Provided by: clang-15_15.0.7-10_amd64 bug

NAME

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

SYNOPSIS

       clang [options] filename 

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 parse 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.

       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 <https://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=<standard>
              Specify the language standard to compile for.

              Supported values for the C language are:
                 c89
                 c90
                 iso9899:1990

                     ISO C 1990
                 iso9899:199409

                     ISO C 1990 with amendment 1
                 gnu89
                 gnu90

                     ISO C 1990 with GNU extensions
                 c99
                 iso9899:1999

                     ISO C 1999
                 gnu99

                     ISO C 1999 with GNU extensions
                 c11
                 iso9899:2011

                     ISO C 2011
                 gnu11

                     ISO C 2011 with GNU extensions
                 c17
                 iso9899:2017

                     ISO C 2017
                 gnu17

                     ISO C 2017 with GNU extensions

              The default C language standard is gnu17, except on PS4, where it is gnu99.

              Supported values for the C++ language are:
                 c++98
                 c++03

                     ISO C++ 1998 with amendments
                 gnu++98
                 gnu++03

                     ISO C++ 1998 with amendments and GNU extensions
                 c++11

                     ISO C++ 2011 with amendments
                 gnu++11

                     ISO C++ 2011 with amendments and GNU extensions
                 c++14

                     ISO C++ 2014 with amendments
                 gnu++14

                     ISO C++ 2014 with amendments and GNU extensions
                 c++17

                     ISO C++ 2017 with amendments
                 gnu++17

                     ISO C++ 2017 with amendments and GNU extensions
                 c++20

                     ISO C++ 2020 with amendments
                 gnu++20

                     ISO C++ 2020 with amendments and GNU extensions
                 c++2b

                     Working draft for ISO C++ 2023
                 gnu++2b

                     Working draft for ISO C++ 2023 with GNU extensions

              The default C++ language standard is gnu++14.

              Supported values for the OpenCL language are:
                 cl1.0

                     OpenCL 1.0
                 cl1.1

                     OpenCL 1.1
                 cl1.2

                     OpenCL 1.2
                 cl2.0

                     OpenCL 2.0

              The default OpenCL language standard is cl1.0.

              Supported values for the CUDA language are:
                 cuda

                     NVIDIA CUDA(tm)

       -stdlib=<library>
              Specify  the  C++  standard  library  to  use;  supported options are libstdc++ and
              libc++. If not specified, platform default will be used.

       -rtlib=<library>
              Specify the compiler runtime library to  use;  supported  options  are  libgcc  and
              compiler-rt. If not specified, platform default will be used.

       -ansi  Same as -std=c89.

       -ObjC, -ObjC++
              Treat source input files as Objective-C and Object-C++ inputs respectively.

       -trigraphs
              Enable trigraphs.

       -ffreestanding
              Indicate  that  the  file  should  be  compiled  for  a freestanding, not a hosted,
              environment.  Note  that  it  is  assumed  that  a  freestanding  environment  will
              additionally  provide  memcpy, memmove, memset and memcmp implementations, as these
              are needed for efficient codegen for many programs.

       -fno-builtin
              Disable special handling and optimizations of well-known  library  functions,  like
              strlen() and malloc().

       -fno-builtin-<function>
              Disable  special handling and optimizations for the specific library function.  For
              example, -fno-builtin-strlen removes any special handling for the strlen()  library
              function.

       -fno-builtin-std-<function>
              Disable  special  handling  and optimizations for the specific C++ standard library
              function in namespace std. For example,  -fno-builtin-std-move_if_noexcept  removes
              any special handling for the std::move_if_noexcept() library function.

              For  C  standard  library  functions that the C++ standard library also provides in
              namespace std, use -fno-builtin-<function> instead.

       -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, -flax-vector-conversions=<kind>, -fno-lax-vector-conversions
              Allow  loose  type checking rules for implicit vector conversions.  Possible values
              of <kind>:

              • none: allow no implicit conversions between vectors

              • integer: allow implicit bitcasts between integer  vectors  of  the  same  overall
                bit-width

              • all: allow implicit bitcasts between any vectors of the same overall bit-width

              <kind> defaults to integer if unspecified.

       -fblocks
              Enable the “Blocks” language feature.

       -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, -fno-objc-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.

       -target <architecture>
              Specify the architecture to build for (all platforms).

       --print-supported-cpus
              Print  out  a  list of supported processors for the given target (specified through
              --target=<architecture> or -arch <architecture>). If no target  is  specified,  the
              system default target will be used.

       -mcpu=?, -mtune=?
              Acts as an alias for --print-supported-cpus.

       -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, -Og, -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.

                 -Og   Like  -O1.  In  future  versions,  this  option  might  disable  different
                 optimizations in order to improve debuggability.

                 -O Equivalent to -O1.

                 -O4 and higher
                     Currently equivalent to -O3

       -g, -gline-tables-only, -gmodules
              Control debug information output.  Note that Clang debug information works best  at
              -O0.  When more than one option starting with -g is specified, the last one wins:
                 -g Generate debug information.

                 -gline-tables-only  Generate  only line table debug information. This allows for
                 symbolicated backtraces with inlining information,  but  does  not  include  any
                 information about variables, their locations or types.

                 -gmodules  Generate debug information that contains external references to types
                 defined in Clang modules or precompiled headers instead  of  emitting  redundant
                 debug  type  information  into  every  object  file.   This option transparently
                 switches the Clang module format to object file containers that hold  the  Clang
                 module  together with the debug information.  When compiling a program that uses
                 Clang modules or  precompiled  headers,  this  option  produces  complete  debug
                 information with faster compile times and much smaller object files.

                 This  option  should not be used when building static libraries for distribution
                 to other machines because the debug info will contain references to  the  module
                 cache on the machine the object files in the library were built on.

       -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.

       -feliminate-unused-debug-types
              By default, Clang does not emit type information for types that are defined but not
              used in a program. To retain the debug info for these unused  types,  the  negation
              -fno-eliminate-unused-debug-types can be used.

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

       -ftls-model=<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, -flto=full, -flto=thin, -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).

              The default for -flto is  “full”,  in  which  the  LLVM  bitcode  is  suitable  for
              monolithic  Link  Time Optimization (LTO), where the linker merges all such modules
              into a single combined module for optimization. With “thin”, ThinLTO compilation is
              invoked instead.

              NOTE:
                 On  Darwin, when using -flto along with -g and compiling and linking in separate
                 steps, you  also  need  to  pass  -Wl,-object_path_lto,<lto-filename>.o  at  the
                 linking step to instruct the ld64 linker not to delete the temporary object file
                 generated during Link Time Optimization (this flag is  automatically  passed  to
                 the  linker by Clang if compilation and linking are done in a single step). This
                 allows debugging the executable as well as generating  the  .dSYM  bundle  using
                 dsymutil(1).

   Driver Options
       -###   Print (but do not run) the commands to run for this compilation.

       --help Display available options.

       -Qunused-arguments
              Do not emit any warnings 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 the currently used compiler runtime library (“libgcc.a”
              or “libclang_rt.builtins.*.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.

       -save-stats, -save-stats=cwd, -save-stats=obj
              Save internal code generation (LLVM) statistics to a file in the current  directory
              (-save-stats/”-save-stats=cwd”)    or    the   directory   of   the   output   file
              (“-save-state=obj”).

       -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
       -D<macroname>=<value>
              Adds an implicit #define into the predefines buffer which is read before the source
              file is preprocessed.

       -U<macroname>
              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.

       -I<directory>
              Add the specified directory to the search path for include files.

       -F<directory>
              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 delimiter, 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.

BUGS

       To  report  bugs,  please  visit <https://github.com/llvm/llvm-project/issues/>.  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>)

COPYRIGHT

       2007-2023, The Clang Team