From d097c9535a4d7a9053335d76329b95e25345c81e Mon Sep 17 00:00:00 2001
From: Steffen Schuemann <s.schuemann@pobox.com>
Date: Sun, 23 Sep 2018 14:12:42 +0200
Subject: [PATCH] [Closes #1] fs::canonical now errors on empty path and
 fs::weakly_canonical doesn't call canonical with empty path anymore

---
 filesystem.h             | 19 +++++++++++++++----
 test/filesystem_test.cpp |  9 +++++----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/filesystem.h b/filesystem.h
index 6ce1c80..ee423a2 100644
--- a/filesystem.h
+++ b/filesystem.h
@@ -2615,6 +2615,10 @@ inline path canonical(const path& p)
 
 inline path canonical(const path& p, std::error_code& ec)
 {
+    if(p.empty()) {
+        ec = detail::make_error_code(detail::portable_error::not_found);
+        return path();
+    }
     path work = p.is_absolute() ? p : absolute(p, ec);
     path root = work.root_path();
     path result;
@@ -3813,9 +3817,14 @@ inline path weakly_canonical(const path& p, std::error_code& ec) noexcept
                     return path();
                 }
                 scan = false;
-                result = canonical(result, ec) / pe;
-                if (ec) {
-                    break;
+                if(!result.empty()) {
+                    result = canonical(result, ec) / pe;
+                    if (ec) {
+                        break;
+                    }
+                }
+                else {
+                    result /= pe;
                 }
             }
         }
@@ -3824,7 +3833,9 @@ inline path weakly_canonical(const path& p, std::error_code& ec) noexcept
         }
     }
     if (scan) {
-        result = canonical(result, ec);
+        if(!result.empty()) {
+            result = canonical(result, ec);
+        }
     }
     return ec ? path() : result.lexically_normal();
 }
diff --git a/test/filesystem_test.cpp b/test/filesystem_test.cpp
index f895de0..8c4efdf 100644
--- a/test/filesystem_test.cpp
+++ b/test/filesystem_test.cpp
@@ -1101,7 +1101,7 @@ TEST_CASE("30.10.15.1 absolute", "[filesystem][operations][fs.op.absolute]")
 
 TEST_CASE("30.10.15.2 canonical", "[filesystem][operations][fs.op.canonical]")
 {
-    CHECK(fs::canonical("") == fs::current_path());
+    CHECK_THROWS_AS(fs::canonical(""), fs::filesystem_error);
     CHECK(fs::canonical(fs::current_path()) == fs::current_path());
 
     CHECK(fs::canonical(".") == fs::current_path());
@@ -1462,6 +1462,7 @@ TEST_CASE("30.10.15.13 exists", "[filesystem][operations][fs.op.exists]")
 {
     TemporaryDirectory t(TempOpt::change_path);
     std::error_code ec;
+    CHECK(!fs::exists(""));
     CHECK(!fs::exists("foo"));
     CHECK(!fs::exists("foo", ec));
     CHECK(!ec);
@@ -2130,9 +2131,9 @@ TEST_CASE("30.10.15.38 temporary_directory_path", "[filesystem][operations][fs.o
 
 TEST_CASE("30.10.15.39 weakly_canonical", "[filesystem][operations][fs.op.weakly_canonical]")
 {
-    CHECK(fs::weakly_canonical("foo/bar") == fs::current_path() / "foo/bar");
-    CHECK(fs::weakly_canonical("foo/./bar") == fs::current_path() / "foo/bar");
-    CHECK(fs::weakly_canonical("foo/../bar") == fs::current_path() / "bar");
+    CHECK(fs::weakly_canonical("foo/bar") == "foo/bar");
+    CHECK(fs::weakly_canonical("foo/./bar") == "foo/bar");
+    CHECK(fs::weakly_canonical("foo/../bar") == "bar");
 
     {
         TemporaryDirectory t(TempOpt::change_path);