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[RFA] Implement __VA_OPT__
- From: Tom Tromey <tom at tromey dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Tom Tromey <tom at tromey dot com>
- Date: Sat, 16 Sep 2017 15:49:18 -0600
- Subject: [RFA] Implement __VA_OPT__
- Authentication-results: sourceware.org; auth=none
This implements __VA_OPT__, a new preprocessor feature added in C++2A.
The paper can be found here:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0306r4.html
I am not completely sure that I have handled the error reporting
correctly. I chose to allow __VA_OPT__ generally, on the theory that,
because it is a reserved identifier, programs should not be referring
to it anyway. Also, this approach makes it possible for __VA_OPT__ to
be used in system headers even when the -std/-pedantic settings may
otherwise disallow it.
Bootstrapped and regression tested on x86-64 Fedora 25.
gcc/ChangeLog
2017-09-16 Tom Tromey <tom@tromey.com>
* doc/cpp.texi (Variadic Macros): Document __VA_OPT__.
gcc/testsuite/ChangeLog
2017-09-16 Tom Tromey <tom@tromey.com>
* c-c++-common/cpp/va-opt.c: New file.
* c-c++-common/cpp/va-opt-error.c: New file.
libcpp/ChangeLog
2017-09-16 Tom Tromey <tom@tromey.com>
* pch.c (cpp_read_state): Set n__VA_OPT__.
* macro.c (vaopt_state): New class.
(_cpp_arguments_ok): Check va_opt flag.
(replace_args, create_iso_definition): Use vaopt_state.
* lex.c (lex_identifier_intern): Possibly issue errors for
__VA_OPT__.
(lex_identifier): Likewise.
* internal.h (struct lexer_state) <va_args_ok>: Update comment.
(struct spec_nodes) <n__VA_OPT__>: New field.
* init.c (struct lang_flags) <va_opt>: New field.
(lang_defaults): Add entries for C++2A. Update all entries for
va_opt.
(cpp_set_lang): Initialize va_opt.
* include/cpplib.h (enum c_lang) <CLK_GNUCXX2A, CLK_CXX2A>: New
constants.
(struct cpp_options) <va_opt>: New field.
* identifiers.c (_cpp_init_hashtable): Initialize n__VA_OPT__.
---
gcc/ChangeLog | 4 +
gcc/doc/cpp.texi | 46 +++++--
gcc/testsuite/ChangeLog | 5 +
gcc/testsuite/c-c++-common/cpp/va-opt-error.c | 28 +++++
gcc/testsuite/c-c++-common/cpp/va-opt.c | 42 +++++++
libcpp/ChangeLog | 20 +++
libcpp/identifiers.c | 2 +
libcpp/include/cpplib.h | 3 +
libcpp/init.c | 40 +++---
libcpp/internal.h | 3 +-
libcpp/lex.c | 30 +++++
libcpp/macro.c | 170 +++++++++++++++++++++++++-
libcpp/pch.c | 1 +
13 files changed, 362 insertions(+), 32 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/cpp/va-opt-error.c
create mode 100644 gcc/testsuite/c-c++-common/cpp/va-opt.c
diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi
index 52f2606..3990165 100644
--- a/gcc/doc/cpp.texi
+++ b/gcc/doc/cpp.texi
@@ -1675,20 +1675,27 @@ macro. We could define @code{eprintf} like this, instead:
@end smallexample
@noindent
-This formulation looks more descriptive, but unfortunately it is less
-flexible: you must now supply at least one argument after the format
-string. In standard C, you cannot omit the comma separating the named
-argument from the variable arguments. Furthermore, if you leave the
-variable argument empty, you will get a syntax error, because
-there will be an extra comma after the format string.
+This formulation looks more descriptive, but historically it was less
+flexible: you had to supply at least one argument after the format
+string. In standard C, you could not omit the comma separating the
+named argument from the variable arguments. (Note that this
+restriction has been lifted in C++20, and never existed in GNU C; see
+below.)
+
+Furthermore, if you left the variable argument empty, you would have
+gotten a syntax error, because there would have een an extra comma
+after the format string.
@smallexample
eprintf("success!\n", );
@expansion{} fprintf(stderr, "success!\n", );
@end smallexample
-GNU CPP has a pair of extensions which deal with this problem. First,
-you are allowed to leave the variable argument out entirely:
+This has been fixed in C++20, and GNU CPP also has a pair of
+extensions which deal with this problem.
+
+First, in GNU CPP, and in C++ beginning in C++20, you are allowed to
+leave the variable argument out entirely:
@smallexample
eprintf ("success!\n")
@@ -1696,8 +1703,24 @@ eprintf ("success!\n")
@end smallexample
@noindent
-Second, the @samp{##} token paste operator has a special meaning when
-placed between a comma and a variable argument. If you write
+Second, C++20 introduces the @code{@w{__VA_OPT__}} function macro.
+This macro may only appear in the definition of a variadic macro. If
+the variable argument has any tokens, then a @code{@w{__VA_OPT__}}
+invocation expands to its argument; but if the variable argument does
+not have any tokens, the @code{@w{__VA_OPT__}} expands to nothing:
+
+@smallexample
+#define eprintf(format, @dots{}) \\
+ fprintf (stderr, format __VA_OPT__(,) __VA_ARGS__)
+@end smallexample
+
+@code{@w{__VA_OPT__}} is also available in GNU C and GNU C++.
+
+Historically, GNU has also had another extension to handle the
+trailing comma: the @samp{##} token paste operator has a special
+meaning when placed between a comma and a variable argument. Despite
+the introduction of @code{@w{__VA_OPT__}}, this extension remains
+supported in GNU CPP, for backward compatibility. If you write
@smallexample
#define eprintf(format, @dots{}) fprintf (stderr, format, ##__VA_ARGS__)
@@ -1730,6 +1753,9 @@ of macro. It may also be forbidden in open text; the standard is
ambiguous. We recommend you avoid using it except for its defined
purpose.
+Likewise, C++ forbids @code{@w{__VA_OPT__}} anywhere outside the
+replacement list of a variadic macro.
+
Variadic macros became a standard part of the C language with C99.
GNU CPP previously supported them
with a named variable argument
diff --git a/gcc/testsuite/c-c++-common/cpp/va-opt-error.c b/gcc/testsuite/c-c++-common/cpp/va-opt-error.c
new file mode 100644
index 0000000..7718916
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/va-opt-error.c
@@ -0,0 +1,28 @@
+/* { dg-do preprocess }*/
+/* { dg-options "-std=gnu99" { target c } } */
+/* { dg-options "-std=c++2a" { target c++ } } */
+
+#define ERR1(x) __VA_OPT__ /* { dg-error "__VA_OPT__ can only appear" } */
+#define ERR2(x) __VA_OPT__( /* { dg-error "can only appear" } */
+#define ERR3(x) __VA_OPT__() /* { dg-error "can only appear" } */
+
+#define ERR4(x,...) __VA_OPT__ /* { dg-error "unterminated __VA_OPT__" } */
+#define ERR5(x,...) __VA_OPT__( /* { dg-error "unterminated" } */
+#define ERR6(x,...) __VA_OPT__(() /* { dg-error "unterminated" } */
+
+#define ERR7(x,...) __VA_OPT__(__VA_OPT__) /* { dg-error "may not appear" } */
+#define ERR7(x,...) __VA_OPT__(__VA_OPT__()) /* { dg-error "may not appear" } */
+
+#define ERR8(x, y,...) x __VA_OPT__(##) y /* { dg-error "either end" } */
+#define ERR9(x, y,...) x __VA_OPT__(x ##) y /* { dg-error "either end" } */
+#define ERRA(x, y,...) x x __VA_OPT__(## y) /* { dg-error "either end" } */
+
+#define ERRB __VA_OPT__ /* { dg-error "can only appear" } */
+#define ERRC(__VA_OPT__) x /* { dg-error "can only appear" } */
+
+__VA_OPT__ /* { dg-error "can only appear" } */
+
+#define ERRD(x)
+ERRD(__VA_OPT__) /* { dg-error "can only appear" } */
+
+#define __VA_OPT__ /* { dg-error "can only appear" } */
diff --git a/gcc/testsuite/c-c++-common/cpp/va-opt.c b/gcc/testsuite/c-c++-common/cpp/va-opt.c
new file mode 100644
index 0000000..243d33b
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/va-opt.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99" { target c } } */
+/* { dg-options "-std=c++2a" { target c++ } } */
+
+extern void f0 (void);
+extern void f1 (int);
+extern void f2 (int, int);
+extern void f3 (int, int, int);
+extern void f4 (int, int, int, int);
+extern int s (const char *);
+
+#define CALL(F, ...) F (7 __VA_OPT__(,) __VA_ARGS__)
+#define CP(F, X, Y, ...) F (__VA_OPT__(X ## Y,) __VA_ARGS__)
+#define CS(F, ...) F(__VA_OPT__(s(# __VA_ARGS__)))
+#define D(F, ...) F(__VA_OPT__(__VA_ARGS__) __VA_OPT__(,) __VA_ARGS__)
+#define CALL0(...) __VA_OPT__(f2)(0 __VA_OPT__(,)__VA_ARGS__)
+
+void t (void)
+{
+ CALL (f1);
+ CALL (f1, );
+ CALL (f2, 1);
+ CALL (f3, 1, 2);
+
+ int one = 1;
+ int two = 2;
+ int onetwo = 23;
+
+ CP (f0, one, two);
+ CP (f0, one, two, );
+ CP (f2, one, two, 3);
+
+ CS (f0);
+ CS (f1, 1, 2, 3, 4);
+
+ D (f0);
+ D (f2, 1);
+ D (f4, 1, 2);
+
+ CALL0 ();
+ CALL0 (23);
+}
diff --git a/libcpp/identifiers.c b/libcpp/identifiers.c
index 220f9b9..e456fd3 100644
--- a/libcpp/identifiers.c
+++ b/libcpp/identifiers.c
@@ -70,6 +70,8 @@ _cpp_init_hashtable (cpp_reader *pfile, cpp_hash_table *table)
s->n_false = cpp_lookup (pfile, DSC("false"));
s->n__VA_ARGS__ = cpp_lookup (pfile, DSC("__VA_ARGS__"));
s->n__VA_ARGS__->flags |= NODE_DIAGNOSTIC;
+ s->n__VA_OPT__ = cpp_lookup (pfile, DSC("__VA_OPT__"));
+ s->n__VA_OPT__->flags |= NODE_DIAGNOSTIC;
s->n__has_include__ = cpp_lookup (pfile, DSC("__has_include__"));
s->n__has_include_next__ = cpp_lookup (pfile, DSC("__has_include_next__"));
}
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 804132a..fc98175 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -478,6 +478,9 @@ struct cpp_options
/* Nonzero for C++ 2014 Standard digit separators. */
unsigned char digit_separators;
+ /* Nonzero for C++2a __VA_OPT__ feature. */
+ unsigned char va_opt;
+
/* Holds the name of the target (execution) character set. */
const char *narrow_charset;
diff --git a/libcpp/init.c b/libcpp/init.c
index 16ff202..2bf76a7 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -91,28 +91,29 @@ struct lang_flags
char digit_separators;
char trigraphs;
char utf8_char_literals;
+ char va_opt;
};
static const struct lang_flags lang_defaults[] =
-{ /* c99 c++ xnum xid c11 std digr ulit rlit udlit bincst digsep trig u8chlit */
- /* GNUC89 */ { 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0 },
- /* GNUC99 */ { 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0 },
- /* GNUC11 */ { 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0 },
- /* STDC89 */ { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0 },
- /* STDC94 */ { 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0 },
- /* STDC99 */ { 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0 },
- /* STDC11 */ { 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0 },
- /* GNUCXX */ { 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0 },
- /* CXX98 */ { 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0 },
- /* GNUCXX11 */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0 },
- /* CXX11 */ { 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0 },
- /* GNUCXX14 */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0 },
- /* CXX14 */ { 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0 },
- /* GNUCXX17 */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1 },
- /* CXX17 */ { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1 },
- /* GNUCXX2A */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1 },
- /* CXX2A */ { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1 },
- /* ASM */ { 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
+{ /* c99 c++ xnum xid c11 std digr ulit rlit udlit bincst digsep trig u8chlit vaopt */
+ /* GNUC89 */ { 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0 },
+ /* GNUC99 */ { 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0 },
+ /* GNUC11 */ { 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0 },
+ /* STDC89 */ { 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0 },
+ /* STDC94 */ { 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0 },
+ /* STDC99 */ { 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0 },
+ /* STDC11 */ { 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0 },
+ /* GNUCXX */ { 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0 },
+ /* CXX98 */ { 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0 },
+ /* GNUCXX11 */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0 },
+ /* CXX11 */ { 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0 },
+ /* GNUCXX14 */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0 },
+ /* CXX14 */ { 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0 },
+ /* GNUCXX1Z */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0 },
+ /* CXX1Z */ { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0 },
+ /* GNUCXX2A */ { 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1 },
+ /* CXX2A */ { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1 },
+ /* ASM */ { 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};
/* Sets internal flags correctly for a given language. */
@@ -137,6 +138,7 @@ cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
CPP_OPTION (pfile, digit_separators) = l->digit_separators;
CPP_OPTION (pfile, trigraphs) = l->trigraphs;
CPP_OPTION (pfile, utf8_char_literals) = l->utf8_char_literals;
+ CPP_OPTION (pfile, va_opt) = l->va_opt;
}
/* Initialize library global state. */
diff --git a/libcpp/internal.h b/libcpp/internal.h
index f24e85c..0a33aba 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -246,7 +246,7 @@ struct lexer_state
all directives apart from #define. */
unsigned char save_comments;
- /* Nonzero if lexing __VA_ARGS__ is valid. */
+ /* Nonzero if lexing __VA_ARGS__ and __VA_OPT__ are valid. */
unsigned char va_args_ok;
/* Nonzero if lexing poisoned identifiers is valid. */
@@ -282,6 +282,7 @@ struct spec_nodes
cpp_hashnode *n_true; /* C++ keyword true */
cpp_hashnode *n_false; /* C++ keyword false */
cpp_hashnode *n__VA_ARGS__; /* C99 vararg macros */
+ cpp_hashnode *n__VA_OPT__; /* C++ vararg macros */
cpp_hashnode *n__has_include__; /* __has_include__ operator */
cpp_hashnode *n__has_include_next__; /* __has_include_next__ operator */
};
diff --git a/libcpp/lex.c b/libcpp/lex.c
index 40ff801..eca4a23 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -1396,6 +1396,21 @@ lex_identifier_intern (cpp_reader *pfile, const uchar *base)
" of a C99 variadic macro");
}
+ /* __VA_OPT__ should only appear in the replacement list of a
+ variadic macro. */
+ if (result == pfile->spec_nodes.n__VA_OPT__
+ && !pfile->state.va_args_ok)
+ {
+ if (CPP_OPTION (pfile, cplusplus))
+ cpp_error (pfile, CPP_DL_ERROR,
+ "__VA_OPT__ can only appear in the expansion"
+ " of a C++11 variadic macro");
+ else
+ cpp_error (pfile, CPP_DL_ERROR,
+ "__VA_OPT__ can only appear in the expansion"
+ " of a C99 variadic macro");
+ }
+
/* For -Wc++-compat, warn about use of C++ named operators. */
if (result->flags & NODE_WARN_OPERATOR)
cpp_warning (pfile, CPP_W_CXX_OPERATOR_NAMES,
@@ -1485,6 +1500,21 @@ lex_identifier (cpp_reader *pfile, const uchar *base, bool starts_ucn,
" of a C99 variadic macro");
}
+ /* __VA_OPT__ should only appear in the replacement list of a
+ variadic macro. */
+ if (result == pfile->spec_nodes.n__VA_OPT__
+ && !pfile->state.va_args_ok)
+ {
+ if (CPP_OPTION (pfile, cplusplus))
+ cpp_error (pfile, CPP_DL_ERROR,
+ "__VA_OPT__ can only appear in the expansion"
+ " of a C++11 variadic macro");
+ else
+ cpp_error (pfile, CPP_DL_ERROR,
+ "__VA_OPT__ can only appear in the expansion"
+ " of a C99 variadic macro");
+ }
+
/* For -Wc++-compat, warn about use of C++ named operators. */
if (result->flags & NODE_WARN_OPERATOR)
cpp_warning (pfile, CPP_W_CXX_OPERATOR_NAMES,
diff --git a/libcpp/macro.c b/libcpp/macro.c
index de18c22..b16a24e 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -89,6 +89,155 @@ struct macro_arg_saved_data {
union _cpp_hashnode_value value;
};
+static const char *vaopt_paste_error =
+ N_("'##' cannot appear at either end of __VA_OPT__");
+
+/* A class for tracking __VA_OPT__ state while iterating over a
+ sequence of tokens. This is used during both macro definition and
+ expansion. */
+class vaopt_state {
+
+ public:
+
+ /* Initialize the state tracker. ANY_ARGS is true if variable
+ arguments were provided to the macro invocation. */
+ vaopt_state (cpp_reader *pfile, bool is_variadic, bool any_args)
+ : m_pfile (pfile),
+ m_allowed (any_args),
+ m_variadic (is_variadic),
+ m_state (0),
+ m_last_was_paste (false),
+ m_paste_location (0),
+ m_location (0)
+ {
+ }
+
+ enum update_type
+ {
+ ERROR,
+ DROP,
+ INCLUDE
+ };
+
+ /* Given a token, update the state of this tracker and return a
+ boolean indicating whether the token should be be included in the
+ expansion. */
+ update_type update (const cpp_token *token)
+ {
+ /* If the macro isn't variadic, just don't bother. */
+ if (!m_variadic)
+ return INCLUDE;
+
+ if (token->type == CPP_NAME
+ && token->val.node.node == m_pfile->spec_nodes.n__VA_OPT__)
+ {
+ if (m_state > 0)
+ {
+ cpp_error_at (m_pfile, CPP_DL_ERROR, token->src_loc,
+ "__VA_OPT__ may not appear in a __VA_OPT__");
+ return ERROR;
+ }
+ ++m_state;
+ m_location = token->src_loc;
+ return DROP;
+ }
+ else if (m_state == 1)
+ {
+ if (token->type != CPP_OPEN_PAREN)
+ {
+ cpp_error_at (m_pfile, CPP_DL_ERROR, m_location,
+ "__VA_OPT__ must be followed by an "
+ "open parenthesis");
+ return ERROR;
+ }
+ ++m_state;
+ return DROP;
+ }
+ else if (m_state >= 2)
+ {
+ if (m_state == 2 && token->type == CPP_PASTE)
+ {
+ cpp_error_at (m_pfile, CPP_DL_ERROR, token->src_loc,
+ vaopt_paste_error);
+ return ERROR;
+ }
+ /* Advance states before further considering this token, in
+ case we see a close paren immediately after the open
+ paren. */
+ if (m_state == 2)
+ ++m_state;
+
+ bool was_paste = m_last_was_paste;
+ m_last_was_paste = false;
+ if (token->type == CPP_PASTE)
+ {
+ m_last_was_paste = true;
+ m_paste_location = token->src_loc;
+ }
+ else if (token->type == CPP_OPEN_PAREN)
+ ++m_state;
+ else if (token->type == CPP_CLOSE_PAREN)
+ {
+ --m_state;
+ if (m_state == 2)
+ {
+ /* Saw the final paren. */
+ m_state = 0;
+
+ if (was_paste)
+ {
+ cpp_error_at (m_pfile, CPP_DL_ERROR, token->src_loc,
+ vaopt_paste_error);
+ return ERROR;
+ }
+
+ return DROP;
+ }
+ }
+ return m_allowed ? INCLUDE : DROP;
+ }
+
+ /* Nothing to do with __VA_OPT__. */
+ return INCLUDE;
+ }
+
+ /* Ensure that any __VA_OPT__ was completed. If ok, return true.
+ Otherwise, issue an error and return false. */
+ bool completed ()
+ {
+ if (m_variadic && m_state != 0)
+ cpp_error_at (m_pfile, CPP_DL_ERROR, m_location,
+ "unterminated __VA_OPT__");
+ return m_state == 0;
+ }
+
+ private:
+
+ /* The cpp_reader. */
+ cpp_reader *m_pfile;
+
+ /* True if there were varargs. */
+ bool m_allowed;
+ /* True if the macro is variadic. */
+ bool m_variadic;
+
+ /* The state variable:
+ 0 means not parsing
+ 1 means __VA_OPT__ seen, looking for "("
+ 2 means "(" seen (so the next token can't be "##")
+ >= 3 means looking for ")", the number encodes the paren depth. */
+ int m_state;
+
+ /* If true, the previous token was ##. This is used to detect when
+ a paste occurs at the end of the sequence. */
+ bool m_last_was_paste;
+ /* The location of the paste token. */
+ source_location m_paste_location;
+
+ /* Location of the __VA_OPT__ token. */
+ source_location m_location;
+};
+
/* Macro expansion. */
static int enter_macro_context (cpp_reader *, cpp_hashnode *,
@@ -768,7 +917,8 @@ _cpp_arguments_ok (cpp_reader *pfile, cpp_macro *macro, const cpp_hashnode *node
if (argc < macro->paramc)
{
- /* As an extension, variadic arguments are allowed to not appear in
+ /* In C++2a (here the va_opt flag is used), and also as a GNU
+ extension, variadic arguments are allowed to not appear in
the invocation at all.
e.g. #define debug(format, args...) something
debug("string");
@@ -778,7 +928,8 @@ _cpp_arguments_ok (cpp_reader *pfile, cpp_macro *macro, const cpp_hashnode *node
if (argc + 1 == macro->paramc && macro->variadic)
{
- if (CPP_PEDANTIC (pfile) && ! macro->syshdr)
+ if (CPP_PEDANTIC (pfile) && ! macro->syshdr
+ && ! CPP_OPTION (pfile, va_opt))
{
if (CPP_OPTION (pfile, cplusplus))
cpp_error (pfile, CPP_DL_PEDWARN,
@@ -1670,6 +1821,8 @@ replace_args (cpp_reader *pfile, cpp_hashnode *node, cpp_macro *macro,
num_macro_tokens);
}
i = 0;
+ vaopt_state state_tracker (pfile, macro->variadic,
+ args[macro->paramc - 1].count > 0);
for (src = macro->exp.tokens; src < limit; src++)
{
unsigned int arg_tokens_count;
@@ -1677,6 +1830,10 @@ replace_args (cpp_reader *pfile, cpp_hashnode *node, cpp_macro *macro,
const cpp_token **paste_flag = NULL;
const cpp_token **tmp_token_ptr;
+ /* __VA_OPT__ handling. */
+ if (state_tracker.update (src) != vaopt_state::INCLUDE)
+ continue;
+
if (src->type != CPP_MACRO_ARG)
{
/* Allocate a virtual location for token SRC, and add that
@@ -3068,6 +3225,9 @@ create_iso_definition (cpp_reader *pfile, cpp_macro *macro)
*token = *ctoken;
}
+ /* The argument doesn't matter here. */
+ vaopt_state state_tracker (pfile, macro->variadic, true);
+
for (;;)
{
/* Check the stringifying # constraint 6.10.3.2.1 of
@@ -3136,10 +3296,16 @@ create_iso_definition (cpp_reader *pfile, cpp_macro *macro)
}
}
+ if (state_tracker.update (token) == vaopt_state::ERROR)
+ return false;
+
following_paste_op = (token->type == CPP_PASTE);
token = lex_expansion_token (pfile, macro);
}
+ if (!state_tracker.completed ())
+ return false;
+
macro->exp.tokens = (cpp_token *) BUFF_FRONT (pfile->a_buff);
macro->traditional = 0;
diff --git a/libcpp/pch.c b/libcpp/pch.c
index cad4b87..b685a38 100644
--- a/libcpp/pch.c
+++ b/libcpp/pch.c
@@ -835,6 +835,7 @@ cpp_read_state (cpp_reader *r, const char *name, FILE *f,
s->n_true = cpp_lookup (r, DSC("true"));
s->n_false = cpp_lookup (r, DSC("false"));
s->n__VA_ARGS__ = cpp_lookup (r, DSC("__VA_ARGS__"));
+ s->n__VA_OPT__ = cpp_lookup (r, DSC("__VA_OPT__"));
s->n__has_include__ = cpp_lookup (r, DSC("__has_include__"));
s->n__has_include_next__ = cpp_lookup (r, DSC("__has_include_next__"));
}
--
2.9.4