xenial (1) clang-3.5.1.gz

Provided by: clang-3.5_3.5.2-3ubuntu1_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.

       -fstandalone-debug -fno-standalone-debug
           Clang supports a number of optimizations to reduce the size of debug information in the binary. They
           work based on the assumption that the debug type information can be spread out over multiple
           compilation units.  For instance, Clang will not emit type definitions for types that are not needed
           by a module and could be replaced with a forward declaration.  Further, Clang will only emit type
           info for a dynamic C++ class in the module that contains the vtable for the class.

           The -fstandalone-debug option turns off these optimizations.  This is useful when working with
           3rd-party libraries that don't come with debug information.  This is the default on Darwin.  Note
           that Clang will never emit type information for types that are not referenced at all by the program.

       -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 (but do not run) 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>).