On Thu, Jun 13, 2024 at 7:44 AM Jason Merrill <ja...@redhat.com> wrote:
>
> On 6/13/24 10:31, 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.
>
> This bit-field should be unneeded now, along with the uses of it.
Thank you! I'll update the patch shortly.
>
> > (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>
> > ---
> > gcc/c-family/c.opt | 4 ++++
> > gcc/doc/invoke.texi | 10 ++++++++--
> > .../g++.dg/warn/Wno-pragma-once-outside-header.C | 5 +++++
> > .../g++.dg/warn/Wpragma-once-outside-header.C | 6 ++++++
> > libcpp/directives.cc | 9 ++++++---
> > libcpp/include/cpplib.h | 7 ++++++-
> > libcpp/init.cc | 1 +
> > 7 files changed, 36 insertions(+), 6 deletions(-)
> > 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.opt b/gcc/c-family/c.opt
> > index 403abc1f26e..3439f36fe45 100644
> > --- a/gcc/c-family/c.opt
> > +++ b/gcc/c-family/c.opt
> > @@ -1188,6 +1188,10 @@ 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)
> > CppReason(CPP_W_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 9456ced468a..c7f17ca9eb7 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
> > @@ -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
> > 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..324b0638c3f
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/warn/Wpragma-once-outside-header.C
> > @@ -0,0 +1,6 @@
> > +// { dg-do assemble }
> > +// { dg-options "-Werror=pragma-once-outside-header" }
> > +// { dg-message "some warnings being treated as errors" "" {target
> > "*-*-*"} 0 }
> > +
> > +#pragma once // { dg-error "#pragma once in main file" }
> > +int main() {}
> > 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");
> >
> > check_eol (pfile, false);
> > _cpp_mark_file_once_only (pfile, pfile->buffer->file);
> > @@ -2822,4 +2826,3 @@ _cpp_bracket_include(cpp_reader *pfile)
> > {
> > return glue_header_name (pfile);
> > }
> > -
> > diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
> > index c62374d3192..21deaf72ec5 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;
> > @@ -701,7 +705,8 @@ enum cpp_warning_reason {
> > CPP_W_EXPANSION_TO_DEFINED,
> > CPP_W_BIDIRECTIONAL,
> > CPP_W_INVALID_UTF8,
> > - CPP_W_UNICODE
> > + CPP_W_UNICODE,
> > + CPP_W_PRAGMA_ONCE_OUTSIDE_HEADER
> > };
> >
> > /* Callback for header lookup for HEADER, which is the name of a
> > diff --git a/libcpp/init.cc b/libcpp/init.cc
> > index c457fa659e7..ba6e5f08446 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
>
