From 4f1d1a48fe7ebe1282d7608a59cb059e1367e584 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Wed, 27 Apr 2022 00:50:30 +0300 Subject: libcamera: object: Silence gcc false positive error in release mode MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit gcc 10 and 11 produce an error when compiling libcamera in release mode: In file included from ../../src/libcamera/base/object.cpp:13: ../../include/libcamera/base/message.h: In member function ‘void libcamera::Object::notifyThreadMove()’: ../../include/libcamera/base/message.h:58:47: error: array subscript ‘const libcamera::InvokeMessage[0]’ is partly outside array bounds of ‘libcamera::Message [1]’ [-Werror=array-bounds] 58 | Semaphore *semaphore() const { return semaphore_; } | ^~~~~~~~~~ ../../src/libcamera/base/object.cpp:280:17: note: while referencing ‘msg’ 280 | Message msg(Message::ThreadMoveMessage); | ^~~ This seems to be a false positive, given that msg->type() can never be equal to Message::InvokeMessage in Object::message() when called from Object::notifyThreadMove(), as the message is created there with the Message::ThreadMoveMessage type. The problem as been reported in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105400, but the error nonetheless needs to be fixed without waiting for a new gcc release, and a dynamic_cast does the job with a small additional runtime cost that shouldn't be a big issue, given that moving objects between threads is a rare operation. Bug: https://bugs.libcamera.org/show_bug.cgi?id=125 Signed-off-by: Laurent Pinchart Reviewed-by: Kieran Bingham --- src/libcamera/base/object.cpp | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/libcamera/base/object.cpp b/src/libcamera/base/object.cpp index ec5b55d1..92cecd22 100644 --- a/src/libcamera/base/object.cpp +++ b/src/libcamera/base/object.cpp @@ -189,7 +189,11 @@ void Object::message(Message *msg) { switch (msg->type()) { case Message::InvokeMessage: { - InvokeMessage *iMsg = static_cast(msg); + /* + * A static_cast should be enough, but gcc 10 and 11 choke on + * it in release mode (with -O2 or -O3). + */ + InvokeMessage *iMsg = dynamic_cast(msg); Semaphore *semaphore = iMsg->semaphore(); iMsg->invoke(); -- cgit v1.2.1