PR c++/52538 Extend C++11 UDLs to be compatible with inttypes.h macros (issue6109043)
Gabriel Dos Reis
gdr@integrable-solutions.net
Mon Apr 23 12:10:00 GMT 2012
On Sun, Apr 22, 2012 at 10:59 PM, Ollie Wild <aaw@google.com> wrote:
> Add new option, -Wreserved-user-defined-literal.
Just shorten it to -Wliteral-suffix.
>
> 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.
the non-CPP part is OK with the above change.
You would need Tom's approval for the CPP part.
>
> 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);
> }
>
> Tested via bootstrap + test.
>
> Okay for trunk?
>
> Thanks,
> Ollie
>
>
> 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 4eacd19..f79020c 100644
> --- a/gcc/c-family/c-common.c
> +++ b/gcc/c-family/c-common.c
> @@ -8820,6 +8820,7 @@ 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 17e1958..a812762 100644
> --- a/gcc/c-family/c-opts.c
> +++ b/gcc/c-family/c-opts.c
> @@ -510,6 +510,10 @@ 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 d8c944d..c8a0c84 100644
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -593,6 +593,10 @@ 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 8ca2f4e..ddf0fc6 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -199,7 +199,7 @@ 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
> @@ -2478,6 +2478,30 @@ struct A @{
> The compiler rearranges 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 9d23002..3589a81 100644
> --- a/libcpp/lex.c
> +++ b/libcpp/lex.c
> @@ -1553,14 +1553,30 @@ 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;
> @@ -1668,15 +1684,31 @@ 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/6109043
More information about the Gcc-patches
mailing list