UsersManual.rst

Clang Compiler User's Manual

• Introduction
  • Terminology
  • Basic Usage
• Command Line Options
  • Options to Control Error and Warning Messages
    • Formatting of Diagnostics
    • Individual Warning Groups
  • Options to Control Clang Crash Diagnostics
  • Options to Emit Optimization Reports
    • Current limitations
  • Other Options
• Language and Target-Independent Features
  • Controlling Errors and Warnings
    • Controlling How Clang Displays Diagnostics
    • Diagnostic Mappings
    • Diagnostic Categories
    • Controlling Diagnostics via Command Line Flags
    • Controlling Diagnostics via Pragmas
    • Controlling Diagnostics in System Headers
    • Enabling All Diagnostics
    • Controlling Static Analyzer Diagnostics
  • Precompiled Headers
    • Generating a PCH File
    • Using a PCH File
    • Relocatable PCH Files
  • Controlling Code Generation
  • Profile Guided Optimization
    • Differences Between Sampling and Instrumentation
    • Using Sampling Profilers
      • Sample Profile Formats
      • Sample Profile Text Format
    • Profiling with Instrumentation
    • Disabling Instrumentation
  • Controlling Debug Information
    • Controlling Size of Debug Information
    • Controlling Macro Debug Info Generation
    • Controlling Debugger "Tuning"
  • Comment Parsing Options
• C Language Features
  • Extensions supported by clang
  • Differences between various standard modes
  • GCC extensions not implemented yet
  • Intentionally unsupported GCC extensions
  • Microsoft extensions
• C++ Language Features
  • Controlling implementation limits
• Objective-C Language Features
• Objective-C++ Language Features
• OpenMP Features
  • Controlling implementation limits
• OpenCL Features
  • OpenCL Specific Options
  • OpenCL Targets
    • Specific Targets
    • Generic Targets
  • OpenCL Header
  • OpenCL Extensions
  • OpenCL Metadata
  • OpenCL-Specific Attributes
    • nosvm
    • opencl_unroll_hint
    • convergent
    • noduplicate
    • address_space
  • OpenCL builtins
• Target-Specific Features and Limitations
  • CPU Architectures Features and Limitations
    • X86
    • ARM
    • PowerPC
    • Other platforms
  • Operating System Features and Limitations
    • Darwin (Mac OS X)
    • Windows
      • Cygwin
      • MinGW32
      • MinGW-w64
• clang-cl
  • Command-Line Options
    • The /fallback Option

Introduction

The Clang Compiler is an open-source compiler for the C family of programming languages, aiming to be the best in class implementation of these languages. Clang builds on the LLVM optimizer and code generator, allowing it to provide high-quality optimization and code generation support for many targets. For more general information, please see the Clang Web Site or the LLVM Web Site.

This document describes important notes about using Clang as a compiler for an end-user, documenting the supported features, command line options, etc. If you are interested in using Clang to build a tool that processes code, please see :doc:`InternalsManual`. If you are interested in the Clang Static Analyzer, please see its web page.

Clang is one component in a complete toolchain for C family languages. A separate document describes the other pieces necessary to :doc:`assemble a complete toolchain <Toolchain>`.

Clang is designed to support the C family of programming languages, which includes :ref:`C <c>`, :ref:`Objective-C <objc>`, :ref:`C++ <cxx>`, and :ref:`Objective-C++ <objcxx>` as well as many dialects of those. For language-specific information, please see the corresponding language specific section:

• :ref:`C Language <c>`: K&R C, ANSI C89, ISO C90, ISO C94 (C89+AMD1), ISO C99 (+TC1, TC2, TC3).
• :ref:`Objective-C Language <objc>`: ObjC 1, ObjC 2, ObjC 2.1, plus variants depending on base language.
• :ref:`C++ Language <cxx>`
• :ref:`Objective C++ Language <objcxx>`
• :ref:`OpenCL C Language <opencl>`: v1.0, v1.1, v1.2, v2.0.

In addition to these base languages and their dialects, Clang supports a broad variety of language extensions, which are documented in the corresponding language section. These extensions are provided to be compatible with the GCC, Microsoft, and other popular compilers as well as to improve functionality through Clang-specific features. The Clang driver and language features are intentionally designed to be as compatible with the GNU GCC compiler as reasonably possible, easing migration from GCC to Clang. In most cases, code "just works". Clang also provides an alternative driver, :ref:`clang-cl`, that is designed to be compatible with the Visual C++ compiler, cl.exe.