On Thu, 2024-06-13 at 07:31 -0700, Ken Matsui 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.
>
> PR preprocessor/89808
>
> gcc/c-family/ChangeLog:
>
> * 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.
> (cpp_warning_reason): Define
> CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER.
> * directives.cc (do_pragma_once): Use
> cpp_warn_pragma_once_outside_header and
> CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER.
> * init.cc (cpp_create_reader): Handle
> cpp_warn_pragma_once_outside_header.
>
> gcc/testsuite/ChangeLog:
>
> * 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>
[...snip...]
Thanks for the updated patch.
> @@ -7983,6 +7983,12 @@ 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
Please run "make html && make regenerate-opt-urls" so that the
diagnostic gets a documentation URL. Sorry that you have to do this
manually (it's to avoid complicating the build dependencies for someone
just building gcc).
[...snip...]
> diff --git a/libcpp/directives.cc b/libcpp/directives.cc
> index 479f8c716e8..68f47104dea 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_warning (pfile, CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER,
> + "#pragma once in main file");
Please put the "#pragma once" in the message in quotes, such as via:
cpp_warning (pfile, CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER,
"%<pragma once%> in main file");
or via:
cpp_warning (pfile, CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER,
"%qs in main file", "pragma once");
Although it's a minor style nit, I'm working on patches to
automatically add URLs to GCC's documentation for certain quoted
strings on sufficiently capable terminals (I've done command-line
options, I'm working on attributes, and I hope to eventually do
pragmas).
Dave
