On Sat, Mar 2, 2024 at 5:04 AM Ken Matsui <kmat...@gcc.gnu.org> wrote:
>
> This patch adds a warning switch for "#pragma once in main file". The
> warning option name is Wpragma-once-outside-header, which is the same
> as Clang.
Ping.
>
> PR preprocessor/89808
>
> gcc/c-family/ChangeLog:
>
> * c-opts.cc (c_common_handle_option): Handle
> OPT_Wpragma_once_outside_header.
> * c.opt (Wpragma_once_outside_header): Define new option.
>
> gcc/ChangeLog:
>
> * doc/invoke.texi (Warning Options): Document
> -Wno-pragma-once-outside-header.
>
> libcpp/ChangeLog:
>
> * include/cpplib.h (struct cpp_options): Define
> cpp_warn_pragma_once_outside_header.
> * directives.cc (do_pragma_once): Use
> cpp_warn_pragma_once_outside_header.
> * init.cc (cpp_create_reader): Handle
> cpp_warn_pragma_once_outside_header.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/Wpragma-once-outside-header.C: New test.
> * g++.dg/warn/Wno-pragma-once-outside-header.C: New test.
> * g++.dg/warn/Wpragma-once-outside-header.C: New test.
>
> Signed-off-by: Ken Matsui <kmat...@gcc.gnu.org>
> ---
> gcc/c-family/c-opts.cc | 9 +++++++++
> gcc/c-family/c.opt | 4 ++++
> gcc/doc/invoke.texi | 10 ++++++++--
> gcc/testsuite/g++.dg/Wpragma-once-outside-header.C | 5 +++++
> .../g++.dg/warn/Wno-pragma-once-outside-header.C | 5 +++++
> .../g++.dg/warn/Wpragma-once-outside-header.C | 5 +++++
> libcpp/directives.cc | 8 ++++++--
> libcpp/include/cpplib.h | 4 ++++
> libcpp/init.cc | 1 +
> 9 files changed, 47 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/Wpragma-once-outside-header.C
> create mode 100644 gcc/testsuite/g++.dg/warn/Wno-pragma-once-outside-header.C
> create mode 100644 gcc/testsuite/g++.dg/warn/Wpragma-once-outside-header.C
>
> diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
> index be3058dca63..4edd8c6c515 100644
> --- a/gcc/c-family/c-opts.cc
> +++ b/gcc/c-family/c-opts.cc
> @@ -430,6 +430,15 @@ c_common_handle_option (size_t scode, const char *arg,
> HOST_WIDE_INT value,
> cpp_opts->warn_num_sign_change = value;
> break;
>
> + case OPT_Wpragma_once_outside_header:
> + if (value == 0)
> + cpp_opts->cpp_warn_pragma_once_outside_header = 0;
> + else if (kind == DK_ERROR)
> + cpp_opts->cpp_warn_pragma_once_outside_header = 2;
> + else
> + cpp_opts->cpp_warn_pragma_once_outside_header = 1;
> + break;
> +
> case OPT_Wunknown_pragmas:
> /* Set to greater than 1, so that even unknown pragmas in
> system headers will be warned about. */
> diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
> index b7a4a1a68e3..6841a5a5e81 100644
> --- a/gcc/c-family/c.opt
> +++ b/gcc/c-family/c.opt
> @@ -1180,6 +1180,10 @@ Wpragmas
> C ObjC C++ ObjC++ Var(warn_pragmas) Init(1) Warning
> Warn about misuses of pragmas.
>
> +Wpragma-once-outside-header
> +C ObjC C++ ObjC++ Var(warn_pragma_once_outside_header) Init(1) Warning
> +Warn about #pragma once outside of a header.
> +
> Wprio-ctor-dtor
> C ObjC C++ ObjC++ Var(warn_prio_ctor_dtor) Init(1) Warning
> Warn if constructor or destructors with priorities from 0 to 100 are used.
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index bdf05be387d..eeb8954bcdf 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -391,8 +391,8 @@ Objective-C and Objective-C++ Dialects}.
> -Wpacked -Wno-packed-bitfield-compat -Wpacked-not-aligned -Wpadded
> -Wparentheses -Wno-pedantic-ms-format
> -Wpointer-arith -Wno-pointer-compare -Wno-pointer-to-int-cast
> --Wno-pragmas -Wno-prio-ctor-dtor -Wredundant-decls
> --Wrestrict -Wno-return-local-addr -Wreturn-type
> +-Wno-pragmas -Wno-pragma-once-outside-header -Wno-prio-ctor-dtor
> +-Wredundant-decls -Wrestrict -Wno-return-local-addr -Wreturn-type
> -Wno-scalar-storage-order -Wsequence-point
> -Wshadow -Wshadow=global -Wshadow=local -Wshadow=compatible-local
> -Wno-shadow-ivar
> @@ -7955,6 +7955,12 @@ Do not warn about misuses of pragmas, such as
> incorrect parameters,
> invalid syntax, or conflicts between pragmas. See also
> @option{-Wunknown-pragmas}.
>
> +@opindex Wno-pragma-once-outside-header
> +@opindex Wpragma-once-outside-header
> +@item -Wno-pragma-once-outside-header
> +Do not warn when @code{#pragma once} is used in a file that is not a header
> +file, such as a main file.
> +
> @opindex Wno-prio-ctor-dtor
> @opindex Wprio-ctor-dtor
> @item -Wno-prio-ctor-dtor
> diff --git a/gcc/testsuite/g++.dg/Wpragma-once-outside-header.C
> b/gcc/testsuite/g++.dg/Wpragma-once-outside-header.C
> new file mode 100644
> index 00000000000..678bd4e7626
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/Wpragma-once-outside-header.C
> @@ -0,0 +1,5 @@
> +/* { dg-do assemble } */
> +/* { dg-options "-Werror=pragma-once-outside-header" } */
> +
> +#pragma once // { dg-error "#pragma once in main file" }
> +int main() {}
> diff --git a/gcc/testsuite/g++.dg/warn/Wno-pragma-once-outside-header.C
> b/gcc/testsuite/g++.dg/warn/Wno-pragma-once-outside-header.C
> new file mode 100644
> index 00000000000..b5be4d25a9d
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wno-pragma-once-outside-header.C
> @@ -0,0 +1,5 @@
> +// { dg-do assemble }
> +// { dg-options "-Wno-pragma-once-outside-header" }
> +
> +#pragma once
> +int main() {}
> diff --git a/gcc/testsuite/g++.dg/warn/Wpragma-once-outside-header.C
> b/gcc/testsuite/g++.dg/warn/Wpragma-once-outside-header.C
> new file mode 100644
> index 00000000000..ae958d3beb8
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/warn/Wpragma-once-outside-header.C
> @@ -0,0 +1,5 @@
> +// { dg-do assemble }
> +// { dg-options "-Werror=pragma-once-outside-header" }
> +
> +#pragma once // { dg-error "#pragma once in main file" }
> +int main() {}
> diff --git a/libcpp/directives.cc b/libcpp/directives.cc
> index 479f8c716e8..b6121a459f8 100644
> --- a/libcpp/directives.cc
> +++ b/libcpp/directives.cc
> @@ -1588,8 +1588,12 @@ do_pragma (cpp_reader *pfile)
> static void
> do_pragma_once (cpp_reader *pfile)
> {
> - if (_cpp_in_main_source_file (pfile))
> - cpp_error (pfile, CPP_DL_WARNING, "#pragma once in main file");
> + const unsigned char warn_level =
> + CPP_OPTION (pfile, cpp_warn_pragma_once_outside_header);
> +
> + if (warn_level && _cpp_in_main_source_file (pfile))
> + cpp_error (pfile, (warn_level == 1 ? CPP_DL_WARNING : CPP_DL_ERROR),
> + "#pragma once in main file");
>
> check_eol (pfile, false);
> _cpp_mark_file_once_only (pfile, pfile->buffer->file);
> diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
> index c62374d3192..d25b9606153 100644
> --- a/libcpp/include/cpplib.h
> +++ b/libcpp/include/cpplib.h
> @@ -583,6 +583,10 @@ struct cpp_options
> 2 if it should be a pedwarn. */
> unsigned char cpp_warn_invalid_utf8;
>
> + /* True if libcpp should warn about #pragma once outside of a header.
> + 2 if it should be an error, i.e., -Werror. */
> + unsigned char cpp_warn_pragma_once_outside_header;
> +
> /* True if libcpp should warn about invalid forms of delimited or named
> escape sequences. */
> bool cpp_warn_unicode;
> diff --git a/libcpp/init.cc b/libcpp/init.cc
> index 54fc9236d38..4be1afdb2c2 100644
> --- a/libcpp/init.cc
> +++ b/libcpp/init.cc
> @@ -235,6 +235,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table
> *table,
> CPP_OPTION (pfile, cpp_warn_bidirectional) = bidirectional_unpaired;
> CPP_OPTION (pfile, cpp_warn_invalid_utf8) = 0;
> CPP_OPTION (pfile, cpp_warn_unicode) = 1;
> + CPP_OPTION (pfile, cpp_warn_pragma_once_outside_header) = 1;
> CPP_OPTION (pfile, cpp_input_charset_explicit) = 0;
>
> /* Default CPP arithmetic to something sensible for the host for the
> --
> 2.44.0
>
