private static IReadOnlySet <string> GetEmbedddedSourcePaths(CommandLineArguments arguments)
{
if (arguments.EmbeddedFiles.IsEmpty)
{
return(SpecializedCollections.EmptyReadOnlySet <string>());
}
// Note that we require an exact match between source and embedded file paths (case-sensitive
// and without normalization). If two files are the same but spelled differently, they will
// be handled as separate files, meaning the embedding pass will read the content a second
// time. This can also lead to more than one document entry in the PDB for the same document
// if the PDB document de-duping policy in emit (normalize + case-sensitive in C#,
// normalize + case-insensitive in VB) is not enough to converge them.
var set = new HashSet <string>(arguments.EmbeddedFiles.Select(f => f.Path));
set.IntersectWith(arguments.SourceFiles.Select(f => f.Path));
return(SpecializedCollections.StronglyTypedReadOnlySet(set));
}