From f7bfcdd7aae4faa8a13e203e0694e5428ffa6776 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Wed, 14 Oct 2020 18:00:04 +0900
Subject: [PATCH 01/25] fix: check all the elements in an array

while checking if the array is array-of-tables or not (heterogeneous
arrays are allowed, so there might be an array that has a table and
an integer at the same time)
---
 toml/serializer.hpp | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index ed07f46..cf47710 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -244,7 +244,17 @@ struct serializer
 
     std::string operator()(const array_type& v) const
     {
-        if(!v.empty() && v.front().is_table())// v is an array of tables
+        if(v.empty())
+        {
+            return std::string("[]");
+        }
+
+        // Since TOML v0.5.0, heterogeneous arrays are allowed. So we need to
+        // check all the element in an array to check if the array is an array
+        // of tables.
+        const bool is_array_of_tables = std::all_of(v.begin(), v.end(),
+                [](const value_type& elem) {return elem.is_table();});
+        if(is_array_of_tables)
         {
             // if it's not inlined, we need to add `[[table.key]]`.
             // but if it can be inlined,
@@ -322,10 +332,6 @@ struct serializer
             }
             return token;
         }
-        if(v.empty())
-        {
-            return std::string("[]");
-        }
 
         // not an array of tables. normal array.
         // first, try to make it inline if none of the elements have a comment.

From 382e3dc3ab3ea26ba8567f3ecd84b476afcec44a Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Wed, 14 Oct 2020 22:27:29 +0900
Subject: [PATCH 02/25] refactor: use serializer::is_array_of_tables

---
 toml/serializer.hpp | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index cf47710..433997b 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -248,13 +248,7 @@ struct serializer
         {
             return std::string("[]");
         }
-
-        // Since TOML v0.5.0, heterogeneous arrays are allowed. So we need to
-        // check all the element in an array to check if the array is an array
-        // of tables.
-        const bool is_array_of_tables = std::all_of(v.begin(), v.end(),
-                [](const value_type& elem) {return elem.is_table();});
-        if(is_array_of_tables)
+        if(this->is_array_of_tables(v))
         {
             // if it's not inlined, we need to add `[[table.key]]`.
             // but if it can be inlined,
@@ -674,8 +668,16 @@ struct serializer
     bool is_array_of_tables(const value_type& v) const
     {
         if(!v.is_array()) {return false;}
-        const auto& a = v.as_array();
-        return !a.empty() && a.front().is_table();
+        return is_array_of_tables(v.as_array());
+    }
+    bool is_array_of_tables(const array_type& v) const
+    {
+        // Since TOML v0.5.0, heterogeneous arrays are allowed. So we need to
+        // check all the element in an array to check if the array is an array
+        // of tables.
+        return std::all_of(v.begin(), v.end(), [](const value_type& elem) {
+                return elem.is_table();
+            });
     }
 
   private:

From 9090b8273ce536bbf26ccff1fa3b492968cca767 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Sun, 18 Oct 2020 17:20:06 +0900
Subject: [PATCH 03/25] refactor: move array-of-table stuff to a function

---
 toml/serializer.hpp | 159 +++++++++++++++++++++++---------------------
 1 file changed, 82 insertions(+), 77 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index 433997b..385e79b 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -250,86 +250,12 @@ struct serializer
         }
         if(this->is_array_of_tables(v))
         {
-            // if it's not inlined, we need to add `[[table.key]]`.
-            // but if it can be inlined,
-            // ```
-            // table.key = [
-            //   {...},
-            //   # comment
-            //   {...},
-            // ]
-            // ```
-            if(this->can_be_inlined_)
-            {
-                std::string token;
-                if(!keys_.empty())
-                {
-                    token += format_key(keys_.back());
-                    token += " = ";
-                }
-                bool failed = false;
-                token += "[\n";
-                for(const auto& item : v)
-                {
-                    // if an element of the table has a comment, the table
-                    // cannot be inlined.
-                    if(this->has_comment_inside(item.as_table()))
-                    {
-                        failed = true;
-                        break;
-                    }
-                    if(!no_comment_)
-                    {
-                        for(const auto& c : item.comments())
-                        {
-                            token += '#';
-                            token += c;
-                            token += '\n';
-                        }
-                    }
-
-                    const auto t = this->make_inline_table(item.as_table());
-
-                    if(t.size() + 1 > width_ || // +1 for the last comma {...},
-                       std::find(t.cbegin(), t.cend(), '\n') != t.cend())
-                    {
-                        failed = true;
-                        break;
-                    }
-                    token += t;
-                    token += ",\n";
-                }
-                if(!failed)
-                {
-                    token += "]\n";
-                    return token;
-                }
-                // if failed, serialize them as [[array.of.tables]].
-            }
-
-            std::string token;
-            for(const auto& item : v)
-            {
-                if(!no_comment_)
-                {
-                    for(const auto& c : item.comments())
-                    {
-                        token += '#';
-                        token += c;
-                        token += '\n';
-                    }
-                }
-                token += "[[";
-                token += format_keys(keys_);
-                token += "]]\n";
-                token += this->make_multiline_table(item.as_table());
-            }
-            return token;
+            return make_array_of_tables(v);
         }
 
         // not an array of tables. normal array.
         // first, try to make it inline if none of the elements have a comment.
-        if(!this->has_comment_inside(v))
+        if( ! this->has_comment_inside(v))
         {
             const auto inl = this->make_inline_array(v);
             if(inl.size() < this->width_ &&
@@ -350,7 +276,7 @@ struct serializer
         token += "[\n";
         for(const auto& item : v)
         {
-            if(!item.comments().empty() && !no_comment_)
+            if( ! item.comments().empty() && !no_comment_)
             {
                 // if comment exists, the element must be the only element in the line.
                 // e.g. the following is not allowed.
@@ -665,6 +591,85 @@ struct serializer
         return token;
     }
 
+    std::string make_array_of_tables(const array_type& v) const
+    {
+        // if it's not inlined, we need to add `[[table.key]]`.
+        // but if it can be inlined,
+        // ```
+        // table.key = [
+        //   {...},
+        //   # comment
+        //   {...},
+        // ]
+        // ```
+        if(this->can_be_inlined_)
+        {
+            std::string token;
+            if(!keys_.empty())
+            {
+                token += format_key(keys_.back());
+                token += " = ";
+            }
+            bool failed = false;
+            token += "[\n";
+            for(const auto& item : v)
+            {
+                // if an element of the table has a comment, the table
+                // cannot be inlined.
+                if(this->has_comment_inside(item.as_table()))
+                {
+                    failed = true;
+                    break;
+                }
+                if(!no_comment_)
+                {
+                    for(const auto& c : item.comments())
+                    {
+                        token += '#';
+                        token += c;
+                        token += '\n';
+                    }
+                }
+
+                const auto t = this->make_inline_table(item.as_table());
+
+                if(t.size() + 1 > width_ || // +1 for the last comma {...},
+                   std::find(t.cbegin(), t.cend(), '\n') != t.cend())
+                {
+                    failed = true;
+                    break;
+                }
+                token += t;
+                token += ",\n";
+            }
+            if(!failed)
+            {
+                token += "]\n";
+                return token;
+            }
+            // if failed, serialize them as [[array.of.tables]].
+        }
+
+        std::string token;
+        for(const auto& item : v)
+        {
+            if(!no_comment_)
+            {
+                for(const auto& c : item.comments())
+                {
+                    token += '#';
+                    token += c;
+                    token += '\n';
+                }
+            }
+            token += "[[";
+            token += format_keys(keys_);
+            token += "]]\n";
+            token += this->make_multiline_table(item.as_table());
+        }
+        return token;
+    }
+
     bool is_array_of_tables(const value_type& v) const
     {
         if(!v.is_array()) {return false;}

From fd50b11523e247efa21d90eafe70eccaec7121b9 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Sun, 18 Oct 2020 18:30:04 +0900
Subject: [PATCH 04/25] refactor: add write_comments()

---
 toml/serializer.hpp | 56 ++++++++++++++++-----------------------------
 1 file changed, 20 insertions(+), 36 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index 385e79b..79a6b92 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -523,15 +523,8 @@ struct serializer
                 continue;
             }
 
-            if(!kv.second.comments().empty() && !no_comment_)
-            {
-                for(const auto& c : kv.second.comments())
-                {
-                    token += '#';
-                    token += c;
-                    token += '\n';
-                }
-            }
+            token += write_comments(kv.second);
+
             const auto key_and_sep    = format_key(kv.first) + " = ";
             const auto residual_width = (this->width_ > key_and_sep.size()) ?
                                         this->width_ - key_and_sep.size() : 0;
@@ -577,15 +570,7 @@ struct serializer
                 tmp += '\n';
             }
 
-            if(!kv.second.comments().empty() && !no_comment_)
-            {
-                for(const auto& c : kv.second.comments())
-                {
-                    token += '#';
-                    token += c;
-                    token += '\n';
-                }
-            }
+            token += write_comments(kv.second);
             token += tmp;
         }
         return token;
@@ -621,15 +606,8 @@ struct serializer
                     failed = true;
                     break;
                 }
-                if(!no_comment_)
-                {
-                    for(const auto& c : item.comments())
-                    {
-                        token += '#';
-                        token += c;
-                        token += '\n';
-                    }
-                }
+                // write comments for the table itself
+                token += write_comments(item);
 
                 const auto t = this->make_inline_table(item.as_table());
 
@@ -653,15 +631,7 @@ struct serializer
         std::string token;
         for(const auto& item : v)
         {
-            if(!no_comment_)
-            {
-                for(const auto& c : item.comments())
-                {
-                    token += '#';
-                    token += c;
-                    token += '\n';
-                }
-            }
+            token += write_comments(item);
             token += "[[";
             token += format_keys(keys_);
             token += "]]\n";
@@ -670,6 +640,20 @@ struct serializer
         return token;
     }
 
+    std::string write_comments(const value_type& v) const
+    {
+        std::string retval;
+        if(this->no_comment_) {return retval;}
+
+        for(const auto& c : v.comments())
+        {
+            retval += '#';
+            retval += c;
+            retval += '\n';
+        }
+        return retval;
+    }
+
     bool is_array_of_tables(const value_type& v) const
     {
         if(!v.is_array()) {return false;}

From fce6ff317e2dabe330625e2eda7d4819278e3ea6 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Sun, 18 Oct 2020 18:36:05 +0900
Subject: [PATCH 05/25] refactor: distinguish the reason of failure

---
 toml/serializer.hpp | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index 79a6b92..95ea1ff 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -595,7 +595,9 @@ struct serializer
                 token += format_key(keys_.back());
                 token += " = ";
             }
-            bool failed = false;
+
+            bool exceed_column = false;
+            bool has_comment   = false;
             token += "[\n";
             for(const auto& item : v)
             {
@@ -603,7 +605,7 @@ struct serializer
                 // cannot be inlined.
                 if(this->has_comment_inside(item.as_table()))
                 {
-                    failed = true;
+                    has_comment = true;
                     break;
                 }
                 // write comments for the table itself
@@ -614,13 +616,13 @@ struct serializer
                 if(t.size() + 1 > width_ || // +1 for the last comma {...},
                    std::find(t.cbegin(), t.cend(), '\n') != t.cend())
                 {
-                    failed = true;
+                    exceed_column = true;
                     break;
                 }
                 token += t;
                 token += ",\n";
             }
-            if(!failed)
+            if(!exceed_column && !has_comment)
             {
                 token += "]\n";
                 return token;

From 908b91079b6cf603f2d08094d84b37b660f0de07 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Sun, 18 Oct 2020 20:43:33 +0900
Subject: [PATCH 06/25] fix: distinguish the comments and try to keep it

If a value has a comment, we need to try to write it explicitly.
---
 toml/serializer.hpp | 85 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 66 insertions(+), 19 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index 95ea1ff..e702ead 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -97,8 +97,10 @@ struct serializer
                const int         float_prec     = std::numeric_limits<toml::floating>::max_digits10,
                const bool        can_be_inlined = false,
                const bool        no_comment     = false,
-               std::vector<toml::key> ks        = {})
+               std::vector<toml::key> ks        = {},
+               const bool     value_has_comment = false)
         : can_be_inlined_(can_be_inlined), no_comment_(no_comment),
+          value_has_comment_(value_has_comment && !no_comment),
           float_prec_(float_prec), width_(w), keys_(std::move(ks))
     {}
     ~serializer() = default;
@@ -483,8 +485,10 @@ struct serializer
         for(const auto& item : v)
         {
             if(is_first) {is_first = false;} else {token += ',';}
-            token += visit(serializer((std::numeric_limits<std::size_t>::max)(),
-                                      this->float_prec_, true), item);
+            token += visit(serializer(
+                (std::numeric_limits<std::size_t>::max)(), this->float_prec_,
+                /* inlined */ true, /*no comment*/ false, /*keys*/ {},
+                /*has_comment*/ !item.comments().empty()), item);
         }
         token += ']';
         return token;
@@ -503,8 +507,10 @@ struct serializer
             if(is_first) {is_first = false;} else {token += ',';}
             token += format_key(kv.first);
             token += '=';
-            token += visit(serializer((std::numeric_limits<std::size_t>::max)(),
-                                      this->float_prec_, true), kv.second);
+            token += visit(serializer(
+                (std::numeric_limits<std::size_t>::max)(), this->float_prec_,
+                /* inlined */ true, /*no comment*/ false, /*keys*/ {},
+                /*has_comment*/ !kv.second.comments().empty()), kv.second);
         }
         token += '}';
         return token;
@@ -514,8 +520,16 @@ struct serializer
     {
         std::string token;
 
-        // print non-table stuff first. because after printing [foo.bar], the
-        // remaining non-table values will be assigned into [foo.bar], not [foo]
+        // print non-table elements first.
+        // ```toml
+        // [foo]         # a table we're writing now here
+        // key = "value" # <- non-table element, "key"
+        // # ...
+        // [foo.bar] # <- table element, "bar"
+        // ```
+        // because after printing [foo.bar], the remaining non-table values will
+        // be assigned into [foo.bar], not [foo]. Those values should be printed
+        // earlier.
         for(const auto& kv : v)
         {
             if(kv.second.is_table() || is_array_of_tables(kv.second))
@@ -529,8 +543,10 @@ struct serializer
             const auto residual_width = (this->width_ > key_and_sep.size()) ?
                                         this->width_ - key_and_sep.size() : 0;
             token += key_and_sep;
-            token += visit(serializer(residual_width, this->float_prec_, true),
-                           kv.second);
+            token += visit(serializer(residual_width, this->float_prec_,
+                /*can be inlined*/ true, /*no comment*/ false, /*keys*/ {},
+                /*has_comment*/ !kv.second.comments().empty()), kv.second);
+
             if(token.back() != '\n')
             {
                 token += '\n';
@@ -556,8 +572,8 @@ struct serializer
             ks.push_back(kv.first);
 
             auto tmp = visit(serializer(this->width_, this->float_prec_,
-                !multiline_table_printed, this->no_comment_, ks),
-                kv.second);
+                !multiline_table_printed, this->no_comment_, ks,
+                /*has_comment*/ !kv.second.comments().empty()), kv.second);
 
             if((!multiline_table_printed) &&
                std::find(tmp.cbegin(), tmp.cend(), '\n') != tmp.cend())
@@ -579,7 +595,7 @@ struct serializer
     std::string make_array_of_tables(const array_type& v) const
     {
         // if it's not inlined, we need to add `[[table.key]]`.
-        // but if it can be inlined,
+        // but if it can be inlined, we can format it as the following.
         // ```
         // table.key = [
         //   {...},
@@ -587,7 +603,33 @@ struct serializer
         //   {...},
         // ]
         // ```
-        if(this->can_be_inlined_)
+        // This function checks if inlinization is possible or not, and then
+        // format the array-of-tables in a proper way.
+        //
+        // Note about comments:
+        //
+        // If the array itself has a comment (value_has_comment_ == true), we
+        // should try to make it inline.
+        // ```toml
+        // # comment about array
+        // array = [
+        //   # comment about table element
+        //   {of = "table"}
+        // ]
+        // ```
+        // If it is formatted as a multiline table, the two comments becomes
+        // indistinguishable.
+        // ```toml
+        // # comment about array
+        // # comment about table element
+        // [[array]]
+        // of = "table"
+        // ```
+        // So we need to try to make it inline, and it force-inlines regardless
+        // of the line width limit.
+        //     It may fail if the element of a table has comment. In that case,
+        // the array-of-tables will be formatted as a multiline table.
+        if(this->can_be_inlined_ || this->value_has_comment_)
         {
             std::string token;
             if(!keys_.empty())
@@ -596,8 +638,7 @@ struct serializer
                 token += " = ";
             }
 
-            bool exceed_column = false;
-            bool has_comment   = false;
+            bool failed = false;
             token += "[\n";
             for(const auto& item : v)
             {
@@ -605,7 +646,7 @@ struct serializer
                 // cannot be inlined.
                 if(this->has_comment_inside(item.as_table()))
                 {
-                    has_comment = true;
+                    failed = true;
                     break;
                 }
                 // write comments for the table itself
@@ -616,13 +657,18 @@ struct serializer
                 if(t.size() + 1 > width_ || // +1 for the last comma {...},
                    std::find(t.cbegin(), t.cend(), '\n') != t.cend())
                 {
-                    exceed_column = true;
-                    break;
+                    // if the value itself has a comment, ignore the line width limit
+                    if( ! this->value_has_comment_)
+                    {
+                        failed = true;
+                        break;
+                    }
                 }
                 token += t;
                 token += ",\n";
             }
-            if(!exceed_column && !has_comment)
+
+            if( ! failed)
             {
                 token += "]\n";
                 return token;
@@ -675,6 +721,7 @@ struct serializer
 
     bool        can_be_inlined_;
     bool        no_comment_;
+    bool        value_has_comment_;
     int         float_prec_;
     std::size_t width_;
     std::vector<toml::key> keys_;

From 0dafa7ee42739311ba6d455a41700febdeb11263 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Sun, 18 Oct 2020 20:45:12 +0900
Subject: [PATCH 07/25] test: add case where a table should be inlined

array-of-table implicitly defines an array. If the array itself has a
comment, we need to format it explicitly.
---
 tests/test_serialize_file.cpp | 58 +++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/tests/test_serialize_file.cpp b/tests/test_serialize_file.cpp
index f7384bb..b5c408e 100644
--- a/tests/test_serialize_file.cpp
+++ b/tests/test_serialize_file.cpp
@@ -10,6 +10,7 @@
 #include <map>
 #include <iostream>
 #include <fstream>
+#include <sstream>
 
 template<typename Comment,
          template<typename ...> class Table,
@@ -303,3 +304,60 @@ BOOST_AUTO_TEST_CASE(test_format_key)
         BOOST_TEST("\"special-chars-\\\\-\\\"-\\b-\\f-\\r-\\n-\\t\"" == toml::format_key(key));
     }
 }
+
+// In toml11, an implicitly-defined value does not have any comments.
+// So, in the following file,
+// ```toml
+// # comment
+// [[array-of-tables]]
+// foo = "bar"
+// ```
+// The array named "array-of-tables" does not have the comment, but the first
+// element of the array has. That means that, the above file is equivalent to
+// the following.
+// ```toml
+// array-of-tables = [
+//     # comment
+//     {foo = "bar"},
+// ]
+// ```
+// If the array itself has a comment (value_has_comment_ == true), we should try
+// to make it inline.
+// ```toml
+// # comment about array
+// array-of-tables = [
+//   # comment about table element
+//   {foo = "bar"}
+// ]
+// ```
+// If it is formatted as a multiline table, the two comments becomes
+// indistinguishable.
+// ```toml
+// # comment about array
+// # comment about table element
+// [[array-of-tables]]
+// foo = "bar"
+// ```
+// So we need to try to make it inline, and it force-inlines regardless
+// of the line width limit.
+//     It may fail if the element of a table has comment. In that case,
+// the array-of-tables will be formatted as a multiline table.
+BOOST_AUTO_TEST_CASE(test_distinguish_comment)
+{
+    const std::string str = R"(# comment about array itself
+array_of_table = [
+    # comment about the first element (table)
+    {key = "value"},
+])";
+    std::istringstream iss(str);
+    const auto data = toml::parse<toml::preserve_comments>(iss);
+    const auto serialized = toml::format(data, /*width = */ 0);
+
+    std::istringstream reparse(serialized);
+    const auto parsed = toml::parse<toml::preserve_comments>(reparse);
+
+    BOOST_TEST(parsed.at("array_of_table").comments().size()  == 1u);
+    BOOST_TEST(parsed.at("array_of_table").comments().front() == " comment about array itself");
+    BOOST_TEST(parsed.at("array_of_table").at(0).comments().size()  == 1u);
+    BOOST_TEST(parsed.at("array_of_table").at(0).comments().front() == " comment about the first element (table)");
+}

From a6581ee66b44bd70b2f8c51fa10895e499385d54 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Tue, 3 Nov 2020 20:34:01 +0900
Subject: [PATCH 08/25] fix: an empty array is not an array of table

---
 toml/serializer.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index e702ead..fec7d08 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -704,7 +704,7 @@ struct serializer
 
     bool is_array_of_tables(const value_type& v) const
     {
-        if(!v.is_array()) {return false;}
+        if(!v.is_array() || v.as_array().empty()) {return false;}
         return is_array_of_tables(v.as_array());
     }
     bool is_array_of_tables(const array_type& v) const

From 1ead14589e1ba07ca6bf82743c936091840165f1 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Wed, 4 Nov 2020 23:24:02 +0900
Subject: [PATCH 09/25] fix: check if it is empty before calling back()

---
 toml/region.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/toml/region.hpp b/toml/region.hpp
index 6761aed..37ba3a3 100644
--- a/toml/region.hpp
+++ b/toml/region.hpp
@@ -344,7 +344,7 @@ struct region final : public region_base
                     {
                         // unwrap the first '#' by std::next.
                         auto str = make_string(std::next(comment_found), iter);
-                        if(str.back() == '\r') {str.pop_back();}
+                        if(!str.empty() && str.back() == '\r') {str.pop_back();}
                         com.push_back(std::move(str));
                     }
                     else
@@ -397,7 +397,7 @@ struct region final : public region_base
                 {
                     // unwrap the first '#' by std::next.
                     auto str = make_string(std::next(comment_found), this->line_end());
-                    if(str.back() == '\r') {str.pop_back();}
+                    if(!str.empty() && str.back() == '\r') {str.pop_back();}
                     com.push_back(std::move(str));
                 }
             }

From 9b472a6c72fc9668446ee8c258594a787ed60f28 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Wed, 4 Nov 2020 23:24:59 +0900
Subject: [PATCH 10/25] fix: check it is empty before calling back

---
 toml/serializer.hpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index fec7d08..bef1827 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -122,7 +122,7 @@ struct serializer
         std::snprintf(buf.data(), buf.size(), fmt, this->float_prec_, f);
 
         std::string token(buf.begin(), std::prev(buf.end()));
-        if(token.back() == '.') // 1. => 1.0
+        if(!token.empty() && token.back() == '.') // 1. => 1.0
         {
             token += '0';
         }
@@ -304,7 +304,7 @@ struct serializer
                     token += '\n';
                 }
                 token += toml::visit(*this, item);
-                if(token.back() == '\n') {token.pop_back();}
+                if(!token.empty() && token.back() == '\n') {token.pop_back();}
                 token += ",\n";
                 continue;
             }
@@ -312,7 +312,7 @@ struct serializer
             next_elem += toml::visit(*this, item);
 
             // comma before newline.
-            if(next_elem.back() == '\n') {next_elem.pop_back();}
+            if(!next_elem.empty() && next_elem.back() == '\n') {next_elem.pop_back();}
 
             // if current line does not exceeds the width limit, continue.
             if(current_line.size() + next_elem.size() + 1 < this->width_)
@@ -339,7 +339,10 @@ struct serializer
         }
         if(!current_line.empty())
         {
-            if(current_line.back() != '\n') {current_line += '\n';}
+            if(!current_line.empty() && current_line.back() != '\n')
+            {
+                current_line += '\n';
+            }
             token += current_line;
         }
         token += "]\n";

From 935da51769ad40732879780214c1ac674b37f621 Mon Sep 17 00:00:00 2001
From: Alex Merry <alex.merry@nanoporetech.com>
Date: Wed, 9 Dec 2020 10:15:38 +0000
Subject: [PATCH 11/25] Add missing include for ostringstream

Since region.hpp no longer includes <iostream> (but only <iomanip>),
source_location.hpp no longer includes a header that provides
std::ostringstream. Including <sstream> fixes this.
---
 toml/source_location.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/toml/source_location.hpp b/toml/source_location.hpp
index a386710..fa175b5 100644
--- a/toml/source_location.hpp
+++ b/toml/source_location.hpp
@@ -3,6 +3,7 @@
 #ifndef TOML11_SOURCE_LOCATION_HPP
 #define TOML11_SOURCE_LOCATION_HPP
 #include <cstdint>
+#include <sstream>
 
 #include "region.hpp"
 

From db2d33ca4be2315549a6b46c17617629180b1723 Mon Sep 17 00:00:00 2001
From: Alex Merry <alex.merry@nanoporetech.com>
Date: Wed, 9 Dec 2020 10:39:10 +0000
Subject: [PATCH 12/25] Add missing header for std::out_of_range exception

Failure seen on GCC 4.8.5 when including "toml/value.hpp".
---
 toml/comments.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/toml/comments.hpp b/toml/comments.hpp
index 1e17544..92fc8e1 100644
--- a/toml/comments.hpp
+++ b/toml/comments.hpp
@@ -4,6 +4,7 @@
 #define TOML11_COMMENTS_HPP
 #include <initializer_list>
 #include <iterator>
+#include <stdexcept>
 #include <string>
 #include <type_traits>
 #include <utility>

From 2fb8793f1af4a4c1727eca7780597ce5cafa6629 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Tue, 29 Dec 2020 18:52:07 +0900
Subject: [PATCH 13/25] doc: add document about basic_value and toml::into

related to #146.
---
 README.md | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 4bd139c..fcc4b0e 100644
--- a/README.md
+++ b/README.md
@@ -1303,9 +1303,9 @@ struct foo
     double      b;
     std::string c;
 
-    toml::table into_toml() const // you need to mark it const.
+    toml::value into_toml() const // you need to mark it const.
     {
-        return toml::table{{"a", this->a}, {"b", this->b}, {"c", this->c}};
+        return toml::value{{"a", this->a}, {"b", this->b}, {"c", this->c}};
     }
 };
 } // ext
@@ -1332,9 +1332,9 @@ namespace toml
 template<>
 struct into<ext::foo>
 {
-    static toml::table into_toml(const ext::foo& f)
+    static toml::value into_toml(const ext::foo& f)
     {
-        return toml::table{{"a", f.a}, {"b", f.b}, {"c", f.c}};
+        return toml::value{{"a", f.a}, {"b", f.b}, {"c", f.c}};
     }
 };
 } // toml
@@ -1346,6 +1346,27 @@ toml::value v(f);
 Any type that can be converted to `toml::value`, e.g. `int`, `toml::table` and
 `toml::array` are okay to return from `into_toml`.
 
+You can also return a custom `toml::basic_value` from `toml::into`.
+
+```cpp
+namespace toml
+{
+template<>
+struct into<ext::foo>
+{
+    static toml::basic_value<toml::preserve_comments> into_toml(const ext::foo& f)
+    {
+        toml::basic_value<toml::preserve_comments> v{{"a", f.a}, {"b", f.b}, {"c", f.c}};
+        v.comments().push_back(" comment");
+        return v;
+    }
+};
+} // toml
+```
+
+But note that, if this `basic_value` would be assigned into other `toml::value`
+that discards `comments`, the comments would be dropped.
+
 ## Formatting user-defined error messages
 
 When you encounter an error after you read the toml value, you may want to

From e9144b41fbedaf63cefd38afe40b66c5c29f3bb5 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Tue, 29 Dec 2020 18:53:10 +0900
Subject: [PATCH 14/25] test: returning toml::value directly from into<T>

---
 tests/test_extended_conversions.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/test_extended_conversions.cpp b/tests/test_extended_conversions.cpp
index 428f477..47cbc97 100644
--- a/tests/test_extended_conversions.cpp
+++ b/tests/test_extended_conversions.cpp
@@ -70,9 +70,9 @@ struct from<extlib::foo>
 template<>
 struct into<extlib::foo>
 {
-    static toml::table into_toml(const extlib::foo& f)
+    static toml::value into_toml(const extlib::foo& f)
     {
-        return toml::table{{"a", f.a}, {"b", f.b}};
+        return toml::value{{"a", f.a}, {"b", f.b}};
     }
 };
 

From d3de13656205d31c347d35d1aaba333fe893099d Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Mon, 25 Jan 2021 17:25:29 +0900
Subject: [PATCH 15/25] doc: simplity example code a bit

---
 README.md | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index fcc4b0e..f2ce9e3 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,10 @@ toml11 is a C++11 (or later) header-only toml parser/encoder depending only on C
 
 int main()
 {
+    // ```toml
+    // title = "an example toml file"
+    // nums  = [3, 1, 4, 1, 5]
+    // ```
     auto data = toml::parse("example.toml");
 
     // find a value with the specified type from a table
@@ -37,9 +41,9 @@ int main()
     std::vector<int> nums = toml::find<std::vector<int>>(data, "nums");
 
     // access with STL-like manner
-    if(not data.at("a").contains("b"))
+    if(not data.contains("foo"))
     {
-        data["a"]["b"] = "c";
+        data["foo"] = "bar";
     }
 
     // pass a fallback

From 08859c36d044ae321d36af1e36e2cc54c2503566 Mon Sep 17 00:00:00 2001
From: sneakypete81 <sneakypete81@users.noreply.github.com>
Date: Sat, 30 Jan 2021 20:04:00 +0000
Subject: [PATCH 16/25] Fix typo in error message

---
 toml/parser.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/toml/parser.hpp b/toml/parser.hpp
index 9dbfd7b..a1fa318 100644
--- a/toml/parser.hpp
+++ b/toml/parser.hpp
@@ -930,7 +930,7 @@ parse_key(location& loc)
         return ok(std::make_pair(std::vector<key>(1, smpl.unwrap().first),
                                  smpl.unwrap().second));
     }
-    return err(format_underline("toml::parse_key: an invalid key appeaed.",
+    return err(format_underline("toml::parse_key: an invalid key appeared.",
                 {{source_location(loc), "is not a valid key"}}, {
                 "bare keys  : non-empty strings composed only of [A-Za-z0-9_-].",
                 "quoted keys: same as \"basic strings\" or 'literal strings'.",

From b924e70e3cda1f3044c3b9879e22ced85d62b3a5 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 11:44:11 +0900
Subject: [PATCH 17/25] feat: add a simple way to disable <filesystem>

As jwillikers pointed out in #150, there is a case where compiler
defines the corresponding feature test macro of <filesystem> but is
actually not available. The macro is a way to disable the feature
regardless of the status of feature test macro.
---
 toml/parser.hpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/toml/parser.hpp b/toml/parser.hpp
index a1fa318..c3df644 100644
--- a/toml/parser.hpp
+++ b/toml/parser.hpp
@@ -13,12 +13,14 @@
 #include "types.hpp"
 #include "value.hpp"
 
+#ifndef TOML11_DISABLE_STD_FILESYSTEM
 #ifdef __cpp_lib_filesystem
 #if __has_include(<filesystem>)
 #define TOML11_HAS_STD_FILESYSTEM
 #include <filesystem>
 #endif // has_include(<string_view>)
 #endif // __cpp_lib_filesystem
+#endif // TOML11_DISABLE_STD_FILESYSTEM
 
 namespace toml
 {

From 970f7cb36a2471c9a8bef5953d486b345e10531f Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 13:34:30 +0900
Subject: [PATCH 18/25] ci: trying to update boost installation settings [skip
 travis] [skip appveyor]

---
 .github/workflows/main.yml | 173 +++++++++++++++++++------------------
 1 file changed, 90 insertions(+), 83 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index dfcf41f..07aa1ed 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -3,88 +3,88 @@ name: build
 on: [push, pull_request]
 
 jobs:
-  build-linux-gcc:
-    runs-on: Ubuntu-18.04
-    strategy:
-      matrix:
-        # g++-4.8 and 4.9 are tested on Travis.CI.
-        compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
-        standard: ['11', '14', '17', '20']
-        exclude:
-            - {compiler: 'g++-5', standard: '17'}
-            - {compiler: 'g++-6', standard: '17'}
-            - {compiler: 'g++-5', standard: '20'}
-            - {compiler: 'g++-6', standard: '20'}
-            - {compiler: 'g++-7', standard: '20'}
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-          submodules: true
-      - name: Install
-        run: |
-            sudo apt-add-repository ppa:mhier/libboost-latest
-            sudo apt-get update
-            sudo apt-get install boost1.70
-            if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
-                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-                sudo apt-get update
-                sudo apt-get install ${{ matrix.compiler }}
-            fi
-      - name: Configure
-        run: |
-            mkdir build && cd build
-            if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
-                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
-            else
-                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-            fi
-      - name: Build
-        run: |
-            cd build && cmake --build .
-      - name: Test
-        run: |
-            cd build && ctest --output-on-failure
-  build-linux-clang:
-    runs-on: Ubuntu-18.04
-    strategy:
-      matrix:
-        compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
-        standard: ['11', '14', '17', '20']
-        exclude:
-            - {compiler: '3.9', standard: '17'}
-            - {compiler: '4.0', standard: '17'}
-            - {compiler: '5.0', standard: '17'}
-            - {compiler: '3.9', standard: '20'}
-            - {compiler: '4.0', standard: '20'}
-            - {compiler: '5.0', standard: '20'}
-            - {compiler: '6.0', standard: '20'}
-            - {compiler: '7',   standard: '20'}
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-          submodules: true
-      - name: Install
-        run: |
-            sudo apt-add-repository ppa:mhier/libboost-latest
-            sudo apt-get update
-            sudo apt-get install boost1.70
-            if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
-                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-                sudo apt-get update
-                sudo apt-get install clang-${{ matrix.compiler }}
-            fi
-      - name: Configure
-        run: |
-            mkdir build && cd build
-            cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-      - name: Build
-        run: |
-            cd build && cmake --build .
-      - name: Test
-        run: |
-            cd build && ctest --output-on-failure
+#   build-linux-gcc:
+#     runs-on: Ubuntu-18.04
+#     strategy:
+#       matrix:
+#         # g++-4.8 and 4.9 are tested on Travis.CI.
+#         compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
+#         standard: ['11', '14', '17', '20']
+#         exclude:
+#             - {compiler: 'g++-5', standard: '17'}
+#             - {compiler: 'g++-6', standard: '17'}
+#             - {compiler: 'g++-5', standard: '20'}
+#             - {compiler: 'g++-6', standard: '20'}
+#             - {compiler: 'g++-7', standard: '20'}
+#     steps:
+#       - name: Checkout
+#         uses: actions/checkout@v2
+#         with:
+#           submodules: true
+#       - name: Install
+#         run: |
+#             sudo apt-add-repository ppa:mhier/libboost-latest
+#             sudo apt-get update
+#             sudo apt-get install boost1.70
+#             if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
+#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+#                 sudo apt-get update
+#                 sudo apt-get install ${{ matrix.compiler }}
+#             fi
+#       - name: Configure
+#         run: |
+#             mkdir build && cd build
+#             if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
+#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
+#             else
+#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+#             fi
+#       - name: Build
+#         run: |
+#             cd build && cmake --build .
+#       - name: Test
+#         run: |
+#             cd build && ctest --output-on-failure
+#   build-linux-clang:
+#     runs-on: Ubuntu-18.04
+#     strategy:
+#       matrix:
+#         compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
+#         standard: ['11', '14', '17', '20']
+#         exclude:
+#             - {compiler: '3.9', standard: '17'}
+#             - {compiler: '4.0', standard: '17'}
+#             - {compiler: '5.0', standard: '17'}
+#             - {compiler: '3.9', standard: '20'}
+#             - {compiler: '4.0', standard: '20'}
+#             - {compiler: '5.0', standard: '20'}
+#             - {compiler: '6.0', standard: '20'}
+#             - {compiler: '7',   standard: '20'}
+#     steps:
+#       - name: Checkout
+#         uses: actions/checkout@v2
+#         with:
+#           submodules: true
+#       - name: Install
+#         run: |
+#             sudo apt-add-repository ppa:mhier/libboost-latest
+#             sudo apt-get update
+#             sudo apt-get install boost1.70
+#             if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
+#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+#                 sudo apt-get update
+#                 sudo apt-get install clang-${{ matrix.compiler }}
+#             fi
+#       - name: Configure
+#         run: |
+#             mkdir build && cd build
+#             cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+#       - name: Build
+#         run: |
+#             cd build && cmake --build .
+#       - name: Test
+#         run: |
+#             cd build && ctest --output-on-failure
   build-windows-msvc:
     runs-on: windows-2019
     strategy:
@@ -96,6 +96,13 @@ jobs:
         uses: actions/checkout@v2
         with:
           submodules: true
+      - name: Install
+        run: |
+            (New-Object System.Net.WebClient).DownloadFile("https://github.com/actions/boost-versions/releases/download/1.72.0-20200608.4/boost-1.72.0-win32-msvc14.2-x86_64.tar.gz", "$env:TEMP\\boost.tar.gz")
+            7z.exe x "$env:TEMP\\boost.tar.gz" -o"$env:TEMP\\boostArchive" -y | Out-Null
+            7z.exe x "$env:TEMP\\boostArchive" -o"$env:TEMP\\boost" -y | Out-Null
+            Push-Location -Path "$env:TEMP\\boost"
+            Invoke-Expression .\\setup.ps1
       - uses: ilammy/msvc-dev-cmd@v1
       - name: Configure
         shell: cmd
@@ -103,7 +110,7 @@ jobs:
             file --mime-encoding tests/test_literals.cpp
             mkdir build
             cd build
-            cmake ../ -G "NMake Makefiles" -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DBoost_ADDITIONAL_VERSIONS=1.72.0 -DBoost_USE_MULTITHREADED=ON -DBoost_ARCHITECTURE=-x64 -DBoost_NO_BOOST_CMAKE=ON -DBOOST_ROOT=%BOOST_ROOT_1_72_0%
+            cmake ../ -G "NMake Makefiles" -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DBoost_NO_BOOST_CMAKE=ON -DBOOST_ROOT="C:\\hostedtoolcache\\windows\\Boost\\1.72.0\\x86_64"
       - name: Build
         working-directory: ./build
         run: |

From 2c5cc431fe8b732fda8d1e433c699a7636f64633 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 14:33:55 +0900
Subject: [PATCH 19/25] ci: re-activate linux CI

---
 .github/workflows/main.yml | 164 ++++++++++++++++++-------------------
 1 file changed, 82 insertions(+), 82 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 07aa1ed..452569c 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -3,88 +3,88 @@ name: build
 on: [push, pull_request]
 
 jobs:
-#   build-linux-gcc:
-#     runs-on: Ubuntu-18.04
-#     strategy:
-#       matrix:
-#         # g++-4.8 and 4.9 are tested on Travis.CI.
-#         compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
-#         standard: ['11', '14', '17', '20']
-#         exclude:
-#             - {compiler: 'g++-5', standard: '17'}
-#             - {compiler: 'g++-6', standard: '17'}
-#             - {compiler: 'g++-5', standard: '20'}
-#             - {compiler: 'g++-6', standard: '20'}
-#             - {compiler: 'g++-7', standard: '20'}
-#     steps:
-#       - name: Checkout
-#         uses: actions/checkout@v2
-#         with:
-#           submodules: true
-#       - name: Install
-#         run: |
-#             sudo apt-add-repository ppa:mhier/libboost-latest
-#             sudo apt-get update
-#             sudo apt-get install boost1.70
-#             if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
-#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-#                 sudo apt-get update
-#                 sudo apt-get install ${{ matrix.compiler }}
-#             fi
-#       - name: Configure
-#         run: |
-#             mkdir build && cd build
-#             if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
-#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
-#             else
-#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-#             fi
-#       - name: Build
-#         run: |
-#             cd build && cmake --build .
-#       - name: Test
-#         run: |
-#             cd build && ctest --output-on-failure
-#   build-linux-clang:
-#     runs-on: Ubuntu-18.04
-#     strategy:
-#       matrix:
-#         compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
-#         standard: ['11', '14', '17', '20']
-#         exclude:
-#             - {compiler: '3.9', standard: '17'}
-#             - {compiler: '4.0', standard: '17'}
-#             - {compiler: '5.0', standard: '17'}
-#             - {compiler: '3.9', standard: '20'}
-#             - {compiler: '4.0', standard: '20'}
-#             - {compiler: '5.0', standard: '20'}
-#             - {compiler: '6.0', standard: '20'}
-#             - {compiler: '7',   standard: '20'}
-#     steps:
-#       - name: Checkout
-#         uses: actions/checkout@v2
-#         with:
-#           submodules: true
-#       - name: Install
-#         run: |
-#             sudo apt-add-repository ppa:mhier/libboost-latest
-#             sudo apt-get update
-#             sudo apt-get install boost1.70
-#             if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
-#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-#                 sudo apt-get update
-#                 sudo apt-get install clang-${{ matrix.compiler }}
-#             fi
-#       - name: Configure
-#         run: |
-#             mkdir build && cd build
-#             cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-#       - name: Build
-#         run: |
-#             cd build && cmake --build .
-#       - name: Test
-#         run: |
-#             cd build && ctest --output-on-failure
+  build-linux-gcc:
+    runs-on: Ubuntu-18.04
+    strategy:
+      matrix:
+        # g++-4.8 and 4.9 are tested on Travis.CI.
+        compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
+        standard: ['11', '14', '17', '20']
+        exclude:
+            - {compiler: 'g++-5', standard: '17'}
+            - {compiler: 'g++-6', standard: '17'}
+            - {compiler: 'g++-5', standard: '20'}
+            - {compiler: 'g++-6', standard: '20'}
+            - {compiler: 'g++-7', standard: '20'}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Install
+        run: |
+            sudo apt-add-repository ppa:mhier/libboost-latest
+            sudo apt-get update
+            sudo apt-get install boost1.70
+            if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
+                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+                sudo apt-get update
+                sudo apt-get install ${{ matrix.compiler }}
+            fi
+      - name: Configure
+        run: |
+            mkdir build && cd build
+            if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
+                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
+            else
+                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+            fi
+      - name: Build
+        run: |
+            cd build && cmake --build .
+      - name: Test
+        run: |
+            cd build && ctest --output-on-failure
+  build-linux-clang:
+    runs-on: Ubuntu-18.04
+    strategy:
+      matrix:
+        compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
+        standard: ['11', '14', '17', '20']
+        exclude:
+            - {compiler: '3.9', standard: '17'}
+            - {compiler: '4.0', standard: '17'}
+            - {compiler: '5.0', standard: '17'}
+            - {compiler: '3.9', standard: '20'}
+            - {compiler: '4.0', standard: '20'}
+            - {compiler: '5.0', standard: '20'}
+            - {compiler: '6.0', standard: '20'}
+            - {compiler: '7',   standard: '20'}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Install
+        run: |
+            sudo apt-add-repository ppa:mhier/libboost-latest
+            sudo apt-get update
+            sudo apt-get install boost1.70
+            if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
+                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+                sudo apt-get update
+                sudo apt-get install clang-${{ matrix.compiler }}
+            fi
+      - name: Configure
+        run: |
+            mkdir build && cd build
+            cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+      - name: Build
+        run: |
+            cd build && cmake --build .
+      - name: Test
+        run: |
+            cd build && ctest --output-on-failure
   build-windows-msvc:
     runs-on: windows-2019
     strategy:

From 5e0ee32854397cfe2a0531d7c7bff90ce953a8cb Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 14:38:53 +0900
Subject: [PATCH 20/25] ci: trying to add macos to github actions [skip travis]
 [skip appveyor]

it is already listed in travis CI, but not in the GH actions
---
 .github/workflows/main.yml | 229 ++++++++++++++++++++-----------------
 1 file changed, 127 insertions(+), 102 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 452569c..4e36ed9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -3,19 +3,94 @@ name: build
 on: [push, pull_request]
 
 jobs:
-  build-linux-gcc:
-    runs-on: Ubuntu-18.04
+#   build-linux-gcc:
+#     runs-on: Ubuntu-18.04
+#     strategy:
+#       matrix:
+#         # g++-4.8 and 4.9 are tested on Travis.CI.
+#         compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
+#         standard: ['11', '14', '17', '20']
+#         exclude:
+#             - {compiler: 'g++-5', standard: '17'}
+#             - {compiler: 'g++-6', standard: '17'}
+#             - {compiler: 'g++-5', standard: '20'}
+#             - {compiler: 'g++-6', standard: '20'}
+#             - {compiler: 'g++-7', standard: '20'}
+#     steps:
+#       - name: Checkout
+#         uses: actions/checkout@v2
+#         with:
+#           submodules: true
+#       - name: Install
+#         run: |
+#             sudo apt-add-repository ppa:mhier/libboost-latest
+#             sudo apt-get update
+#             sudo apt-get install boost1.70
+#             if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
+#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+#                 sudo apt-get update
+#                 sudo apt-get install ${{ matrix.compiler }}
+#             fi
+#       - name: Configure
+#         run: |
+#             mkdir build && cd build
+#             if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
+#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
+#             else
+#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+#             fi
+#       - name: Build
+#         run: |
+#             cd build && cmake --build .
+#       - name: Test
+#         run: |
+#             cd build && ctest --output-on-failure
+#   build-linux-clang:
+#     runs-on: Ubuntu-18.04
+#     strategy:
+#       matrix:
+#         compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
+#         standard: ['11', '14', '17', '20']
+#         exclude:
+#             - {compiler: '3.9', standard: '17'}
+#             - {compiler: '4.0', standard: '17'}
+#             - {compiler: '5.0', standard: '17'}
+#             - {compiler: '3.9', standard: '20'}
+#             - {compiler: '4.0', standard: '20'}
+#             - {compiler: '5.0', standard: '20'}
+#             - {compiler: '6.0', standard: '20'}
+#             - {compiler: '7',   standard: '20'}
+#     steps:
+#       - name: Checkout
+#         uses: actions/checkout@v2
+#         with:
+#           submodules: true
+#       - name: Install
+#         run: |
+#             sudo apt-add-repository ppa:mhier/libboost-latest
+#             sudo apt-get update
+#             sudo apt-get install boost1.70
+#             if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
+#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+#                 sudo apt-get update
+#                 sudo apt-get install clang-${{ matrix.compiler }}
+#             fi
+#       - name: Configure
+#         run: |
+#             mkdir build && cd build
+#             cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+#       - name: Build
+#         run: |
+#             cd build && cmake --build .
+#       - name: Test
+#         run: |
+#             cd build && ctest --output-on-failure
+
+  build-osx:
+    runs-on: macos-10.15
     strategy:
       matrix:
-        # g++-4.8 and 4.9 are tested on Travis.CI.
-        compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
         standard: ['11', '14', '17', '20']
-        exclude:
-            - {compiler: 'g++-5', standard: '17'}
-            - {compiler: 'g++-6', standard: '17'}
-            - {compiler: 'g++-5', standard: '20'}
-            - {compiler: 'g++-6', standard: '20'}
-            - {compiler: 'g++-7', standard: '20'}
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -23,104 +98,54 @@ jobs:
           submodules: true
       - name: Install
         run: |
-            sudo apt-add-repository ppa:mhier/libboost-latest
-            sudo apt-get update
-            sudo apt-get install boost1.70
-            if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
-                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-                sudo apt-get update
-                sudo apt-get install ${{ matrix.compiler }}
-            fi
+            brew install boost
       - name: Configure
         run: |
             mkdir build && cd build
-            if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
-                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
-            else
-                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-            fi
+            cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
       - name: Build
         run: |
             cd build && cmake --build .
       - name: Test
         run: |
             cd build && ctest --output-on-failure
-  build-linux-clang:
-    runs-on: Ubuntu-18.04
-    strategy:
-      matrix:
-        compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
-        standard: ['11', '14', '17', '20']
-        exclude:
-            - {compiler: '3.9', standard: '17'}
-            - {compiler: '4.0', standard: '17'}
-            - {compiler: '5.0', standard: '17'}
-            - {compiler: '3.9', standard: '20'}
-            - {compiler: '4.0', standard: '20'}
-            - {compiler: '5.0', standard: '20'}
-            - {compiler: '6.0', standard: '20'}
-            - {compiler: '7',   standard: '20'}
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-          submodules: true
-      - name: Install
-        run: |
-            sudo apt-add-repository ppa:mhier/libboost-latest
-            sudo apt-get update
-            sudo apt-get install boost1.70
-            if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
-                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-                sudo apt-get update
-                sudo apt-get install clang-${{ matrix.compiler }}
-            fi
-      - name: Configure
-        run: |
-            mkdir build && cd build
-            cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-      - name: Build
-        run: |
-            cd build && cmake --build .
-      - name: Test
-        run: |
-            cd build && ctest --output-on-failure
-  build-windows-msvc:
-    runs-on: windows-2019
-    strategy:
-      matrix:
-        standard: ['11', '14', '17', '20']
-        config: ['Release', 'Debug']
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2
-        with:
-          submodules: true
-      - name: Install
-        run: |
-            (New-Object System.Net.WebClient).DownloadFile("https://github.com/actions/boost-versions/releases/download/1.72.0-20200608.4/boost-1.72.0-win32-msvc14.2-x86_64.tar.gz", "$env:TEMP\\boost.tar.gz")
-            7z.exe x "$env:TEMP\\boost.tar.gz" -o"$env:TEMP\\boostArchive" -y | Out-Null
-            7z.exe x "$env:TEMP\\boostArchive" -o"$env:TEMP\\boost" -y | Out-Null
-            Push-Location -Path "$env:TEMP\\boost"
-            Invoke-Expression .\\setup.ps1
-      - uses: ilammy/msvc-dev-cmd@v1
-      - name: Configure
-        shell: cmd
-        run: |
-            file --mime-encoding tests/test_literals.cpp
-            mkdir build
-            cd build
-            cmake ../ -G "NMake Makefiles" -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DBoost_NO_BOOST_CMAKE=ON -DBOOST_ROOT="C:\\hostedtoolcache\\windows\\Boost\\1.72.0\\x86_64"
-      - name: Build
-        working-directory: ./build
-        run: |
-            cmake --build . --config "${{ matrix.config }}"
-      - name: Test
-        working-directory: ./build
-        run: |
-            ./tests/test_literals --log_level=all
-            file --mime-encoding tests/toml/tests/example.toml
-            file --mime-encoding tests/toml/tests/fruit.toml
-            file --mime-encoding tests/toml/tests/hard_example.toml
-            file --mime-encoding tests/toml/tests/hard_example_unicode.toml
-            ctest --build-config "${{ matrix.config }}" --output-on-failure
+
+#   build-windows-msvc:
+#     runs-on: windows-2019
+#     strategy:
+#       matrix:
+#         standard: ['11', '14', '17', '20']
+#         config: ['Release', 'Debug']
+#     steps:
+#       - name: Checkout
+#         uses: actions/checkout@v2
+#         with:
+#           submodules: true
+#       - name: Install
+#         run: |
+#             (New-Object System.Net.WebClient).DownloadFile("https://github.com/actions/boost-versions/releases/download/1.72.0-20200608.4/boost-1.72.0-win32-msvc14.2-x86_64.tar.gz", "$env:TEMP\\boost.tar.gz")
+#             7z.exe x "$env:TEMP\\boost.tar.gz" -o"$env:TEMP\\boostArchive" -y | Out-Null
+#             7z.exe x "$env:TEMP\\boostArchive" -o"$env:TEMP\\boost" -y | Out-Null
+#             Push-Location -Path "$env:TEMP\\boost"
+#             Invoke-Expression .\\setup.ps1
+#       - uses: ilammy/msvc-dev-cmd@v1
+#       - name: Configure
+#         shell: cmd
+#         run: |
+#             file --mime-encoding tests/test_literals.cpp
+#             mkdir build
+#             cd build
+#             cmake ../ -G "NMake Makefiles" -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DBoost_NO_BOOST_CMAKE=ON -DBOOST_ROOT="C:\\hostedtoolcache\\windows\\Boost\\1.72.0\\x86_64"
+#       - name: Build
+#         working-directory: ./build
+#         run: |
+#             cmake --build . --config "${{ matrix.config }}"
+#       - name: Test
+#         working-directory: ./build
+#         run: |
+#             ./tests/test_literals --log_level=all
+#             file --mime-encoding tests/toml/tests/example.toml
+#             file --mime-encoding tests/toml/tests/fruit.toml
+#             file --mime-encoding tests/toml/tests/hard_example.toml
+#             file --mime-encoding tests/toml/tests/hard_example_unicode.toml
+#             ctest --build-config "${{ matrix.config }}" --output-on-failure

From 42cc111b059ab1fa793d9a98cbe3a5ccb203d7dc Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 15:01:40 +0900
Subject: [PATCH 21/25] ci: activate linux/windows

confirmed that macos works.
---
 .github/workflows/main.yml | 242 ++++++++++++++++++-------------------
 1 file changed, 121 insertions(+), 121 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 4e36ed9..c66ad87 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -3,88 +3,88 @@ name: build
 on: [push, pull_request]
 
 jobs:
-#   build-linux-gcc:
-#     runs-on: Ubuntu-18.04
-#     strategy:
-#       matrix:
-#         # g++-4.8 and 4.9 are tested on Travis.CI.
-#         compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
-#         standard: ['11', '14', '17', '20']
-#         exclude:
-#             - {compiler: 'g++-5', standard: '17'}
-#             - {compiler: 'g++-6', standard: '17'}
-#             - {compiler: 'g++-5', standard: '20'}
-#             - {compiler: 'g++-6', standard: '20'}
-#             - {compiler: 'g++-7', standard: '20'}
-#     steps:
-#       - name: Checkout
-#         uses: actions/checkout@v2
-#         with:
-#           submodules: true
-#       - name: Install
-#         run: |
-#             sudo apt-add-repository ppa:mhier/libboost-latest
-#             sudo apt-get update
-#             sudo apt-get install boost1.70
-#             if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
-#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-#                 sudo apt-get update
-#                 sudo apt-get install ${{ matrix.compiler }}
-#             fi
-#       - name: Configure
-#         run: |
-#             mkdir build && cd build
-#             if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
-#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
-#             else
-#                 cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-#             fi
-#       - name: Build
-#         run: |
-#             cd build && cmake --build .
-#       - name: Test
-#         run: |
-#             cd build && ctest --output-on-failure
-#   build-linux-clang:
-#     runs-on: Ubuntu-18.04
-#     strategy:
-#       matrix:
-#         compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
-#         standard: ['11', '14', '17', '20']
-#         exclude:
-#             - {compiler: '3.9', standard: '17'}
-#             - {compiler: '4.0', standard: '17'}
-#             - {compiler: '5.0', standard: '17'}
-#             - {compiler: '3.9', standard: '20'}
-#             - {compiler: '4.0', standard: '20'}
-#             - {compiler: '5.0', standard: '20'}
-#             - {compiler: '6.0', standard: '20'}
-#             - {compiler: '7',   standard: '20'}
-#     steps:
-#       - name: Checkout
-#         uses: actions/checkout@v2
-#         with:
-#           submodules: true
-#       - name: Install
-#         run: |
-#             sudo apt-add-repository ppa:mhier/libboost-latest
-#             sudo apt-get update
-#             sudo apt-get install boost1.70
-#             if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
-#                 sudo apt-add-repository ppa:ubuntu-toolchain-r/test
-#                 sudo apt-get update
-#                 sudo apt-get install clang-${{ matrix.compiler }}
-#             fi
-#       - name: Configure
-#         run: |
-#             mkdir build && cd build
-#             cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
-#       - name: Build
-#         run: |
-#             cd build && cmake --build .
-#       - name: Test
-#         run: |
-#             cd build && ctest --output-on-failure
+  build-linux-gcc:
+    runs-on: Ubuntu-18.04
+    strategy:
+      matrix:
+        # g++-4.8 and 4.9 are tested on Travis.CI.
+        compiler: ['g++-9', 'g++-8', 'g++-7', 'g++-6', 'g++-5']
+        standard: ['11', '14', '17', '20']
+        exclude:
+            - {compiler: 'g++-5', standard: '17'}
+            - {compiler: 'g++-6', standard: '17'}
+            - {compiler: 'g++-5', standard: '20'}
+            - {compiler: 'g++-6', standard: '20'}
+            - {compiler: 'g++-7', standard: '20'}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Install
+        run: |
+            sudo apt-add-repository ppa:mhier/libboost-latest
+            sudo apt-get update
+            sudo apt-get install boost1.70
+            if [[ "${{ matrix.compiler }}" == "g++-6" || "${{ matrix.compiler }}" == "g++-5" ]] ; then
+                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+                sudo apt-get update
+                sudo apt-get install ${{ matrix.compiler }}
+            fi
+      - name: Configure
+        run: |
+            mkdir build && cd build
+            if [[ "${{ matrix.compiler }}" == "g++-8" && ( "${{ matrix.standard }}" == "17" || "${{ matrix.standard }}" == "20" ) ]] ; then
+                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DTOML11_REQUIRE_FILESYSTEM_LIBRARY=ON
+            else
+                cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_COMPILER=${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+            fi
+      - name: Build
+        run: |
+            cd build && cmake --build .
+      - name: Test
+        run: |
+            cd build && ctest --output-on-failure
+  build-linux-clang:
+    runs-on: Ubuntu-18.04
+    strategy:
+      matrix:
+        compiler: ['10', '9', '8', '7', '6.0', '5.0', '4.0', '3.9']
+        standard: ['11', '14', '17', '20']
+        exclude:
+            - {compiler: '3.9', standard: '17'}
+            - {compiler: '4.0', standard: '17'}
+            - {compiler: '5.0', standard: '17'}
+            - {compiler: '3.9', standard: '20'}
+            - {compiler: '4.0', standard: '20'}
+            - {compiler: '5.0', standard: '20'}
+            - {compiler: '6.0', standard: '20'}
+            - {compiler: '7',   standard: '20'}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Install
+        run: |
+            sudo apt-add-repository ppa:mhier/libboost-latest
+            sudo apt-get update
+            sudo apt-get install boost1.70
+            if [[ "${{ matrix.compiler }}" != "6" && "${{ matrix.compiler }}" != "8" && "${{ matrix.compiler }}" != "9" ]] ; then
+                sudo apt-add-repository ppa:ubuntu-toolchain-r/test
+                sudo apt-get update
+                sudo apt-get install clang-${{ matrix.compiler }}
+            fi
+      - name: Configure
+        run: |
+            mkdir build && cd build
+            cmake .. -Dtoml11_BUILD_TEST=ON -DCMAKE_C_COMPILER=clang-${{ matrix.compiler }} -DCMAKE_CXX_COMPILER=clang++-${{ matrix.compiler }} -DCMAKE_CXX_STANDARD=${{ matrix.standard }}
+      - name: Build
+        run: |
+            cd build && cmake --build .
+      - name: Test
+        run: |
+            cd build && ctest --output-on-failure
 
   build-osx:
     runs-on: macos-10.15
@@ -110,42 +110,42 @@ jobs:
         run: |
             cd build && ctest --output-on-failure
 
-#   build-windows-msvc:
-#     runs-on: windows-2019
-#     strategy:
-#       matrix:
-#         standard: ['11', '14', '17', '20']
-#         config: ['Release', 'Debug']
-#     steps:
-#       - name: Checkout
-#         uses: actions/checkout@v2
-#         with:
-#           submodules: true
-#       - name: Install
-#         run: |
-#             (New-Object System.Net.WebClient).DownloadFile("https://github.com/actions/boost-versions/releases/download/1.72.0-20200608.4/boost-1.72.0-win32-msvc14.2-x86_64.tar.gz", "$env:TEMP\\boost.tar.gz")
-#             7z.exe x "$env:TEMP\\boost.tar.gz" -o"$env:TEMP\\boostArchive" -y | Out-Null
-#             7z.exe x "$env:TEMP\\boostArchive" -o"$env:TEMP\\boost" -y | Out-Null
-#             Push-Location -Path "$env:TEMP\\boost"
-#             Invoke-Expression .\\setup.ps1
-#       - uses: ilammy/msvc-dev-cmd@v1
-#       - name: Configure
-#         shell: cmd
-#         run: |
-#             file --mime-encoding tests/test_literals.cpp
-#             mkdir build
-#             cd build
-#             cmake ../ -G "NMake Makefiles" -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DBoost_NO_BOOST_CMAKE=ON -DBOOST_ROOT="C:\\hostedtoolcache\\windows\\Boost\\1.72.0\\x86_64"
-#       - name: Build
-#         working-directory: ./build
-#         run: |
-#             cmake --build . --config "${{ matrix.config }}"
-#       - name: Test
-#         working-directory: ./build
-#         run: |
-#             ./tests/test_literals --log_level=all
-#             file --mime-encoding tests/toml/tests/example.toml
-#             file --mime-encoding tests/toml/tests/fruit.toml
-#             file --mime-encoding tests/toml/tests/hard_example.toml
-#             file --mime-encoding tests/toml/tests/hard_example_unicode.toml
-#             ctest --build-config "${{ matrix.config }}" --output-on-failure
+  build-windows-msvc:
+    runs-on: windows-2019
+    strategy:
+      matrix:
+        standard: ['11', '14', '17', '20']
+        config: ['Release', 'Debug']
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          submodules: true
+      - name: Install
+        run: |
+            (New-Object System.Net.WebClient).DownloadFile("https://github.com/actions/boost-versions/releases/download/1.72.0-20200608.4/boost-1.72.0-win32-msvc14.2-x86_64.tar.gz", "$env:TEMP\\boost.tar.gz")
+            7z.exe x "$env:TEMP\\boost.tar.gz" -o"$env:TEMP\\boostArchive" -y | Out-Null
+            7z.exe x "$env:TEMP\\boostArchive" -o"$env:TEMP\\boost" -y | Out-Null
+            Push-Location -Path "$env:TEMP\\boost"
+            Invoke-Expression .\\setup.ps1
+      - uses: ilammy/msvc-dev-cmd@v1
+      - name: Configure
+        shell: cmd
+        run: |
+            file --mime-encoding tests/test_literals.cpp
+            mkdir build
+            cd build
+            cmake ../ -G "NMake Makefiles" -Dtoml11_BUILD_TEST=ON -DCMAKE_CXX_STANDARD=${{ matrix.standard }} -DBoost_NO_BOOST_CMAKE=ON -DBOOST_ROOT="C:\\hostedtoolcache\\windows\\Boost\\1.72.0\\x86_64"
+      - name: Build
+        working-directory: ./build
+        run: |
+            cmake --build . --config "${{ matrix.config }}"
+      - name: Test
+        working-directory: ./build
+        run: |
+            ./tests/test_literals --log_level=all
+            file --mime-encoding tests/toml/tests/example.toml
+            file --mime-encoding tests/toml/tests/fruit.toml
+            file --mime-encoding tests/toml/tests/hard_example.toml
+            file --mime-encoding tests/toml/tests/hard_example_unicode.toml
+            ctest --build-config "${{ matrix.config }}" --output-on-failure

From 17a15d3c18f25f96ea2eed38519d90809ce40171 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 22:33:05 +0900
Subject: [PATCH 22/25] doc: update contributor list and link in README

---
 README.md | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index f2ce9e3..06cd511 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ toml11
 
 toml11 is a C++11 (or later) header-only toml parser/encoder depending only on C++ standard library.
 
-- It is compatible to the latest version of [TOML v1.0.0-rc.2](https://toml.io/en/v1.0.0-rc.2).
+- It is compatible to the latest version of [TOML v1.0.0](https://toml.io/en/v1.0.0).
 - It is one of the most TOML standard compliant libraries, tested with [the language agnostic test suite for TOML parsers by BurntSushi](https://github.com/BurntSushi/toml-test).
 - It shows highly informative error messages. You can see the error messages about invalid files at [CircleCI](https://circleci.com/gh/ToruNiina/toml11).
 - It has configurable container. You can use any random-access containers and key-value maps as backend containers.
@@ -1873,6 +1873,12 @@ I appreciate the help of the contributors who introduced the great feature to th
   - Fix include path in README
 - Mohammed Alyousef (@MoAlyousef)
   - Made testing optional in CMake
+- Ivan Shynkarenka (@chronoxor)
+  - Fix compilation error in `<filesystem>` with MinGW
+- Alex Merry (@amerry)
+  - Add missing include files
+- sneakypete81 (@sneakypete81)
+  - Fix typo in error message
 
 
 ## Licensing terms

From 5e3f8f910535a9b6670f1f86be2d8c03801899d2 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Thu, 25 Mar 2021 22:43:37 +0900
Subject: [PATCH 23/25] chore: update version values

---
 CMakeLists.txt | 2 +-
 toml.hpp       | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5dbeb2b..c0be74b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.1)
 enable_testing()
 
-project(toml11 VERSION 3.6.0)
+project(toml11 VERSION 3.6.1)
 
 option(toml11_BUILD_TEST "Build toml tests" OFF)
 option(toml11_TEST_WITH_ASAN  "use LLVM address sanitizer" OFF)
diff --git a/toml.hpp b/toml.hpp
index 232329d..e989798 100644
--- a/toml.hpp
+++ b/toml.hpp
@@ -35,7 +35,7 @@
 
 #define TOML11_VERSION_MAJOR 3
 #define TOML11_VERSION_MINOR 6
-#define TOML11_VERSION_PATCH 0
+#define TOML11_VERSION_PATCH 1
 
 #include "toml/parser.hpp"
 #include "toml/literal.hpp"

From c121492071373a497a1477ea6855a2814de16039 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Mon, 29 Mar 2021 17:48:03 +0900
Subject: [PATCH 24/25] fix: uneven spacing between tables

related: issue #152
---
 toml/serializer.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index bef1827..2442ed9 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -582,6 +582,7 @@ struct serializer
                std::find(tmp.cbegin(), tmp.cend(), '\n') != tmp.cend())
             {
                 multiline_table_printed = true;
+                tmp += '\n';
             }
             else
             {

From a3b8dd678726dcc4b32d42929d65c53e3ecdd856 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Wed, 31 Mar 2021 10:52:18 +0900
Subject: [PATCH 25/25] fix(#152): add newline btw kv-pair and subtables

---
 toml/serializer.hpp | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/toml/serializer.hpp b/toml/serializer.hpp
index 2442ed9..77aef58 100644
--- a/toml/serializer.hpp
+++ b/toml/serializer.hpp
@@ -578,20 +578,35 @@ struct serializer
                 !multiline_table_printed, this->no_comment_, ks,
                 /*has_comment*/ !kv.second.comments().empty()), kv.second);
 
+            // If it is the first time to print a multi-line table, it would be
+            // helpful to separate normal key-value pair and subtables by a
+            // newline.
+            // (this checks if the current key-value pair contains newlines.
+            //  but it is not perfect because multi-line string can also contain
+            //  a newline. in such a case, an empty line will be written) TODO
             if((!multiline_table_printed) &&
                std::find(tmp.cbegin(), tmp.cend(), '\n') != tmp.cend())
             {
                 multiline_table_printed = true;
-                tmp += '\n';
+                token += '\n'; // separate key-value pairs and subtables
+
+                token += write_comments(kv.second);
+                token += tmp;
+
+                // care about recursive tables (all tables in each level prints
+                // newline and there will be a full of newlines)
+                if(tmp.substr(tmp.size() - 2, 2) != "\n\n" &&
+                   tmp.substr(tmp.size() - 4, 4) != "\r\n\r\n" )
+                {
+                    token += '\n';
+                }
             }
             else
             {
-                // still inline tables only.
-                tmp += '\n';
+                token += write_comments(kv.second);
+                token += tmp;
+                token += '\n';
             }
-
-            token += write_comments(kv.second);
-            token += tmp;
         }
         return token;
     }