->getElementType());
+  case Type::STK_FixedPoint:
+    switch (InitType->getAs<BuiltinType>()->getKind()) {
+      case BuiltinType::ShortAccum:
+      case BuiltinType::SatShortAccum:
+        return "0.0hk";
+      case BuiltinType::Accum:
+      case BuiltinType::SatAccum:
+        return "0.0k";
+      case BuiltinType::LongAccum:
+      case BuiltinType::SatLongAccum:
+        return "0.0lk";
+      case BuiltinType::UShortAccum:
+      case BuiltinType::SatUShortAccum:
+        return "0.0uhk";
+      case BuiltinType::UAccum:
+      case BuiltinType::SatUAccum:
+        return "0.0uk";
+      case BuiltinType::ULongAccum:
+      case BuiltinType::SatULongAccum:
+        return "0.0ulk";
+      case BuiltinType::ShortFract:
+      case BuiltinType::SatShortFract:
+        return "0.0hr";
+      case BuiltinType::Fract:
+      case BuiltinType::SatFract:
+        return "0.0r";
+      case BuiltinType::LongFract:
+      case BuiltinType::SatLongFract:
+        return "0.0lr";
+      case BuiltinType::UShortFract:
+      case BuiltinType::SatUShortFract:
+        return "0.0uhr";
+      case BuiltinType::UFract:
+      case BuiltinType::SatUFract:
+        return "0.0ur";
+      case BuiltinType::ULongFract:
+      case BuiltinType::SatULongFract:
+        return "0.0ulr";
+      default:
+        llvm_unreachable("Unhandled fixed point BuiltinType");
+    }
   }
   llvm_unreachable("Invalid scalar type kind");
 }