To compile files in Open Folder mode:
Alternatively:
If no Compiler directives have been set for the file and the open folder contains prebuilt .idy files, Visual Studio uses these files to provide the Compiler directives for compiling the source files. Visual Studio persists these directives in the file properties.
If there are any Compiler directives specified at workspace as well as folder or file level, Visual Studio will use these to compile the files.