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>
---
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
--
2.45.1
