CLANG, CLANG++, CLANG-CPP(1) Clang CLANG, CLANG++, CLANG-CPP(1) #
CLANG, CLANG++, CLANG-CPP(1) Clang CLANG, CLANG++, CLANG-CPP(1)
NNAAMMEE #
clang, clang++, clang-cpp - the Clang C, C++, and Objective-C compiler
SSYYNNOOPPSSIISS #
ccllaanngg [_o_p_t_i_o_n_s] _f_i_l_e_n_a_m_e _._._.
DDEESSCCRRIIPPTTIIOONN #
ccllaanngg 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:
DDrriivveerr 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.
PPrreepprroocceessssiinngg
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.
PPaarrssiinngg aanndd SSeemmaannttiicc AAnnaallyyssiiss
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).
CCooddee GGeenneerraattiioonn aanndd OOppttiimmiizzaattiioonn
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.
AAsssseemmbblleerr
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.
LLiinnkkeerr 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.
CCllaanngg SSttaattiicc AAnnaallyyzzeerr
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 <_h_t_t_p_s_:_/_/_c_l_a_n_g_-_a_n_a_l_y_z_e_r_._l_l_v_m_._o_r_g>
for more details on how to use the static analyzer.
OOPPTTIIOONNSS #
SSttaaggee SSeelleeccttiioonn OOppttiioonnss
--EE Run the preprocessor stage.
--ffssyynnttaaxx--oonnllyy
Run the preprocessor, parser and semantic analysis stages.
--SS Run the previous stages as well as LLVM generation and
optimization stages and target-specific code generation, producing
an assembly file.
--cc Run all of the above, plus the assembler, generating a target ".o"
object file.
nnoo ssttaaggee sseelleeccttiioonn ooppttiioonn
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.
LLaanngguuaaggee SSeelleeccttiioonn aanndd MMooddee OOppttiioonnss
--xx <<llaanngguuaaggee>>
Treat subsequent input files as having type language.
--ssttdd==<<ssttaannddaarrdd>>
Specify the language standard to compile for.
Supported values for the C language are:
cc8899
cc9900
iissoo99889999::11999900
ISO C 1990 #
iissoo99889999::119999440099
ISO C 1990 with amendment 1
ggnnuu8899
ggnnuu9900
ISO C 1990 with GNU extensions
cc9999
iissoo99889999::11999999
ISO C 1999 #
ggnnuu9999
ISO C 1999 with GNU extensions
cc1111
iissoo99889999::22001111
ISO C 2011 #
ggnnuu1111
ISO C 2011 with GNU extensions
cc1177
iissoo99889999::22001177
ISO C 2017 #
ggnnuu1177
ISO C 2017 with GNU extensions
The default C language standard is ggnnuu1177, except on PS4, where it
is ggnnuu9999.
Supported values for the C++ language are:
cc++++9988
cc++++0033
ISO C++ 1998 with amendments
ggnnuu++++9988
ggnnuu++++0033
ISO C++ 1998 with amendments and GNU extensions
cc++++1111
ISO C++ 2011 with amendments
ggnnuu++++1111
ISO C++ 2011 with amendments and GNU extensions
cc++++1144
ISO C++ 2014 with amendments
ggnnuu++++1144
ISO C++ 2014 with amendments and GNU extensions
cc++++1177
ISO C++ 2017 with amendments
ggnnuu++++1177
ISO C++ 2017 with amendments and GNU extensions
cc++++2200
ISO C++ 2020 with amendments
ggnnuu++++2200
ISO C++ 2020 with amendments and GNU extensions
cc++++22bb
Working draft for ISO C++ 2023
ggnnuu++++22bb
Working draft for ISO C++ 2023 with GNU extensions
The default C++ language standard is ggnnuu++++1177.
Supported values for the OpenCL language are:
ccll11..00
OpenCL 1.0
ccll11..11
OpenCL 1.1
ccll11..22
OpenCL 1.2
ccll22..00
OpenCL 2.0
The default OpenCL language standard is ccll11..00.
Supported values for the CUDA language are:
ccuuddaa
NVIDIA CUDA(tm)
--ssttddlliibb==<<lliibbrraarryy>>
Specify the C++ standard library to use; supported options are
libstdc++ and libc++. If not specified, platform default will be
used.
--rrttlliibb==<<lliibbrraarryy>>
Specify the compiler runtime library to use; supported options are
libgcc and compiler-rt. If not specified, platform default will be
used.
--aannssii Same as -std=c89.
--OObbjjCC,, --OObbjjCC++++
Treat source input files as Objective-C and Object-C++ inputs
respectively.
--ttrriiggrraapphhss
Enable trigraphs.
--ffffrreeeessttaannddiinngg
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 _m_e_m_c_p_y, _m_e_m_m_o_v_e, _m_e_m_s_e_t and
_m_e_m_c_m_p implementations, as these are needed for efficient codegen
for many programs.
--ffnnoo--bbuuiillttiinn
Disable special handling and optimizations of well-known library
functions, like ssttrrlleenn(()) and mmaalllloocc(()).
--ffnnoo--bbuuiillttiinn--<<ffuunnccttiioonn>>
Disable special handling and optimizations for the specific
library function. For example, --ffnnoo--bbuuiillttiinn--ssttrrlleenn removes any
special handling for the ssttrrlleenn(()) library function.
--ffnnoo--bbuuiillttiinn--ssttdd--<<ffuunnccttiioonn>>
Disable special handling and optimizations for the specific C++
standard library function in namespace ssttdd. For example,
--ffnnoo--bbuuiillttiinn--ssttdd--mmoovvee__iiff__nnooeexxcceepptt removes any special handling for
the ssttdd::::mmoovvee__iiff__nnooeexxcceepptt(()) library function.
For C standard library functions that the C++ standard library
also provides in namespace ssttdd, use _-_f_n_o_-_b_u_i_l_t_i_n_-_<_f_u_n_c_t_i_o_n_>
instead.
--ffmmaatthh--eerrrrnnoo
Indicate that math functions should be treated as updating eerrrrnnoo.
--ffppaassccaall--ssttrriinnggss
Enable support for Pascal-style strings with "\pfoo".
--ffmmss--eexxtteennssiioonnss
Enable support for Microsoft extensions.
--ffmmsscc--vveerrssiioonn==
Set _MSC_VER. Defaults to 1300 on Windows. Not set otherwise.
--ffbboorrllaanndd--eexxtteennssiioonnss
Enable support for Borland extensions.
--ffwwrriittaabbllee--ssttrriinnggss
Make all string literals default to writable. This disables
uniquing of strings and other optimizations.
--ffllaaxx--vveeccttoorr--ccoonnvveerrssiioonnss,, --ffllaaxx--vveeccttoorr--ccoonnvveerrssiioonnss==<<kkiinndd>>,,
--ffnnoo--llaaxx--vveeccttoorr--ccoonnvveerrssiioonnss
Allow loose type checking rules for implicit vector conversions.
Possible values of <kind>:
• nnoonnee: allow no implicit conversions between vectors
• iinntteeggeerr: allow implicit bitcasts between integer vectors of the
same overall bit-width
• aallll: allow implicit bitcasts between any vectors of the same
overall bit-width
<kind> defaults to iinntteeggeerr if unspecified.
--ffbblloocckkss
Enable the "Blocks" language feature.
--ffoobbjjcc--aabbii--vveerrssiioonn==vveerrssiioonn
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).
--ffoobbjjcc--nnoonnffrraaggiillee--aabbii--vveerrssiioonn==<<vveerrssiioonn>>
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 _-_f_o_b_j_c_-_n_o_n_f_r_a_g_i_l_e_-_a_b_i, or because it is
the platform default).
--ffoobbjjcc--nnoonnffrraaggiillee--aabbii,, --ffnnoo--oobbjjcc--nnoonnffrraaggiillee--aabbii
Enable use of the Objective-C non-fragile ABI. On platforms for
which this is the default ABI, it can be disabled with
_-_f_n_o_-_o_b_j_c_-_n_o_n_f_r_a_g_i_l_e_-_a_b_i.
TTaarrggeett SSeelleeccttiioonn OOppttiioonnss 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.
--aarrcchh <<aarrcchhiitteeccttuurree>>
Specify the architecture to build for (Mac OS X specific).
--ttaarrggeett <<aarrcchhiitteeccttuurree>>
Specify the architecture to build for (all platforms).
--mmmmaaccoossxx--vveerrssiioonn--mmiinn==<<vveerrssiioonn>>
When building for macOS, specify the minimum version supported by
your application.
--mmiipphhoonneeooss--vveerrssiioonn--mmiinn
When building for iPhone OS, specify the minimum version supported
by your application.
----pprriinntt--ssuuppppoorrtteedd--ccppuuss
Print out a list of supported processors for the given target
(specified through ----ttaarrggeett==<<aarrcchhiitteeccttuurree>> or _-_a_r_c_h
<<aarrcchhiitteeccttuurree>>). If no target is specified, the system default
target will be used.
--mmccppuu==??,, --mmttuunnee==??
Acts as an alias for _-_-_p_r_i_n_t_-_s_u_p_p_o_r_t_e_d_-_c_p_u_s.
--mmaarrcchh==<<ccppuu>>
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.
CCooddee GGeenneerraattiioonn OOppttiioonnss
--OO00,, --OO11,, --OO22,, --OO33,, --OOffaasstt,, --OOss,, --OOzz,, --OOgg,, --OO,, --OO44
Specify which optimization level to use:
_-_O_0 Means "no optimization": this level compiles the fastest
and generates the most debuggable code.
_-_O_1 Somewhere between _-_O_0 and _-_O_2.
_-_O_2 Moderate level of optimization which enables most
optimizations.
_-_O_3 Like _-_O_2, 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).
_-_O_f_a_s_t Enables all the optimizations from _-_O_3 along with other
aggressive optimizations that may violate strict compliance
with language standards.
_-_O_s Like _-_O_2 with extra optimizations to reduce code size.
_-_O_z Like _-_O_s (and thus _-_O_2), but reduces code size further.
_-_O_g Like _-_O_1. In future versions, this option might disable
different optimizations in order to improve debuggability.
_-_O Equivalent to _-_O_1.
_-_O_4 and higher
Currently equivalent to _-_O_3
--gg,, --gglliinnee--ttaabblleess--oonnllyy,, --ggmmoodduulleess
Control debug information output. Note that Clang debug
information works best at _-_O_0. When more than one option starting
with _-_g is specified, the last one wins:
_-_g Generate debug information.
_-_g_l_i_n_e_-_t_a_b_l_e_s_-_o_n_l_y 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.
_-_g_m_o_d_u_l_e_s 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.
--ffssttaannddaalloonnee--ddeebbuugg --ffnnoo--ssttaannddaalloonnee--ddeebbuugg
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 _-_f_s_t_a_n_d_a_l_o_n_e_-_d_e_b_u_g 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.
--ffeelliimmiinnaattee--uunnuusseedd--ddeebbuugg--ttyyppeess
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
--ffnnoo--eelliimmiinnaattee--uunnuusseedd--ddeebbuugg--ttyyppeess can be used.
--ffeexxcceeppttiioonnss
Enable generation of unwind information. This allows exceptions to
be thrown through Clang compiled stack frames. This is on by
default in x86-64.
--ffttrraappvv
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.
--ffvviissiibbiilliittyy
This flag sets the default visibility level.
--ffccoommmmoonn,, --ffnnoo--ccoommmmoonn
This flag specifies that variables without initializers get common
linkage. It can be disabled with _-_f_n_o_-_c_o_m_m_o_n.
--ffttllss--mmooddeell==<<mmooddeell>>
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.
--ffllttoo,, --ffllttoo==ffuullll,, --ffllttoo==tthhiinn,, --eemmiitt--llllvvmm
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 _-_f_l_t_o 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", _T_h_i_n_L_T_O compilation is invoked instead.
NNOOTTEE:: #
On Darwin, when using _-_f_l_t_o along with _-_g and compiling and
linking in separate steps, you also need to pass
--WWll,,--oobbjjeecctt__ppaatthh__llttoo,,<<llttoo--ffiilleennaammee>>..oo 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 ..ddSSYYMM bundle using
ddssyymmuuttiill((11)).
DDrriivveerr OOppttiioonnss
--###### Print (but do not run) the commands to run for this compilation.
----hheellpp Display available options.
--QQuunnuusseedd--aarrgguummeennttss
Do not emit any warnings for unused driver arguments.
--WWaa,,<<aarrggss>>
Pass the comma separated arguments in args to the assembler.
--WWll,,<<aarrggss>>
Pass the comma separated arguments in args to the linker.
--WWpp,,<<aarrggss>>
Pass the comma separated arguments in args to the preprocessor.
--XXaannaallyyzzeerr <<aarrgg>>
Pass arg to the static analyzer.
--XXaasssseemmbblleerr <<aarrgg>>
Pass arg to the assembler.
--XXlliinnkkeerr <<aarrgg>>
Pass arg to the linker.
--XXpprreepprroocceessssoorr <<aarrgg>>
Pass arg to the preprocessor.
--oo <<ffiillee>>
Write output to file.
--pprriinntt--ffiillee--nnaammee==<<ffiillee>>
Print the full library path of file.
--pprriinntt--lliibbggcccc--ffiillee--nnaammee
Print the library path for the currently used compiler runtime
library ("libgcc.a" or "libclang_rt.builtins.*.a").
--pprriinntt--pprroogg--nnaammee==<<nnaammee>>
Print the full program path of name.
--pprriinntt--sseeaarrcchh--ddiirrss
Print the paths used for finding libraries and programs.
--ssaavvee--tteemmppss
Save intermediate compilation results.
--ssaavvee--ssttaattss,, --ssaavvee--ssttaattss==ccwwdd,, --ssaavvee--ssttaattss==oobbjj
Save internal code generation (LLVM) statistics to a file in the
current directory (_-_s_a_v_e_-_s_t_a_t_s/"-save-stats=cwd") or the directory
of the output file ("-save-state=obj").
--iinntteeggrraatteedd--aass,, --nnoo--iinntteeggrraatteedd--aass
Used to enable and disable, respectively, the use of the
integrated assembler. Whether the integrated assembler is on by
default is target dependent.
--ttiimmee Time individual commands.
--ffttiimmee--rreeppoorrtt
Print timing summary of each stage of compilation.
--vv Show commands to run and use verbose output.
DDiiaaggnnoossttiiccss OOppttiioonnss
--ffsshhooww--ccoolluummnn,, --ffsshhooww--ssoouurrccee--llooccaattiioonn,, --ffccaarreett--ddiiaaggnnoossttiiccss,,
--ffddiiaaggnnoossttiiccss--ffiixxiitt--iinnffoo,, --ffddiiaaggnnoossttiiccss--ppaarrsseeaabbllee--ffiixxiittss,,
--ffddiiaaggnnoossttiiccss--pprriinntt--ssoouurrccee--rraannggee--iinnffoo,, --ffpprriinntt--ssoouurrccee--rraannggee--iinnffoo,,
--ffddiiaaggnnoossttiiccss--sshhooww--ooppttiioonn,, --ffmmeessssaaggee--lleennggtthh
These options control how Clang prints out information about
diagnostics (errors and warnings). Please see the Clang User's
Manual for more information.
PPrreepprroocceessssoorr OOppttiioonnss
--DD<<mmaaccrroonnaammee>>==<<vvaalluuee>>
Adds an implicit #define into the predefines buffer which is read
before the source file is preprocessed.
--UU<<mmaaccrroonnaammee>>
Adds an implicit #undef into the predefines buffer which is read
before the source file is preprocessed.
--iinncclluuddee <<ffiilleennaammee>>
Adds an implicit #include into the predefines buffer which is read
before the source file is preprocessed.
--II<<ddiirreeccttoorryy>>
Add the specified directory to the search path for include files.
--FF<<ddiirreeccttoorryy>>
Add the specified directory to the search path for framework
include files.
--nnoossttddiinncc
Do not search the standard system directories or compiler builtin
directories for include files.
--nnoossttddlliibbiinncc
Do not search the standard system directories for include files,
but do search compiler builtin include directories.
--nnoobbuuiillttiinniinncc
Do not search clang's builtin directory for include files.
EENNVVIIRROONNMMEENNTT #
TTMMPPDDIIRR,, TTEEMMPP,, TTMMPP #
These environment variables are checked, in order, for the
location to write temporary files used during the compilation
process.
CCPPAATTHH 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.
CC__IINNCCLLUUDDEE__PPAATTHH,, OOBBJJCC__IINNCCLLUUDDEE__PPAATTHH,, CCPPLLUUSS__IINNCCLLUUDDEE__PPAATTHH,, #
OOBBJJCCPPLLUUSS__IINNCCLLUUDDEE__PPAATTHH #
These environment variables specify additional paths, as for
_C_P_A_T_H, which are only used when processing the appropriate
language.
MMAACCOOSSXX__DDEEPPLLOOYYMMEENNTT__TTAARRGGEETT #
If _-_m_m_a_c_o_s_x_-_v_e_r_s_i_o_n_-_m_i_n is unspecified, the default deployment
target is read from this environment variable. This option only
affects Darwin targets.
BBUUGGSS #
To report bugs, please visit
<_h_t_t_p_s_:_/_/_g_i_t_h_u_b_._c_o_m_/_l_l_v_m_/_l_l_v_m_-_p_r_o_j_e_c_t_/_i_s_s_u_e_s_/>. Most bug reports should
include preprocessed source files (use the _-_E option) and the full output
of the compiler, along with information to reproduce.
SSEEEE AALLSSOO #
aass((11)), ccllaanngg--llooccaall((11)), lldd((11))
AAUUTTHHOORR #
Maintained by the Clang / LLVM Team (<http://clang.llvm.org>)
CCOOPPYYRRIIGGHHTT #
2007-2023, The Clang Team
16 October 21, 2023 CLANG, CLANG++, CLANG-CPP(1)