add include/ruby/backward/cxxanyargs.hpp

Compilation of extension libraries written in C++ are reportedly
broken due to https://github.com/ruby/ruby/pull/2404

The root cause of this issue was that the definition of ANYARGS
differ between C and C++, and that of C++ is incompatible with the
updated ones.

We are using the incompatibility against itself.  In C++ two distinct
function prototypes can be overloaded.  We provide the old, ANYARGSed
prototypes in addition to the current granular ones; and let the
older ones warn about types.

1 files changed, 376 insertions, 0 deletions

diff --git a/include/ruby/backward/cxxanyargs.hpp b/include/ruby/backward/cxxanyargs.hpp
new file mode 100644
index 0000000000..70191a91d0
--- /dev/null
+++ b/include/ruby/backward/cxxanyargs.hpp
@@ -0,0 +1,376 @@
+#ifndef RUBY_BACKWARD_CXXANYARGS_HPP // -*- C++ -*-
+#define RUBY_BACKWARD_CXXANYARGS_HPP
+/// @file
+/// @brief      Provides old prototypes for C++ programs.
+/// @author     \@shyouhei
+/// @copyright  This  file  is  a  part   of  the  programming  language  Ruby.
+///             Permission  is hereby  granted, to  either redistribute  and/or
+///             modify this file, provided that the conditions mentioned in the
+///             file COPYING are met.  Consult the file for details.
+/// @note       DO NOT  MODERNIZE THIS FILE!   As the  file name implies  it is
+///             meant to  be a backwards  compatibility shim.  Please  stick to
+///             C++ 98 and never use newer features, like `constexpr`.
+
+/// @brief  The main namespace.
+/// @note   The name  "ruby" might  already be  taken, but that  must not  be a
+///         problem because namespaces are allowed to reopen.
+namespace ruby {
+
+/// @brief  Backwards compatibility layer.
+namespace backward {
+
+/// @brief  Provides ANYARGS deprecation warnings.
+///
+/// In C,  ANYARGS means there  is no function prototype.   Literally anything,
+/// even including  nothing, can be  a valid  ANYARGS.  So passing  a correctly
+/// prototyped function pointer  to an ANYARGS-ed function  parameter is valid,
+/// at the same time passing an ANYARGS-ed function pointer to a granular typed
+/// function  parameter is  also  valid.  However  on the  other  hand in  C++,
+/// ANYARGS doesn't actually mean any number of arguments.  C++'s ANYARGS means
+/// _variadic_ number of arguments.  This is incompatible with ordinal, correct
+/// function prototypes.
+///
+/// Luckily, function  prototypes being distinct  each other means they  can be
+/// overloaded.  We can provide a compatibility layer for older Ruby APIs which
+/// used to have ANYARGS.  This namespace includes such attempts.
+namespace cxxanyargs {
+
+/// @brief ANYARGS-ed function type.
+typedef VALUE type(ANYARGS);
+
+/// @brief ANYARGS-ed function type, void variant.
+typedef void void_type(ANYARGS);
+
+/// @brief ANYARGS-ed function type, int variant.
+typedef int int_type(ANYARGS);
+
+/// @name Hooking global variables
+/// @{
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Define a function-backended global variable.
+/// @param[in]   q  Name of the variable.
+/// @param[in]   w  Getter function.
+/// @param[in]   e  Setter function.
+/// @note        Both functions can be nullptr.
+/// @see         rb_define_hooked_variable()
+/// @deprecated  Use glanular typed overload instead.
+inline void
+rb_define_virtual_variable(const char *q, type *w, void_type *e)
+{
+    rb_gvar_getter_t *r = reinterpret_cast<rb_gvar_getter_t*>(w);
+    rb_gvar_setter_t *t = reinterpret_cast<rb_gvar_setter_t*>(e);
+    ::rb_define_virtual_variable(q, r, t);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Define a function-backended global variable.
+/// @param[in]   q  Name of the variable.
+/// @param[in]   w  Variable storage.
+/// @param[in]   e  Getter function.
+/// @param[in]   r  Setter function.
+/// @note        Both functions can be nullptr.
+/// @see         rb_define_virtual_variable()
+/// @deprecated  Use glanular typed overload instead.
+inline void
+rb_define_hooked_variable(const char *q, VALUE *w, type *e, void_type *r)
+{
+    rb_gvar_getter_t *t = reinterpret_cast<rb_gvar_getter_t*>(e);
+    rb_gvar_setter_t *y = reinterpret_cast<rb_gvar_setter_t*>(r);
+    ::rb_define_hooked_variable(q, w, t, y);
+}
+
+/// @}
+/// @name Exceptions and tag jumps
+/// @{
+
+DEPRECATED_BY(::rb_block_call,)
+/// @brief       Old way to implement iterators.
+/// @param[in]   q  A function that can yield.
+/// @param[in]   w  Passed to `q`.
+/// @param[in]   e  What is to be yielded.
+/// @param[in]   r  Passed to `e`.
+/// @return      The return value of `q`.
+/// @note        `e` can be nullptr.
+/// @deprecated  This function is obsolated since  long before 2.x era.  Do not
+///              use it any longer.  rb_block_call() is provided instead.
+inline VALUE
+rb_iterate(VALUE(*q)(VALUE), VALUE w, type *e, VALUE r)
+{
+    rb_block_call_func_t t = reinterpret_cast<rb_block_call_func_t>(e);
+    return ::rb_iterate(q, w, t, r);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Call a method with a block.
+/// @param[in]   q  The self.
+/// @param[in]   w  The method.
+/// @param[in]   e  The 3 of elems of `r`
+/// @param[in]   r  The arguments.
+/// @param[in]   t  What is to be yielded.
+/// @param[in]   y  Passed to `t`
+/// @return      Return value of `q#w(*r,&t)`
+/// @note        't' can be nullptr.
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_block_call(VALUE q, ID w, int e, const VALUE *r, type *t, VALUE y)
+{
+    rb_block_call_func_t u = reinterpret_cast<rb_block_call_func_t>(t);
+    return ::rb_block_call(q, w, e, r, u, y);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       An equivalent of `rescue` clause.
+/// @param[in]   q  A function that can raise.
+/// @param[in]   w  Passed to `q`.
+/// @param[in]   e  A function that cleans-up.
+/// @param[in]   r  Passed to `e`.
+/// @return      The return value of `q` if  no exception occurs, or the return
+///              value of `e` if otherwise.
+/// @note        `e` can be nullptr.
+/// @see         rb_ensure()
+/// @see         rb_rescue2()
+/// @see         rb_protect()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_rescue(type *q, VALUE w, type *e, VALUE r)
+{
+    typedef VALUE func1_t(VALUE);
+    typedef VALUE func2_t(VALUE, VALUE);
+    func1_t *t = reinterpret_cast<func1_t*>(q);
+    func2_t *y = reinterpret_cast<func2_t*>(e);
+    return ::rb_rescue(t, w, y, r);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       An equivalent of `rescue` clause.
+/// @param[in]   q    A function that can raise.
+/// @param[in]   w    Passed to `q`.
+/// @param[in]   e    A function that cleans-up.
+/// @param[in]   r    Passed to `e`.
+/// @param[in]   ...  0-terminated list of subclass of @ref rb_eException.
+/// @return      The return value of `q` if  no exception occurs, or the return
+///              value of `e` if otherwise.
+/// @note        `e` can be nullptr.
+/// @see         rb_ensure()
+/// @see         rb_rescue()
+/// @see         rb_protect()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_rescue2(type *q, VALUE w, type *e, VALUE r, ...)
+{
+    typedef VALUE func1_t(VALUE);
+    typedef VALUE func2_t(VALUE, VALUE);
+    func1_t *t = reinterpret_cast<func1_t*>(q);
+    func2_t *y = reinterpret_cast<func2_t*>(e);
+    va_list ap;
+    va_start(ap, r);
+    return ::rb_vrescue2(t, w, y, r, ap);
+    va_end(ap);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       An equivalent of `ensure` clause.
+/// @param[in]   q  A function that can raise.
+/// @param[in]   w  Passed to `q`.
+/// @param[in]   e  A function that ensures.
+/// @param[in]   r  Passed to `e`.
+/// @return      The return value of `q`.
+/// @note        It makes no sense to pass nullptr to `e`.
+/// @see         rb_rescue()
+/// @see         rb_rescue2()
+/// @see         rb_protect()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_ensure(type *q, VALUE w, type *e, VALUE r)
+{
+    typedef VALUE func1_t(VALUE);
+    func1_t *t = reinterpret_cast<func1_t*>(q);
+    func1_t *y = reinterpret_cast<func1_t*>(e);
+    return ::rb_ensure(t, w, y, r);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       An equivalent of `Kernel#catch`.
+/// @param[in]   q  The "tag" string.
+/// @param[in]   w  A function that can throw.
+/// @param[in]   e  Passed to `w`.
+/// @return      What was thrown.
+/// @note        `q` can be a nullptr but makes no sense to pass nullptr to`w`.
+/// @see         rb_block_call()
+/// @see         rb_protect()
+/// @see         rb_rb_catch_obj()
+/// @see         rb_rescue()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_catch(const char *q, type *w, VALUE e)
+{
+    rb_block_call_func_t r = reinterpret_cast<rb_block_call_func_t>(w);
+    return ::rb_catch(q, r, e);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       An equivalent of `Kernel#catch`.
+/// @param[in]   q  The "tag" object.
+/// @param[in]   w  A function that can throw.
+/// @param[in]   e  Passed to `w`.
+/// @return      What was thrown.
+/// @note        It makes no sense to pass nullptr to`w`.
+/// @see         rb_block_call()
+/// @see         rb_protect()
+/// @see         rb_rb_catch_obj()
+/// @see         rb_rescue()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_catch_obj(VALUE q, type *w, VALUE e)
+{
+    rb_block_call_func_t r = reinterpret_cast<rb_block_call_func_t>(w);
+    return ::rb_catch_obj(q, r, e);
+}
+
+/// @}
+/// @name Procs, Fibers and Threads
+/// @{
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Creates a @ref rb_cFiber instance.
+/// @param[in]   q  The fiber body.
+/// @param[in]   w  Passed to `q`.
+/// @return      What was allocated.
+/// @note        It makes no sense to pass nullptr to`q`.
+/// @see         rb_proc_new()
+/// @see         rb_thread_creatr()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_fiber_new(type *q, VALUE w)
+{
+    rb_block_call_func_t e = reinterpret_cast<rb_block_call_func_t>(q);
+    return ::rb_fiber_new(e, w);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Creates a @ref rb_cProc instance.
+/// @param[in]   q  The proc body.
+/// @param[in]   w  Passed to `q`.
+/// @return      What was allocated.
+/// @note        It makes no sense to pass nullptr to`q`.
+/// @see         rb_fiber_new()
+/// @see         rb_thread_creatr()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_proc_new(type *q, VALUE w)
+{
+    rb_block_call_func_t e = reinterpret_cast<rb_block_call_func_t>(q);
+    return ::rb_proc_new(e, w);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Creates a @ref rb_cThread instance.
+/// @param[in]   q  The thread body.
+/// @param[in]   w  Passed to `q`.
+/// @return      What was allocated.
+/// @note        It makes no sense to pass nullptr to`q`.
+/// @see         rb_proc_new()
+/// @see         rb_fiber_new()
+/// @deprecated  Use glanular typed overload instead.
+inline VALUE
+rb_thread_create(type *q, void *w)
+{
+    typedef VALUE ptr_t(void*);
+    ptr_t *e = reinterpret_cast<ptr_t*>(q);
+    return ::rb_thread_create(e, w);
+}
+
+/// @}
+/// @name Hash and st_table
+/// @{
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Iteration over the given table.
+/// @param[in]   q  A table to scan.
+/// @param[in]   w  A function to iterate.
+/// @param[in]   e  Passed to `w`.
+/// @retval      0  Always returns 0.
+/// @note        It makes no sense to pass nullptr to`w`.
+/// @see         st_foreach_check()
+/// @see         rb_hash_foreach()
+/// @deprecated  Use glanular typed overload instead.
+inline int
+st_foreach(st_table *q, int_type *w, st_data_t e)
+{
+    st_foreach_callback_func *r =
+        reinterpret_cast<st_foreach_callback_func*>(w);
+    return ::st_foreach(q, r, e);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Iteration over the given table.
+/// @param[in]   q  A table to scan.
+/// @param[in]   w  A function to iterate.
+/// @param[in]   e  Passed to `w`.
+/// @retval      0  Successful end of iteration.
+/// @retval      1  Element removed during traversing.
+/// @note        It makes no sense to pass nullptr to`w`.
+/// @see         st_foreach()
+/// @deprecated  Use glanular typed overload instead.
+inline int
+st_foreach_check(st_table *q, int_type *w, st_data_t e, st_data_t)
+{
+    st_foreach_check_callback_func *t =
+        reinterpret_cast<st_foreach_check_callback_func*>(w);
+    return ::st_foreach_check(q, t, e, 0);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Iteration over the given table.
+/// @param[in]   q  A table to scan.
+/// @param[in]   w  A function to iterate.
+/// @param[in]   e  Passed to `w`.
+/// @note        It makes no sense to pass nullptr to`w`.
+/// @see         st_foreach_check()
+/// @deprecated  Use glanular typed overload instead.
+inline void
+st_foreach_safe(st_table *q, int_type *w, st_data_t e)
+{
+    st_foreach_callback_func *r =
+        reinterpret_cast<st_foreach_callback_func*>(w);
+    ::st_foreach_safe(q, r, e);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Iteration over the given hash.
+/// @param[in]   q  A hash to scan.
+/// @param[in]   w  A function to iterate.
+/// @param[in]   e  Passed to `w`.
+/// @note        It makes no sense to pass nullptr to`w`.
+/// @see         st_foreach()
+/// @deprecated  Use glanular typed overload instead.
+inline void
+rb_hash_foreach(VALUE q, int_type *w, VALUE e)
+{
+    st_foreach_callback_func *r =
+        reinterpret_cast<st_foreach_callback_func*>(w);
+    ::rb_hash_foreach(q, r, e);
+}
+
+DEPRECATED_TYPE(("Use of ANYARGS in this function is deprected"),)
+/// @brief       Iteration over each instance variable of the object.
+/// @param[in]   q  An object.
+/// @param[in]   w  A function to iterate.
+/// @param[in]   e  Passed to `w`.
+/// @note        It makes no sense to pass nullptr to`w`.
+/// @see         st_foreach()
+/// @deprecated  Use glanular typed overload instead.
+inline void
+rb_ivar_foreach(VALUE q, int_type *w, VALUE e)
+{
+    st_foreach_callback_func *r =
+        reinterpret_cast<st_foreach_callback_func*>(w);
+    ::rb_ivar_foreach(q, r, e);
+}
+
+/// @}
+}}}
+
+using namespace ruby::backward::cxxanyargs;
+#endif // RUBY_BACKWARD_CXXANYARGS_HPP