[vcpkg] Make Filesystem::remove_all faster #7570

I added benchmarks to measure how fast the parallel remove_all code was
-- it turns out, about 3x slower than stdfs::remove_all. Since this was
the case, I removed all of the parallelism and rewrote it serially, and
ended up about 30% faster than stdfs::remove_all (in addition to
supporting symlinks).

In addition, I did the following three orthogonal changes:
  - simplified the work queue, basing it on Billy O'Neal's idea
  - Fix warnings on older versions of compilers in tests, by splitting
    the pragmas out of pch.h.
  - Ran clang-format on some files

In fixing up remove_all, the following changes were made:
  - On Windows, regular symlinks and directory symlinks are distinct;
    as an example, to remove directory symlinks (and junctions, for that
    matter), one must use RemoveDirectory. Only on Windows, I added new
    `file_type` and `file_status` types, with `file_type` including a new
    `directory_symlink` enumerator, and `file_status` being exactly the
    same as the old one except using the new `file_type`. On Unix, I
    didn't make that change since they don't make a distinction.
  - I added new `symlink_status` and `status` functions which use the
    new `file_status` on Windows.
  - I made `Filesystem::exists` call `fs::exists(status(p))`, as opposed
    to the old version which called `stdfs::exists` directly.
  - Added benchmarks to `vcpkg-test/files.cpp`. They test the
    performance of `remove_all` on small directories (~20 files), with
    symlinks and without, and on large directories (~2000 files), with
    symlinks and without.

1 files changed, 52 insertions, 26 deletions

diff --git a/toolsrc/include/vcpkg-test/util.h b/toolsrc/include/vcpkg-test/util.h
index fa650abc8..8a458a3e5 100644
--- a/toolsrc/include/vcpkg-test/util.h
+++ b/toolsrc/include/vcpkg-test/util.h
@@ -1,42 +1,68 @@
+#include <vcpkg-test/catch.h>
+#include <vcpkg/pragmas.h>
+
 #include <vcpkg/base/files.h>
 #include <vcpkg/statusparagraph.h>
 
 #include <memory>
 
-namespace vcpkg::Test {
+#define CHECK_EC(ec)                                                                                                   \
+    do                                                                                                                 \
+    {                                                                                                                  \
+        if (ec)                                                                                                        \
+        {                                                                                                              \
+            FAIL(ec.message());                                                                                        \
+        }                                                                                                              \
+    } while (0)
 
-std::unique_ptr<vcpkg::StatusParagraph> make_status_pgh(const char* name,
-                                                        const char* depends = "",
-                                                        const char* default_features = "",
-                                                        const char* triplet = "x86-windows");
+namespace vcpkg::Test
+{
+    std::unique_ptr<vcpkg::StatusParagraph> make_status_pgh(const char* name,
+                                                            const char* depends = "",
+                                                            const char* default_features = "",
+                                                            const char* triplet = "x86-windows");
 
-std::unique_ptr<vcpkg::StatusParagraph> make_status_feature_pgh(const char* name,
-                                                                const char* feature,
-                                                                const char* depends = "",
-                                                                const char* triplet = "x86-windows");
+    std::unique_ptr<vcpkg::StatusParagraph> make_status_feature_pgh(const char* name,
+                                                                    const char* feature,
+                                                                    const char* depends = "",
+                                                                    const char* triplet = "x86-windows");
 
-vcpkg::PackageSpec unsafe_pspec(std::string name, vcpkg::Triplet t = vcpkg::Triplet::X86_WINDOWS);
+    vcpkg::PackageSpec unsafe_pspec(std::string name, vcpkg::Triplet t = vcpkg::Triplet::X86_WINDOWS);
 
-template<class T, class S>
-T&& unwrap(vcpkg::ExpectedT<T, S>&& p)
-{
-    REQUIRE(p.has_value());
-    return std::move(*p.get());
-}
+    template<class T, class S>
+    T&& unwrap(vcpkg::ExpectedT<T, S>&& p)
+    {
+        REQUIRE(p.has_value());
+        return std::move(*p.get());
+    }
 
-template<class T>
-T&& unwrap(vcpkg::Optional<T>&& opt)
-{
-    REQUIRE(opt.has_value());
-    return std::move(*opt.get());
-}
+    template<class T>
+    T&& unwrap(vcpkg::Optional<T>&& opt)
+    {
+        REQUIRE(opt.has_value());
+        return std::move(*opt.get());
+    }
+
+    struct AllowSymlinks
+    {
+        enum Tag : bool
+        {
+            No = false,
+            Yes = true,
+        } tag;
+
+        constexpr AllowSymlinks(Tag tag) noexcept : tag(tag) {}
+
+        constexpr explicit AllowSymlinks(bool b) noexcept : tag(b ? Yes : No) {}
 
-extern const bool SYMLINKS_ALLOWED;
+        constexpr operator bool() const noexcept { return tag == Yes; }
+    };
 
-extern const fs::path TEMPORARY_DIRECTORY;
+    AllowSymlinks can_create_symlinks() noexcept;
 
-void create_symlink(const fs::path& file, const fs::path& target, std::error_code& ec);
+    const fs::path& base_temporary_directory() noexcept;
 
-void create_directory_symlink(const fs::path& file, const fs::path& target, std::error_code& ec);
+    void create_symlink(const fs::path& file, const fs::path& target, std::error_code& ec);
 
+    void create_directory_symlink(const fs::path& file, const fs::path& target, std::error_code& ec);
 }