ocaml: phase 6 Filename module + Char.compare/equal/escaped (+7 tests, 569 total)

Filename module (forward-slash only, no Windows-separator detection):

  basename '/foo/bar/baz.ml'        = 'baz.ml'
  dirname  '/foo/bar/baz.ml'        = '/foo/bar'
  extension 'baz.tar.gz'            = '.gz'
  chop_extension 'hello.ml'         = 'hello'
  concat 'a' 'b'                    = 'a/b'
  is_relative 'a/b'                 = true
  current_dir_name = '.', parent_dir_name = '..', dir_sep = '/'

Char additions:

  equal a b                         = (a = b)
  compare a b                       = code(a) - code(b)
  escaped '\n'                      = '\\n'    (likewise t, r, \\, ")

lib/ocaml/test.sh

@@ -1404,6 +1404,24 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 5152)
 (eval "(ocaml-run \"let f ?x ~y = x + y in f ?x:1 ~y:2\")")
 
+;; ── Filename module ──────────────────────────────────────────
+(epoch 5160)
+(eval "(ocaml-run \"Filename.basename \\\"/foo/bar/baz.ml\\\"\")")
+(epoch 5161)
+(eval "(ocaml-run \"Filename.dirname \\\"/foo/bar/baz.ml\\\"\")")
+(epoch 5162)
+(eval "(ocaml-run \"Filename.extension \\\"baz.tar.gz\\\"\")")
+(epoch 5163)
+(eval "(ocaml-run \"Filename.concat \\\"a\\\" \\\"b\\\"\")")
+(epoch 5164)
+(eval "(ocaml-run \"Filename.chop_extension \\\"hello.ml\\\"\")")
+
+;; ── Char.compare / equal / escaped ─────────────────────────
+(epoch 5170)
+(eval "(ocaml-run \"Char.compare \\\"b\\\" \\\"a\\\"\")")
+(epoch 5171)
+(eval "(ocaml-run \"Char.equal \\\"a\\\" \\\"a\\\"\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 360 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -2232,6 +2250,17 @@ check 5150 "f ~x:3 ~y:7 sum"              '10'
 check 5151 "f ~x ~y punning"              '20'
 check 5152 "f ?x:1 ~y:2 (no Some wrap)"   '3'
 
+# ── Filename module ─────────────────────────────────────────────
+check 5160 "basename /foo/bar/baz.ml"     '"baz.ml"'
+check 5161 "dirname /foo/bar/baz.ml"      '"/foo/bar"'
+check 5162 "extension baz.tar.gz"         '".gz"'
+check 5163 "concat a b"                   '"a/b"'
+check 5164 "chop_extension hello.ml"      '"hello"'
+
+# ── Char.compare / equal ────────────────────────────────────────
+check 5170 "Char.compare b a"             '1'
+check 5171 "Char.equal a a"               'true'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"