Re: [PATCH] gettext: more-consistent no-op macros

Paul Eggert <[email protected]> Mon, 24 Aug 2026 14:12:44 -0700

Newsgroups	gmane.comp.lib.gnulib.bugs
Organization	UCLA Computer Science Department
Message-ID	<[email protected]>

On 2026-08-24 13:23, Bruno Haible wrote:
> As far as I can see, your patch will have the effect that
>    gettext (some_function_that_returns_a_string ())
> will produce a syntax error in C++ mode.
> 
> Am I correct?
Sounds right. Would the attached (untested) patch address the C++ issue?

gettext.diff (text/x-patch, 5.8 KB)

diff --git a/lib/gettext.h b/lib/gettext.h
index 8ae3885fd7..5b7eb708d8 100644
--- a/lib/gettext.h
+++ b/lib/gettext.h
@@ -59,6 +59,14 @@
 #  endif
 # endif
 
+/* Like the C cast ((type) (expr)), but do only the conversion that
+   an ordinary function call argument would do.  */
+#ifdef __cplusplus
+# define _LIBGETTEXT_FUNCAST(type, expr) (type (expr))
+#else
+# define _LIBGETTEXT_FUNCAST(type, expr) ((type) {(expr)})
+#endif
+
 /* Disabled NLS.  */
 /* When gcc is used with option -Wformat=2, we need to silence
    "warning: format not a string literal, argument types not checked [-Wformat-nonliteral]"
@@ -162,39 +170,43 @@ dcgettext (const char *domain, const char *msgid, int category)
 #  endif
 # elif defined __clang__
 #  undef gettext
-#  define gettext(Msgid) ((const char *) {(Msgid)})
+#  define gettext(Msgid) (_LIBGETTEXT_FUNCAST (const char *, Msgid))
 #  undef dgettext
 #  define dgettext(Domainname, Msgid) \
-     ((void) (const char *) {(Domainname)}, gettext (Msgid))
+     ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), gettext (Msgid))
 #  undef dcgettext
 #  define dcgettext(Domainname, Msgid, Category) \
-     ((void) (int) {(Category)}, dgettext (Domainname, Msgid))
+     ((void) _LIBGETTEXT_FUNCAST (int, Category), dgettext (Domainname, Msgid))
 # else
 /* The conversions to 'const char *' via compound literals serve the purpose
    of producing warnings for invalid uses of the value returned from these
    functions and for invalid-typed Msgid arguments.  */
 #  undef gettext
-#  define gettext(Msgid) ((const char *) {(Msgid)})
+#  define gettext(Msgid) _LIBGETTEXT_FUNCAST (const char *, Msgid)
 /* The conversions via compound literals serve the purpose of producing warnings
    for invalid-typed arguments.  */
 #  undef dgettext
 #  define dgettext(Domainname, Msgid) \
-     ((void) (const char *) {(Domainname)}, gettext (Msgid))
+     ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), gettext (Msgid))
 #  undef dcgettext
 #  define dcgettext(Domainname, Msgid, Category) \
-     ((void) (int) {(Category)}, dgettext (Domainname, Msgid))
+     ((void) _LIBGETTEXT_FUNCAST (int, Category), dgettext (Domainname, Msgid))
 # endif
 
 # if (defined __GNUC__ && defined __cplusplus) || defined __clang__
 #  undef ngettext
 #  define ngettext(Msgid1, Msgid2, N) \
-     ((N) == 1 ? (const char *) {(Msgid1)} : (const char *) {(Msgid2)})
+     ((N) == 1 \
+      ? _LIBGETTEXT_FUNCAST (const char *, Msgid1) \
+      : _LIBGETTEXT_FUNCAST (const char *, Msgid2))
 #  undef dngettext
 #  define dngettext(Domainname, Msgid1, Msgid2, N) \
-     ((void) (const char *) {(Domainname)}, ngettext (Msgid1, Msgid2, N))
+     ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), \
+      ngettext (Msgid1, Msgid2, N))
 #  undef dcngettext
 #  define dcngettext(Domainname, Msgid1, Msgid2, N, Category) \
-     ((void) (int) {(Category)}, dngettext (Domainname, Msgid1, Msgid2, N))
+     ((void) _LIBGETTEXT_FUNCAST (int, Category), \
+      dngettext (Domainname, Msgid1, Msgid2, N))
 # elif defined __GNUC__ && !defined __cplusplus
 /* Silence -Wuseless-cast warnings.  */
 #  if __GNUC__ >= 14
@@ -202,13 +214,17 @@ dcgettext (const char *domain, const char *msgid, int category)
 #  endif
 #  undef ngettext
 #  define ngettext(Msgid1, Msgid2, N) \
-     ((N) == 1 ? (const char *) {(Msgid1)} : (const char *) {(Msgid2)})
+     ((N) == 1 \
+      ? _LIBGETTEXT_FUNCAST (const char *, Msgid1) \
+      : _LIBGETTEXT_FUNCAST (const char *, Msgid2))
 #  undef dngettext
 #  define dngettext(Domainname, Msgid1, Msgid2, N) \
-     ((void) (const char *) {(Domainname)}, ngettext (Msgid1, Msgid2, N))
+     ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), \
+      ngettext (Msgid1, Msgid2, N))
 #  undef dcngettext
 #  define dcngettext(Domainname, Msgid1, Msgid2, N, Category) \
-     ((void) (int) {(Category)}, dngettext (Domainname, Msgid1, Msgid2, N))
+     ((void) _LIBGETTEXT_FUNCAST (int, Category), \
+      dngettext (Domainname, Msgid1, Msgid2, N))
 # else
 /* The conversions to 'const char *' via compound literals serve the purpose
    of producing warnings for invalid uses of the value returned from these
@@ -216,26 +232,30 @@ dcgettext (const char *domain, const char *msgid, int category)
 #  undef ngettext
 #  define ngettext(Msgid1, Msgid2, N) \
      ((N) == 1 \
-      ? ((void) (Msgid2), (const char *) {(Msgid1)}) \
-      : ((void) (Msgid1), (const char *) {(Msgid2)}))
+      ? ((void) (Msgid2), _LIBGETTEXT_FUNCAST (const char *, Msgid1)) \
+      : ((void) (Msgid1), _LIBGETTEXT_FUNCAST (const char *, Msgid2)))
 /* The conversions via compound literals serve the purpose of producing warnings
    for invalid-typed arguments.  */
 #  undef dngettext
 #  define dngettext(Domainname, Msgid1, Msgid2, N) \
-     ((void) (const char *) {(Domainname)}, ngettext (Msgid1, Msgid2, N))
+     ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), \
+      ngettext (Msgid1, Msgid2, N))
 #  undef dcngettext
 #  define dcngettext(Domainname, Msgid1, Msgid2, N, Category) \
-     ((void) (int) {(Category)}, dngettext (Domainname, Msgid1, Msgid2, N))
+     ((void) _LIBGETTEXT_FUNCAST (int, Category), \
+      dngettext (Domainname, Msgid1, Msgid2, N))
 # endif
 
 # undef textdomain
-# define textdomain(Domainname) ((const char *) {(Domainname)})
+# define textdomain(Domainname) _LIBGETTEXT_FUNCAST (const char *, Domainname)
 # undef bindtextdomain
 # define bindtextdomain(Domainname, Dirname) \
-    ((void) (const char *) {(Domainname)}, (const char *) {(Dirname)})
+    ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), \
+     _LIBGETTEXT_FUNCAST (const char *, Dirname))
 # undef bind_textdomain_codeset
 # define bind_textdomain_codeset(Domainname, Codeset) \
-    ((void) (const char *) {(Domainname)}, (const char *) {(Codeset)})
+    ((void) _LIBGETTEXT_FUNCAST (const char *, Domainname), \
+     _LIBGETTEXT_FUNCAST (const char *, Codeset))
 
 #endif