Add support for Tiny C Compiler (#138)

Adds support for detecting TCC by checking for __TINYC__ macro.
TCC pre-defines environment-specific macros similar to the ones
used by GCC and Clang so the rest of library works out of the box.

include/boost/predef/compiler.h

@@ -37,6 +37,7 @@ http://www.boost.org/LICENSE_1_0.txt)
 #include <boost/predef/compiler/pgi.h>
 #include <boost/predef/compiler/sgi_mipspro.h>
 #include <boost/predef/compiler/sunpro.h>
+#include <boost/predef/compiler/tcc.h>
 #include <boost/predef/compiler/tendra.h>
 #include <boost/predef/compiler/visualc.h>
 #include <boost/predef/compiler/watcom.h>

include/boost/predef/compiler/gcc.h

@@ -11,6 +11,7 @@ http://www.boost.org/LICENSE_1_0.txt)
 /* Other compilers that emulate this one need to be detected first. */
 
 #include <boost/predef/compiler/clang.h>
+#include <boost/predef/compiler/tcc.h>
 
 #include <boost/predef/version_number.h>
 #include <boost/predef/make.h>

include/boost/predef/compiler/tcc.h

@@ -0,0 +1,85 @@
+/*
+Copyright Kornel Ponikwicki 2025
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE_1_0.txt or copy at
+http://www.boost.org/LICENSE_1_0.txt)
+*/
+
+#ifndef BOOST_PREDEF_COMPILER_TCC_H
+#define BOOST_PREDEF_COMPILER_TCC_H
+
+#include <boost/predef/version_number.h>
+#include <boost/predef/make.h>
+
+/* tag::reference[]
+= `BOOST_COMP_TCC`
+
+https://en.wikipedia.org/wiki/Tiny_C_Compiler[Tiny C Compiler] (TinyCC or TCC for short).
+Version number available as major, minor, and patch.
+
+[options="header"]
+|===
+| {predef_symbol} | {predef_version}
+
+| `+__TINYC__+` | {predef_detection}
+
+| `+__TINYC__+` | 0.9.P
+|===
+*/ // end::reference[]
+
+#define BOOST_COMP_TCC BOOST_VERSION_NUMBER_NOT_AVAILABLE
+
+#if defined(__TINYC__) && !defined(BOOST_COMP_TCC_DETECTION)
+    /* Helper macros for checking if __TINYC__ expands to any value */
+#   define _BOOST_COMP_TCC_HAS_VALUE(VALUE) (_BOOST_COMP_TCC_EXPAND(VALUE) != 1)
+#   define _BOOST_COMP_TCC_EXPAND(VALUE) _BOOST_COMP_TCC_CONCAT(VALUE)
+#   define _BOOST_COMP_TCC_CONCAT(VALUE) (VALUE ## 1)
+    /*
+    TCC version is defined in __TINYC__ as {MINOR}{PATCH},
+    meaning that 0.9.27 would be 927 (0 for {MAJOR} is skipped).
+    Before 0.9.26 macro was defined but not set to any value.
+    Since TCC was always released under versions 0.9.x
+    we can assume that said macro either ranges between 926 and 999
+    or that the version is at least 0.9.0.
+    This will, of course, break if {MAJOR} or {MINOR} changes,
+    which has never happened (as of January 2025).
+    */
+#   if _BOOST_COMP_TCC_HAS_VALUE(__TINYC__)
+#       if (__TINYC__ < 926 || __TINYC__ > 999)
+#           error "Cannot determine TCC version from __TINYC__"
+#       endif
+#       define BOOST_COMP_TCC_DETECTION BOOST_VERSION_NUMBER(\
+            0,\
+            __TINYC__/100,\
+            __TINYC__%100)
+#   else
+#       define BOOST_COMP_TCC_DETECTION BOOST_VERSION_NUMBER(0,9,0)
+#   endif
+    /* We will not need these macros anymore */
+#   undef _BOOST_COMP_TCC_HAS_VALUE
+#   undef _BOOST_COMP_TCC_EXPAND
+#   undef _BOOST_COMP_TCC_CONCAT
+#endif
+
+#ifdef BOOST_COMP_TCC_DETECTION
+#   if defined(BOOST_PREDEF_DETAIL_COMP_DETECTED)
+#       define BOOST_COMP_TCC_EMULATED BOOST_COMP_TCC_DETECTION
+#   else
+#       undef BOOST_COMP_TCC
+#       define BOOST_COMP_TCC BOOST_COMP_TCC_DETECTION
+#   endif
+#   define BOOST_COMP_TCC_AVAILABLE
+#   include <boost/predef/detail/comp_detected.h>
+#endif
+
+#define BOOST_COMP_TCC_NAME "Tiny C Compiler"
+
+#endif
+
+#include <boost/predef/detail/test.h>
+BOOST_PREDEF_DECLARE_TEST(BOOST_COMP_TCC,BOOST_COMP_TCC_NAME)
+
+#ifdef BOOST_COMP_TCC_EMULATED
+#include <boost/predef/detail/test.h>
+BOOST_PREDEF_DECLARE_TEST(BOOST_COMP_TCC_EMULATED,BOOST_COMP_TCC_NAME)
+#endif