From 619a1f45b40bff8e5b7d4ce3af0726c6525b4f75 Mon Sep 17 00:00:00 2001
From: Lawrence Kidder <kidder@astro.cornell.edu>
Date: Wed, 30 Jun 2021 15:09:09 -0400
Subject: [PATCH 1/2] Fix segfault on my new desktop using clang 12

Add ASSERTS making sure a cached filter does not change its filtering parameters.
Capture the parameters rather than capturing this.
Pass the lambda directly to make_static_cache instead naming it.
See Issue #3298 for more details.
---
 .../LinearOperators/ExponentialFilter.cpp     | 27 ++++++++++++++-----
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/NumericalAlgorithms/LinearOperators/ExponentialFilter.cpp b/src/NumericalAlgorithms/LinearOperators/ExponentialFilter.cpp
index 42dde227815d..24d4028271a2 100644
--- a/src/NumericalAlgorithms/LinearOperators/ExponentialFilter.cpp
+++ b/src/NumericalAlgorithms/LinearOperators/ExponentialFilter.cpp
@@ -24,12 +24,19 @@ Exponential<FilterIndex>::Exponential(const double alpha,
 template <size_t FilterIndex>
 const Matrix& Exponential<FilterIndex>::filter_matrix(const Mesh<1>& mesh) const
     noexcept {
-  const auto cache_function = [this](
-      const size_t extents, const Spectral::Basis basis,
-      const Spectral::Quadrature quadrature) noexcept {
-    return Spectral::filtering::exponential_filter(
-        Mesh<1>{extents, basis, quadrature}, alpha_, half_power_);
-  };
+  const static double cached_alpha = alpha_;
+
+  ASSERT(cached_alpha == alpha_, "Filter was cached with alpha = "
+                                     << cached_alpha << ", but alpha is now "
+                                     << alpha_
+                                     << ".\nUse a different FilterIndex if you "
+                                        "need a filter with new parameters\n");
+  const static double cached_half_power = half_power_;
+  ASSERT(cached_half_power == half_power_,
+         "Filter was cached with half power = "
+             << cached_half_power << ", but half power is now " << half_power_
+             << ".\nUse a different FilterIndex if you need a filter with new "
+                "parameters\n");
 
   const static auto cache = make_static_cache<
       CacheRange<1_st,
@@ -38,7 +45,13 @@ const Matrix& Exponential<FilterIndex>::filter_matrix(const Mesh<1>& mesh) const
       CacheEnumeration<Spectral::Basis, Spectral::Basis::Legendre,
                        Spectral::Basis::Chebyshev>,
       CacheEnumeration<Spectral::Quadrature, Spectral::Quadrature::Gauss,
-                       Spectral::Quadrature::GaussLobatto>>(cache_function);
+                       Spectral::Quadrature::GaussLobatto>>(
+      [alpha = alpha_, half_power = half_power_](
+          const size_t extents, const Spectral::Basis basis,
+          const Spectral::Quadrature quadrature) noexcept {
+        return Spectral::filtering::exponential_filter(
+            Mesh<1>{extents, basis, quadrature}, alpha, half_power);
+      });
   return cache(mesh.extents(0), mesh.basis(0), mesh.quadrature(0));
 }
 

From e6c716cd06b9e9c1f7f916997f6106b55afa7f5d Mon Sep 17 00:00:00 2001
From: Lawrence Kidder <kidder@astro.cornell.edu>
Date: Wed, 30 Jun 2021 15:35:22 -0400
Subject: [PATCH 2/2] Fix narrowing warning

---
 tests/Unit/IO/Test_H5.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/Unit/IO/Test_H5.cpp b/tests/Unit/IO/Test_H5.cpp
index 5137e85f00dd..b8573614dd1b 100644
--- a/tests/Unit/IO/Test_H5.cpp
+++ b/tests/Unit/IO/Test_H5.cpp
@@ -548,7 +548,7 @@ SPECTRE_TEST_CASE("Unit.IO.H5.ReadData", "[Unit][IO][H5]") {
   h5::write_data(group_id, std::vector<double>{1.0 / 3.0}, {},
                  "scalar_dataset");
   CHECK(h5::read_data<0, double>(group_id, "scalar_dataset") == 1.0 / 3.0);
-  h5::write_data(group_id, std::vector<float>{1.0 / 3.0}, {},
+  h5::write_data(group_id, std::vector<float>{1.0f / 3.0f}, {},
                  "scalar_dataset_float");
   CHECK(h5::read_data<0, float>(group_id, "scalar_dataset_float") ==
         static_cast<float>(1.0 / 3.0));