Dear Joseph,
On Thu, Oct 8, 2020 at 1:36 PM Joseph Myers <[email protected]> wrote:
>
> This documentation doesn't seem sufficient to use the macros. Do they
> expand to (narrow) string literals? To an unquoted sequence of
> characters? I think from the implementation that the answer is strings
> (so, in particular, not usable for testing anything in #if conditionals),
> but the documentation ought to say so. The test ought to verify the form
> of the expansion as well (even if it can't do anything useful at execution
> time, because if you make the macros reflect the command-line options they
> are character set names that are meaningful on the host, and any
> conversion functionality on the target may not use the same names as the
> host).
You're right; sorry about that, I should have been more thorough!
I thought about adding a test to check the name itself (e.g, for
"UTF-8"), but that might make tests fail on platforms where the
default SOURCE_CHARSET from the dev files is not, in fact, UTF-8. I
could also try to pass some options but then I'd have to guarantee
that the encoding was available on all testable platforms, too...!
In the end, for the tests, I just initialize two "const char[]"
directly from the macro expansions to make sure we are getting
strings. It seeeeeems to work okay. Attached is the revised patch with
better docs and test!
Sincerely,
JeanHeyd
2020-10-08 JeanHeyd "ThePhD" Meneide <[email protected]>
* gcc/c-family/c-cppbuiltin.c: Add predefined macro
definitions for charsets
* gcc/doc/cpp.texi: Document new predefined macro.
* gcc/testsuite/c-c++-common/cpp/wide-narrow-predef-macros.c (new):
New test for macro definitions to always exist.
* libcpp/include/cpplib.h: Add functions declarations for
retrieving charset names
* libcpp/directives.c: Add function definitions to retrieve charset
names.
* libcpp/internal.h: Add to/from name preservations
diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index 74ecca8de8e..8de25786592 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -866,6 +866,13 @@ c_cpp_builtins (cpp_reader *pfile)
define_language_independent_builtin_macros (pfile);
+ /* encoding definitions used by users and libraries */
+ builtin_define_with_value ("__GNUC_EXECUTION_CHARSET_NAME",
+ cpp_get_narrow_charset_name (pfile), 1);
+ builtin_define_with_value ("__GNUC_WIDE_EXECUTION_CHARSET_NAME",
+ cpp_get_wide_charset_name (pfile), 1);
+
+
if (c_dialect_cxx ())
{
int major;
diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi
index 33f876ab706..90f1162add1 100644
--- a/gcc/doc/cpp.texi
+++ b/gcc/doc/cpp.texi
@@ -2451,6 +2451,15 @@ features are supported by GCC.
@item __NO_MATH_ERRNO__
This macro is defined if @option{-fno-math-errno} is used, or enabled
by another option such as @option{-ffast-math} or by default.
+
+@item __GNUC_EXECUTION_CHARSET_NAME
+@itemx __GNUC_WIDE_EXECUTION_CHARSET_NAME
+These macros are defined to expand to a narrow string literal of
+the name of the narrow and wide compile-time execution character
+set used. It directly reflects the name passed to the options
+@option{-fexec-charset} and @option{-fwide-exec-charset}, or the defaults
+documented for those options (that is, it can expand to something like
+@code{"UTF-8"}). @xref{Invocation}.
@end table
@node System-specific Predefined Macros
diff --git a/gcc/testsuite/c-c++-common/cpp/wide-narrow-predef-macros.c
b/gcc/testsuite/c-c++-common/cpp/wide-narrow-predef-macros.c
new file mode 100644
index 00000000000..d5440f8a61e
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/wide-narrow-predef-macros.c
@@ -0,0 +1,13 @@
+/*
+ { dg-do compile }
+ */
+
+#if !defined(__GNUC_EXECUTION_CHARSET_NAME)
+#error "Required implementation macro for comple-time charset name is not
present"
+#endif
+#if !defined(__GNUC_WIDE_EXECUTION_CHARSET_NAME)
+#error "Required implementation macro for wide comple-time charset name is not
present"
+#endif
+
+const char narrow_name[] = __GNUC_EXECUTION_CHARSET_NAME;
+const char wide_name[] = __GNUC_WIDE_EXECUTION_CHARSET_NAME;
diff --git a/libcpp/charset.c b/libcpp/charset.c
index 28b81c9c864..3e5578b1390 100644
--- a/libcpp/charset.c
+++ b/libcpp/charset.c
@@ -638,6 +638,9 @@ init_iconv_desc (cpp_reader *pfile, const char *to, const
char *from)
char *pair;
size_t i;
+ ret.to = to;
+ ret.from = from;
+
if (!strcasecmp (to, from))
{
ret.func = convert_no_conversion;
diff --git a/libcpp/directives.c b/libcpp/directives.c
index f59718708e4..ad540872581 100644
--- a/libcpp/directives.c
+++ b/libcpp/directives.c
@@ -2571,6 +2571,20 @@ cpp_set_callbacks (cpp_reader *pfile, cpp_callbacks *cb)
pfile->cb = *cb;
}
+/* The narrow character set identifier. */
+const char *
+cpp_get_narrow_charset_name (cpp_reader *pfile)
+{
+ return pfile->narrow_cset_desc.to;
+}
+
+/* The wide character set identifier. */
+const char *
+cpp_get_wide_charset_name (cpp_reader *pfile)
+{
+ return pfile->wide_cset_desc.to;
+}
+
/* The dependencies structure. (Creates one if it hasn't already been.) */
class mkdeps *
cpp_get_deps (cpp_reader *pfile)
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 8e398863cf6..69a5042d0bf 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -971,6 +971,11 @@ extern cpp_callbacks *cpp_get_callbacks (cpp_reader *)
ATTRIBUTE_PURE;
extern void cpp_set_callbacks (cpp_reader *, cpp_callbacks *);
extern class mkdeps *cpp_get_deps (cpp_reader *) ATTRIBUTE_PURE;
+/* Call these to get name data about the various compile-time
+ charsets. */
+extern const char *cpp_get_narrow_charset_name (cpp_reader *) ATTRIBUTE_PURE;
+extern const char *cpp_get_wide_charset_name (cpp_reader *) ATTRIBUTE_PURE;
+
/* This function reads the file, but does not start preprocessing. It
returns the name of the original file; this is the same as the
input file, except for preprocessed input. This will generate at
diff --git a/libcpp/internal.h b/libcpp/internal.h
index b728df74562..a6402d77ced 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -48,6 +48,8 @@ struct cset_converter
convert_f func;
iconv_t cd;
int width;
+ const char* from;
+ const char* to;
};
#define BITS_PER_CPPCHAR_T (CHAR_BIT * sizeof (cppchar_t))
