When building a testdir of all of gnulib with clang 9 on a glibc system,
I see these compilation errors:
In file included from ../../gltests/test-list-c++.cc:23:
../gllib/string.h:821:22: error: functions that differ only in their return
type cannot be overloaded
_GL_WARN_ON_USE_CXX (strchr, const char *, (const char *, int),
^ ~~~~~~
../gllib/string.h:544:16: note: expanded from macro '_GL_WARN_ON_USE_CXX'
extern rettype function parameters_and_attributes \
~~~~~~~ ^
/usr/include/string.h:231:14: note: previous declaration is here
extern char *strchr (const char *__s, int __c)
~~~~~~^
In file included from ../../gltests/test-list-c++.cc:23:
../gllib/string.h:1016:22: error: functions that differ only in their return
type cannot be overloaded
_GL_WARN_ON_USE_CXX (strpbrk, const char *, (const char *, const char *),
^ ~~~~~~
../gllib/string.h:544:16: note: expanded from macro '_GL_WARN_ON_USE_CXX'
extern rettype function parameters_and_attributes \
~~~~~~~ ^
/usr/include/string.h:310:14: note: previous declaration is here
extern char *strpbrk (const char *__s, const char *__accept)
~~~~~~^
In file included from ../../gltests/test-list-c++.cc:23:
../gllib/string.h:1045:22: error: functions that differ only in their return
type cannot be overloaded
_GL_WARN_ON_USE_CXX (strrchr, const char *, (const char *, int),
^ ~~~~~~
../gllib/string.h:544:16: note: expanded from macro '_GL_WARN_ON_USE_CXX'
extern rettype function parameters_and_attributes \
~~~~~~~ ^
/usr/include/string.h:258:14: note: previous declaration is here
extern char *strrchr (const char *__s, int __c)
~~~~~~^
3 errors generated.
So, where gcc wants a declaration of 'strchr', 'strpbrk', 'strrchr' with
return type 'const char *' (see [1]), clang wants to see a return type
'char *'.
[1] https://lists.gnu.org/archive/html/bug-gnulib/2020-05/msg00099.html
2020-08-09 Bruno Haible <br...@clisp.org>
string: Fix build error in C++ mode with clang (regression from today).
* lib/warn-on-use.h (_GL_WARN_ON_USE_CXX): Expect two rettype
parameters, one for GCC, one for clang.
* lib/c++defs.h (_GL_CXXALIASWARN1_2): Update.
* lib/string.in.h (strchr, strpbrk, strrchr): For clang, pass 'char *'
as return type.
diff --git a/lib/c++defs.h b/lib/c++defs.h
index 75d6250..cd56ea2 100644
--- a/lib/c++defs.h
+++ b/lib/c++defs.h
@@ -298,7 +298,7 @@
we enable the warning only when not optimizing. */
# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
# define
_GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
- _GL_WARN_ON_USE_CXX (func, rettype, parameters_and_attributes, \
+ _GL_WARN_ON_USE_CXX (func, rettype, rettype, parameters_and_attributes, \
"The symbol ::" #func " refers to the system
function. " \
"Use " #namespace "::" #func " instead.")
# else
diff --git a/lib/string.in.h b/lib/string.in.h
index c18efa7..ef702e3 100644
--- a/lib/string.in.h
+++ b/lib/string.in.h
@@ -329,7 +329,8 @@ _GL_WARN_ON_USE (stpncpy, "stpncpy is unportable - "
GB18030 and the character to be searched is a digit. */
# undef strchr
/* Assume strchr is always declared. */
-_GL_WARN_ON_USE_CXX (strchr, const char *, (const char *, int),
+_GL_WARN_ON_USE_CXX (strchr,
+ const char *, char *, (const char *, int),
"strchr cannot work correctly on character strings "
"in some multibyte locales - "
"use mbschr if you care about internationalization");
@@ -524,7 +525,8 @@ _GL_CXXALIASWARN (strpbrk);
locale encoding is GB18030 and one of the characters to be searched is a
digit. */
# undef strpbrk
-_GL_WARN_ON_USE_CXX (strpbrk, const char *, (const char *, const char *),
+_GL_WARN_ON_USE_CXX (strpbrk,
+ const char *, char *, (const char *, const char *),
"strpbrk cannot work correctly on character strings "
"in multibyte locales - "
"use mbspbrk if you care about internationalization");
@@ -532,7 +534,8 @@ _GL_WARN_ON_USE_CXX (strpbrk, const char *, (const char *,
const char *),
#elif defined GNULIB_POSIXCHECK
# undef strpbrk
# if HAVE_RAW_DECL_STRPBRK
-_GL_WARN_ON_USE_CXX (strpbrk, const char *, (const char *, const char *),
+_GL_WARN_ON_USE_CXX (strpbrk,
+ const char *, char *, (const char *, const char *),
"strpbrk is unportable - "
"use gnulib module strpbrk for portability");
# endif
@@ -553,7 +556,8 @@ _GL_WARN_ON_USE (strspn, "strspn cannot work correctly on
character strings "
GB18030 and the character to be searched is a digit. */
# undef strrchr
/* Assume strrchr is always declared. */
-_GL_WARN_ON_USE_CXX (strrchr, const char *, (const char *, int),
+_GL_WARN_ON_USE_CXX (strrchr,
+ const char *, char *, (const char *, int),
"strrchr cannot work correctly on character strings "
"in some multibyte locales - "
"use mbsrchr if you care about internationalization");
diff --git a/lib/warn-on-use.h b/lib/warn-on-use.h
index a39e3a3..5ff2163 100644
--- a/lib/warn-on-use.h
+++ b/lib/warn-on-use.h
@@ -106,33 +106,33 @@ _GL_WARN_EXTERN_C int _gl_warn_on_use
# endif
#endif
-/* _GL_WARN_ON_USE_CXX (function, rettype, parameters_and_attributes, "string")
- is like _GL_WARN_ON_USE (function, "string"), except that in C++ mode the
+/* _GL_WARN_ON_USE_CXX (function, rettype_gcc, rettype_clang,
parameters_and_attributes, "message")
+ is like _GL_WARN_ON_USE (function, "message"), except that in C++ mode the
function is declared with the given prototype, consisting of return type,
parameters, and attributes.
This variant is useful for overloaded functions in C++. _GL_WARN_ON_USE does
not work in this case. */
#ifndef _GL_WARN_ON_USE_CXX
# if !defined __cplusplus
-# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg) \
+# define
_GL_WARN_ON_USE_CXX(function,rettype_gcc,rettype_clang,parameters_and_attributes,msg)
\
_GL_WARN_ON_USE (function, msg)
# else
# if 4 < __GNUC__ || (__GNUC__ == 4 && 3 <= __GNUC_MINOR__)
/* A compiler attribute is available in gcc versions 4.3.0 and later. */
-# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg)
\
-extern rettype function parameters_and_attributes \
+# define
_GL_WARN_ON_USE_CXX(function,rettype_gcc,rettype_clang,parameters_and_attributes,msg)
\
+extern rettype_gcc function parameters_and_attributes \
__attribute__ ((__warning__ (msg)))
# elif __clang_major__ >= 4
/* Another compiler attribute is available in clang. */
-# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg)
\
-extern rettype function parameters_and_attributes \
+# define
_GL_WARN_ON_USE_CXX(function,rettype_gcc,rettype_clang,parameters_and_attributes,msg)
\
+extern rettype_clang function parameters_and_attributes \
__attribute__ ((__diagnose_if__ (1, msg, "warning")))
# elif __GNUC__ >= 3 && GNULIB_STRICT_CHECKING
/* Verify the existence of the function. */
-# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg)
\
-extern rettype function parameters_and_attributes
+# define
_GL_WARN_ON_USE_CXX(function,rettype_gcc,rettype_clang,parameters_and_attributes,msg)
\
+extern rettype_gcc function parameters_and_attributes
# else /* Unsupported. */
-# define _GL_WARN_ON_USE_CXX(function,rettype,parameters_and_attributes,msg)
\
+# define
_GL_WARN_ON_USE_CXX(function,rettype_gcc,rettype_clang,parameters_and_attributes,msg)
\
_GL_WARN_EXTERN_C int _gl_warn_on_use
# endif
# endif
