Ruby: include/ruby/internal/assume.h File Reference

Ruby 3.4.9p82 (2026-03-11 revision 76cca827ab52ab1d346a728f068d5b8da3e2952b)

Macros
assume.h File Reference

Defines RBIMPL_ASSUME / RBIMPL_UNREACHABLE. More...

`#include "ruby/internal/config.h"`
`#include "ruby/internal/cast.h"`
`#include "ruby/internal/compiler_since.h"`
`#include "ruby/internal/has/builtin.h"`
`#include "ruby/internal/warning_push.h"`

Go to the source code of this file.

## Macros
#define | RBIMPL_UNREACHABLE_RETURN(_)
| Wraps (or simulates) __builtin_unreachable.
#define | RBIMPL_ASSUME(_)
| Wraps (or simulates) __builtin_unreachable.
#define | RBIMPL_UNREACHABLE()

## Detailed Description

Defines RBIMPL_ASSUME / RBIMPL_UNREACHABLE.

Author
  Ruby developers ruby-.nosp@m.core.nosp@m.@ruby.nosp@m.-lan.nosp@m.g.org

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.

Warning
  Symbols prefixed with either RBIMPL or rbimpl are implementation details. Don't take them as canon. They could rapidly appear then vanish. The name (path) of this header file is also an implementation detail. Do not expect it to persist at the place it is now. Developers are free to move it anywhere anytime at will.

Note
  To ruby-core: remember that this header can be possibly recursively included from extension libraries written in C++. Do not expect for instance __VA_ARGS__ is always available. We assume C99 for ruby itself but we don't assume languages of extension libraries. They could be written in C++98.

These macros must be defined at once because:

- RBIMPL_ASSUME could fallback to RBIMPL_UNREACHABLE.
- RBIMPL_UNREACHABLE could fallback to RBIMPL_ASSUME.

Definition in file assume.h.

## Macro Definition Documentation

## ◆ RBIMPL_ASSUME

#define RBIMPL_ASSUME | ( |  | _ | ) |

Value:
RBIMPL_CAST((void)(_))
_
#define _(args)
This was a transition path from K&R to ANSI.
Definition stdarg.h:35

Wraps (or simulates) __builtin_unreachable.

Wraps (or simulates) __assume.

Definition at line 76 of file assume.h.

Referenced by rb_long2int_inline(), and rb_type().

## ◆ RBIMPL_UNREACHABLE

#define RBIMPL_UNREACHABLE | ( |  | ) |

Value:
RBIMPL_ASSUME(0)
RBIMPL_ASSUME
#define RBIMPL_ASSUME(_)
Wraps (or simulates) __builtin_unreachable.
Definition assume.h:76

Definition at line 84 of file assume.h.

## ◆ RBIMPL_UNREACHABLE_RETURN

#define RBIMPL_UNREACHABLE_RETURN | ( |  | _ | ) |

Value:
return (_)

Wraps (or simulates) __builtin_unreachable.

Definition at line 48 of file assume.h.

Referenced by rb_class_of(), RTYPEDDATA_P(), and RTYPEDDATA_TYPE().