https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47781
Luke Shumaker <lukeshu at lukeshu dot com> changed:
What |Removed |Added
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CC| |lukeshu at lukeshu dot com
--- Comment #31 from Luke Shumaker <lukeshu at lukeshu dot com> ---
Prior art for consideration: Plan 9
Similar to GNU libc's register_printf_specifier() and
register_printf_modifier(), Plan 9 libc has fmtinstall() which can add new
specifiers and modifiers; and to support checking these strings, the compiler
supports `#pragma varargck`:
fmtinstall('C', CONVFUNC) /* since 1e (1992); if CONVFUNC returns 0
then 'C' is a specifier, if it returns 1 it's a modifier */
#pragma varargck argpos FUNC POS /* since 3e (2000); equivalent to putting
`[[gnu::format(printf, POS, POS+1)]]` on FUNC
#pragma varargck flag 'C' /* since 3e (2000); says that 'C' is a
modifier, consumes 0 arguments */
#pragma varargck type "C" TYPE /* since 4e (2002); says that 'C' is a
specifier, consumes 1 argument of type TYPE */
fmtinstall()ed modifiers and specifiers can consume any number of arguments,
but `#pragma varargck` only supports indicating that they consume 0 and 1
arguments respectively. Note that Plan 9 printf does not support POSIX-style
position-specifiers; arguments may only be consumed in order.
https://man.cat-v.org/plan_9/1/8c (8c is the x86 compiler)
https://man.cat-v.org/plan_9/2/fmtinstall
