[flang][windows] Support platform-specific path separator.

[Meinersbur]

Summary

Remove the assumption that the path separator is /. Use functions from llvm::sys::path instead.

[klausler]

There may be path separators with UNIX assumptions in the runtime I/O support library, too.

[isuruf]

Is 128 for the path size enough?

[Meinersbur]

In D89369#2345031, @klausler wrote:

There may be path separators with UNIX assumptions in the runtime I/O support library, too.

The runtime, such already has Windows-specific code mostly added by @isuruf.

In D89369#2345042, @isuruf wrote:

Is 128 for the path size enough?

This is a SmallString, the equivalent of SmallVector<char,128> which will grow when more characters are needed.

flang/lib/Parser/source.cpp

 //===-- lib/Parser/source.cpp ---------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "flang/Parser/source.h"
 #include "flang/Common/idioms.h"
 #include "flang/Parser/char-buffer.h"
 #include "llvm/Support/Errno.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <memory>
 #include <vector>
 
 namespace Fortran::parser {
 
 SourceFile::~SourceFile() { Close(); }
void SourceFile::IdentifyPayload() {
   constexpr llvm::StringLiteral UTF8_BOM{"\xef\xbb\xbf"};
   if (content.startswith(UTF8_BOM)) {
     bom_end_ = UTF8_BOM.size();
     encoding_ = Encoding::UTF_8;
   }
 }
 
 std::string DirectoryName(std::string path) {
-  auto lastSlash{path.rfind("/")};
-  return lastSlash == std::string::npos ? path : path.substr(0, lastSlash);
+  llvm::SmallString<128> pathBuf{path};
+  llvm::sys::path::remove_filename(pathBuf);
+  return pathBuf.str().str();
 }
 
 std::string LocateSourceFile(
     std::string name, const std::vector<std::string> &searchPath) {
-  if (name.empty() || name == "-" || name[0] == '/') {
+  if (name.empty() || name == "-" || llvm::sys::path::is_absolute(name)) {
     return name;
   }
   for (const std::string &dir : searchPath) {
-    std::string path{dir + '/' + name};
+    llvm::SmallString<128> path{dir};
+    llvm::sys::path::append(path, name);
     bool isDir{false};
     auto er = llvm::sys::fs::is_directory(path, isDir);
     if (!er && !isDir) {
-      return path;
+      return path.str().str();
     }
   }
   return name;
 }
 
 std::size_t RemoveCarriageReturns(llvm::MutableArrayRef<char> buf) {
   std::size_t wrote{0};
   char *buffer{buf.data()};

flang/test/Semantics/getsymbols02.f90

 ! Tests -fget-symbols-sources with modules.
 
 PROGRAM helloworld
     use mm2b
     implicit none
     integer::i
     i = callget5()
 ENDPROGRAM
 
 ! RUN: %f18 -fparse-only %S/Inputs/getsymbols02-a.f90
 ! RUN: %f18 -fparse-only %S/Inputs/getsymbols02-b.f90
 ! RUN: %f18 -fget-symbols-sources -fparse-only %s 2>&1 | FileCheck %s
-! CHECK: callget5: ./mm2b.mod,
-! CHECK: get5: ./mm2a.mod,
+! CHECK: callget5: .{{[/\\]}}mm2b.mod,
+! CHECK: get5: .{{[/\\]}}mm2a.mod,