Fix os.stem, os.short_stem.

core/os/path.odin

@@ -382,25 +382,21 @@ Returns an empty string if there is no stem. e.g: '.gitignore'.
 Returns an empty string if there's a trailing path separator.
 */
 stem :: proc(path: string) -> string {
-	if len(path) > 0 {
-		if is_path_separator(path[len(path) - 1]) {
-			// NOTE(tetra): Trailing separator
-			return ""
-		} else if path[0] == '.' {
-			return ""
-		}
+	// If the last character is a path separator, there is no file.
+	if is_path_separator(path[len(path) - 1]) {
+		return ""
 	}
 
-	// NOTE(tetra): Get the basename
-	path := path
-	if i := strings.last_index_any(path, Path_Separator_Chars); i != -1 {
-		path = path[i+1:]
+	// Get the base path.
+	p := base(path)
+	if i := strings.last_index_any(p, Path_Separator_Chars); i != -1 {
+		p = p[i+1:]
 	}
 
-	if i := strings.last_index_byte(path, '.'); i != -1 {
-		return path[:i]
+	if i := strings.last_index_byte(p, '.'); i != -1 {
+		return p[:i]
 	}
-	return path
+	return p
 }
 
 /*

tests/core/path/filepath/test_core_filepath.odin

@@ -109,4 +109,27 @@ delete_split :: proc(s: []string) {
 		delete(part)
 	}
 	delete(s)
+}
+
+@(test)
+test_stem :: proc(t: ^testing.T) {
+	@static stem := [][2]string{
+		{"builder.tar.gz",   "builder.tar"},
+		{"./builder.tar.gz", "builder.tar"},
+		{"./builder/",       ""},
+	}
+
+	@static short_stem := [][2]string{
+		{"builder.tar",   "builder"},
+		{"./builder.tar", "builder"},
+		{"./builder/",    ""},
+	}
+
+	for d in stem {
+		testing.expect_value(t, filepath.stem(d[0]), d[1])
+	}
+
+	for d in short_stem {
+		testing.expect_value(t, filepath.stem(d[0]), d[1])
+	}
 }