Index: clang/lib/AST/Interp/ByteCodeExprGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -1073,8 +1073,12 @@
     return this->emitNullPtr(E);
   case PT_FnPtr:
     return this->emitNullFnPtr(E);
-  case PT_Float:
-    assert(false);
+  case PT_Float: {
+    const auto &Sem = Ctx.getASTContext().getFloatTypeSemantics(E->getType());
+
+    APFloat Val(Sem);
+    return this->emitConstFloat(Val, E);
+  }
   }
   llvm_unreachable("unknown primitive type");
 }
Index: clang/test/AST/Interp/floats.cpp
===================================================================
--- clang/test/AST/Interp/floats.cpp
+++ clang/test/AST/Interp/floats.cpp
@@ -78,3 +78,17 @@
   }
   static_assert(f2() == __FLT_MAX__, "");
 }
+
+namespace ZeroInit {
+  template<typename FloatT>
+  struct A {
+    int a;
+    FloatT f;
+  };
+
+  constexpr A<float> a{12};
+  static_assert(a.f == 0.0f);
+
+  constexpr A<double> b{12};
+  static_assert(a.f == 0.0);
+};