Prevent duplicate input parameters in inputs file but allow CLI override

Source/ERF_InputsName.H

@@ -5,4 +5,84 @@
 
 extern std::string inputs_name;
 
+namespace
+{
+    std::string trim_copy (std::string s)
+    {
+        auto b = s.find_first_not_of(" \t\r");
+        if (b == std::string::npos) return "";
+
+        auto e = s.find_last_not_of(" \t\r");
+        return s.substr(b, e - b + 1);
+    }
+}
+
+inline void
+CheckForDuplicateInputs (const std::string& inputs_file)
+{
+    std::ifstream ifs(inputs_file);
+
+    if (!ifs.is_open()) {
+        amrex::Abort("Could not open inputs file: " + inputs_file);
+    }
+
+    struct EntryInfo {
+        int line_number;
+        std::string value;
+    };
+
+    std::unordered_map<std::string, EntryInfo> seen;
+
+    std::string line;
+    int line_number = 0;
+    bool found_duplicates = false;
+
+    while (std::getline(ifs, line))
+    {
+        ++line_number;
+
+        // Remove comments
+        auto hash_pos = line.find('#');
+        if (hash_pos != std::string::npos) {
+            line = line.substr(0, hash_pos);
+        }
+
+        line = trim_copy(line);
+
+        // Skip blank lines
+        if (line.empty()) continue;
+
+        // Skip lines that are not assignments
+        auto eq_pos = line.find('=');
+        if (eq_pos == std::string::npos) continue;
+
+        std::string key   = trim_copy(line.substr(0, eq_pos));
+        std::string value = trim_copy(line.substr(eq_pos + 1));
+
+        auto it = seen.find(key);
+
+        if (it != seen.end())
+        {
+            found_duplicates = true;
+
+            amrex::Print()
+                << "\nDuplicate input detected:\n"
+                << "    Key         : " << key << "\n"
+                << "    First line  : " << it->second.line_number
+                << "    Value       : " << it->second.value << "\n"
+                << "    Second line : " << line_number
+                << "    Value       : " << value << "\n";
+        }
+        else
+        {
+            seen.emplace(key, EntryInfo{line_number, value});
+        }
+    }
+
+    if (found_duplicates)
+    {
+        amrex::Abort("Duplicate inputs detected in inputs file");
+    }
+}
+
 #endif

Source/main.cpp

@@ -128,6 +128,7 @@ return code;
 #else
     amrex::Initialize(argc,argv,true,MPI_COMM_WORLD,add_par);
 #endif
+    CheckForDuplicateInputs(argv[1]);
 
 #ifdef ERF_USE_KOKKOS
     // Initialize kokkos