From 0870a560939079644892c9ff2e650e2a45339243 Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 15 Apr 2021 11:57:48 -0400
Subject: [PATCH] expand exception message to include cause of file open
 failure

---
 src/potential_file_reader.cpp | 3 ++-
 src/text_file_reader.cpp      | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/potential_file_reader.cpp b/src/potential_file_reader.cpp
index 2730a3d109..bddfca9bce 100644
--- a/src/potential_file_reader.cpp
+++ b/src/potential_file_reader.cpp
@@ -62,7 +62,8 @@ PotentialFileReader::PotentialFileReader(LAMMPS *lmp,
   try {
     reader = open_potential(filename);
     if (!reader) {
-      error->one(FLERR, fmt::format("cannot open {} potential file {}", potential_name, filename));
+      error->one(FLERR, fmt::format("cannot open {} potential file {}: {}",
+                                    potential_name, filename, utils::getsyserror()));
     }
   } catch (FileReaderException &e) {
     error->one(FLERR, e.what());
diff --git a/src/text_file_reader.cpp b/src/text_file_reader.cpp
index af27bfb16d..7a6e914639 100644
--- a/src/text_file_reader.cpp
+++ b/src/text_file_reader.cpp
@@ -46,7 +46,8 @@ TextFileReader::TextFileReader(const std::string &filename, const std::string &f
   fp = fopen(filename.c_str(), "r");
 
   if (fp == nullptr) {
-    throw FileReaderException(fmt::format("cannot open {} file {}", filetype, filename));
+    throw FileReaderException(fmt::format("cannot open {} file {}: {}",
+                              filetype, filename, utils::getsyserror()));
   }
 }