clang-typecheck

A command line tool to type check a C++ source file with a clang compilation database.

The database contains the compiler commands - with all flags, defines and includes - of all source files of the project. The easiest way to get a database is for a cmake build project by calling cmake with the option -DCMAKE_EXPORT_COMPILE_COMMANDS=ON. After the complete rebuild of the project the root of the build directory will contain a database named compile_commands.json.

clang-typecheck extracts the compiler command for the given source file from the database, executes it and outputs the output of the compiler.

The design of clang-typecheck was to get the most minimal program, that doesn't need any configuration and should just work.

There're several programs operating with a database and also doing type checking, like rtags or YouComplete, but either - in the case of rtags - they do the type checking asynchronously, which makes it harder to integrate into several editors or - in the case of YouCompleteMe - they feel quite a bit heavyweight, are harder to configure and slow done vim quite a bit.

Another issue is, that these programs sometimes use clang for the type checking and not the compiler used in the database, which might give different warnings for the type checking and the building.

clang-typecheck isn't the best fit for on the fly type checking - here the asynchronously solutions are more appropriate - it is meant for synchronous on demand type checking - by pressing some editor shortcut - with minimal hassle to configure.

Installation

clang-typecheck is build with Rust so at least rustc and cargo are needed to build it.

The easiest way to get both is by using rustup:

$> curl https://sh.rustup.rs -sSf | sh

After this call you should have a rustc and cargo binary available at ~/.cargo/bin/, so adding this path to the PATH enviroment variable is recommendable.

For non unix like platforms take a look at here.

And now building and installing clang-typecheck:

$> cargo install clang-typecheck

The build binary will be located at ~/.cargo/bin/clang-typecheck.

Usage

Type checking a source file with a database:

$> clang-typecheck  /absolute_path_to/SomeSource.cpp  path_to/compile_commands.json

This will look up SomeSource.cpp in compile_commands.json, executes the compiler command and outputs the output of the compiler.

This makes it possible to use clang-typecheck as a compiler replacement in editors that parse the output of the compiler and display the errors.

Text Editor Integration

vim-clang-typecheck

Possible Issues

The compiler commands for source files are cached at ~/.clang_typecheck/cache/cmds, so that multiple type checks of the same source don't need to look up the command again in the database. Normally this shouldn't be an issue, because the commands in the database very rarely change in a way that affects type checking, but if there're problems, then the cache at ~/.clang_typecheck/cache/cmds can be just cleared.

Currently only the gcc and clang compilers are supported, because to prevent the object file creation and only apply the type checking the flag -fsyntax-only is appended to the compiler command, which is known by both.