[Support] Add a new path style for Windows with forward slashes

This behaves just like the regular Windows style, with both separator
forms accepted, but with get_separator() returning forward slashes.

Add a more descriptive name for the existing style, keeping the old
name around as an alias initially.

Add a new function `make_preferred()` (like the C++17
`std::filesystem::path` function with the same name), which converts
windows paths to the preferred separator form (while this one works on
any platform and takes a `path::Style` argument).

Contrary to `native()` (just like `make_preferred()` in `std::filesystem`),
this doesn't do anything at all on Posix, it doesn't try to reinterpret
backslashes into forward slashes there.

Differential Revision: https://reviews.llvm.org/D111879

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/lib/Support/Path.cpp b/llvm/lib/Support/Path.cpp
index 536d114..cea6df8 100644
--- a/llvm/lib/Support/Path.cpp
+++ b/llvm/lib/Support/Path.cpp
@@ -37,13 +37,15 @@ namespace {
   using llvm::sys::path::Style;
 
   inline Style real_style(Style style) {
+    if (style != Style::native)
+      return style;
     if (is_style_posix(style))
       return Style::posix;
     return Style::windows;
   }
 
   inline const char *separators(Style style) {
-    if (real_style(style) == Style::windows)
+    if (is_style_windows(style))
       return "\\/";
     return "/";
   }
@@ -547,7 +549,9 @@ void native(SmallVectorImpl<char> &Path, Style style) {
   if (Path.empty())
     return;
   if (is_style_windows(style)) {
-    std::replace(Path.begin(), Path.end(), '/', '\\');
+    for (char &Ch : Path)
+      if (is_separator(Ch, style))
+        Ch = preferred_separator(style);
     if (Path[0] == '~' && (Path.size() == 1 || is_separator(Path[1], style))) {
       SmallString<128> PathHome;
       home_directory(PathHome);
@@ -601,7 +605,7 @@ bool is_separator(char value, Style style) {
 }
 
 StringRef get_separator(Style style) {
-  if (is_style_windows(style))
+  if (real_style(style) == Style::windows)
     return "\\";
   return "/";
 }