Provided by: clang-3.4_3.4-1ubuntu3_amd64 bug

NAME

       clang - the Clang C, C++, and Objective-C compiler

SYNOPSIS

       clang [-c|-S|-E] -std=standard -g
         [-O0|-O1|-O2|-O3|-Ofast|-Os|-Oz|-O|-O4]
         -Wwarnings... -pedantic
         -Idir... -Ldir...
         -Dmacro[=defn]
         -ffeature-option...
         -mmachine-option...
         -o output-file
         -stdlib=library
         input-filenames

DESCRIPTION

       clang is a C, C++, and Objective-C compiler which encompasses preprocessing, parsing,
       optimization, code generation, assembly, and linking.  Depending on which high-level mode
       setting is passed, Clang will stop before doing a full link.  While Clang is highly
       integrated, it is important to understand the stages of compilation, to understand how to
       invoke it.  These stages are:

       Driver
           The clang executable is actually a small driver which controls the overall execution
           of other tools such as the compiler, assembler and linker.  Typically you do not need
           to interact with the driver, but you transparently use it to run the other tools.

       Preprocessing
           This stage handles tokenization of the input source file, macro expansion, #include
           expansion and handling of other preprocessor directives.  The output of this stage is
           typically called a ".i" (for C), ".ii" (for C++), ".mi" (for Objective-C) , or ".mii"
           (for Objective-C++) file.

       Parsing and Semantic Analysis
           This stage parses the input file, translating preprocessor tokens into a parse tree.
           Once in the form of a parser tree, it applies semantic analysis to compute types for
           expressions as well and determine whether the code is well formed. This stage is
           responsible for generating most of the compiler warnings as well as parse errors.  The
           output of this stage is an "Abstract Syntax Tree" (AST).

       Code Generation and Optimization
           This stage translates an AST into low-level intermediate code (known as "LLVM IR") and
           ultimately to machine code.  This phase is responsible for optimizing the generated
           code and handling target-specific code generation.  The output of this stage is
           typically called a ".s" file or "assembly" file.

           Clang also supports the use of an integrated assembler, in which the code generator
           produces object files directly. This avoids the overhead of generating the ".s" file
           and of calling the target assembler.

       Assembler
           This stage runs the target assembler to translate the output of the compiler into a
           target object file.  The output of this stage is typically called a ".o" file or
           "object" file.

       Linker
           This stage runs the target linker to merge multiple object files into an executable or
           dynamic library.  The output of this stage is typically called an "a.out", ".dylib" or
           ".so" file.

       The Clang compiler supports a large number of options to control each of these stages.  In
       addition to compilation of code, Clang also supports other tools:

       Clang Static Analyzer

       The Clang Static Analyzer is a tool that scans source code to try to find bugs through
       code analysis.  This tool uses many parts of Clang and is built into the same driver.
       Please see <http://clang-analyzer.llvm.org> for more details on how to use the static
       analyzer.

OPTIONS

   Stage Selection Options
       -E  Run the preprocessor stage.

       -fsyntax-only
           Run the preprocessor, parser and type checking stages.

       -S  Run the previous stages as well as LLVM generation and optimization stages and target-
           specific code generation, producing an assembly file.

       -c  Run all of the above, plus the assembler, generating a target ".o" object file.

       no stage selection option
           If no stage selection option is specified, all stages above are run, and the linker is
           run to combine the results into an executable or shared library.

   Language Selection and Mode Options
       -x language
           Treat subsequent input files as having type language.

       -std=language
           Specify the language standard to compile for.

       -stdlib=library
           Specify the C++ standard library to use; supported options are libstdc++ and libc++.

       -ansi
           Same as -std=c89.

       -ObjC++
           Treat source input files as Objective-C++ inputs.

       -ObjC
           Treat source input files as Objective-C inputs.

       -trigraphs
           Enable trigraphs.

       -ffreestanding
           Indicate that the file should be compiled for a freestanding, not a hosted,
           environment.

       -fno-builtin
           Disable special handling and optimizations of builtin functions like strlen and
           malloc.

       -fmath-errno
           Indicate that math functions should be treated as updating errno.

       -fpascal-strings
           Enable support for Pascal-style strings with "\pfoo".

       -fms-extensions
           Enable support for Microsoft extensions.

       -fmsc-version=
           Set _MSC_VER. Defaults to 1300 on Windows. Not set otherwise.

       -fborland-extensions
           Enable support for Borland extensions.

       -fwritable-strings
           Make all string literals default to writable.  This disables uniquing of strings and
           other optimizations.

       -flax-vector-conversions
           Allow loose type checking rules for implicit vector conversions.

       -fblocks
           Enable the "Blocks" language feature.

       -fobjc-gc-only
           Indicate that Objective-C code should be compiled in GC-only mode, which only works
           when Objective-C Garbage Collection is enabled.

       -fobjc-gc
           Indicate that Objective-C code should be compiled in hybrid-GC mode, which works with
           both GC and non-GC mode.

       -fobjc-abi-version=version
           Select the Objective-C ABI version to use. Available versions are 1 (legacy "fragile"
           ABI), 2 (non-fragile ABI 1), and 3 (non-fragile ABI 2).

       -fobjc-nonfragile-abi-version=version
           Select the Objective-C non-fragile ABI version to use by default. This will only be
           used as the Objective-C ABI when the non-fragile ABI is enabled (either via
           -fobjc-nonfragile-abi, or because it is the platform default).

       -fobjc-nonfragile-abi
           Enable use of the Objective-C non-fragile ABI. On platforms for which this is the
           default ABI, it can be disabled with -fno-objc-nonfragile-abi.

   Target Selection Options
       Clang fully supports cross compilation as an inherent part of its design.  Depending on
       how your version of Clang is configured, it may have support for a number of cross
       compilers, or may only support a native target.

       -arch architecture
           Specify the architecture to build for.

       -mmacosx-version-min=version
           When building for Mac OS/X, specify the minimum version supported by your application.

       -miphoneos-version-min
           When building for iPhone OS, specify the minimum version supported by your
           application.

       -march=cpu
           Specify that Clang should generate code for a specific processor family member and
           later.  For example, if you specify -march=i486, the compiler is allowed to generate
           instructions that are valid on i486 and later processors, but which may not exist on
           earlier ones.

   Code Generation Options
       -O0 -O1 -O2 -O3 -Ofast -Os -Oz -O -O4
           Specify which optimization level to use:

           -O0 Means "no optimization": this level compiles the fastest and generates the most
               debuggable code.

           -O1 Somewhere between -O0 and -O2.

           -O2 Moderate level of optimization which enables most optimizations.

           -O3 Like -O2, except that it enables optimizations that take longer to perform or that
               may generate larger code (in an attempt to make the program run faster).

           -Ofast
               Enables all the optimizations from -O3 along with other aggressive optimizations
               that may violate strict compliance with language standards.

           -Os Like -O2 with extra optimizations to reduce code size.

           -Oz Like -Os (and thus -O2), but reduces code size further.

           -O  Equivalent to -O2.

           -O4 and higher
               Currently equivalent to -O3

       -g  Generate debug information.  Note that Clang debug information works best at -O0.  At
           higher optimization levels, only line number information is currently available.

       -fexceptions
           Enable generation of unwind information, this allows exceptions to be thrown through
           Clang compiled stack frames.  This is on by default in x86-64.

       -ftrapv
           Generate code to catch integer overflow errors.  Signed integer overflow is undefined
           in C, with this flag, extra code is generated to detect this and abort when it
           happens.

       -fvisibility
           This flag sets the default visibility level.

       -fcommon
           This flag specifies that variables without initializers get common linkage.  It can be
           disabled with -fno-common.

       -ftls-model
           Set the default thread-local storage (TLS) model to use for thread-local variables.
           Valid values are: "global-dynamic", "local-dynamic", "initial-exec" and "local-exec".
           The default is "global-dynamic". The default model can be overridden with the
           tls_model attribute. The compiler will try to choose a more efficient model if
           possible.

       -flto -emit-llvm
           Generate output files in LLVM formats, suitable for link time optimization. When used
           with -S this generates LLVM intermediate language assembly files, otherwise this
           generates LLVM bitcode format object files (which may be passed to the linker
           depending on the stage selection options).

   Driver Options
       -###
           Print the commands to run for this compilation.

       --help
           Display available options.

       -Qunused-arguments
           Don't emit warning for unused driver arguments.

       -Wa,args
           Pass the comma separated arguments in args to the assembler.

       -Wl,args
           Pass the comma separated arguments in args to the linker.

       -Wp,args
           Pass the comma separated arguments in args to the preprocessor.

       -Xanalyzer arg
           Pass arg to the static analyzer.

       -Xassembler arg
           Pass arg to the assembler.

       -Xlinker arg
           Pass arg to the linker.

       -Xpreprocessor arg
           Pass arg to the preprocessor.

       -o file
           Write output to file.

       -print-file-name=file
           Print the full library path of file.

       -print-libgcc-file-name
           Print the library path for "libgcc.a".

       -print-prog-name=name
           Print the full program path of name.

       -print-search-dirs
           Print the paths used for finding libraries and programs.

       -save-temps
           Save intermediate compilation results.

       -integrated-as -no-integrated-as
           Used to enable and disable, respectively, the use of the integrated assembler. Whether
           the integrated assembler is on by default is target dependent.

       -time
           Time individual commands.

       -ftime-report
           Print timing summary of each stage of compilation.

       -v  Show commands to run and use verbose output.

   Diagnostics Options
       -fshow-column -fshow-source-location -fcaret-diagnostics -fdiagnostics-fixit-info
       -fdiagnostics-parseable-fixits -fdiagnostics-print-source-range-info
       -fprint-source-range-info -fdiagnostics-show-option -fmessage-length
           These options control how Clang prints out information about diagnostics (errors and
           warnings).  Please see the Clang User's Manual for more information.

   Preprocessor Options
       -Dmacroname=value
           Adds an implicit #define into the predefines buffer which is read before the source
           file is preprocessed.

       -Umacroname
           Adds an implicit #undef into the predefines buffer which is read before the source
           file is preprocessed.

       -include filename
           Adds an implicit #include into the predefines buffer which is read before the source
           file is preprocessed.

       -Idirectory
           Add the specified directory to the search path for include files.

       -Fdirectory
           Add the specified directory to the search path for framework include files.

       -nostdinc
           Do not search the standard system directories or compiler builtin directories for
           include files.

       -nostdlibinc
           Do not search the standard system directories for include files, but do search
           compiler builtin include directories.

       -nobuiltininc
           Do not search clang's builtin directory for include files.

ENVIRONMENT

       TMPDIR, TEMP, TMP
           These environment variables are checked, in order, for the location to write temporary
           files used during the compilation process.

       CPATH
           If this environment variable is present, it is treated as a delimited list of paths to
           be added to the default system include path list. The delimiter is the platform
           dependent delimitor, as used in the PATH environment variable.

           Empty components in the environment variable are ignored.

       C_INCLUDE_PATH, OBJC_INCLUDE_PATH, CPLUS_INCLUDE_PATH, OBJCPLUS_INCLUDE_PATH
           These environment variables specify additional paths, as for CPATH, which are only
           used when processing the appropriate language.

       MACOSX_DEPLOYMENT_TARGET
           If -mmacosx-version-min is unspecified, the default deployment target is read from
           this environment variable.  This option only affects darwin targets.

BUGS

       To report bugs, please visit <http://llvm.org/bugs/>.  Most bug reports should include
       preprocessed source files (use the -E option) and the full output of the compiler, along
       with information to reproduce.

SEE ALSO

        as(1), ld(1)

AUTHOR

       Maintained by the Clang / LLVM Team (<http://clang.llvm.org>).