It seems this is a part of Onigmo's API, not Ruby's.

According to MSVC manual (*1), cl.exe can skip including a header file
when that:

- contains #pragma once, or
- starts with #ifndef, or
- starts with #if ! defined.

GCC has a similar trick (*2), but it acts more stricter (e. g. there
must be _no tokens_ outside of #ifndef...#endif).

Sun C lacked #pragma once for a looong time.  Oracle Developer Studio
12.5 finally implemented it, but we cannot assume such recent version.

This changeset modifies header files so that each of them include
strictly one #ifndef...#endif.  I believe this is the most portable way
to trigger compiler optimizations. [Bug #16770]

*1: https://docs.microsoft.com/en-us/cpp/preprocessor/once
*2: https://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html

* include/ruby/defines.h (RUBY_SYMBOL_EXPORT_{BEGIN,END}): visibility
  control macros.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40122 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@28709 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

  string.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14912 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

  (rb_enc_nth): don't check the return value of rb_enc_mbclen.
  (rb_enc_strlen): ditto.
  (rb_enc_precise_mbclen): return needmore(1) if e <= p.
  (rb_enc_get_ascii): new function for extracting ASCII character.

* include/ruby/encoding.h (rb_enc_get_ascii): declared.

* include/ruby/regex.h (ismbchar): removed.

* re.c (rb_reg_expr_str): use rb_enc_get_ascii.
  (unescape_escaped_nonascii): use rb_enc_precise_mbclen to determine
  the termination of escaped non-ASCII character.
  (unescape_nonascii): use rb_enc_precise_mbclen.
  (rb_reg_quote): use rb_enc_get_ascii.
  (rb_reg_regsub): use rb_enc_get_ascii.

* string.c (rb_str_reverse) don't check the return value of
  rb_enc_mbclen.
  (rb_str_split_m): don't call rb_enc_mbclen with e <= p.

* parse.y (is_identchar): use ISASCII.
  (parser_ismbchar): removed.
  (parser_precise_mbclen): new macro.
  (parser_isascii): new macro.
  (parser_tokadd_mbchar): use parser_precise_mbclen to check invalid
  character precisely.
  (parser_tokadd_string): use parser_isascii.
  (parser_yylex): ditto.
  (is_special_global_name): don't call is_identchar with e <= p.
  (rb_enc_symname_p): ditto.

  [ruby-dev:32455]

* ext/tk/sample/tkextlib/vu/canvSticker2.rb: remove coding cookie
  because the encoding is not UTF-8.  [ruby-dev:32475]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14131 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

  <yugui@yugui.sakura.ne.jp>.  [ruby-dev:31748]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13348 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

* parse.y: encoding aware parsing.

* parse.y (pragma_encoding): encoding specification pragma.

* parse.y (rb_intern3): encoding specified symbols.

* string.c (rb_str_length): length based on characters.  
  for older behavior, bytesize method added.

* string.c (rb_str_index_m): index based on characters.  rindex as
  well.

* string.c (succ_char): encoding aware succeeding string.

* string.c (rb_str_reverse): reverse based on characters.

* string.c (rb_str_inspect): encoding aware string description.

* string.c (rb_str_upcase_bang): encoding aware case conversion.
  downcase, capitalize, swapcase as well.

* string.c (rb_str_tr_bang): tr based on characters.  delete,
  squeeze, tr_s, count as well.

* string.c (rb_str_split_m): split based on characters.

* string.c (rb_str_each_line): encoding aware each_line.

* string.c (rb_str_each_char): added.  iteration based on
  characters.

* string.c (rb_str_strip_bang): encoding aware whitespace
  stripping.  lstrip, rstrip as well.

* string.c (rb_str_justify): encoding aware justifying (ljust,
  rjust, center).

* string.c (str_encoding): get encoding attribute from a string. 

* re.c (rb_reg_initialize): encoding aware regular expression

* sprintf.c (rb_str_format): formatting (i.e. length count) based
  on characters.

* io.c (rb_io_getc): getc to return one-character string.
  for older behavior, getbyte method added.

* ext/stringio/stringio.c (strio_getc): ditto.

* io.c (rb_io_ungetc): allow pushing arbitrary string at the
  current reading point.

* ext/stringio/stringio.c (strio_ungetc): ditto.

* ext/strscan/strscan.c: encoding support.

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