Subject: Re: [PATCH v3 1/3] gettext: remove optional non-standard parens in N_() definition

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Fri, 10 Sep 2021 17:39:57 +0200

On Fri, Sep 03 2021, Carlo Marcelo Arenas Belón wrote:

> From: Ævar Arnfjörð Bjarmason <[email-masked]>
>
> Remove the USE_PARENS_AROUND_GETTEXT_N compile-time option which was
> meant to catch an inadvertent mistake which is too obscure to
> maintain this facility.
>
> The backstory of how USE_PARENS_AROUND_GETTEXT_N came about is: When I
> added the N_() macro in 65784830366 (i18n: add no-op _() and N_()
> wrappers, 2011-02-22) it was defined as:
>
>     #define N_(msgid) (msgid)
>
> This is non-standard C, as was noticed and fixed in 642f85faab2 (i18n:
> avoid parenthesized string as array initializer, 2011-04-07).
> I.e. this needed to be defined as:
>
>     #define N_(msgid) msgid
>
> Then in e62cd35a3e8 (i18n: log: mark parseopt strings for translation,
> 2012-08-20) when "builtin_log_usage" was marked for translation the
> string concatenation for passing to usage() added in 1c370ea4e51
> (Show usage string for 'git log -h', 'git show -h' and 'git diff -h',
> 2009-08-06) was faithfully preserved:
>
> -       "git log [<options>] [<since>..<until>] [[--] <path>...]\n"
> -       "   or: git show [options] <object>...",
> +       N_("git log [<options>] [<since>..<until>] [[--] <path>...]\n")
> +       N_("   or: git show [options] <object>..."),
>
> This was then fixed to be the expected array of usage strings in
> e66dc0cc4b1 (log.c: fix translation markings, 2015-01-06) rather than
> a string with multiple "\n"-delimited usage strings, and finally in
> 290c8e7a3fe (gettext.h: add parentheses around N_ expansion if
> supported, 2015-01-11) USE_PARENS_AROUND_GETTEXT_N was added to ensure
> this mistake didn't happen again.
>
> I think that even if this was a N_()-specific issue this
> USE_PARENS_AROUND_GETTEXT_N facility wouldn't be worth it, the issue
> would be too rare to worry about.
>
> But I also think that 290c8e7a3fe which introduced
> USE_PARENS_AROUND_GETTEXT_N misattributed the problem. The issue
> wasn't with the N_() macro added in e62cd35a3e8, but that before the
> N_() macro existed in the codebase the initial migration to
> parse_options() in 1c370ea4e51 continued passsing in a "\n"-delimited
> string, when the new API it was migrating to supported and expected
> the passing of an array.
>
> Helped-by: Eric Sunshine <[email-masked]>
> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
> Signed-off-by: Carlo Marcelo Arenas Belón <[email-masked]>
> ---
>  Makefile          | 20 +-------------------
>  config.mak.dev    |  2 --
>  gettext.h         | 24 ------------------------
>  git-compat-util.h |  4 ----
>  4 files changed, 1 insertion(+), 49 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 9573190f1d..4e94073c2a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -409,15 +409,6 @@ all::
>  # Define NEEDS_LIBRT if your platform requires linking with librt (glibc version
>  # before 2.17) for clock_gettime and CLOCK_MONOTONIC.
>  #
> -# Define USE_PARENS_AROUND_GETTEXT_N to "yes" if your compiler happily
> -# compiles the following initialization:
> -#
> -#   static const char s[] = ("FOO");
> -#
> -# and define it to "no" if you need to remove the parentheses () around the
> -# constant.  The default is "auto", which means to use parentheses if your
> -# compiler is detected to support it.
> -#
>  # Define HAVE_BSD_SYSCTL if your platform has a BSD-compatible sysctl function.
>  #
>  # Define HAVE_GETDELIM if your system has the getdelim() function.
> @@ -497,8 +488,7 @@ all::
>  #
>  #    pedantic:
>  #
> -#        Enable -pedantic compilation. This also disables
> -#        USE_PARENS_AROUND_GETTEXT_N to produce only relevant warnings.
> +#        Enable -pedantic compilation.
>  
>  GIT-VERSION-FILE: FORCE
>  	@$(SHELL_PATH) ./GIT-VERSION-GEN
> @@ -1347,14 +1337,6 @@ ifneq (,$(SOCKLEN_T))
>  	BASIC_CFLAGS += -Dsocklen_t=$(SOCKLEN_T)
>  endif
>  
> -ifeq (yes,$(USE_PARENS_AROUND_GETTEXT_N))
> -	BASIC_CFLAGS += -DUSE_PARENS_AROUND_GETTEXT_N=1
> -else
> -ifeq (no,$(USE_PARENS_AROUND_GETTEXT_N))
> -	BASIC_CFLAGS += -DUSE_PARENS_AROUND_GETTEXT_N=0
> -endif
> -endif
> -
>  ifeq ($(uname_S),Darwin)
>  	ifndef NO_FINK
>  		ifeq ($(shell test -d /sw/lib && echo y),y)
> diff --git a/config.mak.dev b/config.mak.dev
> index 022fb58218..41d6345bc0 100644
> --- a/config.mak.dev
> +++ b/config.mak.dev
> @@ -4,8 +4,6 @@ SPARSE_FLAGS += -Wsparse-error
>  endif
>  ifneq ($(filter pedantic,$(DEVOPTS)),)
>  DEVELOPER_CFLAGS += -pedantic
> -# don't warn for each N_ use
> -DEVELOPER_CFLAGS += -DUSE_PARENS_AROUND_GETTEXT_N=0
>  endif
>  DEVELOPER_CFLAGS += -Wall
>  DEVELOPER_CFLAGS += -Wdeclaration-after-statement
> diff --git a/gettext.h b/gettext.h
> index c8b34fd612..d209911ebb 100644
> --- a/gettext.h
> +++ b/gettext.h
> @@ -55,31 +55,7 @@ const char *Q_(const char *msgid, const char *plu, unsigned long n)
>  }
>  
>  /* Mark msgid for translation but do not translate it. */
> -#if !USE_PARENS_AROUND_GETTEXT_N
>  #define N_(msgid) msgid
> -#else
> -/*
> - * Strictly speaking, this will lead to invalid C when
> - * used this way:
> - *	static const char s[] = N_("FOO");
> - * which will expand to
> - *	static const char s[] = ("FOO");
> - * and in valid C, the initializer on the right hand side must
> - * be without the parentheses.  But many compilers do accept it
> - * as a language extension and it will allow us to catch mistakes
> - * like:
> - *	static const char *msgs[] = {
> - *		N_("one")
> - *		N_("two"),
> - *		N_("three"),
> - *		NULL
> - *	};
> - * (notice the missing comma on one of the lines) by forcing
> - * a compilation error, because parenthesised ("one") ("two")
> - * will not get silently turned into ("onetwo").
> - */
> -#define N_(msgid) (msgid)
> -#endif
>  
>  const char *get_preferred_languages(void);
>  int is_utf8_locale(void);
> diff --git a/git-compat-util.h b/git-compat-util.h
> index b46605300a..ddc65ff61d 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -1253,10 +1253,6 @@ int warn_on_fopen_errors(const char *path);
>   */
>  int open_nofollow(const char *path, int flags);
>  
> -#if !defined(USE_PARENS_AROUND_GETTEXT_N) && defined(__GNUC__)
> -#define USE_PARENS_AROUND_GETTEXT_N 1
> -#endif
> -
>  #ifndef SHELL_PATH
>  # define SHELL_PATH "/bin/sh"
>  #endif

A note & cross-link: I've submitted a v2 of another series where we'll
effectively duplicate the check being removed here, see
https://lore.kernel.org/git/[email-masked]/

Well, it's not a general N_() multi-line checker like the proposed
https://lore.kernel.org/git/[email-masked]/
and this USE_PARENS_AROUND_GETTEXT_N, but we added
USE_PARENS_AROUND_GETTEXT_N to begin with for these usage strings. The
bad usage of that usage API (phew!, that's a mouthful) will be caught by
that usage CAPI being stricter now.