[PATCH 7/7] kconfig/randconfig: enable UBSAN for randconfig

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

Introduce an additional Kconfig check to only offer the option if the
compiler supports -fsanitize=undefined.

We no longer use Travis CI, so the original motivation for not enabling
UBSAN might no longer present.  Regardless, the option won't be present in
the first place if the compiler doesn't support -fsanitize=undefined.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/Kconfig                        | 4 ++++
 xen/Kconfig.debug                  | 2 +-
 xen/tools/kconfig/allrandom.config | 1 -
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/xen/Kconfig b/xen/Kconfig
index 72fdb8376087..2128f0ccfc0b 100644
--- a/xen/Kconfig
+++ b/xen/Kconfig
@@ -37,6 +37,10 @@ config CC_HAS_VISIBILITY_ATTRIBUTE
 config CC_SPLIT_SECTIONS
        bool
 
+# Compiler supports -fsanitize=undefined
+config CC_HAS_UBSAN
+       def_bool $(cc-option,-fsanitize=undefined)
+
 # Set code alignment.
 #
 # Allow setting on a boolean basis, and then convert such selection to an
diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index c4a8d86912e0..f7cc5ffaabd7 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -98,7 +98,7 @@ config SCRUB_DEBUG
 
 config UBSAN
        bool "Undefined behaviour sanitizer"
-       depends on HAS_UBSAN
+       depends on HAS_UBSAN && CC_HAS_UBSAN
        help
          Enable undefined behaviour sanitizer. It uses compiler to insert code
          snippets so that undefined behaviours in C are detected during 
runtime.
diff --git a/xen/tools/kconfig/allrandom.config 
b/xen/tools/kconfig/allrandom.config
index 76f74320b5b0..c7753ac4addb 100644
--- a/xen/tools/kconfig/allrandom.config
+++ b/xen/tools/kconfig/allrandom.config
@@ -1,4 +1,3 @@
 # Explicit option choices not subject to regular RANDCONFIG
 
 CONFIG_GCOV_FORMAT_AUTODETECT=y
-CONFIG_UBSAN=n
-- 
2.48.1