From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Wed, 15 Mar 2023 17:49:23 +0000 (-0600)
Subject: Do not allow assigning to rvalue references of Tensor.
X-Git-Tag: v9.5.0-rc1~468^2~2
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f6d035119b91d618a81599b3e00412a87a1bf6d8;p=dealii.git

Do not allow assigning to rvalue references of Tensor.
---

diff --git a/include/deal.II/base/tensor.h b/include/deal.II/base/tensor.h
index fe4ff27b41..1750f8b42d 100644
--- a/include/deal.II/base/tensor.h
+++ b/include/deal.II/base/tensor.h
@@ -291,7 +291,16 @@ public:
    */
   template <typename OtherNumber>
   constexpr DEAL_II_HOST_DEVICE Tensor &
-                                operator=(const OtherNumber &d);
+                                operator=(const OtherNumber &d) &;
+
+  /**
+   * Assign a scalar to the current object. This overload is used for
+   * rvalue references; because it does not make sense to assign
+   * something to a temporary, the function is deleted.
+   */
+  template <typename OtherNumber>
+  constexpr DEAL_II_HOST_DEVICE Tensor &
+                                operator=(const OtherNumber &d) && = delete;
 
   /**
    * Test for equality of two tensors.
@@ -685,7 +694,15 @@ public:
    * <tt>t=0</tt> to reset all elements of the tensor to zero.
    */
   constexpr Tensor &
-  operator=(const Number &d);
+  operator=(const Number &d) &;
+
+  /**
+   * Assign a scalar to the current object. This overload is used for
+   * rvalue references; because it does not make sense to assign
+   * something to a temporary, the function is deleted.
+   */
+  constexpr DEAL_II_HOST_DEVICE Tensor &
+                                operator=(const Number &d) && = delete;
 
 #ifdef DEAL_II_DELETED_MOVE_CONSTRUCTOR_BUG
   /**
@@ -1095,7 +1112,7 @@ Tensor<0, dim, Number>::operator=(Tensor<0, dim, Number> &&other) noexcept
 template <int dim, typename Number>
 template <typename OtherNumber>
 constexpr DEAL_II_HOST_DEVICE_ALWAYS_INLINE Tensor<0, dim, Number> &
-Tensor<0, dim, Number>::operator=(const OtherNumber &d)
+Tensor<0, dim, Number>::operator=(const OtherNumber &d) &
 {
   value = internal::NumberType<Number>::value(d);
   return *this;
@@ -1542,7 +1559,7 @@ Tensor<rank_, dim, Number>::operator=(const Tensor<rank_, dim, OtherNumber> &t)
 
 template <int rank_, int dim, typename Number>
 constexpr inline DEAL_II_ALWAYS_INLINE Tensor<rank_, dim, Number> &
-Tensor<rank_, dim, Number>::operator=(const Number &d)
+Tensor<rank_, dim, Number>::operator=(const Number &d) &
 {
   Assert(numbers::value_is_zero(d), ExcScalarAssignmentOnlyForZeroValue());
   (void)d;