Add multicolumnfloattable environment.

This environment lets us describe our multi-column tables containing
lists of headers, library symbols, etc. in column-major order instead
of in row-major order.

Author: zygoloid

source/lib-intro.tex

@@ -1009,94 +1009,78 @@
 \defnx{\Cpp{} library headers}{header!C++ library},
 shown in \tref{cpp.library.headers}.
 
-\begin{floattable}{\Cpp{} library headers}{tab:cpp.library.headers}
+\begin{multicolfloattable}{\Cpp{} library headers}{tab:cpp.library.headers}
 {llll}
-\topline
-\tcode{<algorithm>} &
-\tcode{<functional>} &
-\tcode{<numeric>} &
+\tcode{<algorithm>} \\
+\tcode{<any>} \\
+\tcode{<array>} \\
+\tcode{<atomic>} \\
+\tcode{<bitset>} \\
+\tcode{<charconv>} \\
+\tcode{<chrono>} \\
+\tcode{<codecvt>} \\
+\tcode{<compare>} \\
+\tcode{<complex>} \\
+\tcode{<condition_variable>} \\
+\tcode{<deque>} \\
+\tcode{<exception>} \\
+\tcode{<execution>} \\
+\tcode{<filesystem>} \\
+\tcode{<forward_list>} \\
+\tcode{<fstream>} \\
+\columnbreak
+\tcode{<functional>} \\
+\tcode{<future>} \\
+\tcode{<initializer_list>} \\
+\tcode{<iomanip>} \\
+\tcode{<ios>} \\
+\tcode{<iosfwd>} \\
+\tcode{<iostream>} \\
+\tcode{<istream>} \\
+\tcode{<iterator>} \\
+\tcode{<limits>} \\
+\tcode{<list>} \\
+\tcode{<locale>} \\
+\tcode{<map>} \\
+\tcode{<memory>} \\
+\tcode{<memory_resource>} \\
+\tcode{<mutex>} \\
+\tcode{<new>} \\
+\tcode{<numeric>} \\
+\columnbreak
+\tcode{<optional>} \\
+\tcode{<ostream>} \\
+\tcode{<queue>} \\
+\tcode{<random>} \\
+\tcode{<ratio>} \\
+\tcode{<regex>} \\
+\tcode{<scoped_allocator>} \\
+\tcode{<set>} \\
+\tcode{<shared_mutex>} \\
+\tcode{<span>} \\
+\tcode{<sstream>} \\
+\tcode{<stack>} \\
+\tcode{<stdexcept>} \\
+\tcode{<streambuf>} \\
+\tcode{<string>} \\
 \tcode{<string_view>} \\
-
-\tcode{<any>} &
-\tcode{<future>} &
-\tcode{<optional>} &
+\tcode{<strstream>} \\
+\columnbreak
 \tcode{<syncstream>} \\
-
-\tcode{<array>} &
-\tcode{<initializer_list>} &
-\tcode{<ostream>} &
 \tcode{<system_error>} \\
-
-\tcode{<atomic>} &
-\tcode{<iomanip>} &
-\tcode{<queue>} &
 \tcode{<thread>} \\
-
-\tcode{<bitset>} &
-\tcode{<ios>} &
-\tcode{<random>} &
 \tcode{<tuple>} \\
-
-\tcode{<charconv>} &
-\tcode{<iosfwd>} &
-\tcode{<ratio>} &
-\tcode{<type_traits>} \\
-
-\tcode{<chrono>} &
-\tcode{<iostream>} &
-\tcode{<regex>} &
 \tcode{<typeindex>} \\
-
-\tcode{<codecvt>} &
-\tcode{<istream>} &
-\tcode{<scoped_allocator>} &
 \tcode{<typeinfo>} \\
-
-\tcode{<compare>} &
-\tcode{<iterator>} &
-\tcode{<set>} &
+\tcode{<type_traits>} \\
 \tcode{<unordered_map>} \\
-
-\tcode{<complex>} &
-\tcode{<limits>} &
-\tcode{<shared_mutex>} &
 \tcode{<unordered_set>} \\
-
-\tcode{<condition_variable>} &
-\tcode{<list>} &
-\tcode{<span>} &
 \tcode{<utility>} \\
-
-\tcode{<deque>} &
-\tcode{<locale>} &
-\tcode{<sstream>} &
 \tcode{<valarray>} \\
-
-\tcode{<exception>} &
-\tcode{<map>} &
-\tcode{<stack>} &
 \tcode{<variant>} \\
-
-\tcode{<execution>} &
-\tcode{<memory>} &
-\tcode{<stdexcept>} &
 \tcode{<vector>} \\
-
-\tcode{<filesystem>} &
-\tcode{<memory_resource>} &
-\tcode{<streambuf>} &
 \tcode{<version>} \\
-
-\tcode{<forward_list>} &
-\tcode{<mutex>} &
-\tcode{<strstream>} &
-\\
-
-\tcode{<fstream>} &
-\tcode{<new>} &
-\tcode{<string>} &
-\\
-\end{floattable}
+\end{multicolfloattable}
 
 
 \pnum
@@ -1109,44 +1093,39 @@
 \tcode{<stdnoreturn.h>}\indextext{\idxhdr{stdnoreturn.h}!absence thereof},
 \tcode{<threads.h>}\indextext{\idxhdr{threads.h}!absence thereof}.}
 
-\begin{floattable}{\Cpp{} headers for C library facilities}{tab:cpp.c.headers}
+\begin{multicolfloattable}{\Cpp{} headers for C library facilities}{tab:cpp.c.headers}
 {lllll}
-\topline
-
-\tcode{<cassert>}           &
-\tcode{<cinttypes>}         &
-\tcode{<csignal>}           &
-\tcode{<cstdio>}            &
-\tcode{<cwchar>}            \\
-
-\tcode{<ccomplex>}          &
-\tcode{<ciso646>}           &
-\tcode{<cstdalign>}         &
-\tcode{<cstdlib>}           &
-\tcode{<cwctype>}           \\
-
-\tcode{<cctype>}            &
-\tcode{<climits>}           &
-\tcode{<cstdarg>}           &
-\tcode{<cstring>}           & \\
-
-\tcode{<cerrno>}            &
-\tcode{<clocale>}           &
-\tcode{<cstdbool>}          &
-\tcode{<ctgmath>}           & \\
-
-\tcode{<cfenv>}             &
-\tcode{<cmath>}             &
-\tcode{<cstddef>}           &
-\tcode{<ctime>}             & \\
-
-\tcode{<cfloat>}            &
-\tcode{<csetjmp>}           &
-\tcode{<cstdint>}           &
-\tcode{<cuchar>}            & \\
-
-
-\end{floattable}
+\tcode{<cassert>} \\
+\tcode{<ccomplex>} \\
+\tcode{<cctype>} \\
+\tcode{<cerrno>} \\
+\tcode{<cfenv>} \\
+\tcode{<cfloat>} \\
+\columnbreak
+\tcode{<cinttypes>} \\
+\tcode{<ciso646>} \\
+\tcode{<climits>} \\
+\tcode{<clocale>} \\
+\tcode{<cmath>} \\
+\tcode{<csetjmp>} \\
+\columnbreak
+\tcode{<csignal>} \\
+\tcode{<cstdalign>} \\
+\tcode{<cstdarg>} \\
+\tcode{<cstdbool>} \\
+\tcode{<cstddef>} \\
+\tcode{<cstdint>} \\
+\columnbreak
+\tcode{<cstdio>} \\
+\tcode{<cstdlib>} \\
+\tcode{<cstring>} \\
+\tcode{<ctgmath>} \\
+\tcode{<ctime>} \\
+\tcode{<cuchar>} \\
+\columnbreak
+\tcode{<cwchar>} \\
+\tcode{<cwctype>} \\
+\end{multicolfloattable}
 
 \pnum
 Except as noted in \ref{library} through \ref{\lastlibchapter}
@@ -1211,102 +1190,86 @@
 that may be declared in some header.
 These names are also subject to the restrictions of~\ref{macro.names}.
 
-\begin{floattable}{C standard Annex K names}{tab:c.annex.k.names}
+\begin{multicolfloattable}{C standard Annex K names}{tab:c.annex.k.names}
 {llll}
-\topline
-\tcode{abort_handler_s} &
-\tcode{mbstowcs_s} &
-\tcode{strncat_s} &
+\tcode{abort_handler_s} \\
+\tcode{asctime_s} \\
+\tcode{bsearch_s} \\
+\tcode{constraint_handler_t} \\
+\tcode{ctime_s} \\
+\tcode{errno_t} \\
+\tcode{fopen_s} \\
+\tcode{fprintf_s} \\
+\tcode{freopen_s} \\
+\tcode{fscanf_s} \\
+\tcode{fwprintf_s} \\
+\tcode{fwscanf_s} \\
+\tcode{getenv_s} \\
+\tcode{gets_s} \\
+\tcode{gmtime_s} \\
+\tcode{ignore_handler_s} \\
+\tcode{localtime_s} \\
+\tcode{L_tmpnam_s} \\
+\tcode{mbsrtowcs_s} \\
+\columnbreak
+\tcode{mbstowcs_s} \\
+\tcode{memcpy_s} \\
+\tcode{memmove_s} \\
+\tcode{memset_s} \\
+\tcode{printf_s} \\
+\tcode{qsort_s} \\
+\tcode{RSIZE_MAX} \\
+\tcode{rsize_t} \\
+\tcode{scanf_s} \\
+\tcode{set_constraint_handler_s} \\
+\tcode{snprintf_s} \\
+\tcode{snwprintf_s} \\
+\tcode{sprintf_s} \\
+\tcode{sscanf_s} \\
+\tcode{strcat_s} \\
+\tcode{strcpy_s} \\
+\tcode{strerrorlen_s} \\
+\tcode{strerror_s} \\
+\tcode{strlen_s} \\
+\columnbreak
+\tcode{strncat_s} \\
+\tcode{strncpy_s} \\
+\tcode{strtok_s} \\
+\tcode{swprintf_s} \\
+\tcode{swscanf_s} \\
+\tcode{tmpfile_s} \\
+\tcode{TMP_MAX_S} \\
+\tcode{tmpnam_s} \\
+\tcode{vfprintf_s} \\
+\tcode{vfscanf_s} \\
+\tcode{vfwprintf_s} \\
+\tcode{vfwscanf_s} \\
+\tcode{vprintf_s} \\
+\tcode{vscanf_s} \\
+\tcode{vsnprintf_s} \\
+\tcode{vsnwprintf_s} \\
+\tcode{vsprintf_s} \\
+\tcode{vsscanf_s} \\
+\tcode{vswprintf_s} \\
+\columnbreak
 \tcode{vswscanf_s} \\
-
-\tcode{asctime_s} &
-\tcode{memcpy_s} &
-\tcode{strncpy_s} &
 \tcode{vwprintf_s} \\
-
-\tcode{bsearch_s} &
-\tcode{memmove_s} &
-\tcode{strtok_s} &
 \tcode{vwscanf_s} \\
-
-\tcode{constraint_handler_t} &
-\tcode{memset_s} &
-\tcode{swprintf_s} &
 \tcode{wcrtomb_s} \\
-
-\tcode{ctime_s} &
-\tcode{printf_s} &
-\tcode{swscanf_s} &
 \tcode{wcscat_s} \\
-
-\tcode{errno_t} &
-\tcode{qsort_s} &
-\tcode{tmpfile_s} &
 \tcode{wcscpy_s} \\
-
-\tcode{fopen_s} &
-\tcode{RSIZE_MAX} &
-\tcode{TMP_MAX_S} &
 \tcode{wcsncat_s} \\
-
-\tcode{fprintf_s} &
-\tcode{rsize_t} &
-\tcode{tmpnam_s} &
 \tcode{wcsncpy_s} \\
-
-\tcode{freopen_s} &
-\tcode{scanf_s} &
-\tcode{vfprintf_s} &
 \tcode{wcsnlen_s} \\
-
-\tcode{fscanf_s} &
-\tcode{set_constraint_handler_s} &
-\tcode{vfscanf_s} &
 \tcode{wcsrtombs_s} \\
-
-\tcode{fwprintf_s} &
-\tcode{snprintf_s} &
-\tcode{vfwprintf_s} &
 \tcode{wcstok_s} \\
-
-\tcode{fwscanf_s} &
-\tcode{snwprintf_s} &
-\tcode{vfwscanf_s} &
 \tcode{wcstombs_s} \\
-
-\tcode{getenv_s} &
-\tcode{sprintf_s} &
-\tcode{vprintf_s} &
 \tcode{wctomb_s} \\
-
-\tcode{gets_s} &
-\tcode{sscanf_s} &
-\tcode{vscanf_s} &
 \tcode{wmemcpy_s} \\
-
-\tcode{gmtime_s} &
-\tcode{strcat_s} &
-\tcode{vsnprintf_s} &
 \tcode{wmemmove_s} \\
-
-\tcode{ignore_handler_s} &
-\tcode{strcpy_s} &
-\tcode{vsnwprintf_s} &
 \tcode{wprintf_s} \\
-
-\tcode{L_tmpnam_s} &
-\tcode{strerror_s} &
-\tcode{vsprintf_s} &
 \tcode{wscanf_s} \\
-
-\tcode{localtime_s} &
-\tcode{strerrorlen_s} &
-\tcode{vsscanf_s} & \\
-
-\tcode{mbsrtowcs_s} &
-\tcode{strlen_s} &
-\tcode{vswprintf_s} & \\
-\end{floattable}
+\end{multicolfloattable}
 
 \rSec3[compliance]{Freestanding implementations}