[libcamera-devel] [PATCH] libcamera: base: Suppress clang-11 compile error on ARM32

[Laurent Pinchart]

From: Naushir Patuck <naush at raspberrypi.com>

Compiling backtrace.cpp for ARM32 produces the following error with the
clang-11 (and later) compiler:

--------------------
../src/libcamera/base/backtrace.cpp:195:12: error: use of SP or PC in the list is deprecated [-Werror,-Winline-asm]
        int ret = unw_getcontext(&uc);
                  ^
/usr/include/arm-linux-gnueabihf/libunwind-common.h:114:29: note: expanded from macro 'unw_getcontext'
                                        ^
/usr/include/arm-linux-gnueabihf/libunwind-arm.h:270:5: note: expanded from macro 'unw_tdep_getcontext'
    "stmia %[base], {r0-r15}"                                           \
    ^
<inline asm>:1:2: note: instantiated into assembly here
        stmia r0, {r0-r15}
--------------------

Suppress this compilation error with a clang-specific pragma around the
offending statements.

Further information about this error can be found at
https://github.com/dotnet/runtime/issues/38652

Bug: https://bugs.libcamera.org/show_bug.cgi?id=136
Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
Tested-by: Jacopo Mondi <jacopo at jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/libcamera/base/backtrace.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/libcamera/base/backtrace.cpp b/src/libcamera/base/backtrace.cpp
index 483492c390c3..be30589d255e 100644
--- a/src/libcamera/base/backtrace.cpp
+++ b/src/libcamera/base/backtrace.cpp
@@ -191,10 +191,22 @@ __attribute__((__noinline__))
 bool Backtrace::unwindTrace()
 {
 #if HAVE_UNWIND
+/*
+ * unw_getcontext() for ARM32 is an inline assembly function using the stmia
+ * instruction to store SP and PC. This is considered by clang-11 as deprecated,
+ * and generates a warning.
+ */
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Winline-asm"
+#endif
 	unw_context_t uc;
 	int ret = unw_getcontext(&uc);
 	if (ret)
 		return false;
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
 
 	unw_cursor_t cursor;
 	ret = unw_init_local(&cursor, &uc);

base-commit: ba6435930f08e802cffc688d90f156a8959a0f86
-- 
Regards,

Laurent Pinchart