Replace hardcoded forward slash with path::MAIN_SEPARATOR

Fixes #40149

src/libstd/sys_common/backtrace.rs

@@ -19,7 +19,7 @@ use io;
 use libc;
 use str;
 use sync::atomic::{self, Ordering};
-use path::Path;
+use path::{self, Path};
 use sys::mutex::Mutex;
 use ptr;
 
@@ -262,7 +262,7 @@ fn output_fileline(w: &mut Write, file: &[u8], line: libc::c_int,
         if let Ok(cwd) = env::current_dir() {
             if let Ok(stripped) = file_path.strip_prefix(&cwd) {
                 if let Some(s) = stripped.to_str() {
-                    write!(w, "  at ./{}:{}", s, line)?;
+                    write!(w, "  at .{}{}:{}", path::MAIN_SEPARATOR, s, line)?;
                     already_printed = true;
                 }
             }

src/libsyntax/parse/parser.rs

@@ -59,7 +59,7 @@ use util::ThinVec;
 
 use std::collections::HashSet;
 use std::{cmp, mem, slice};
-use std::path::{Path, PathBuf};
+use std::path::{self, Path, PathBuf};
 
 bitflags! {
     flags Restrictions: u8 {
@@ -5146,7 +5146,7 @@ impl<'a> Parser<'a> {
     pub fn default_submod_path(id: ast::Ident, dir_path: &Path, codemap: &CodeMap) -> ModulePath {
         let mod_name = id.to_string();
         let default_path_str = format!("{}.rs", mod_name);
-        let secondary_path_str = format!("{}/mod.rs", mod_name);
+        let secondary_path_str = format!("{}{}mod.rs", mod_name, path::MAIN_SEPARATOR);
         let default_path = dir_path.join(&default_path_str);
         let secondary_path = dir_path.join(&secondary_path_str);
         let default_exists = codemap.file_exists(&default_path);
@@ -5224,8 +5224,9 @@ impl<'a> Parser<'a> {
             };
             err.span_note(id_sp,
                           &format!("maybe move this module `{0}` to its own directory \
-                                     via `{0}/mod.rs`",
-                                    this_module));
+                                    via `{0}{1}mod.rs`",
+                                   this_module,
+                                   path::MAIN_SEPARATOR));
             if paths.path_exists {
                 err.span_note(id_sp,
                               &format!("... or maybe `use` the module `{}` instead \

src/test/parse-fail/mod_file_not_exist.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// ignore-windows
+
 // compile-flags: -Z parse-only
 
 mod not_a_real_file; //~ ERROR file not found for module `not_a_real_file`

src/test/parse-fail/mod_file_not_exist_windows.rs

@@ -0,0 +1,32 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-gnu
+// ignore-android
+// ignore-bitrig
+// ignore-macos
+// ignore-dragonfly
+// ignore-freebsd
+// ignore-haiku
+// ignore-ios
+// ignore-linux
+// ignore-netbsd
+// ignore-openbsd
+// ignore-solaris
+// ignore-emscripten
+
+// compile-flags: -Z parse-only
+
+mod not_a_real_file; //~ ERROR file not found for module `not_a_real_file`
+//~^ HELP name the file either not_a_real_file.rs or not_a_real_file\mod.rs inside the directory
+
+fn main() {
+    assert_eq!(mod_file_aux::bar(), 10);
+}