While not necessarily a tool in itself, compiler warnings can be used and tweaked to achieve even better output from the one tool every C++ developer will be using: the C++ compiler.
Since the compiler can already do some deeper checks than those required by the standard, it is advised to take advantage of this possibility. When using a compiler such as GCC or Clang, the recommended setting involves -Wall -Wextra flags. This will generate much more diagnostics and result in warnings when your code doesn't follow the diagnostics. If you want to be really strict, you can also enable -Werror, which will turn all the warnings into errors and prevent the compilation of code that doesn't pass the enhanced diagnostics. If you want to keep strictly to the standards, there are the -pedantic and -pedantic-errors flags that will look for conformance against the standards.
When using CMake for building, you can use the following...