fix rust lints #1545

Job	Run time
Test Big Endian	9m 17s
ASAN	6m 17s
Bazel	5m 19s
macOS	14m 49s
UBSAN	8m 24s
Ubuntu 18.04 (Build: Debug, Compilers: gcc-6/g++-6, Shared Library: true)	10m 20s
Ubuntu 18.04 (Build: Debug, Compilers: clang-6.0/clang++-6.0, Shared Library: true)	8m 59s
Windows 2019 (Generator: MinGW Makefiles, Shared Library: true)	18m 59s
Windows 2019 (Generator: MinGW Makefiles, Shared Library: false)	19m 7s
Ubuntu 18.04 (Build: Debug, Compilers: clang-6.0/clang++-6.0, Shared Library: false)	9m 20s
Windows 2019 (Generator: Visual Studio 16 2019, Shared Library: true)	9m 32s
Ubuntu 18.04 (Build: Release, Compilers: gcc-6/g++-6, Shared Library: true)	15m 6s
Windows 2019 (Generator: Visual Studio 16 2019, Shared Library: false)	9m 8s
Ubuntu 18.04 (Build: Release, Compilers: gcc-6/g++-6, Shared Library: false)	14m 40s
Ubuntu 18.04 (Build: Release, Compilers: clang-6.0/clang++-6.0, Shared Library: true)	13m 49s
Ubuntu 18.04 (Build: Release, Compilers: clang-6.0/clang++-6.0, Shared Library: false)	14m 19s
	3h 7m 25s

Provide feedback