[meta-multimedia][PATCH] libcamera: Update the patch to upstreamed one

[meta-multimedia][PATCH] libcamera: Update the patch to upstreamed one

[Khem Raj]

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 ...o-variable-to-avoid-range-loop-warni.patch | 155 +++++++++++++-----
 1 file changed, 117 insertions(+), 38 deletions(-)

diff --git a/meta-multimedia/recipes-multimedia/libcamera/libcamera/0001-uvcvideo-Use-auto-variable-to-avoid-range-loop-warni.patch b/meta-multimedia/recipes-multimedia/libcamera/libcamera/0001-uvcvideo-Use-auto-variable-to-avoid-range-loop-warni.patch
index 4ca412c695..86e469bf7e 100644
--- a/meta-multimedia/recipes-multimedia/libcamera/libcamera/0001-uvcvideo-Use-auto-variable-to-avoid-range-loop-warni.patch
+++ b/meta-multimedia/recipes-multimedia/libcamera/libcamera/0001-uvcvideo-Use-auto-variable-to-avoid-range-loop-warni.patch
@@ -1,38 +1,117 @@
-From 767267ef69c001870d41caf9c60dd7fec89b0a13 Mon Sep 17 00:00:00 2001
-From: Khem Raj <raj.khem@gmail.com>
-Date: Wed, 3 Mar 2021 15:11:46 -0800
-Subject: [PATCH] uvcvideo: Use auto variable to avoid range loop warnings
-
-With c++17 loop range bases are defined where copy is obvious since
-iterator returns a copy and not reference, gcc11 will emit a warning
-about this
-
-uvcvideo.cpp:432:33: error: loop variable 'name' of type 'const string&' {aka 'const std::__cxx11::basic_string<cha
-r>&'} binds to a temporary constructed from type 'const char* const' [-Werror=range-loop-construct]
-|   432 |         for (const std::string &name : { "idVendor", "idProduct" }) {
-|       |                                 ^~~~
-
-Therefore making it explicit is better
-
-Upstream-Status: Submitted [https://lists.libcamera.org/pipermail/libcamera-devel/2021-March/017966.html]
-Signed-off-by: Khem Raj <raj.khem@gmail.com>
----
- src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 2 +-
- 1 file changed, 1 insertion(+), 1 deletion(-)
-
-diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
-index 031f96e2..ef23ece7 100644
---- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
-+++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
-@@ -429,7 +429,7 @@ std::string PipelineHandlerUVC::generateId(const UVCCameraData *data)
- 
- 	/* Creata a device ID from the USB devices vendor and product ID. */
- 	std::string deviceId;
--	for (const std::string &name : { "idVendor", "idProduct" }) {
-+	for (const auto name : { "idVendor", "idProduct" }) {
- 		std::ifstream file(path + "/../" + name);
- 
- 		if (!file.is_open())
--- 
-2.30.1
-
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+From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+To: libcamera-devel@lists.libcamera.org
+Cc: Khem Raj <raj.khem@gmail.com>
+Subject: [PATCH v2] libcamera: pipeline: uvcvideo: Avoid reference to temporary object
+Date: Sun, 28 Mar 2021 05:57:41 +0300
+Message-Id: <20210328025741.30246-1-laurent.pinchart@ideasonboard.com>
+X-Mailer: git-send-email 2.28.1
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+
+From: Khem Raj <raj.khem@gmail.com>
+
+A range-based for loop whose range expression is an array of char
+pointers and range variable declaration is a const reference to a
+std::string creates a temporary string from the char pointer and binds
+the range variable reference to it. This creates a const reference to a
+temporary, which is valid in C++, and extends the lifetime of the
+temporary to the lifetime of the reference.
+
+However, lifetime extension in range-based for loops is considered as a
+sign of a potential issue, as a temporary is created for every
+iteration, which can be costly, and the usage of a reference in the
+range declaration doesn't make it obvious that the code isn't simply
+binding a reference to an existing object. gcc 11, with the
+-Wrange-loop-construct option, flags this:
+
+uvcvideo.cpp:432:33: error: loop variable 'name' of type 'const string&' {aka 'const std::__cxx11::basic_string<cha
+r>&'} binds to a temporary constructed from type 'const char* const' [-Werror=range-loop-construct]
+|   432 |         for (const std::string &name : { "idVendor", "idProduct" }) {
+|       |                                 ^~~~
+
+To please the compiler, make the range variable a const char *. This may
+bring a tiny performance improvement, as the name is only used once, in
+a location where the compiler can use
+
+	operator+(const std::string &, const char *)
+
+instead of
+
+	operator+(const std::string &, const std::string &)
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+
+Use a const char * type instead of auto, and update the commit message
+accordingly.
+
+Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+---
+ src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+index 031f96e28449..b6c6ade5ebaf 100644
+--- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
++++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+@@ -429,7 +429,7 @@ std::string PipelineHandlerUVC::generateId(const UVCCameraData *data)
+ 
+ 	/* Creata a device ID from the USB devices vendor and product ID. */
+ 	std::string deviceId;
+-	for (const std::string &name : { "idVendor", "idProduct" }) {
++	for (const char *name : { "idVendor", "idProduct" }) {
+ 		std::ifstream file(path + "/../" + name);
+ 
+ 		if (!file.is_open())
+-- 
+Regards,
+
+Laurent Pinchart
+
-- 
2.31.1