docs/tools/clang.pod

=pod

=head1 NAME

clang - the Clang C and Objective-C compiler

=head1 SYNOPSIS

B<clang> [B<-c>|B<-S>|B<-E>] B<-std=>I<standard> B<-g>
  [B<-O0>|B<-O1>|B<-O2>|B<-Os>|B<-O3>|B<-O4>]
  B<-W>I<warnings...> B<-pedantic>
  B<-I>I<dir...> B<-L>I<dir...>
  B<-D>I<macro[=defn]>
  B<-f>I<feature-option...>
  B<-m>I<machine-option...>
  B<-o> I<output-file>
  I<input-filenames>

=head1 DESCRIPTION

B<clang> is a 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:

=over

=item B<Driver>

The B<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.

=item B<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) or ".mi" (for Objective-C) file.

=item B<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).

=item B<Code Generation and Optimization>

This stage translates an AST into low-level intermediate code or machine code
(depending on the optimization level).  This phase is responsible for optimizing
the generated code and handling target-specfic code generation.  The output of
this stage is typically called a ".s" file.

=item B<Assembly>

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.

=item B<Linking>

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.

=back

The Clang compiler supports a large number of options to control each of these
stages.

=head1 OPTIONS


=head2 Stage Selection Options

=over

=item B<--help>

Display available options.


=item B<-###>

Print the commands to run for this compilation.


=item B<-E>

Only run the preprocessor.

=item B<-S>

Only run preprocess and compilation steps.

=item B<-c>

Only run preprocess, compile, and assemble steps.

=item B<-emit-llvm>

Use the LLVM representation for assembler and object files.




=back






=over

=item B<--analyze>

Run the static analyzer.
=item B<-ObjC++>

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

=item B<-ObjC>

Treat source input files as Objective-C inputs.

=item B<-Qunused-arguments>

Don't emit warning for unused driver arguments.

=item B<-Wa,>I<args>

Pass the comma separated arguments in I<args> to the assembler.

=item B<-Wl,>I<args>

Pass the comma separated arguments in I<args> to the linker.

=item B<-Wp,>I<args>

Pass the comma separated arguments in I<args> to the preprocessor.

=item B<-Xanalyzer> I<arg>

Pass I<arg> to the static analyzer.

=item B<-Xassembler> I<arg>

Pass I<arg> to the assembler.

=item B<-Xclang> I<arg>

Pass I<arg> to the clang compiler.

=item B<-Xlinker> I<arg>

Pass I<arg> to the linker.

=item B<-Xpreprocessor> I<arg>

Pass I<arg> to the preprocessor.

=item B<-o> I<file>               

Write output to I<file>.

=item B<-pipe>

Use pipes between commands, when possible.

=item B<-print-file-name>=I<file>

Print the full library path of I<file>.

=item B<-print-libgcc-file-name>

Print the library path for "libgcc.a".

=item B<-print-prog-name>=I<name>

Print the full program path of I<name>.

=item B<-print-search-dirs>

Print the paths used for finding libraries and programs.

=item B<-save-temps>

Save intermediate compilation results.

=item B<-time>

Time individual commands.

=item B<-v>

Show commands to run and use verbose output.

=item B<-x> I<language>

Treat subsequent input files as having type I<language>.

=back

=head1 ENVIRONMENT

FIXME: Fill in environment.

=head1 BUGS

It is inconceivable that Clang may have a bug.

=head1 SEE ALSO

FIXME: See also?

=head1 AUTHOR

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

=cut