Redefined M4 Macros

With a few exceptions, all the M4 native macros are moved in the ‘m4_’ pseudo-namespace, e.g., M4sugar renames define as m4_define etc.

Some M4 macros are redefined, and are slightly incompatible with their native equivalent.

— Macro: dnl

This macro kept its original name: no m4_dnl is defined.

— Macro: m4_defn (macro)

Unlike the M4 builtin, this macro fails if macro is not defined. See m4_undefine.

— Macro: m4_exit (exit-status)

This macro corresponds to m4exit.

— Macro: m4_if (comment)
— Macro: m4_if (string-1, string-2, equal, [not-equal])
— Macro: m4_if (string-1, string-2, equal, ...)

This macro corresponds to ifelse.

— Macro: m4_include (file)
— Macro: m4_sinclude (file)

Like the M4 builtins, but warn against multiple inclusions of file.

— Macro: m4_bpatsubst (string, regexp, [replacement])

This macro corresponds to patsubst. The name m4_patsubst is kept for future versions of M4sh, on top of GNU M4 which will provide extended regular expression syntax via epatsubst.

— Macro: m4_popdef (macro)

Unlike the M4 builtin, this macro fails if macro is not defined. See m4_undefine.

— Macro: m4_bregexp (string, regexp, [replacement])

This macro corresponds to regexp. The name m4_regexp is kept for future versions of M4sh, on top of GNU M4 which will provide extended regular expression syntax via eregexp.

— Macro: m4_wrap (text)

This macro corresponds to m4wrap.
Posix requires arguments of multiple m4wrap calls to be reprocessed at EOF in the same order as the original calls. GNU M4 versions through 1.4.x, however, reprocess them in reverse order. Your code should not depend on the order.
Also, Posix requires m4wrap to ignore its second and succeeding arguments, but GNU M4 versions through 1.4.x concatenate the arguments with intervening spaces. Your code should not pass more than one argument.
You are encouraged to end text with ‘[]’, to avoid unexpected token pasting between consecutive invocations of m4_wrap, as in:
          m4_define([foo], [bar])
          m4_define([foofoo], [OUCH])
          m4_wrap([foo])
          m4_wrap([foo])
          =>OUCH
     

— Macro: m4_undefine (macro)

Unlike the M4 builtin, this macro fails if macro is not defined. Use
          m4_ifdef([macro], [m4_undefine([macro])])
     
to recover the behavior of the builtin.

8.3.1 Redefined M4 Macros