Change io::Reader and company to return ReadError::Eof instead of 0.

It's debatable if Eof should be considered an error or not.
But it is pretty clear it generally is a special response that
needs special handling, so easier to keep with the unexpected lot.

Also keeps better at higher abstraction levels, such as the line
reader.

4 files changed, 45 insertions, 51 deletions

diff --git a/test/io.cc b/test/io.cc
index 843c83e..04d97d6 100644
--- a/test/io.cc
+++ b/test/io.cc
@@ -128,8 +128,8 @@ TEST_F(IoTest, read_empty) {
   ASSERT_TRUE(ret.has_value());
   std::string tmp(10, ' ');
   auto ret2 = ret.value()->read(tmp.data(), tmp.size());
-  ASSERT_TRUE(ret2.has_value());
-  EXPECT_EQ(0, ret2.value());
+  ASSERT_FALSE(ret2.has_value());
+  EXPECT_EQ(io::ReadError::Eof, ret2.error());
 }
 
 TEST_F(IoTest, skip_empty) {
@@ -138,8 +138,8 @@ TEST_F(IoTest, skip_empty) {
   auto ret = io::openat(dirfd(), "test");
   ASSERT_TRUE(ret.has_value());
   auto ret2 = ret.value()->skip(10);
-  ASSERT_TRUE(ret2.has_value());
-  EXPECT_EQ(0, ret2.value());
+  ASSERT_FALSE(ret2.has_value());
+  EXPECT_EQ(io::ReadError::Eof, ret2.error());
 }
 
 TEST_F(IoTest, read) {
diff --git a/test/line.cc b/test/line.cc
index 71d75c5..e0ea002 100644
--- a/test/line.cc
+++ b/test/line.cc
@@ -12,7 +12,7 @@ TEST(line, empty) {
   EXPECT_EQ(0, reader->number());
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(0, reader->number());
 }
 
@@ -25,7 +25,7 @@ TEST(line, one_line) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -46,7 +46,7 @@ TEST(line, many_lines) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -67,7 +67,7 @@ TEST(line, many_lines_mixed) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -80,7 +80,7 @@ TEST(line, empty_line) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -101,7 +101,7 @@ TEST(line, max_line) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -110,8 +110,7 @@ TEST(line, read_error) {
       io_make_breaking(io::memory("foo bar fum\nfim zam"), /* offset */ 5));
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_FALSE(line.error().eof);
-  EXPECT_EQ(io::ReadError::Error, line.error().io_error.value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
 }
 
 TEST(line, read_error_newline) {
@@ -119,8 +118,7 @@ TEST(line, read_error_newline) {
       io_make_breaking(io::memory("foo bar\r\nfim zam"), /* offset */ 8));
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_FALSE(line.error().eof);
-  EXPECT_EQ(io::ReadError::Error, line.error().io_error.value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
 }
 
 TEST(line, blocky) {
@@ -134,7 +132,7 @@ TEST(line, blocky) {
   EXPECT_EQ("fim zam", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(line, blocky_newline) {
@@ -148,7 +146,7 @@ TEST(line, blocky_newline) {
   EXPECT_EQ("fim zam", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(line, eof_newline) {
@@ -158,7 +156,7 @@ TEST(line, eof_newline) {
   EXPECT_EQ("foo bar", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(line, max_newline) {
@@ -171,7 +169,7 @@ TEST(line, max_newline) {
   EXPECT_EQ("r", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(line, max_line_overflow) {
diff --git a/test/uio.cc b/test/uio.cc
index 47646e0..7d4c073 100644
--- a/test/uio.cc
+++ b/test/uio.cc
@@ -12,16 +12,16 @@ TEST(uio_u8, empty) {
   auto uio = u8::open(io::memory(""));
   std::string tmp;
   auto ret = uio->repeat_read(tmp, 10);
-  ASSERT_TRUE(ret.has_value());
-  EXPECT_EQ(0, ret.value());
+  ASSERT_FALSE(ret.has_value());
+  EXPECT_EQ(io::ReadError::Eof, ret.error());
 }
 
 TEST(uio_u16, empty) {
   auto uio = u16::open(io::memory(""));
   std::u16string tmp;
   auto ret = uio->repeat_read(tmp, 10);
-  ASSERT_TRUE(ret.has_value());
-  EXPECT_EQ(0, ret.value());
+  ASSERT_FALSE(ret.has_value());
+  EXPECT_EQ(io::ReadError::Eof, ret.error());
 }
 
 TEST(uio_u8, sample) {
diff --git a/test/uline.cc b/test/uline.cc
index ca3f2bb..8eb6a91 100644
--- a/test/uline.cc
+++ b/test/uline.cc
@@ -15,7 +15,7 @@ TEST(u8line, empty) {
   EXPECT_EQ(0, reader->number());
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(0, reader->number());
 }
 
@@ -29,7 +29,7 @@ TEST(u8line, one_line) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -50,7 +50,7 @@ TEST(u8line, many_lines) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -71,7 +71,7 @@ TEST(u8line, many_lines_mixed) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -84,7 +84,7 @@ TEST(u8line, empty_line) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -106,7 +106,7 @@ TEST(u8line, max_line) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -115,8 +115,7 @@ TEST(u8line, read_error) {
       io_make_breaking(io::memory("foo bar fum\nfim zam"), /* offset */ 5)));
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_FALSE(line.error().eof);
-  EXPECT_EQ(io::ReadError::Error, line.error().io_error.value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
 }
 
 TEST(u8line, read_error_newline) {
@@ -124,8 +123,7 @@ TEST(u8line, read_error_newline) {
       io_make_breaking(io::memory("foo bar\r\nfim zam"), /* offset */ 8)));
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_FALSE(line.error().eof);
-  EXPECT_EQ(io::ReadError::Error, line.error().io_error.value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
 }
 
 TEST(u8line, blocky) {
@@ -140,7 +138,7 @@ TEST(u8line, blocky) {
   EXPECT_EQ("fim zam", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u8line, blocky_newline) {
@@ -155,7 +153,7 @@ TEST(u8line, blocky_newline) {
   EXPECT_EQ("fim zam", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u8line, eof_newline) {
@@ -165,7 +163,7 @@ TEST(u8line, eof_newline) {
   EXPECT_EQ("foo bar", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u8line, max_newline) {
@@ -178,7 +176,7 @@ TEST(u8line, max_newline) {
   EXPECT_EQ("r", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u8line, max_line_overflow) {
@@ -195,7 +193,7 @@ TEST(u16line, empty) {
   EXPECT_EQ(0, reader->number());
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(0, reader->number());
 }
 
@@ -209,7 +207,7 @@ TEST(u16line, one_line) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -224,7 +222,7 @@ TEST(u16line, one_line_u16) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -245,7 +243,7 @@ TEST(u16line, many_lines) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -266,7 +264,7 @@ TEST(u16line, many_lines_mixed) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -279,7 +277,7 @@ TEST(u16line, empty_line) {
   EXPECT_EQ(1, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(1, reader->number());
 }
 
@@ -301,7 +299,7 @@ TEST(u16line, max_line) {
   EXPECT_EQ(3, reader->number());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
   EXPECT_EQ(3, reader->number());
 }
 
@@ -310,8 +308,7 @@ TEST(u16line, read_error) {
       io_make_breaking(io::memory("foo bar fum\nfim zam"), /* offset */ 5)));
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_FALSE(line.error().eof);
-  EXPECT_EQ(io::ReadError::Error, line.error().io_error.value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
 }
 
 TEST(u16line, read_error_newline) {
@@ -319,8 +316,7 @@ TEST(u16line, read_error_newline) {
       io_make_breaking(io::memory("foo bar\r\nfim zam"), /* offset */ 8)));
   auto line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_FALSE(line.error().eof);
-  EXPECT_EQ(io::ReadError::Error, line.error().io_error.value());
+  EXPECT_EQ(io::ReadError::Error, line.error());
 }
 
 TEST(u16line, blocky) {
@@ -335,7 +331,7 @@ TEST(u16line, blocky) {
   EXPECT_EQ(u"fim zam", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u16line, blocky_newline) {
@@ -350,7 +346,7 @@ TEST(u16line, blocky_newline) {
   EXPECT_EQ(u"fim zam", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u16line, eof_newline) {
@@ -360,7 +356,7 @@ TEST(u16line, eof_newline) {
   EXPECT_EQ(u"foo bar", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u16line, max_newline) {
@@ -373,7 +369,7 @@ TEST(u16line, max_newline) {
   EXPECT_EQ(u"r", line.value());
   line = reader->read();
   ASSERT_FALSE(line.has_value());
-  EXPECT_TRUE(line.error().eof);
+  EXPECT_EQ(io::ReadError::Eof, line.error());
 }
 
 TEST(u16line, max_line_overflow) {