Let --to-yaml correctly resolve relative paths

Author: sebproell

apps/global_full/4C_global_full_main.cpp

@@ -349,6 +349,13 @@ int main(int argc, char* argv[])
     if (Core::Communication::my_mpi_rank(lcomm) == 0)
     {
       std::filesystem::path inputfile_name = argv[2];
+      // Always make the input file path relative to the working directory. This ensures that any
+      // absolute path encountered in the input file stays that way.
+      if (inputfile_name.is_absolute())
+      {
+        inputfile_name = std::filesystem::relative(inputfile_name);
+      }
+
       std::filesystem::path outputfile_name;
       if (argc == 3)
       {
@@ -370,7 +377,7 @@ int main(int argc, char* argv[])
       Core::IO::InputFile input_file = Global::set_up_input_file(lcomm);
       input_file.read(inputfile_name);
       std::ofstream output_file(outputfile_name);
-      input_file.write_as_yaml(output_file);
+      input_file.write_as_yaml(output_file, outputfile_name);
       printf("The input file has been converted to yaml format");
       if (argc == 3) printf(", saved as %s", outputfile_name.c_str());
       printf("\n");

src/core/io/src/4C_io_input_file.cpp

@@ -1032,7 +1032,7 @@ namespace Core::IO
     out << tree;
   }
 
-  void InputFile::write_as_yaml(std::ostream& out) const
+  void InputFile::write_as_yaml(std::ostream& out, const std::filesystem::path& file_name) const
   {
     auto tree = init_yaml_tree_with_exceptions();
     tree.rootref() |= ryml::MAP;
@@ -1048,7 +1048,8 @@ namespace Core::IO
       {
         auto& spec = pimpl_->valid_sections_.at(section_name);
         match_section(section_name, container);
-        YamlNodeRef section_node{tree.rootref(), ""};
+        YamlNodeRef section_node{
+            tree.rootref(), file_name.empty() ? std::filesystem::path{} : file_name};
         spec.emit(section_node, container);
       }
       else

src/core/io/src/4C_io_input_file.hpp

@@ -251,11 +251,12 @@ namespace Core::IO
 
     /**
      * Write the content of the input file to the given output stream @p out. The content is
-     * written in .yaml format.
+     * written in .yaml format. The optional @p file_name is used to construct correct relative
+     * paths for all path parameters.
      *
      * @note You probably only want to call this function on rank 0.
      */
-    void write_as_yaml(std::ostream& out) const;
+    void write_as_yaml(std::ostream& out, const std::filesystem::path& file_name = {}) const;
 
    private:
     std::unique_ptr<Internal::InputFileImpl> pimpl_;

src/core/io/src/4C_io_yaml.cpp

@@ -7,8 +7,6 @@
 
 #include "4C_io_yaml.hpp"
 
-#include <iostream>
-
 FOUR_C_NAMESPACE_OPEN
 
 namespace
@@ -53,11 +51,11 @@ void Core::IO::emit_value_as_yaml(YamlNodeRef node, const bool& value)
 void Core::IO::emit_value_as_yaml(YamlNodeRef node, const std::filesystem::path& value)
 {
   node.node |= ryml::VAL_DQUO;
-  if (node.associated_file.empty())
+  if (node.associated_file.empty() || value.is_absolute())
   {
     node.node << value.string();
   }
-  // Make the path relative to the associated file.
+  // Make the relative path relative to the associated file.
   else
   {
     auto relative_path = std::filesystem::relative(value, node.associated_file.parent_path());