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Re: [google/integration] Extend C++11 UDLs to be compatible with inttypes.h macros (issue6104051)


Let's let the discussion _start_ before assuming it'll be protracted.
;) I don't think it'll kill us to run the next round of testing in
C++98 mode. If the patch doesn't look close to acceptance in a couple
days, I think it'll make sense to put the then-current version into
the google branches while people are agreeing about what to do in the
long run.

On Sun, Apr 22, 2012 at 8:14 PM, Ollie Wild <aaw@google.com> wrote:
> I'd like to get this into the google branches first because this is blocking
> testing.
>
> I fully expect this to result in some protracted discussion before it can be
> accepted into trunk.
>
> Ollie
>
>
> On Sun, Apr 22, 2012 at 10:10 PM, Jeffrey Yasskin <jyasskin@google.com>
> wrote:
>>
>> Could you try to get this into mainline instead of just the google
>> branches? In http://gcc.gnu.org/PR52538, Jonathan sounded like he'd
>> consider accepting it.
>>
>> On Sun, Apr 22, 2012 at 7:54 PM, Ollie Wild <aaw@google.com> wrote:
>> > Add new option, -Wreserved-user-defined-literal.
>> >
>> > This option, which is enabled by default, causes the preprocessor to
>> > warn
>> > when a string or character literal is followed by a ud-suffix which does
>> > not begin with an underscore. ?According to [lex.ext]p10, this is
>> > ill-formed.
>> >
>> > Also modifies the preprocessor to treat such ill-formed suffixes as
>> > separate
>> > preprocessing tokens. ?This is consistent with the Clang front end (see
>> > http://llvm.org/viewvc/llvm-project?view=rev&revision=152287), and
>> > enables
>> > backwards compatibility with code that uses formatting macros from
>> > <inttypes.h>, as in the following code block:
>> >
>> > ?int main() {
>> > ? ?int64_t i64 = 123;
>> > ? ?printf("My int64: %"PRId64"\n", i64);
>> > ?}
>> >
>> > Google ref b/6377711.
>> >
>> > 2012-04-22 ? Ollie Wild ?<aaw@google.com>
>> >
>> > ? ? ? ?* gcc/c-family/c-common.c:
>> > ? ? ? ?* gcc/c-family/c-opts.c (c_common_handle_option):
>> > ? ? ? ?* gcc/c-family/c.opt:
>> > ? ? ? ?* gcc/doc/invoke.texi (struct A):
>> > ? ? ? ?* gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C
>> > (test):
>> > ? ? ? ?(main):
>> > ? ? ? ?* libcpp/include/cpplib.h (struct cpp_options):
>> > ? ? ? ?* libcpp/init.c (cpp_create_reader):
>> > ? ? ? ?* libcpp/lex.c (lex_raw_string):
>> > ? ? ? ?(lex_string):
>> >
>> > diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
>> > index 1d19251..915dc25 100644
>> > --- a/gcc/c-family/c-common.c
>> > +++ b/gcc/c-family/c-common.c
>> > @@ -8724,6 +8724,7 @@ static const struct reason_option_codes_t
>> > option_codes[] = {
>> > ? {CPP_W_NORMALIZE, ? ? ? ? ? ? ? ? ? ?OPT_Wnormalized_},
>> > ? {CPP_W_INVALID_PCH, ? ? ? ? ? ? ? ? ?OPT_Winvalid_pch},
>> > ? {CPP_W_WARNING_DIRECTIVE, ? ? ? ? ? ?OPT_Wcpp},
>> > + ?{CPP_W_RESERVED_USER_LITERALS,
>> > OPT_Wreserved_user_defined_literal},
>> > ? {CPP_W_NONE, ? ? ? ? ? ? ? ? ? ? ? ? 0}
>> > ?};
>> >
>> > diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
>> > index 5118928..dab6ce5 100644
>> > --- a/gcc/c-family/c-opts.c
>> > +++ b/gcc/c-family/c-opts.c
>> > @@ -509,6 +509,10 @@ c_common_handle_option (size_t scode, const char
>> > *arg, int value,
>> > ? ? ? ? ?break;
>> > ? ? ? ?}
>> >
>> > + ? ?case OPT_Wreserved_user_defined_literal:
>> > + ? ? ?cpp_opts->warn_reserved_user_literals = value;
>> > + ? ? ?break;
>> > +
>> > ? ? case OPT_Wreturn_type:
>> > ? ? ? warn_return_type = value;
>> > ? ? ? break;
>> > diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
>> > index 40ff96c..f610513 100644
>> > --- a/gcc/c-family/c.opt
>> > +++ b/gcc/c-family/c.opt
>> > @@ -589,6 +589,10 @@ Wreorder
>> > ?C++ ObjC++ Var(warn_reorder) Warning
>> > ?Warn when the compiler reorders code
>> >
>> > +Wreserved-user-defined-literal
>> > +C++ ObjC++ Warning
>> > +Warn when a string or character literal is followed by a ud-suffix
>> > which does not begin with an underscore.
>> > +
>> > ?Wreturn-type
>> > ?C ObjC C++ ObjC++ Var(warn_return_type) Warning
>> > ?Warn whenever a function's return type defaults to \"int\" (C), or
>> > about inconsistent return types (C++)
>> > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> > index 1b61e76..d425079 100644
>> > --- a/gcc/doc/invoke.texi
>> > +++ b/gcc/doc/invoke.texi
>> > @@ -198,7 +198,7 @@ in the following sections.
>> > ?-fvisibility-ms-compat @gol
>> > ?-Wabi ?-Wconversion-null ?-Wctor-dtor-privacy @gol
>> > ?-Wdelete-non-virtual-dtor -Wnarrowing -Wnoexcept @gol
>> > --Wnon-virtual-dtor ?-Wreorder @gol
>> > +-Wnon-virtual-dtor ?-Wreorder -Wreserved-user-defined-literal @gol
>> > ?-Weffc++ ?-Wstrict-null-sentinel @gol
>> > ?-Wno-non-template-friend ?-Wold-style-cast @gol
>> > ?-Woverloaded-virtual ?-Wno-pmf-conversions @gol
>> > @@ -2474,6 +2474,30 @@ struct A @{
>> > ?The compiler will rearrange the member initializers for @samp{i}
>> > ?and @samp{j} to match the declaration order of the members, emitting
>> > ?a warning to that effect. ?This warning is enabled by @option{-Wall}.
>> > +
>> > +@item -Wreserved-user-defined-literal @r{(C++ and Objective-C++ only)}
>> > +@opindex Wreserved-user-defined-literal
>> > +@opindex Wno-reserved-user-defined-literal
>> > +Warn when a string or character literal is followed by a ud-suffix
>> > which does
>> > +not begin with an underscore. ?As a conforming extension, GCC treats
>> > such
>> > +suffixes as separate preprocessing tokens in order to maintain
>> > backwards
>> > +compatibility with code that uses formatting macros from
>> > @code{<inttypes.h>}.
>> > +For example:
>> > +
>> > +@smallexample
>> > +#define __STDC_FORMAT_MACROS
>> > +#include <inttypes.h>
>> > +#include <stdio.h>
>> > +
>> > +int main() @{
>> > + ?int64_t i64 = 123;
>> > + ?printf("My int64: %"PRId64"\n", i64);
>> > +@}
>> > +@end smallexample
>> > +
>> > +In this case, @code{PRId64} is treated as a separate preprocessing
>> > token.
>> > +
>> > +This warning is enabled by default.
>> > ?@end table
>> >
>> > ?The following @option{-W@dots{}} options are not affected by
>> > @option{-Wall}.
>> > diff --git a/gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C
>> > b/gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C
>> > new file mode 100644
>> > index 0000000..66de5c0
>> > --- /dev/null
>> > +++ b/gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C
>> > @@ -0,0 +1,29 @@
>> > +// { dg-do run }
>> > +// { dg-options "-std=c++0x" }
>> > +
>> > +// Make sure -Wreserved-user-defined-literal is enabled by default and
>> > +// triggers as expected.
>> > +
>> > +#define BAR "bar"
>> > +#define PLUS_ONE + 1
>> > +
>> > +#include <cstdint>
>> > +#include <cassert>
>> > +
>> > +
>> > +void
>> > +test()
>> > +{
>> > + ?char c = '3'PLUS_ONE; ? ? ? ? ?// { dg-warning "invalid suffix on
>> > literal" }
>> > + ?char s[] = "foo"BAR; ? // { dg-warning "invalid suffix on literal" }
>> > +
>> > + ?assert(c == '4');
>> > + ?assert(s[3] != '\0');
>> > + ?assert(s[3] == 'b');
>> > +}
>> > +
>> > +int
>> > +main()
>> > +{
>> > + ?test();
>> > +}
>> > diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
>> > index bf59d01..84cacb0 100644
>> > --- a/libcpp/include/cpplib.h
>> > +++ b/libcpp/include/cpplib.h
>> > @@ -427,6 +427,10 @@ struct cpp_options
>> > ? /* Nonzero for C++ 2011 Standard user-defnied literals. ?*/
>> > ? unsigned char user_literals;
>> >
>> > + ?/* Nonzero means warn when a string or character literal is followed
>> > by a
>> > + ? ? ud-suffix which does not beging with an underscore. ?*/
>> > + ?unsigned char warn_reserved_user_literals;
>> > +
>> > ? /* Holds the name of the target (execution) character set. ?*/
>> > ? const char *narrow_charset;
>> >
>> > @@ -906,7 +910,8 @@ enum {
>> > ? CPP_W_CXX_OPERATOR_NAMES,
>> > ? CPP_W_NORMALIZE,
>> > ? CPP_W_INVALID_PCH,
>> > - ?CPP_W_WARNING_DIRECTIVE
>> > + ?CPP_W_WARNING_DIRECTIVE,
>> > + ?CPP_W_RESERVED_USER_LITERALS
>> > ?};
>> >
>> > ?/* Output a diagnostic of some kind. ?*/
>> > diff --git a/libcpp/init.c b/libcpp/init.c
>> > index 5fa82ca..2688699 100644
>> > --- a/libcpp/init.c
>> > +++ b/libcpp/init.c
>> > @@ -175,6 +175,7 @@ cpp_create_reader (enum c_lang lang, hash_table
>> > *table,
>> > ? CPP_OPTION (pfile, warn_variadic_macros) = 1;
>> > ? CPP_OPTION (pfile, warn_builtin_macro_redefined) = 1;
>> > ? CPP_OPTION (pfile, warn_normalize) = normalized_C;
>> > + ?CPP_OPTION (pfile, warn_reserved_user_literals) = 1;
>> >
>> > ? /* Default CPP arithmetic to something sensible for the host for the
>> > ? ? ?benefit of dumb users like fix-header. ?*/
>> > diff --git a/libcpp/lex.c b/libcpp/lex.c
>> > index 0ad9660..ba8ed9e 100644
>> > --- a/libcpp/lex.c
>> > +++ b/libcpp/lex.c
>> > @@ -1491,14 +1491,30 @@ lex_raw_string (cpp_reader *pfile, cpp_token
>> > *token, const uchar *base,
>> >
>> > ? if (CPP_OPTION (pfile, user_literals))
>> > ? ? {
>> > + ? ? ?/* According to C++11 [lex.ext]p10, a ud-suffix not starting with
>> > an
>> > + ? ? ? ?underscore is ill-formed. ?Since this breaks programs using
>> > macros
>> > + ? ? ? ?from inttypes.h, we generate a warning and treat the ud-suffix
>> > as a
>> > + ? ? ? ?separate preprocessing token. ?This approach is under
>> > discussion by
>> > + ? ? ? ?the standards committee, and has been adopted as a conforming
>> > + ? ? ? ?extension by other front ends such as clang. */
>> > + ? ? ?if (ISALPHA(*cur))
>> > + ? ? ? {
>> > + ? ? ? ? // Raise a warning, but do not consume subsequent tokens.
>> > + ? ? ? ? if (CPP_OPTION (pfile, warn_reserved_user_literals))
>> > + ? ? ? ? ? cpp_warning_with_line (pfile, CPP_W_RESERVED_USER_LITERALS,
>> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?token->src_loc, 0,
>> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?"invalid suffix on literal; C++11
>> > requires "
>> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?"a space between literal and
>> > identifier");
>> > + ? ? ? }
>> > ? ? ? /* Grab user defined literal suffix. ?*/
>> > - ? ? ?if (ISIDST (*cur))
>> > + ? ? ?else if (*cur == '_')
>> > ? ? ? ?{
>> > ? ? ? ? ?type = cpp_userdef_string_add_type (type);
>> > ? ? ? ? ?++cur;
>> > +
>> > + ? ? ? ? while (ISIDNUM (*cur))
>> > + ? ? ? ? ? ++cur;
>> > ? ? ? ?}
>> > - ? ? ?while (ISIDNUM (*cur))
>> > - ? ? ? ++cur;
>> > ? ? }
>> >
>> > ? pfile->buffer->cur = cur;
>> > @@ -1606,15 +1622,31 @@ lex_string (cpp_reader *pfile, cpp_token *token,
>> > const uchar *base)
>> >
>> > ? if (CPP_OPTION (pfile, user_literals))
>> > ? ? {
>> > + ? ? ?/* According to C++11 [lex.ext]p10, a ud-suffix not starting with
>> > an
>> > + ? ? ? ?underscore is ill-formed. ?Since this breaks programs using
>> > macros
>> > + ? ? ? ?from inttypes.h, we generate a warning and treat the ud-suffix
>> > as a
>> > + ? ? ? ?separate preprocessing token. ?This approach is under
>> > discussion by
>> > + ? ? ? ?the standards committee, and has been adopted as a conforming
>> > + ? ? ? ?extension by other front ends such as clang. */
>> > + ? ? ?if (ISALPHA(*cur))
>> > + ? ? ? {
>> > + ? ? ? ? // Raise a warning, but do not consume subsequent tokens.
>> > + ? ? ? ? if (CPP_OPTION (pfile, warn_reserved_user_literals))
>> > + ? ? ? ? ? cpp_warning_with_line (pfile, CPP_W_RESERVED_USER_LITERALS,
>> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?token->src_loc, 0,
>> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?"invalid suffix on literal; C++11
>> > requires "
>> > + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?"a space between literal and
>> > identifier");
>> > + ? ? ? }
>> > ? ? ? /* Grab user defined literal suffix. ?*/
>> > - ? ? ?if (ISIDST (*cur))
>> > + ? ? ?else if (*cur == '_')
>> > ? ? ? ?{
>> > ? ? ? ? ?type = cpp_userdef_char_add_type (type);
>> > ? ? ? ? ?type = cpp_userdef_string_add_type (type);
>> > ? ? ? ? ? ++cur;
>> > +
>> > + ? ? ? ? while (ISIDNUM (*cur))
>> > + ? ? ? ? ? ++cur;
>> > ? ? ? ?}
>> > - ? ? ?while (ISIDNUM (*cur))
>> > - ? ? ? ++cur;
>> > ? ? }
>> >
>> > ? pfile->buffer->cur = cur;
>> >
>> > --
>> > This patch is available for review at
>> > http://codereview.appspot.com/6104051
>
>


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