clang

Compile C, C++, Objective-C, and Objective-C++ code

TLDR

Compile multiple source files into an executable

$ clang [path/to/source1.c path/to/source2.c ...] [[-o|--output]] [path/to/output_executable]

Activate output of all errors and warnings

$ clang [path/to/source.c] -Wall [[-o|--output]] [output_executable]

Show common warnings, debug symbols in output, and optimize without affecting debugging

$ clang [path/to/source.c] -Wall [[-g|--debug]] -Og [[-o|--output]] [path/to/output_executable]

Include libraries from a different path

$ clang [path/to/source.c] [[-o|--output]] [path/to/output_executable] -I[path/to/header] -L[path/to/library] -l[library_name]

Compile source code into LLVM Intermediate Representation (IR)

$ clang [[-S|--assemble]] -emit-llvm [path/to/source.c] [[-o|--output]] [path/to/output.ll]

Compile source code into an object file without linking

$ clang [[-c|--compile]] [path/to/source.c]

Optimize the compiled program for performance

$ clang [path/to/source.c] -O[1|2|3|fast] [[-o|--output]] [path/to/output_executable]

Display version

$ clang --version

-c
    Compile and assemble, but do not link.

-o filename
    Specify the output file.

-g
    Produce debugging information.

-On
    Enable optimization level n (e.g., -O0, -O1, -O2, -O3, -Os).

-Idirectory
    Add directory to the include search path.

-Dmacro[=value]
    Define a macro.

-std=standard
    Specify the language standard (e.g., c99, c++11).

-Wall
    Enable most warning messages.

-Werror
    Treat all warnings as errors.

-Ldirectory
    Add directory to the library search path.

-llibrary
    Link with library.

DESCRIPTION

Clang is a compiler frontend for the C, C++, Objective-C, and Objective-C++ programming languages. It uses LLVM as its backend. It is designed to be highly modular, library-based, and easy to integrate with other tools. Clang aims to provide faster compile times, better diagnostics, and improved support for language standards compared to older compilers like GCC.

Clang not only compiles source code into object code, but it also provides robust static analysis capabilities to detect potential errors and enforce coding standards. Its integration with LLVM allows for extensive optimization and code generation for a wide range of target architectures. It is used extensively in both open-source projects and commercial environments, especially where C/C++ code is dominant.

CAVEATS

The specific options and behavior of clang can vary slightly depending on the version and target platform.

STATIC ANALYSIS

Clang integrates a powerful static analyzer that can detect a wide range of potential issues in source code, such as memory leaks, null pointer dereferences, and buffer overflows. This analysis can be performed separately using the clang-analyze tool.

LANGUAGE EXTENSIONS

Clang supports various language extensions and vendor-specific features. These are often controlled via command-line flags or pragmas. Developers should consult the Clang documentation for details on supported extensions.

HISTORY

Clang development began in 2007 as part of the LLVM project. Its goal was to provide a more modular and extensible compiler than GCC. It gained popularity due to its faster compile times and improved error diagnostics, especially for C++ code. Clang is now a widely used compiler in many environments.