Implement LWG 2937 - equivalent("dne", "exists") is not an error

This patch speculatively implements the PR for LWG 2937, which fixes
two issues with equivalent.

(1) It makes equivalent("dne", "exists") an error. Previously only
    equivalent("dne", "dne") was an error and the former case was not (it returned false).
    Now equivalent reports an error when either input doesn't exist.

(2) It makes equivalent(p1, p2) well-formed when `is_other(p1) && is_other(p2)`.
    Previously this was an error, but there is seemingly no reason why it should be on POSIX system.

llvm-svn: 307117

1 files changed, 75 insertions, 51 deletions

diff --git a/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.equivalent/equivalent.pass.cpp b/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.equivalent/equivalent.pass.cpp
index 621ff8305fc..36ce51abfc8 100644
--- a/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.equivalent/equivalent.pass.cpp
+++ b/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.equivalent/equivalent.pass.cpp
@@ -26,63 +26,87 @@ using namespace std::experimental::filesystem;
 
 TEST_SUITE(equivalent_test_suite)
 
-TEST_CASE(signature_test)
-{
-    const path p; ((void)p);
-    std::error_code ec; ((void)ec);
-    ASSERT_NOEXCEPT(equivalent(p, p, ec));
-    ASSERT_NOT_NOEXCEPT(equivalent(p, p));
+TEST_CASE(signature_test) {
+  const path p;
+  ((void)p);
+  std::error_code ec;
+  ((void)ec);
+  ASSERT_NOEXCEPT(equivalent(p, p, ec));
+  ASSERT_NOT_NOEXCEPT(equivalent(p, p));
 }
 
-TEST_CASE(equivalent_test)
-{
-    struct TestCase {
-        path lhs;
-        path rhs;
-        bool expect;
-    };
-    const TestCase testCases[] = {
-        {StaticEnv::Dir, StaticEnv::Dir, true},
-        {StaticEnv::File, StaticEnv::Dir, false},
-        {StaticEnv::Dir, StaticEnv::SymlinkToDir, true},
-        {StaticEnv::Dir, StaticEnv::SymlinkToFile, false},
-        {StaticEnv::File, StaticEnv::File, true},
-        {StaticEnv::File, StaticEnv::SymlinkToFile, true},
-    };
-    for (auto& TC : testCases) {
-        std::error_code ec;
-        TEST_CHECK(equivalent(TC.lhs, TC.rhs, ec) == TC.expect);
-        TEST_CHECK(!ec);
-    }
+TEST_CASE(equivalent_test) {
+  struct TestCase {
+    path lhs;
+    path rhs;
+    bool expect;
+  };
+  const TestCase testCases[] = {
+      {StaticEnv::Dir, StaticEnv::Dir, true},
+      {StaticEnv::File, StaticEnv::Dir, false},
+      {StaticEnv::Dir, StaticEnv::SymlinkToDir, true},
+      {StaticEnv::Dir, StaticEnv::SymlinkToFile, false},
+      {StaticEnv::File, StaticEnv::File, true},
+      {StaticEnv::File, StaticEnv::SymlinkToFile, true},
+  };
+  for (auto& TC : testCases) {
+    std::error_code ec;
+    TEST_CHECK(equivalent(TC.lhs, TC.rhs, ec) == TC.expect);
+    TEST_CHECK(!ec);
+  }
 }
 
-TEST_CASE(equivalent_reports_double_dne)
-{
-    const path E = StaticEnv::File;
-    const path DNE = StaticEnv::DNE;
-    { // Test that no exception is thrown if one of the paths exists
-        TEST_CHECK(equivalent(E, DNE) == false);
-        TEST_CHECK(equivalent(DNE, E) == false);
-    }
-    { // Test that an exception is thrown if both paths do not exist.
-        TEST_CHECK_THROW(filesystem_error, equivalent(DNE, DNE));
-    }
-    {
-        std::error_code ec;
-        TEST_CHECK(equivalent(DNE, DNE, ec) == false);
-        TEST_CHECK(ec);
-    }
+TEST_CASE(equivalent_reports_error_if_input_dne) {
+  const path E = StaticEnv::File;
+  const path DNE = StaticEnv::DNE;
+  { // Test that an error is reported when either of the paths don't exist
+    std::error_code ec = GetTestEC();
+    TEST_CHECK(equivalent(E, DNE, ec) == false);
+    TEST_CHECK(ec);
+    TEST_CHECK(ec != GetTestEC());
+  }
+  {
+    std::error_code ec = GetTestEC();
+    TEST_CHECK(equivalent(DNE, E, ec) == false);
+    TEST_CHECK(ec);
+    TEST_CHECK(ec != GetTestEC());
+  }
+  {
+    TEST_CHECK_THROW(filesystem_error, equivalent(DNE, E));
+    TEST_CHECK_THROW(filesystem_error, equivalent(E, DNE));
+  }
+  { // Test that an exception is thrown if both paths do not exist.
+    TEST_CHECK_THROW(filesystem_error, equivalent(DNE, DNE));
+  }
+  {
+    std::error_code ec = GetTestEC();
+    TEST_CHECK(equivalent(DNE, DNE, ec) == false);
+    TEST_CHECK(ec);
+    TEST_CHECK(ec != GetTestEC());
+  }
 }
 
-TEST_CASE(equivalent_is_other_succeeds)
-{
-    scoped_test_env env;
-    path const file = env.create_file("file", 42);
-    const path hl1 = env.create_hardlink(file, "hl1");
-    const path hl2 = env.create_hardlink(file, "hl2");
-    TEST_CHECK(equivalent(file, hl1));
-    TEST_CHECK(equivalent(file, hl2));
-    TEST_CHECK(equivalent(hl1, hl2));
+TEST_CASE(equivalent_hardlink_succeeds) {
+  scoped_test_env env;
+  path const file = env.create_file("file", 42);
+  const path hl1 = env.create_hardlink(file, "hl1");
+  const path hl2 = env.create_hardlink(file, "hl2");
+  TEST_CHECK(equivalent(file, hl1));
+  TEST_CHECK(equivalent(file, hl2));
+  TEST_CHECK(equivalent(hl1, hl2));
+}
+
+TEST_CASE(equivalent_is_other_succeeds) {
+  scoped_test_env env;
+  path const file = env.create_file("file", 42);
+  const path sock1 = env.create_socket("sock1");
+  const path sock2 = env.create_socket("sock2");
+  // Required to test behavior for inputs where is_other(p) is true.
+  TEST_REQUIRE(is_other(sock1));
+  TEST_CHECK(!equivalent(file, sock1));
+  TEST_CHECK(!equivalent(sock2, file));
+  TEST_CHECK(!equivalent(sock1, sock2));
+  TEST_CHECK(equivalent(sock1, sock1));
 }
 
 TEST_SUITE_END()