testing: for CI only, trim PWD from the oslc -M output (#1924)

I think this stems from libclang (doing the C preprocessing step
for us) giving us relative paths on all platforms but Windows,
where it gives absolute paths -- with backslaches and C:\ and all.

I'm going to be conservative and not switch to relative paths accross
the board on Windows, but for now just restrict it to the builds we do
for CI, in order to make the related tests pass for Windows on our CI
(where we obviously don't want to have the reference output need to
bake in absolute paths of the place they may happen to execute on the
GHA runners).

Signed-off-by: Larry Gritz <[email protected]>

Author: lgritz

src/liboslcomp/oslcomp.cpp

@@ -590,14 +590,24 @@ OSLCompilerImpl::write_dependency_file(string_view filename)
                          : OIIO::Filesystem::fopen(m_deps_filename, "w"));
     if (depfile) {
         OSL::print(depfile, "{}: {}", target, filename);
-        for (const auto& dep : m_file_dependencies) {
+        for (ustring dep : m_file_dependencies) {
             if (OIIO::Strutil::ends_with(dep, "stdosl.h")
                 && !m_generate_system_deps)
                 continue;  // skip system headers if so instructed
             if (OIIO::Strutil::starts_with(dep, "<"))
                 continue;  // skip pseudo files
             if (dep == filename)
                 continue;  // skip this file, since we already put it first
+#if defined(_WIN32) && defined(OSL_CI)
+            // Special behavior for CI on Windows: remove the directory paths
+            // for the dependencies, or else it won't match the reference
+            // output.
+            using OIIO::Strutil::replace;
+            std::string cwd = replace(OIIO::Filesystem::current_path() + "/",
+                                      "/", "\\", true);
+            auto d          = replace(dep, "\\\\", "\\", true);
+            dep             = ustring(replace(d, cwd, ""));
+#endif
             OSL::print(depfile, " \\\n  {}", dep);
         }
         OSL::print(depfile, "\n");