[wpimath] Upgrade to Drake v1.15.0 (#5310)

wpimath/src/test/native/cpp/drake/common/fmt_eigen.cpp

@@ -0,0 +1,41 @@
+// TODO(jwnimmer-tri) Write our own formatting logic instead of using Eigen IO,
+// and add customization flags for how to display the matrix data.
+#undef EIGEN_NO_IO
+#include "drake/common/fmt_eigen.h"
+
+#include <limits>
+#include <sstream>
+
+namespace drake {
+namespace internal {
+
+template <typename T>
+using FormatterEigenRef =
+    Eigen::Ref<const Eigen::Matrix<T, Eigen::Dynamic, Eigen::Dynamic>>;
+
+template <typename T>
+std::string FormatEigenMatrix(const FormatterEigenRef<T>& matrix) {
+  std::stringstream stream;
+  // We'll print our matrix data using as much precision as we can, so that
+  // console log output and/or error messages paint the full picture. Sadly,
+  // the ostream family of floating-point formatters doesn't know how to do
+  // "shortest round-trip precision". If we set the precision to max_digits,
+  // then simple numbers like "1.1" print as "1.1000000000000001"; instead,
+  // we'll use max_digits - 1 to avoid that problem, with the risk of losing
+  // the last ulps in the printout in case we needed that last digit. This
+  // will all be fixed once we stop using Eigen IO.
+  stream.precision(std::numeric_limits<double>::max_digits10 - 1);
+  stream << matrix;
+  return stream.str();
+}
+
+// Explicitly instantiate for the allowed scalar types in our header.
+template std::string FormatEigenMatrix<double>(
+    const FormatterEigenRef<double>& matrix);
+template std::string FormatEigenMatrix<float>(
+    const FormatterEigenRef<float>& matrix);
+template std::string FormatEigenMatrix<std::string>(
+    const FormatterEigenRef<std::string>& matrix);
+
+}  // namespace internal
+}  // namespace drake