Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6")
missed the fact that <linux/compiler-gcc.h> is included by Clang
as well as by GCC.
Clang actually defines __GNUC__, __GNUC_MINOR__, __GNUC_PATCHLEVEL__
and it looks like GCC 4.2.1.
$ scripts/gcc-version.sh -p clang
040201
If you try to build the kernel with Clang, you will get the
"Sorry, your compiler is too old - please upgrade it."
followed by a bunch of "unknown attribute" warnings.
Add !defined(__clang__) to the minimum version check.
Also, revive the version test blocks for versions >= 4.2.1
in order to disable features not supported by Clang.
Fixes: cafa0010cd51 ("Raise the minimum required gcc version to 4.6")
Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
---
include/linux/compiler-gcc.h | 34 ++++++++++++++++++++++++++++------
1 file changed, 28 insertions(+), 6 deletions(-)
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 250b9b7..8e41fd2 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -10,7 +10,7 @@
+ __GNUC_MINOR__ * 100 \
+ __GNUC_PATCHLEVEL__)
-#if GCC_VERSION < 40600
+#if !defined(__clang__) && GCC_VERSION < 40600
# error Sorry, your compiler is too old - please upgrade it.
#endif
@@ -163,7 +163,16 @@
#define __used __attribute__((__used__))
#define __compiler_offsetof(a, b) \
__builtin_offsetof(a, b)
+#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
+/*
+ * GCC version specific checks
+ *
+ * Keep the version checks for 4.2.1 or newer
+ * because Clang defines GCC_VERSION as 40201
+ */
+
+#if GCC_VERSION >= 40300
/* Mark functions as cold. gcc will assume any path leading to a call
* to them will be unlikely. This means a lot of manual unlikely()s
* are unnecessary now for any paths leading to the usual suspects
@@ -182,15 +191,20 @@
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+#ifndef __CHECKER__
+# define __compiletime_warning(message) __attribute__((warning(message)))
+# define __compiletime_error(message) __attribute__((error(message)))
+#endif /* __CHECKER__ */
+#endif /* GCC_VERSION >= 40300 */
+
+#if GCC_VERSION >= 40400
#define __optimize(level) __attribute__((__optimize__(level)))
#define __nostackprotector __optimize("no-stack-protector")
+#endif /* GCC_VERSION >= 40400 */
-#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
+#if GCC_VERSION >= 40500
#ifndef __CHECKER__
-#define __compiletime_warning(message) __attribute__((warning(message)))
-#define __compiletime_error(message) __attribute__((error(message)))
-
#ifdef LATENT_ENTROPY_PLUGIN
#define __latent_entropy __attribute__((latent_entropy))
#endif
@@ -232,6 +246,9 @@
#define randomized_struct_fields_end } __randomize_layout;
#endif
+#endif /* GCC_VERSION >= 40500 */
+
+#if GCC_VERSION >= 40600
/*
* When used with Link Time Optimization, gcc can optimize away C functions or
* variables which are referenced only from assembly code. __visible tells the
@@ -240,7 +257,7 @@
*/
#define __visible __attribute__((externally_visible))
-/* gcc version specific checks */
+#endif /* GCC_VERSION >= 40600 */
#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
/*
@@ -274,8 +291,10 @@
* folding in __builtin_bswap*() (yet), so don't set these for it.
*/
#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
+#if GCC_VERSION >= 40400
#define __HAVE_BUILTIN_BSWAP32__
#define __HAVE_BUILTIN_BSWAP64__
+#endif
#if GCC_VERSION >= 40800
#define __HAVE_BUILTIN_BSWAP16__
#endif
@@ -327,9 +346,12 @@
#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)
--
2.7.4
