fix: normalize filesystem paths to always use / separator (#433)

compiler/src/utils/dune

@@ -3,7 +3,7 @@
  (public_name grain_utils)
  (synopsis "Utilities for the Grain compiler")
  (libraries fp fs.lib cmdliner compiler-libs.common ppx_sexp_conv.runtime-lib
-   sexplib)
+   sexplib str)
  (inline_tests)
  (preprocess
   (pps ppx_sexp_conv ppx_expect)))

compiler/src/utils/files.re

@@ -9,9 +9,23 @@ let remove_extension = baseName => {
   };
 };
 
+// These utilities are needed until https://github.com/facebookexperimental/reason-native/pull/251
+// is merged into the reason-native/fp library to support Windows-style separators
+let normalize_separators = path => {
+  let platform_sep = Str.regexp(Filename.dir_sep);
+  let normal_sep = "/";
+  Str.global_replace(platform_sep, normal_sep, path);
+};
+
+let to_fp = fname => {
+  Fp.testForPath(normalize_separators(fname));
+};
+
+let get_cwd = () => normalize_separators(Sys.getcwd());
+
 let filename_to_module_name = fname => {
   let baseName =
-    Option.bind(Fp.testForPath(fname), p =>
+    Option.bind(to_fp(fname), p =>
       switch (p) {
       | Absolute(path) => Fp.baseName(path)
       | Relative(path) => Fp.baseName(path)
@@ -33,11 +47,11 @@ let filename_to_module_name = fname => {
 let ensure_parent_directory_exists = fname => {
   // TODO: Use `derelativize` once Fp.t is used everywhere
   let fullPath =
-    switch (Fp.testForPath(fname)) {
+    switch (to_fp(fname)) {
     | Some(Absolute(path)) => path
     | Some(Relative(path)) =>
-      let cwd = Fp.absoluteExn(Sys.getcwd());
-      Fp.join(cwd, path);
+      let base = Fp.absoluteExn(get_cwd());
+      Fp.join(base, path);
     | None =>
       raise(
         Invalid_argument(
@@ -58,12 +72,12 @@ let ensure_parent_directory_exists = fname => {
 */
 let derelativize = (~base=?, fname) => {
   let fullPath =
-    switch (Fp.testForPath(fname)) {
+    switch (to_fp(fname)) {
     | Some(Absolute(path)) => path
     | Some(Relative(path)) =>
       let b =
         switch (base) {
-        | None => Fp.absolute(Sys.getcwd())
+        | None => Fp.absolute(get_cwd())
         | Some(path) => Fp.absolute(path)
         };
       switch (b) {