Support filenames falling in current codepage (Win) (see #122)

CHANGELOG.md

@@ -7,6 +7,10 @@ this project uses date-based 'snapshot' version identifiers.
 
 ## [Unreleased]
 
+### Fixed
+- Support non-ASCII filenames that fall within the system codepage on Windows
+  (see \#122)
+
 ## [2023-09-13]
 
 ### Added

l3build-file-functions.lua

@@ -153,9 +153,15 @@ if os_type == "windows" then
   os_yes     = "for /l %I in (1,1,300) do @echo y"
 end
 
+-- Deal with codepage hell on Windows
+local function fixname(f) return f end 
+if chgstrcp then
+  fixname = chgstrcp.utf8tosyscp
+end
+
 -- Deal with the fact that Windows and Unix use different path separators
 local function unix_to_win(path)
-  return gsub(path, "/", "\\")
+  return fixname(gsub(path, "/", "\\"))
 end
 
 function normalize_path(path)

l3build.dtx

@@ -2141,6 +2141,14 @@
 % Full descriptions of their usage and arguments can be found within the |l3build-manifest-setup.lua|
 % code itself.
 %
+% \section{Known limitations}
+%
+% \subsection{Non-\textsc{ascii} filenames}
+%
+% On Windows, support for non-\textsc{ascii} filenames is limited by the way
+% that Lua handles system calls. While calling \TeX{} engines should work with
+% any name, general file operations will only success if the filename falls
+% within the codepage currently in use by the operating system.
 %
 % \end{documentation}
 %