switch to xmake for package management (#611)

This change removes our dependency on vcpkg for package management, in favour of bringing some code in-tree in the `thirdparty` folder as well as using the xmake build-in package management feature. For the latter, all the package definitions are maintained in the zen repo itself, in the `repo` folder.

It should now also be easier to build the project as it will no longer depend on having the right version of vcpkg installed, which has been a common problem for new people coming in to the codebase. Now you should only need xmake to build.

* Bumps xmake requirement on github runners to 2.9.9 to resolve an issue where xmake on Windows invokes cmake with `v144` toolchain which does not exist
* BLAKE3 is now in-tree at `thirdparty/blake3`
* cpr is now in-tree at `thirdparty/cpr`
* cxxopts is now in-tree at `thirdparty/cxxopts`
* fmt is now in-tree at `thirdparty/fmt`
* robin-map is now in-tree at `thirdparty/robin-map`
* ryml is now in-tree at `thirdparty/ryml`
* sol2 is now in-tree at `thirdparty/sol2`
* spdlog is now in-tree at `thirdparty/spdlog`
* utfcpp is now in-tree at `thirdparty/utfcpp`
* xmake package repo definitions is in `repo`
* implemented support for sanitizers. ASAN is supported on windows, TSAN, UBSAN, MSAN etc are supported on Linux/MacOS though I have not yet tested it extensively on MacOS
* the zencore encryption implementation also now supports using mbedTLS which is used on MacOS, though for now we still use openssl on Linux
* crashpad
* bumps libcurl to 8.11.0 (from 8.8.0) which should address a rare build upload bug

1 files changed, 886 insertions, 0 deletions

diff --git a/thirdparty/fmt/doc/syntax.md b/thirdparty/fmt/doc/syntax.md
new file mode 100644
index 000000000..46d7d2fd2
--- /dev/null
+++ b/thirdparty/fmt/doc/syntax.md
@@ -0,0 +1,886 @@
+# Format String Syntax
+
+Formatting functions such as [`fmt::format`](api.md#format) and [`fmt::print`](
+api.md#print) use the same format string syntax described in this section.
+
+Format strings contain "replacement fields" surrounded by curly braces `{}`.
+Anything that is not contained in braces is considered literal text, which is
+copied unchanged to the output. If you need to include a brace character in
+the literal text, it can be escaped by doubling: `{{` and `}}`.
+
+The grammar for a replacement field is as follows:
+
+<a id="replacement-field"></a>
+<pre><code class="language-json"
+>replacement_field ::= "{" [arg_id] [":" (<a href="#format-spec"
+  >format_spec</a> | <a href="#chrono-format-spec">chrono_format_spec</a>)] "}"
+arg_id            ::= integer | identifier
+integer           ::= digit+
+digit             ::= "0"..."9"
+identifier        ::= id_start id_continue*
+id_start          ::= "a"..."z" | "A"..."Z" | "_"
+id_continue       ::= id_start | digit</code>
+</pre>
+
+In less formal terms, the replacement field can start with an *arg_id* that
+specifies the argument whose value is to be formatted and inserted into the
+output instead of the replacement field. The *arg_id* is optionally followed
+by a *format_spec*, which is preceded by a colon `':'`. These specify a
+non-default format for the replacement value.
+
+See also the [Format Specification
+Mini-Language](#format-specification-mini-language) section.
+
+If the numerical arg_ids in a format string are 0, 1, 2, ... in sequence,
+they can all be omitted (not just some) and the numbers 0, 1, 2, ... will be
+automatically inserted in that order.
+
+Named arguments can be referred to by their names or indices.
+
+Some simple format string examples:
+
+```c++
+"First, thou shalt count to {0}" // References the first argument
+"Bring me a {}"                  // Implicitly references the first argument
+"From {} to {}"                  // Same as "From {0} to {1}"
+```
+
+The *format_spec* field contains a specification of how the value should
+be presented, including such details as field width, alignment, padding,
+decimal precision and so on. Each value type can define its own
+"formatting mini-language" or interpretation of the *format_spec*.
+
+Most built-in types support a common formatting mini-language, which is
+described in the next section.
+
+A *format_spec* field can also include nested replacement fields in
+certain positions within it. These nested replacement fields can contain
+only an argument id; format specifications are not allowed. This allows
+the formatting of a value to be dynamically specified.
+
+See the [Format Examples](#format-examples) section for some examples.
+
+## Format Specification Mini-Language
+
+"Format specifications" are used within replacement fields contained within a
+format string to define how individual values are presented. Each formattable
+type may define how the format specification is to be interpreted.
+
+Most built-in types implement the following options for format
+specifications, although some of the formatting options are only
+supported by the numeric types.
+
+The general form of a *standard format specifier* is:
+
+<a id="format-spec"></a>
+<pre><code class="language-json"
+>format_spec ::= [[fill]align][sign]["#"]["0"][width]["." precision]["L"][type]
+fill        ::= &lt;a character other than '{' or '}'>
+align       ::= "<" | ">" | "^"
+sign        ::= "+" | "-" | " "
+width       ::= <a href="#replacement-field">integer</a> | "{" [<a
+  href="#replacement-field">arg_id</a>] "}"
+precision   ::= <a href="#replacement-field">integer</a> | "{" [<a
+  href="#replacement-field">arg_id</a>] "}"
+type        ::= "a" | "A" | "b" | "B" | "c" | "d" | "e" | "E" | "f" | "F" |
+                "g" | "G" | "o" | "p" | "s" | "x" | "X" | "?"</code>
+</pre>
+
+The *fill* character can be any Unicode code point other than `'{'` or `'}'`.
+The presence of a fill character is signaled by the character following it,
+which must be one of the alignment options. If the second character of
+*format_spec* is not a valid alignment option, then it is assumed that both
+the fill character and the alignment option are absent.
+
+The meaning of the various alignment options is as follows:
+
+<table>
+<tr>
+  <th>Option</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'<'</code></td>
+  <td>
+    Forces the field to be left-aligned within the available space (this is the
+    default for most objects).
+  </td>
+</tr>
+<tr>
+  <td><code>'>'</code></td>
+  <td>
+    Forces the field to be right-aligned within the available space (this is
+    the default for numbers).
+  </td>
+</tr>
+<tr>
+  <td><code>'^'</code></td>
+  <td>Forces the field to be centered within the available space.</td>
+</tr>
+</table>
+
+Note that unless a minimum field width is defined, the field width will
+always be the same size as the data to fill it, so that the alignment
+option has no meaning in this case.
+
+The *sign* option is only valid for floating point and signed integer types,
+and can be one of the following:
+
+<table>
+<tr>
+  <th>Option</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'+'</code></td>
+  <td>
+    Indicates that a sign should be used for both nonnegative as well as
+    negative numbers.
+  </td>
+</tr>
+<tr>
+  <td><code>'-'</code></td>
+  <td>
+    Indicates that a sign should be used only for negative numbers (this is the
+    default behavior).
+  </td>
+</tr>
+<tr>
+  <td>space</td>
+  <td>
+    Indicates that a leading space should be used on nonnegative numbers, and a
+    minus sign on negative numbers.
+  </td>
+</tr>
+</table>
+
+The `'#'` option causes the "alternate form" to be used for the
+conversion. The alternate form is defined differently for different
+types. This option is only valid for integer and floating-point types.
+For integers, when binary, octal, or hexadecimal output is used, this
+option adds the prefix respective `"0b"` (`"0B"`), `"0"`, or `"0x"`
+(`"0X"`) to the output value. Whether the prefix is lower-case or
+upper-case is determined by the case of the type specifier, for example,
+the prefix `"0x"` is used for the type `'x'` and `"0X"` is used for
+`'X'`. For floating-point numbers the alternate form causes the result
+of the conversion to always contain a decimal-point character, even if
+no digits follow it. Normally, a decimal-point character appears in the
+result of these conversions only if a digit follows it. In addition, for
+`'g'` and `'G'` conversions, trailing zeros are not removed from the
+result.
+
+*width* is a decimal integer defining the minimum field width. If not
+specified, then the field width will be determined by the content.
+
+Preceding the *width* field by a zero (`'0'`) character enables
+sign-aware zero-padding for numeric types. It forces the padding to be
+placed after the sign or base (if any) but before the digits. This is
+used for printing fields in the form "+000000120". This option is only
+valid for numeric types and it has no effect on formatting of infinity
+and NaN. This option is ignored when any alignment specifier is present.
+
+The *precision* is a decimal number indicating how many digits should be
+displayed after the decimal point for a floating-point value formatted
+with `'f'` and `'F'`, or before and after the decimal point for a
+floating-point value formatted with `'g'` or `'G'`. For non-number types
+the field indicates the maximum field size - in other words, how many
+characters will be used from the field content. The *precision* is not
+allowed for integer, character, Boolean, and pointer values. Note that a
+C string must be null-terminated even if precision is specified.
+
+The `'L'` option uses the current locale setting to insert the appropriate
+number separator characters. This option is only valid for numeric types.
+
+Finally, the *type* determines how the data should be presented.
+
+The available string presentation types are:
+
+<table>
+<tr>
+  <th>Type</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'s'</code></td>
+  <td>
+    String format. This is the default type for strings and may be omitted.
+  </td>
+</tr>
+<tr>
+  <td><code>'?'</code></td>
+  <td>Debug format. The string is quoted and special characters escaped.</td>
+</tr>
+<tr>
+  <td>none</td>
+  <td>The same as <code>'s'</code>.</td>
+</tr>
+</table>
+
+The available character presentation types are:
+
+<table>
+<tr>
+  <th>Type</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'c'</code></td>
+  <td>
+    Character format. This is the default type for characters and may be
+    omitted.
+  </td>
+</tr>
+<tr>
+  <td><code>'?'</code></td>
+  <td>Debug format. The character is quoted and special characters escaped.</td>
+</tr>
+<tr>
+  <td>none</td>
+  <td>The same as <code>'c'</code>.</td>
+</tr>
+</table>
+
+The available integer presentation types are:
+
+<table>
+<tr>
+  <th>Type</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'b'</code></td>
+  <td>
+    Binary format. Outputs the number in base 2. Using the <code>'#'</code>
+    option with this type adds the prefix <code>"0b"</code> to the output value.    
+  </td>
+</tr>
+<tr>
+  <td><code>'B'</code></td>
+  <td>
+    Binary format. Outputs the number in base 2. Using the <code>'#'</code>
+    option with this type adds the prefix <code>"0B"</code> to the output value.
+  </td>
+</tr>
+<tr>
+  <td><code>'c'</code></td>
+  <td>Character format. Outputs the number as a character.</td>
+</tr>
+<tr>
+  <td><code>'d'</code></td>
+  <td>Decimal integer. Outputs the number in base 10.</td>
+</tr>
+<tr>
+  <td><code>'o'</code></td>
+  <td>Octal format. Outputs the number in base 8.</td>
+</tr>
+<tr>
+  <td><code>'x'</code></td>
+  <td>
+    Hex format. Outputs the number in base 16, using lower-case letters for the
+    digits above 9. Using the <code>'#'</code> option with this type adds the
+    prefix <code>"0x"</code> to the output value.
+  </td>
+</tr>
+<tr>
+  <td><code>'X'</code></td>
+  <td>
+    Hex format. Outputs the number in base 16, using upper-case letters for the
+    digits above 9. Using the <code>'#'</code> option with this type adds the
+    prefix <code>"0X"</code> to the output value.
+  </td>
+</tr>
+<tr>
+  <td>none</td>
+  <td>The same as <code>'d'</code>.</td>
+</tr>
+</table>
+
+Integer presentation types can also be used with character and Boolean values
+with the only exception that `'c'` cannot be used with `bool`. Boolean values
+are formatted using textual representation, either `true` or `false`, if the
+presentation type is not specified.
+
+The available presentation types for floating-point values are:
+
+<table>
+<tr>
+  <th>Type</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'a'</code></td>
+  <td>
+    Hexadecimal floating point format. Prints the number in base 16 with
+    prefix <code>"0x"</code> and lower-case letters for digits above 9.
+    Uses <code>'p'</code> to indicate the exponent.
+  </td>
+</tr>
+<tr>
+  <td><code>'A'</code></td>
+  <td>
+    Same as <code>'a'</code> except it uses upper-case letters for the
+    prefix, digits above 9 and to indicate the exponent.
+  </td>
+</tr>
+<tr>
+  <td><code>'e'</code></td>
+  <td>
+    Exponent notation. Prints the number in scientific notation using
+    the letter 'e' to indicate the exponent.
+  </td>
+</tr>
+<tr>
+  <td><code>'E'</code></td>
+  <td>
+    Exponent notation. Same as <code>'e'</code> except it uses an
+    upper-case <code>'E'</code> as the separator character.
+  </td>
+</tr>
+<tr>
+  <td><code>'f'</code></td>
+  <td>Fixed point. Displays the number as a fixed-point number.</td>
+</tr>
+<tr>
+  <td><code>'F'</code></td>
+  <td>
+    Fixed point. Same as <code>'f'</code>, but converts <code>nan</code>
+    to <code>NAN</code> and <code>inf</code> to <code>INF</code>.
+  </td>
+</tr>
+<tr>
+  <td><code>'g'</code></td>
+  <td>
+    <p>General format. For a given precision <code>p &gt;= 1</code>,
+    this rounds the number to <code>p</code> significant digits and then
+    formats the result in either fixed-point format or in scientific
+    notation, depending on its magnitude.</p>
+    <p>A precision of <code>0</code> is treated as equivalent to a precision
+    of <code>1</code>.</p>
+  </td>
+</tr>
+<tr>
+  <td><code>'G'</code></td>
+  <td>
+    General format. Same as <code>'g'</code> except switches to
+    <code>'E'</code> if the number gets too large. The representations of
+    infinity and NaN are uppercased, too.
+  </td>
+</tr>
+<tr>
+  <td>none</td>
+  <td>
+    Similar to <code>'g'</code>, except that the default precision is as
+    high as needed to represent the particular value.
+  </td>
+</tr>
+</table>
+
+The available presentation types for pointers are:
+
+<table>
+<tr>
+  <th>Type</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'p'</code></td>
+  <td>
+    Pointer format. This is the default type for pointers and may be omitted.
+  </td>
+</tr>
+<tr>
+  <td>none</td>
+  <td>The same as <code>'p'</code>.</td>
+</tr>
+</table>
+
+## Chrono Format Specifications
+
+Format specifications for chrono duration and time point types as well as
+`std::tm` have the following syntax:
+
+<a id="chrono-format-spec"></a>
+<pre><code class="language-json"
+>chrono_format_spec ::= [[<a href="#format-spec">fill</a>]<a href="#format-spec"
+  >align</a>][<a href="#format-spec">width</a>]["." <a href="#format-spec"
+  >precision</a>][chrono_specs]
+chrono_specs       ::= conversion_spec |
+                       chrono_specs (conversion_spec | literal_char)
+conversion_spec    ::= "%" [padding_modifier] [locale_modifier] chrono_type
+literal_char       ::= &lt;a character other than '{', '}' or '%'>
+padding_modifier   ::= "-" | "_"  | "0"
+locale_modifier    ::= "E" | "O"
+chrono_type        ::= "a" | "A" | "b" | "B" | "c" | "C" | "d" | "D" | "e" |
+                       "F" | "g" | "G" | "h" | "H" | "I" | "j" | "m" | "M" |
+                       "n" | "p" | "q" | "Q" | "r" | "R" | "S" | "t" | "T" |
+                       "u" | "U" | "V" | "w" | "W" | "x" | "X" | "y" | "Y" |
+                       "z" | "Z" | "%"</code>
+</pre>
+
+Literal chars are copied unchanged to the output. Precision is valid only
+for `std::chrono::duration` types with a floating-point representation type.
+
+The available presentation types (*chrono_type*) are:
+
+<table>
+<tr>
+  <th>Type</th>
+  <th>Meaning</th>
+</tr>
+<tr>
+  <td><code>'a'</code></td>
+  <td>
+    The abbreviated weekday name, e.g. "Sat". If the value does not contain a
+    valid weekday, an exception of type <code>format_error</code> is thrown.
+  </td>
+</tr>
+<tr>
+  <td><code>'A'</code></td>
+  <td>
+    The full weekday name, e.g. "Saturday". If the value does not contain a
+    valid weekday, an exception of type <code>format_error</code> is thrown.
+  </td>
+</tr>
+<tr>
+  <td><code>'b'</code></td>
+  <td>
+    The abbreviated month name, e.g. "Nov". If the value does not contain a
+    valid month, an exception of type <code>format_error</code> is thrown.
+  </td>
+</tr>
+<tr>
+  <td><code>'B'</code></td>
+  <td>
+    The full month name, e.g. "November". If the value does not contain a valid
+    month, an exception of type <code>format_error</code> is thrown.
+  </td>
+</tr>
+<tr>
+  <td><code>'c'</code></td>
+  <td>
+    The date and time representation, e.g. "Sat Nov 12 22:04:00 1955". The
+    modified command <code>%Ec</code> produces the locale's alternate date and
+    time representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'C'</code></td>
+  <td>
+    The year divided by 100 using floored division, e.g. "19". If the result
+    is a single decimal digit, it is prefixed with 0. The modified command
+    <code>%EC</code> produces the locale's alternative representation of the
+    century.
+  </td>
+</tr>
+<tr>
+  <td><code>'d'</code></td>
+  <td>
+    The day of month as a decimal number. If the result is a single decimal
+    digit, it is prefixed with 0. The modified command <code>%Od</code>
+    produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'D'</code></td>
+  <td>Equivalent to <code>%m/%d/%y</code>, e.g. "11/12/55".</td>
+</tr>
+<tr>
+  <td><code>'e'</code></td>
+  <td>
+    The day of month as a decimal number. If the result is a single decimal
+    digit, it is prefixed with a space. The modified command <code>%Oe</code>
+    produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'F'</code></td>
+  <td>Equivalent to <code>%Y-%m-%d</code>, e.g. "1955-11-12".</td>
+</tr>
+<tr>
+  <td><code>'g'</code></td>
+  <td>
+    The last two decimal digits of the ISO week-based year. If the result is a
+    single digit it is prefixed by 0.
+  </td>
+</tr>
+<tr>
+  <td><code>'G'</code></td>
+  <td>
+    The ISO week-based year as a decimal number. If the result is less than
+    four digits it is left-padded with 0 to four digits.
+  </td>
+</tr>
+<tr>
+  <td><code>'h'</code></td>
+  <td>Equivalent to <code>%b</code>, e.g. "Nov".</td>
+</tr>
+<tr>
+  <td><code>'H'</code></td>
+  <td>
+    The hour (24-hour clock) as a decimal number. If the result is a single
+    digit, it is prefixed with 0. The modified command <code>%OH</code>
+    produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'I'</code></td>
+  <td>
+    The hour (12-hour clock) as a decimal number. If the result is a single
+    digit, it is prefixed with 0. The modified command <code>%OI</code>
+    produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'j'</code></td>
+  <td>
+    If the type being formatted is a specialization of duration, the decimal
+    number of days without padding. Otherwise, the day of the year as a decimal
+    number. Jan 1 is 001. If the result is less than three digits, it is
+    left-padded with 0 to three digits.
+  </td>
+</tr>
+<tr>
+  <td><code>'m'</code></td>
+  <td>
+    The month as a decimal number. Jan is 01. If the result is a single digit,
+    it is prefixed with 0. The modified command <code>%Om</code> produces the
+    locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'M'</code></td>
+  <td>
+    The minute as a decimal number. If the result is a single digit, it
+    is prefixed with 0. The modified command <code>%OM</code> produces the
+    locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'n'</code></td>
+  <td>A new-line character.</td>
+</tr>
+<tr>
+  <td><code>'p'</code></td>
+  <td>The AM/PM designations associated with a 12-hour clock.</td>
+</tr>
+<tr>
+  <td><code>'q'</code></td>
+  <td>The duration's unit suffix.</td>
+</tr>
+<tr>
+  <td><code>'Q'</code></td>
+  <td>
+    The duration's numeric value (as if extracted via <code>.count()</code>).
+  </td>
+</tr>
+<tr>
+  <td><code>'r'</code></td>
+  <td>The 12-hour clock time, e.g. "10:04:00 PM".</td>
+</tr>
+<tr>
+  <td><code>'R'</code></td>
+  <td>Equivalent to <code>%H:%M</code>, e.g. "22:04".</td>
+</tr>
+<tr>
+  <td><code>'S'</code></td>
+  <td>
+    Seconds as a decimal number. If the number of seconds is less than 10, the
+    result is prefixed with 0. If the precision of the input cannot be exactly
+    represented with seconds, then the format is a decimal floating-point number
+    with a fixed format and a precision matching that of the precision of the
+    input (or to a microseconds precision if the conversion to floating-point
+    decimal seconds cannot be made within 18 fractional digits). The modified
+    command <code>%OS</code> produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'t'</code></td>
+  <td>A horizontal-tab character.</td>
+</tr>
+<tr>
+  <td><code>'T'</code></td>
+  <td>Equivalent to <code>%H:%M:%S</code>.</td>
+</tr>
+<tr>
+  <td><code>'u'</code></td>
+  <td>
+    The ISO weekday as a decimal number (1-7), where Monday is 1. The modified
+    command <code>%Ou</code> produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'U'</code></td>
+  <td>
+    The week number of the year as a decimal number. The first Sunday of the
+    year is the first day of week 01. Days of the same year prior to that are
+    in week 00. If the result is a single digit, it is prefixed with 0.
+    The modified command <code>%OU</code> produces the locale's alternative
+    representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'V'</code></td>
+  <td>
+    The ISO week-based week number as a decimal number. If the result is a
+    single digit, it is prefixed with 0. The modified command <code>%OV</code>
+    produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'w'</code></td>
+  <td>
+    The weekday as a decimal number (0-6), where Sunday is 0. The modified
+    command <code>%Ow</code> produces the locale's alternative representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'W'</code></td>
+  <td>
+    The week number of the year as a decimal number. The first Monday of the
+    year is the first day of week 01. Days of the same year prior to that are
+    in week 00. If the result is a single digit, it is prefixed with 0.
+    The modified command <code>%OW</code> produces the locale's alternative
+    representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'x'</code></td>
+  <td>
+    The date representation, e.g. "11/12/55". The modified command
+    <code>%Ex</code> produces the locale's alternate date representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'X'</code></td>
+  <td>
+    The time representation, e.g. "10:04:00". The modified command
+    <code>%EX</code> produces the locale's alternate time representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'y'</code></td>
+  <td>
+    The last two decimal digits of the year. If the result is a single digit
+    it is prefixed by 0. The modified command <code>%Oy</code> produces the
+    locale's alternative representation. The modified command <code>%Ey</code>
+    produces the locale's alternative representation of offset from
+    <code>%EC</code> (year only).
+  </td>
+</tr>
+<tr>
+  <td><code>'Y'</code></td>
+  <td>
+    The year as a decimal number. If the result is less than four digits it is
+    left-padded with 0 to four digits. The modified command <code>%EY</code>
+    produces the locale's alternative full year representation.
+  </td>
+</tr>
+<tr>
+  <td><code>'z'</code></td>
+  <td>
+    The offset from UTC in the ISO 8601:2004 format. For example -0430 refers
+    to 4 hours 30 minutes behind UTC. If the offset is zero, +0000 is used.
+    The modified commands <code>%Ez</code> and <code>%Oz</code> insert a
+    <code>:</code> between the hours and minutes: -04:30. If the offset
+    information is not available, an exception of type
+    <code>format_error</code> is thrown.
+  </td>
+</tr>
+<tr>
+  <td><code>'Z'</code></td>
+  <td>
+    The time zone abbreviation. If the time zone abbreviation is not available,
+    an exception of type <code>format_error</code> is thrown.
+  </td>
+</tr>
+<tr>
+  <td><code>'%'</code></td>
+  <td>A % character.</td>
+</tr>
+</table>
+
+Specifiers that have a calendaric component such as `'d'` (the day of month)
+are valid only for `std::tm` and time points but not durations.
+
+The available padding modifiers (*padding_modifier*) are:
+
+| Type  | Meaning                                 |
+|-------|-----------------------------------------|
+| `'_'` | Pad a numeric result with spaces.       |
+| `'-'` | Do not pad a numeric result string.     |
+| `'0'` | Pad a numeric result string with zeros. |
+
+These modifiers are only supported for the `'H'`, `'I'`, `'M'`, `'S'`, `'U'`,
+`'V'`, `'W'`, `'Y'`, `'d'`, `'j'` and `'m'` presentation types.
+
+## Range Format Specifications
+
+Format specifications for range types have the following syntax:
+
+<pre><code class="language-json"
+>range_format_spec ::= ["n"][range_type][range_underlying_spec]</code>
+</pre>
+
+The `'n'` option formats the range without the opening and closing brackets.
+
+The available presentation types for `range_type` are:
+
+| Type   | Meaning                                                    |
+|--------|------------------------------------------------------------|
+| none   | Default format.                                            |
+| `'s'`  | String format. The range is formatted as a string.         |
+| `'?⁠s'` | Debug format. The range is formatted as an escaped string. |
+
+If `range_type` is `'s'` or `'?s'`, the range element type must be a character
+type. The `'n'` option and `range_underlying_spec` are mutually exclusive with
+`'s'` and `'?s'`.
+
+The `range_underlying_spec` is parsed based on the formatter of the range's
+element type.
+
+By default, a range of characters or strings is printed escaped and quoted.
+But if any `range_underlying_spec` is provided (even if it is empty), then the
+characters or strings are printed according to the provided specification.
+
+Examples:
+
+```c++
+fmt::print("{}", std::vector{10, 20, 30});
+// Output: [10, 20, 30]
+fmt::print("{::#x}", std::vector{10, 20, 30});
+// Output: [0xa, 0x14, 0x1e]
+fmt::print("{}", std::vector{'h', 'e', 'l', 'l', 'o'});
+// Output: ['h', 'e', 'l', 'l', 'o']
+fmt::print("{:n}", std::vector{'h', 'e', 'l', 'l', 'o'});
+// Output: 'h', 'e', 'l', 'l', 'o'
+fmt::print("{:s}", std::vector{'h', 'e', 'l', 'l', 'o'});
+// Output: "hello"
+fmt::print("{:?s}", std::vector{'h', 'e', 'l', 'l', 'o', '\n'});
+// Output: "hello\n"
+fmt::print("{::}", std::vector{'h', 'e', 'l', 'l', 'o'});
+// Output: [h, e, l, l, o]
+fmt::print("{::d}", std::vector{'h', 'e', 'l', 'l', 'o'});
+// Output: [104, 101, 108, 108, 111]
+```
+
+## Format Examples
+
+This section contains examples of the format syntax and comparison with
+the printf formatting.
+
+In most of the cases the syntax is similar to the printf formatting,
+with the addition of the `{}` and with `:` used instead of `%`. For
+example, `"%03.2f"` can be translated to `"{:03.2f}"`.
+
+The new format syntax also supports new and different options, shown in
+the following examples.
+
+Accessing arguments by position:
+
+```c++
+fmt::format("{0}, {1}, {2}", 'a', 'b', 'c');
+// Result: "a, b, c"
+fmt::format("{}, {}, {}", 'a', 'b', 'c');
+// Result: "a, b, c"
+fmt::format("{2}, {1}, {0}", 'a', 'b', 'c');
+// Result: "c, b, a"
+fmt::format("{0}{1}{0}", "abra", "cad");  // arguments' indices can be repeated
+// Result: "abracadabra"
+```
+
+Aligning the text and specifying a width:
+
+```c++
+fmt::format("{:<30}", "left aligned");
+// Result: "left aligned                  "
+fmt::format("{:>30}", "right aligned");
+// Result: "                 right aligned"
+fmt::format("{:^30}", "centered");
+// Result: "           centered           "
+fmt::format("{:*^30}", "centered");  // use '*' as a fill char
+// Result: "***********centered***********"
+```
+
+Dynamic width:
+
+```c++
+fmt::format("{:<{}}", "left aligned", 30);
+// Result: "left aligned                  "
+```
+
+Dynamic precision:
+
+```c++
+fmt::format("{:.{}f}", 3.14, 1);
+// Result: "3.1"
+```
+
+Replacing `%+f`, `%-f`, and `% f` and specifying a sign:
+
+```c++
+fmt::format("{:+f}; {:+f}", 3.14, -3.14);  // show it always
+// Result: "+3.140000; -3.140000"
+fmt::format("{: f}; {: f}", 3.14, -3.14);  // show a space for positive numbers
+// Result: " 3.140000; -3.140000"
+fmt::format("{:-f}; {:-f}", 3.14, -3.14);  // show only the minus -- same as '{:f}; {:f}'
+// Result: "3.140000; -3.140000"
+```
+
+Replacing `%x` and `%o` and converting the value to different bases:
+
+```c++
+fmt::format("int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
+// Result: "int: 42;  hex: 2a;  oct: 52; bin: 101010"
+// with 0x or 0 or 0b as prefix:
+fmt::format("int: {0:d};  hex: {0:#x};  oct: {0:#o};  bin: {0:#b}", 42);
+// Result: "int: 42;  hex: 0x2a;  oct: 052;  bin: 0b101010"
+```
+
+Padded hex byte with prefix and always prints both hex characters:
+
+```c++
+fmt::format("{:#04x}", 0);
+// Result: "0x00"
+```
+
+Box drawing using Unicode fill:
+
+```c++
+fmt::print(
+    "┌{0:─^{2}}┐\n"
+    "│{1: ^{2}}│\n"
+    "└{0:─^{2}}┘\n", "", "Hello, world!", 20);
+```
+
+prints:
+
+```
+┌────────────────────┐
+│   Hello, world!    │
+└────────────────────┘
+```
+
+Using type-specific formatting:
+
+```c++
+#include <fmt/chrono.h>
+
+auto t = tm();
+t.tm_year = 2010 - 1900;
+t.tm_mon = 7;
+t.tm_mday = 4;
+t.tm_hour = 12;
+t.tm_min = 15;
+t.tm_sec = 58;
+fmt::print("{:%Y-%m-%d %H:%M:%S}", t);
+// Prints: 2010-08-04 12:15:58
+```
+
+Using the comma as a thousands separator:
+
+```c++
+#include <fmt/format.h>
+
+auto s = fmt::format(std::locale("en_US.UTF-8"), "{:L}", 1234567890);
+// s == "1,234,567,890"
+```