+++ /dev/null
-From: Arnd Bergmann <arnd@arndb.de>
-Date: Tue, 19 Jun 2018 13:14:56 -0700
-Subject: [PATCH] kbuild: add macro for controlling warnings to
- linux/compiler.h
-
-I have occasionally run into a situation where it would make sense to
-control a compiler warning from a source file rather than doing so from
-a Makefile using the $(cc-disable-warning, ...) or $(cc-option, ...)
-helpers.
-
-The approach here is similar to what glibc uses, using __diag() and
-related macros to encapsulate a _Pragma("GCC diagnostic ...") statement
-that gets turned into the respective "#pragma GCC diagnostic ..." by
-the preprocessor when the macro gets expanded.
-
-Like glibc, I also have an argument to pass the affected compiler
-version, but decided to actually evaluate that one. For now, this
-supports GCC_4_6, GCC_4_7, GCC_4_8, GCC_4_9, GCC_5, GCC_6, GCC_7,
-GCC_8 and GCC_9. Adding support for CLANG_5 and other interesting
-versions is straightforward here. GNU compilers starting with gcc-4.2
-could support it in principle, but "#pragma GCC diagnostic push"
-was only added in gcc-4.6, so it seems simpler to not deal with those
-at all. The same versions show a large number of warnings already,
-so it seems easier to just leave it at that and not do a more
-fine-grained control for them.
-
-The use cases I found so far include:
-
-- turning off the gcc-8 -Wattribute-alias warning inside of the
- SYSCALL_DEFINEx() macro without having to do it globally.
-
-- Reducing the build time for a simple re-make after a change,
- once we move the warnings from ./Makefile and
- ./scripts/Makefile.extrawarn into linux/compiler.h
-
-- More control over the warnings based on other configurations,
- using preprocessor syntax instead of Makefile syntax. This should make
- it easier for the average developer to understand and change things.
-
-- Adding an easy way to turn the W=1 option on unconditionally
- for a subdirectory or a specific file. This has been requested
- by several developers in the past that want to have their subsystems
- W=1 clean.
-
-- Integrating clang better into the build systems. Clang supports
- more warnings than GCC, and we probably want to classify them
- as default, W=1, W=2 etc, but there are cases in which the
- warnings should be classified differently due to excessive false
- positives from one or the other compiler.
-
-- Adding a way to turn the default warnings into errors (e.g. using
- a new "make E=0" tag) while not also turning the W=1 warnings into
- errors.
-
-This patch for now just adds the minimal infrastructure in order to
-do the first of the list above. As the #pragma GCC diagnostic
-takes precedence over command line options, the next step would be
-to convert a lot of the individual Makefiles that set nonstandard
-options to use __diag() instead.
-
-[paul.burton@mips.com:
- - Rebase atop current master.
- - Add __diag_GCC, or more generally __diag_<compiler>, abstraction to
- avoid code outside of linux/compiler-gcc.h needing to duplicate
- knowledge about different GCC versions.
- - Add a comment argument to __diag_{ignore,warn,error} which isn't
- used in the expansion of the macros but serves to push people to
- document the reason for using them - per feedback from Kees Cook.
- - Translate severity to GCC-specific pragmas in linux/compiler-gcc.h
- rather than using GCC-specific in linux/compiler_types.h.
- - Drop all but GCC 8 macros, since we only need to define macros for
- versions that we need to introduce pragmas for, and as of this
- series that's just GCC 8.
- - Capitalize comments in linux/compiler-gcc.h to match the style of
- the rest of the file.
- - Line up macro definitions with tabs in linux/compiler-gcc.h.]
-
-Signed-off-by: Arnd Bergmann <arnd@arndb.de>
-Signed-off-by: Paul Burton <paul.burton@mips.com>
-Tested-by: Christophe Leroy <christophe.leroy@c-s.fr>
-Tested-by: Stafford Horne <shorne@gmail.com>
-Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
----
-
---- a/include/linux/compiler-gcc.h
-+++ b/include/linux/compiler-gcc.h
-@@ -351,3 +351,30 @@
- #if GCC_VERSION >= 50100
- #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
- #endif
-+
-+
-+/*
-+ * Turn individual warnings and errors on and off locally, depending
-+ * on version.
-+ */
-+#define __diag_GCC(version, severity, s) \
-+ __diag_GCC_ ## version(__diag_GCC_ ## severity s)
-+
-+/* Severity used in pragma directives */
-+#define __diag_GCC_ignore ignored
-+#define __diag_GCC_warn warning
-+#define __diag_GCC_error error
-+
-+/* Compilers before gcc-4.6 do not understand "#pragma GCC diagnostic push" */
-+#if GCC_VERSION >= 40600
-+#define __diag_str1(s) #s
-+#define __diag_str(s) __diag_str1(s)
-+#define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
-+#endif
-+
-+#if GCC_VERSION >= 80000
-+#define __diag_GCC_8(s) __diag(s)
-+#else
-+#define __diag_GCC_8(s)
-+#endif
-+
---- a/include/linux/compiler.h
-+++ b/include/linux/compiler.h
-@@ -605,4 +605,23 @@ unsigned long read_word_at_a_time(const
- # define __kprobes
- # define nokprobe_inline inline
- #endif
-+
-+#ifndef __diag
-+#define __diag(string)
-+#endif
-+
-+#ifndef __diag_GCC
-+#define __diag_GCC(version, severity, string)
-+#endif
-+
-+#define __diag_push() __diag(push)
-+#define __diag_pop() __diag(pop)
-+
-+#define __diag_ignore(compiler, version, option, comment) \
-+ __diag_ ## compiler(version, ignore, option)
-+#define __diag_warn(compiler, version, option, comment) \
-+ __diag_ ## compiler(version, warn, option)
-+#define __diag_error(compiler, version, option, comment) \
-+ __diag_ ## compiler(version, error, option)
-+
- #endif /* __LINUX_COMPILER_H */
projects / openwrt / staging / dedeckeh.git / blobdiff