[Qemu-devel] [PATCH for-4.0] compiler.h: Add an explicit check for the compiler version

[Thomas Huth <thuth@redhat.com>]

The questions about our minimum compiler requirement pops up every
couple of months, and we then have to recall the details each time.
So let's document this in a proper way, by adding a comment and
check for the right compiler version to our compiler.h header.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 include/qemu/compiler.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index ca9bc85..775446b 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -22,6 +22,14 @@
 # define QEMU_GNUC_PREREQ(maj, min) 0
 #endif
 
+/*
+ * We need at least GCC 4.1 for atomics support. Clang also supports these,
+ * and reports itself as GCC 4.2, so it passes this check, too.
+ */
+#if !QEMU_GNUC_PREREQ(4, 1)
+#error QEMU needs a compiler that is compatible with GCC v4.1 or newer
+#endif
+
 #define QEMU_NORETURN __attribute__ ((__noreturn__))
 
 #define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
-- 
1.8.3.1