[1/1,v2] c++/106423: Fix pragma suppression of -Wc++20-compat diagnostics.
Commit Message
Gcc's '#pragma GCC diagnostic' directives are processed in "early mode"
(see handle_pragma_diagnostic_early) for the C++ frontend and, as such,
require that the target diagnostic option be enabled for the preprocessor
(see c_option_is_from_cpp_diagnostics). This change modifies the
-Wc++20-compat option definition to register it as a preprocessor option
so that its associated diagnostics can be suppressed. The changes also
implicitly disable the option in C++20 and later modes. These changes
are consistent with the definition of the -Wc++11-compat option.
This support is motivated by the need to suppress the following diagnostic
otherwise issued in C++17 and earlier modes due to the char8_t typedef
present in the uchar.h header file in glibc 2.36.
warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat]
Tests are added to validate suppression of both -Wc++11-compat and
-Wc++20-compat related diagnostics (fixes were only needed for the C++20
case).
Fixes https://gcc.gnu.org/PR106423.
gcc/c-family/ChangeLog:
* c-opts.cc (c_common_post_options): Disable -Wc++20-compat diagnostics
in C++20 and later.
* c.opt (Wc++20-compat): Enable hooks for the preprocessor.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/keywords2.C: New test.
* g++.dg/cpp2a/keywords2.C: New test.
libcpp/ChangeLog:
* include/cpplib.h (cpp_warning_reason): Add CPP_W_CXX20_COMPAT.
* init.cc (cpp_create_reader): Add cpp_warn_cxx20_compat.
---
gcc/c-family/c-opts.cc | 7 +++++++
gcc/c-family/c.opt | 2 +-
gcc/cp/parser.cc | 5 ++++-
gcc/testsuite/g++.dg/cpp0x/keywords2.C | 16 ++++++++++++++++
gcc/testsuite/g++.dg/cpp2a/keywords2.C | 13 +++++++++++++
libcpp/include/cpplib.h | 4 ++++
libcpp/init.cc | 1 +
7 files changed, 46 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/keywords2.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/keywords2.C
Comments
Are there any further concerns with this patch? If not, I extend my
gratitude to anyone so kind as to commit this for me as I don't have
commit access.
I just noticed that I neglected to add a ChangeLog entry for the comment
addition to gcc/cp/parser.cc. Noted inline below. I can re-send the
patch with that update if desired.
Tom.
On 8/1/22 2:49 PM, Tom Honermann wrote:
> Gcc's '#pragma GCC diagnostic' directives are processed in "early mode"
> (see handle_pragma_diagnostic_early) for the C++ frontend and, as such,
> require that the target diagnostic option be enabled for the preprocessor
> (see c_option_is_from_cpp_diagnostics). This change modifies the
> -Wc++20-compat option definition to register it as a preprocessor option
> so that its associated diagnostics can be suppressed. The changes also
> implicitly disable the option in C++20 and later modes. These changes
> are consistent with the definition of the -Wc++11-compat option.
>
> This support is motivated by the need to suppress the following diagnostic
> otherwise issued in C++17 and earlier modes due to the char8_t typedef
> present in the uchar.h header file in glibc 2.36.
> warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat]
>
> Tests are added to validate suppression of both -Wc++11-compat and
> -Wc++20-compat related diagnostics (fixes were only needed for the C++20
> case).
>
> Fixeshttps://gcc.gnu.org/PR106423.
>
> gcc/c-family/ChangeLog:
> * c-opts.cc (c_common_post_options): Disable -Wc++20-compat diagnostics
> in C++20 and later.
> * c.opt (Wc++20-compat): Enable hooks for the preprocessor.
gcc/cp/ChangeLog:
* parser.cc (cp_lexer_saving_tokens): Add comment regarding
diagnostic requirements.
>
> gcc/testsuite/ChangeLog:
> * g++.dg/cpp0x/keywords2.C: New test.
> * g++.dg/cpp2a/keywords2.C: New test.
>
> libcpp/ChangeLog:
> * include/cpplib.h (cpp_warning_reason): Add CPP_W_CXX20_COMPAT.
> * init.cc (cpp_create_reader): Add cpp_warn_cxx20_compat.
> ---
> gcc/c-family/c-opts.cc | 7 +++++++
> gcc/c-family/c.opt | 2 +-
> gcc/cp/parser.cc | 5 ++++-
> gcc/testsuite/g++.dg/cpp0x/keywords2.C | 16 ++++++++++++++++
> gcc/testsuite/g++.dg/cpp2a/keywords2.C | 13 +++++++++++++
> libcpp/include/cpplib.h | 4 ++++
> libcpp/init.cc | 1 +
> 7 files changed, 46 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/keywords2.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/keywords2.C
>
> diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
> index b9f01a65ed7..1ea37ba9742 100644
> --- a/gcc/c-family/c-opts.cc
> +++ b/gcc/c-family/c-opts.cc
> @@ -1046,6 +1046,13 @@ c_common_post_options (const char **pfilename)
> else if (warn_narrowing == -1)
> warn_narrowing = 0;
>
> + if (cxx_dialect >= cxx20)
> + {
> + /* Don't warn about C++20 compatibility changes in C++20 or later. */
> + warn_cxx20_compat = 0;
> + cpp_opts->cpp_warn_cxx20_compat = 0;
> + }
> +
> /* C++17 has stricter evaluation order requirements; let's use some of them
> for earlier C++ as well, so chaining works as expected. */
> if (c_dialect_cxx ()
> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> index 44e1a60ce24..dfdebd596ef 100644
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -455,7 +455,7 @@ Wc++2a-compat
> C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
>
> Wc++20-compat
> -C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
> +C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT)
> Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020.
>
> Wc++11-extensions
> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> index 4f67441eeb1..c3584446827 100644
> --- a/gcc/cp/parser.cc
> +++ b/gcc/cp/parser.cc
> @@ -924,7 +924,10 @@ cp_lexer_saving_tokens (const cp_lexer* lexer)
> /* Store the next token from the preprocessor in *TOKEN. Return true
> if we reach EOF. If LEXER is NULL, assume we are handling an
> initial #pragma pch_preprocess, and thus want the lexer to return
> - processed strings. */
> + processed strings.
> +
> + Diagnostics issued from this function must have their controlling option (if
> + any) in c.opt annotated as a libcpp option via the CppReason property. */
>
> static void
> cp_lexer_get_preprocessor_token (unsigned flags, cp_token *token)
> diff --git a/gcc/testsuite/g++.dg/cpp0x/keywords2.C b/gcc/testsuite/g++.dg/cpp0x/keywords2.C
> new file mode 100644
> index 00000000000..d67d01e31ed
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/keywords2.C
> @@ -0,0 +1,16 @@
> +// { dg-do compile { target c++98_only } }
> +// { dg-options "-Wc++11-compat" }
> +
> +// Validate suppression of -Wc++11-compat diagnostics.
> +#pragma GCC diagnostic ignored "-Wc++11-compat"
> +int alignof;
> +int alignas;
> +int constexpr;
> +int decltype;
> +int noexcept;
> +int nullptr;
> +int static_assert;
> +int thread_local;
> +int _Alignas;
> +int _Alignof;
> +int _Thread_local;
> diff --git a/gcc/testsuite/g++.dg/cpp2a/keywords2.C b/gcc/testsuite/g++.dg/cpp2a/keywords2.C
> new file mode 100644
> index 00000000000..8714a7b26b7
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/keywords2.C
> @@ -0,0 +1,13 @@
> +// { dg-do compile { target c++17_down } }
> +// { dg-options "-Wc++20-compat" }
> +
> +// Validate suppression of -Wc++20-compat diagnostics.
> +#pragma GCC diagnostic ignored "-Wc++20-compat"
> +int constinit;
> +int consteval;
> +int requires;
> +int concept;
> +int co_await;
> +int co_yield;
> +int co_return;
> +int char8_t;
> diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
> index 3eba6f74b57..9d90c18e4f2 100644
> --- a/libcpp/include/cpplib.h
> +++ b/libcpp/include/cpplib.h
> @@ -547,6 +547,9 @@ struct cpp_options
> /* True if warn about differences between C++98 and C++11. */
> bool cpp_warn_cxx11_compat;
>
> + /* True if warn about differences between C++17 and C++20. */
> + bool cpp_warn_cxx20_compat;
> +
> /* Nonzero if bidirectional control characters checking is on. See enum
> cpp_bidirectional_level. */
> unsigned char cpp_warn_bidirectional;
> @@ -655,6 +658,7 @@ enum cpp_warning_reason {
> CPP_W_C90_C99_COMPAT,
> CPP_W_C11_C2X_COMPAT,
> CPP_W_CXX11_COMPAT,
> + CPP_W_CXX20_COMPAT,
> CPP_W_EXPANSION_TO_DEFINED,
> CPP_W_BIDIRECTIONAL
> };
> diff --git a/libcpp/init.cc b/libcpp/init.cc
> index f4ab83d2145..cca3c1dc1e7 100644
> --- a/libcpp/init.cc
> +++ b/libcpp/init.cc
> @@ -202,6 +202,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table *table,
> CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1;
> CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) = -1;
> CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0;
> + CPP_OPTION (pfile, cpp_warn_cxx20_compat) = 0;
> CPP_OPTION (pfile, cpp_warn_deprecated) = 1;
> CPP_OPTION (pfile, cpp_warn_long_long) = 0;
> CPP_OPTION (pfile, dollars_in_ident) = 1;
If there are no further concerns, could a C++ or libcpp maintainer
please commit this for me?
Thank you!
Tom.
On 8/4/22 12:42 PM, Tom Honermann via Gcc-patches wrote:
> Are there any further concerns with this patch? If not, I extend my
> gratitude to anyone so kind as to commit this for me as I don't have
> commit access.
>
> I just noticed that I neglected to add a ChangeLog entry for the
> comment addition to gcc/cp/parser.cc. Noted inline below. I can
> re-send the patch with that update if desired.
>
> Tom.
>
> On 8/1/22 2:49 PM, Tom Honermann wrote:
>> Gcc's '#pragma GCC diagnostic' directives are processed in "early mode"
>> (see handle_pragma_diagnostic_early) for the C++ frontend and, as such,
>> require that the target diagnostic option be enabled for the
>> preprocessor
>> (see c_option_is_from_cpp_diagnostics). This change modifies the
>> -Wc++20-compat option definition to register it as a preprocessor option
>> so that its associated diagnostics can be suppressed. The changes also
>> implicitly disable the option in C++20 and later modes. These changes
>> are consistent with the definition of the -Wc++11-compat option.
>>
>> This support is motivated by the need to suppress the following
>> diagnostic
>> otherwise issued in C++17 and earlier modes due to the char8_t typedef
>> present in the uchar.h header file in glibc 2.36.
>> warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat]
>>
>> Tests are added to validate suppression of both -Wc++11-compat and
>> -Wc++20-compat related diagnostics (fixes were only needed for the C++20
>> case).
>>
>> Fixeshttps://gcc.gnu.org/PR106423.
>>
>> gcc/c-family/ChangeLog:
>> * c-opts.cc (c_common_post_options): Disable -Wc++20-compat
>> diagnostics
>> in C++20 and later.
>> * c.opt (Wc++20-compat): Enable hooks for the preprocessor.
>
> gcc/cp/ChangeLog:
> * parser.cc (cp_lexer_saving_tokens): Add comment regarding
> diagnostic requirements.
>
>>
>> gcc/testsuite/ChangeLog:
>> * g++.dg/cpp0x/keywords2.C: New test.
>> * g++.dg/cpp2a/keywords2.C: New test.
>>
>> libcpp/ChangeLog:
>> * include/cpplib.h (cpp_warning_reason): Add CPP_W_CXX20_COMPAT.
>> * init.cc (cpp_create_reader): Add cpp_warn_cxx20_compat.
>> ---
>> gcc/c-family/c-opts.cc | 7 +++++++
>> gcc/c-family/c.opt | 2 +-
>> gcc/cp/parser.cc | 5 ++++-
>> gcc/testsuite/g++.dg/cpp0x/keywords2.C | 16 ++++++++++++++++
>> gcc/testsuite/g++.dg/cpp2a/keywords2.C | 13 +++++++++++++
>> libcpp/include/cpplib.h | 4 ++++
>> libcpp/init.cc | 1 +
>> 7 files changed, 46 insertions(+), 2 deletions(-)
>> create mode 100644 gcc/testsuite/g++.dg/cpp0x/keywords2.C
>> create mode 100644 gcc/testsuite/g++.dg/cpp2a/keywords2.C
>>
>> diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
>> index b9f01a65ed7..1ea37ba9742 100644
>> --- a/gcc/c-family/c-opts.cc
>> +++ b/gcc/c-family/c-opts.cc
>> @@ -1046,6 +1046,13 @@ c_common_post_options (const char **pfilename)
>> else if (warn_narrowing == -1)
>> warn_narrowing = 0;
>> + if (cxx_dialect >= cxx20)
>> + {
>> + /* Don't warn about C++20 compatibility changes in C++20 or
>> later. */
>> + warn_cxx20_compat = 0;
>> + cpp_opts->cpp_warn_cxx20_compat = 0;
>> + }
>> +
>> /* C++17 has stricter evaluation order requirements; let's use
>> some of them
>> for earlier C++ as well, so chaining works as expected. */
>> if (c_dialect_cxx ()
>> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
>> index 44e1a60ce24..dfdebd596ef 100644
>> --- a/gcc/c-family/c.opt
>> +++ b/gcc/c-family/c.opt
>> @@ -455,7 +455,7 @@ Wc++2a-compat
>> C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
>> Wc++20-compat
>> -C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++
>> ObjC++,Wall)
>> +C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++
>> ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat)
>> CppReason(CPP_W_CXX20_COMPAT)
>> Warn about C++ constructs whose meaning differs between ISO C++
>> 2017 and ISO C++ 2020.
>> Wc++11-extensions
>> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
>> index 4f67441eeb1..c3584446827 100644
>> --- a/gcc/cp/parser.cc
>> +++ b/gcc/cp/parser.cc
>> @@ -924,7 +924,10 @@ cp_lexer_saving_tokens (const cp_lexer* lexer)
>> /* Store the next token from the preprocessor in *TOKEN. Return true
>> if we reach EOF. If LEXER is NULL, assume we are handling an
>> initial #pragma pch_preprocess, and thus want the lexer to return
>> - processed strings. */
>> + processed strings.
>> +
>> + Diagnostics issued from this function must have their controlling
>> option (if
>> + any) in c.opt annotated as a libcpp option via the CppReason
>> property. */
>> static void
>> cp_lexer_get_preprocessor_token (unsigned flags, cp_token *token)
>> diff --git a/gcc/testsuite/g++.dg/cpp0x/keywords2.C
>> b/gcc/testsuite/g++.dg/cpp0x/keywords2.C
>> new file mode 100644
>> index 00000000000..d67d01e31ed
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/cpp0x/keywords2.C
>> @@ -0,0 +1,16 @@
>> +// { dg-do compile { target c++98_only } }
>> +// { dg-options "-Wc++11-compat" }
>> +
>> +// Validate suppression of -Wc++11-compat diagnostics.
>> +#pragma GCC diagnostic ignored "-Wc++11-compat"
>> +int alignof;
>> +int alignas;
>> +int constexpr;
>> +int decltype;
>> +int noexcept;
>> +int nullptr;
>> +int static_assert;
>> +int thread_local;
>> +int _Alignas;
>> +int _Alignof;
>> +int _Thread_local;
>> diff --git a/gcc/testsuite/g++.dg/cpp2a/keywords2.C
>> b/gcc/testsuite/g++.dg/cpp2a/keywords2.C
>> new file mode 100644
>> index 00000000000..8714a7b26b7
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/cpp2a/keywords2.C
>> @@ -0,0 +1,13 @@
>> +// { dg-do compile { target c++17_down } }
>> +// { dg-options "-Wc++20-compat" }
>> +
>> +// Validate suppression of -Wc++20-compat diagnostics.
>> +#pragma GCC diagnostic ignored "-Wc++20-compat"
>> +int constinit;
>> +int consteval;
>> +int requires;
>> +int concept;
>> +int co_await;
>> +int co_yield;
>> +int co_return;
>> +int char8_t;
>> diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
>> index 3eba6f74b57..9d90c18e4f2 100644
>> --- a/libcpp/include/cpplib.h
>> +++ b/libcpp/include/cpplib.h
>> @@ -547,6 +547,9 @@ struct cpp_options
>> /* True if warn about differences between C++98 and C++11. */
>> bool cpp_warn_cxx11_compat;
>> + /* True if warn about differences between C++17 and C++20. */
>> + bool cpp_warn_cxx20_compat;
>> +
>> /* Nonzero if bidirectional control characters checking is on.
>> See enum
>> cpp_bidirectional_level. */
>> unsigned char cpp_warn_bidirectional;
>> @@ -655,6 +658,7 @@ enum cpp_warning_reason {
>> CPP_W_C90_C99_COMPAT,
>> CPP_W_C11_C2X_COMPAT,
>> CPP_W_CXX11_COMPAT,
>> + CPP_W_CXX20_COMPAT,
>> CPP_W_EXPANSION_TO_DEFINED,
>> CPP_W_BIDIRECTIONAL
>> };
>> diff --git a/libcpp/init.cc b/libcpp/init.cc
>> index f4ab83d2145..cca3c1dc1e7 100644
>> --- a/libcpp/init.cc
>> +++ b/libcpp/init.cc
>> @@ -202,6 +202,7 @@ cpp_create_reader (enum c_lang lang,
>> cpp_hash_table *table,
>> CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1;
>> CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) = -1;
>> CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0;
>> + CPP_OPTION (pfile, cpp_warn_cxx20_compat) = 0;
>> CPP_OPTION (pfile, cpp_warn_deprecated) = 1;
>> CPP_OPTION (pfile, cpp_warn_long_long) = 0;
>> CPP_OPTION (pfile, dollars_in_ident) = 1;
Sorry for the delay, I'm travelling with limited internet. I will commit it
early next week if no one beats me to it.
On Thu, Aug 11, 2022, 2:45 PM Tom Honermann via Gcc-patches <
gcc-patches@gcc.gnu.org> wrote:
> If there are no further concerns, could a C++ or libcpp maintainer
> please commit this for me?
>
> Thank you!
>
> Tom.
>
> On 8/4/22 12:42 PM, Tom Honermann via Gcc-patches wrote:
> > Are there any further concerns with this patch? If not, I extend my
> > gratitude to anyone so kind as to commit this for me as I don't have
> > commit access.
> >
> > I just noticed that I neglected to add a ChangeLog entry for the
> > comment addition to gcc/cp/parser.cc. Noted inline below. I can
> > re-send the patch with that update if desired.
> >
> > Tom.
> >
> > On 8/1/22 2:49 PM, Tom Honermann wrote:
> >> Gcc's '#pragma GCC diagnostic' directives are processed in "early mode"
> >> (see handle_pragma_diagnostic_early) for the C++ frontend and, as such,
> >> require that the target diagnostic option be enabled for the
> >> preprocessor
> >> (see c_option_is_from_cpp_diagnostics). This change modifies the
> >> -Wc++20-compat option definition to register it as a preprocessor option
> >> so that its associated diagnostics can be suppressed. The changes also
> >> implicitly disable the option in C++20 and later modes. These changes
> >> are consistent with the definition of the -Wc++11-compat option.
> >>
> >> This support is motivated by the need to suppress the following
> >> diagnostic
> >> otherwise issued in C++17 and earlier modes due to the char8_t typedef
> >> present in the uchar.h header file in glibc 2.36.
> >> warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat]
> >>
> >> Tests are added to validate suppression of both -Wc++11-compat and
> >> -Wc++20-compat related diagnostics (fixes were only needed for the C++20
> >> case).
> >>
> >> Fixeshttps://gcc.gnu.org/PR106423.
> >>
> >> gcc/c-family/ChangeLog:
> >> * c-opts.cc (c_common_post_options): Disable -Wc++20-compat
> >> diagnostics
> >> in C++20 and later.
> >> * c.opt (Wc++20-compat): Enable hooks for the preprocessor.
> >
> > gcc/cp/ChangeLog:
> > * parser.cc (cp_lexer_saving_tokens): Add comment regarding
> > diagnostic requirements.
> >
> >>
> >> gcc/testsuite/ChangeLog:
> >> * g++.dg/cpp0x/keywords2.C: New test.
> >> * g++.dg/cpp2a/keywords2.C: New test.
> >>
> >> libcpp/ChangeLog:
> >> * include/cpplib.h (cpp_warning_reason): Add CPP_W_CXX20_COMPAT.
> >> * init.cc (cpp_create_reader): Add cpp_warn_cxx20_compat.
> >> ---
> >> gcc/c-family/c-opts.cc | 7 +++++++
> >> gcc/c-family/c.opt | 2 +-
> >> gcc/cp/parser.cc | 5 ++++-
> >> gcc/testsuite/g++.dg/cpp0x/keywords2.C | 16 ++++++++++++++++
> >> gcc/testsuite/g++.dg/cpp2a/keywords2.C | 13 +++++++++++++
> >> libcpp/include/cpplib.h | 4 ++++
> >> libcpp/init.cc | 1 +
> >> 7 files changed, 46 insertions(+), 2 deletions(-)
> >> create mode 100644 gcc/testsuite/g++.dg/cpp0x/keywords2.C
> >> create mode 100644 gcc/testsuite/g++.dg/cpp2a/keywords2.C
> >>
> >> diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
> >> index b9f01a65ed7..1ea37ba9742 100644
> >> --- a/gcc/c-family/c-opts.cc
> >> +++ b/gcc/c-family/c-opts.cc
> >> @@ -1046,6 +1046,13 @@ c_common_post_options (const char **pfilename)
> >> else if (warn_narrowing == -1)
> >> warn_narrowing = 0;
> >> + if (cxx_dialect >= cxx20)
> >> + {
> >> + /* Don't warn about C++20 compatibility changes in C++20 or
> >> later. */
> >> + warn_cxx20_compat = 0;
> >> + cpp_opts->cpp_warn_cxx20_compat = 0;
> >> + }
> >> +
> >> /* C++17 has stricter evaluation order requirements; let's use
> >> some of them
> >> for earlier C++ as well, so chaining works as expected. */
> >> if (c_dialect_cxx ()
> >> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> >> index 44e1a60ce24..dfdebd596ef 100644
> >> --- a/gcc/c-family/c.opt
> >> +++ b/gcc/c-family/c.opt
> >> @@ -455,7 +455,7 @@ Wc++2a-compat
> >> C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
> >> Wc++20-compat
> >> -C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++
> >> ObjC++,Wall)
> >> +C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++
> >> ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat)
> >> CppReason(CPP_W_CXX20_COMPAT)
> >> Warn about C++ constructs whose meaning differs between ISO C++
> >> 2017 and ISO C++ 2020.
> >> Wc++11-extensions
> >> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> >> index 4f67441eeb1..c3584446827 100644
> >> --- a/gcc/cp/parser.cc
> >> +++ b/gcc/cp/parser.cc
> >> @@ -924,7 +924,10 @@ cp_lexer_saving_tokens (const cp_lexer* lexer)
> >> /* Store the next token from the preprocessor in *TOKEN. Return true
> >> if we reach EOF. If LEXER is NULL, assume we are handling an
> >> initial #pragma pch_preprocess, and thus want the lexer to return
> >> - processed strings. */
> >> + processed strings.
> >> +
> >> + Diagnostics issued from this function must have their controlling
> >> option (if
> >> + any) in c.opt annotated as a libcpp option via the CppReason
> >> property. */
> >> static void
> >> cp_lexer_get_preprocessor_token (unsigned flags, cp_token *token)
> >> diff --git a/gcc/testsuite/g++.dg/cpp0x/keywords2.C
> >> b/gcc/testsuite/g++.dg/cpp0x/keywords2.C
> >> new file mode 100644
> >> index 00000000000..d67d01e31ed
> >> --- /dev/null
> >> +++ b/gcc/testsuite/g++.dg/cpp0x/keywords2.C
> >> @@ -0,0 +1,16 @@
> >> +// { dg-do compile { target c++98_only } }
> >> +// { dg-options "-Wc++11-compat" }
> >> +
> >> +// Validate suppression of -Wc++11-compat diagnostics.
> >> +#pragma GCC diagnostic ignored "-Wc++11-compat"
> >> +int alignof;
> >> +int alignas;
> >> +int constexpr;
> >> +int decltype;
> >> +int noexcept;
> >> +int nullptr;
> >> +int static_assert;
> >> +int thread_local;
> >> +int _Alignas;
> >> +int _Alignof;
> >> +int _Thread_local;
> >> diff --git a/gcc/testsuite/g++.dg/cpp2a/keywords2.C
> >> b/gcc/testsuite/g++.dg/cpp2a/keywords2.C
> >> new file mode 100644
> >> index 00000000000..8714a7b26b7
> >> --- /dev/null
> >> +++ b/gcc/testsuite/g++.dg/cpp2a/keywords2.C
> >> @@ -0,0 +1,13 @@
> >> +// { dg-do compile { target c++17_down } }
> >> +// { dg-options "-Wc++20-compat" }
> >> +
> >> +// Validate suppression of -Wc++20-compat diagnostics.
> >> +#pragma GCC diagnostic ignored "-Wc++20-compat"
> >> +int constinit;
> >> +int consteval;
> >> +int requires;
> >> +int concept;
> >> +int co_await;
> >> +int co_yield;
> >> +int co_return;
> >> +int char8_t;
> >> diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
> >> index 3eba6f74b57..9d90c18e4f2 100644
> >> --- a/libcpp/include/cpplib.h
> >> +++ b/libcpp/include/cpplib.h
> >> @@ -547,6 +547,9 @@ struct cpp_options
> >> /* True if warn about differences between C++98 and C++11. */
> >> bool cpp_warn_cxx11_compat;
> >> + /* True if warn about differences between C++17 and C++20. */
> >> + bool cpp_warn_cxx20_compat;
> >> +
> >> /* Nonzero if bidirectional control characters checking is on.
> >> See enum
> >> cpp_bidirectional_level. */
> >> unsigned char cpp_warn_bidirectional;
> >> @@ -655,6 +658,7 @@ enum cpp_warning_reason {
> >> CPP_W_C90_C99_COMPAT,
> >> CPP_W_C11_C2X_COMPAT,
> >> CPP_W_CXX11_COMPAT,
> >> + CPP_W_CXX20_COMPAT,
> >> CPP_W_EXPANSION_TO_DEFINED,
> >> CPP_W_BIDIRECTIONAL
> >> };
> >> diff --git a/libcpp/init.cc b/libcpp/init.cc
> >> index f4ab83d2145..cca3c1dc1e7 100644
> >> --- a/libcpp/init.cc
> >> +++ b/libcpp/init.cc
> >> @@ -202,6 +202,7 @@ cpp_create_reader (enum c_lang lang,
> >> cpp_hash_table *table,
> >> CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1;
> >> CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) = -1;
> >> CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0;
> >> + CPP_OPTION (pfile, cpp_warn_cxx20_compat) = 0;
> >> CPP_OPTION (pfile, cpp_warn_deprecated) = 1;
> >> CPP_OPTION (pfile, cpp_warn_long_long) = 0;
> >> CPP_OPTION (pfile, dollars_in_ident) = 1;
>
>
@@ -1046,6 +1046,13 @@ c_common_post_options (const char **pfilename)
else if (warn_narrowing == -1)
warn_narrowing = 0;
+ if (cxx_dialect >= cxx20)
+ {
+ /* Don't warn about C++20 compatibility changes in C++20 or later. */
+ warn_cxx20_compat = 0;
+ cpp_opts->cpp_warn_cxx20_compat = 0;
+ }
+
/* C++17 has stricter evaluation order requirements; let's use some of them
for earlier C++ as well, so chaining works as expected. */
if (c_dialect_cxx ()
@@ -455,7 +455,7 @@ Wc++2a-compat
C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
Wc++20-compat
-C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
+C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT)
Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020.
Wc++11-extensions
@@ -924,7 +924,10 @@ cp_lexer_saving_tokens (const cp_lexer* lexer)
/* Store the next token from the preprocessor in *TOKEN. Return true
if we reach EOF. If LEXER is NULL, assume we are handling an
initial #pragma pch_preprocess, and thus want the lexer to return
- processed strings. */
+ processed strings.
+
+ Diagnostics issued from this function must have their controlling option (if
+ any) in c.opt annotated as a libcpp option via the CppReason property. */
static void
cp_lexer_get_preprocessor_token (unsigned flags, cp_token *token)
new file mode 100644
@@ -0,0 +1,16 @@
+// { dg-do compile { target c++98_only } }
+// { dg-options "-Wc++11-compat" }
+
+// Validate suppression of -Wc++11-compat diagnostics.
+#pragma GCC diagnostic ignored "-Wc++11-compat"
+int alignof;
+int alignas;
+int constexpr;
+int decltype;
+int noexcept;
+int nullptr;
+int static_assert;
+int thread_local;
+int _Alignas;
+int _Alignof;
+int _Thread_local;
new file mode 100644
@@ -0,0 +1,13 @@
+// { dg-do compile { target c++17_down } }
+// { dg-options "-Wc++20-compat" }
+
+// Validate suppression of -Wc++20-compat diagnostics.
+#pragma GCC diagnostic ignored "-Wc++20-compat"
+int constinit;
+int consteval;
+int requires;
+int concept;
+int co_await;
+int co_yield;
+int co_return;
+int char8_t;
@@ -547,6 +547,9 @@ struct cpp_options
/* True if warn about differences between C++98 and C++11. */
bool cpp_warn_cxx11_compat;
+ /* True if warn about differences between C++17 and C++20. */
+ bool cpp_warn_cxx20_compat;
+
/* Nonzero if bidirectional control characters checking is on. See enum
cpp_bidirectional_level. */
unsigned char cpp_warn_bidirectional;
@@ -655,6 +658,7 @@ enum cpp_warning_reason {
CPP_W_C90_C99_COMPAT,
CPP_W_C11_C2X_COMPAT,
CPP_W_CXX11_COMPAT,
+ CPP_W_CXX20_COMPAT,
CPP_W_EXPANSION_TO_DEFINED,
CPP_W_BIDIRECTIONAL
};
@@ -202,6 +202,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table *table,
CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1;
CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) = -1;
CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0;
+ CPP_OPTION (pfile, cpp_warn_cxx20_compat) = 0;
CPP_OPTION (pfile, cpp_warn_deprecated) = 1;
CPP_OPTION (pfile, cpp_warn_long_long) = 0;
CPP_OPTION (pfile, dollars_in_ident) = 1;