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RUSTC(1) User Commands RUSTC(1)

rustc - The Rust compiler

rustc [OPTIONS] INPUT

This program is a compiler for the Rust language, available at https://www.rust-lang.org.

-h, --help
Display the help message.
--cfg SPEC
Configure the compilation environment.
-L [KIND=]PATH
Add a directory to the library search path. The optional KIND can be one of:
dependency
only lookup transitive dependencies here
crate
only lookup local `extern crate` directives here
native
only lookup native libraries here
framework
only look for OSX frameworks here
all
look for anything here (the default)
-l [KIND=]NAME
Link the generated crate(s) to the specified library NAME. The optional KIND can be one of static, dylib, or framework. If omitted, dylib is assumed.
--crate-type [bin|lib|rlib|dylib|cdylib|staticlib]
Comma separated list of types of crates for the compiler to emit.
--crate-name NAME
Specify the name of the crate being built.
--emit [asm|llvm-bc|llvm-ir|obj|link|dep-info|mir][=PATH]
Configure the output that rustc will produce. Each emission may also have an optional explicit output PATH specified for that particular emission kind. This path takes precedence over the -o option.
--print [crate-name|file-names|sysroot|cfg|target-list|target-cpus|target-features|relocation-models|code-models|tls-models|target-spec-json|native-static-libs]
Comma separated list of compiler information to print on stdout.
-g
Equivalent to -C debuginfo=2.
-O
Equivalent to -C opt-level=2.
-o FILENAME
Write output to FILENAME. Ignored if multiple --emit outputs are specified which don't have an explicit path otherwise.
--out-dir DIR
Write output to compiler‐chosen filename in DIR. Ignored if -o is specified. Defaults to the current directory.
--explain OPT
Provide a detailed explanation of an error message.
--test
Build a test harness.
--target TARGET
Target triple for which the code is compiled. This option defaults to the host’s target triple. The target triple has the general format <arch><sub>-<vendor>-<sys>-<abi>, where:
<arch>
x86, arm, thumb, mips, etc.
<sub>
for example on ARM: v5, v6m, v7a, v7m, etc.
<vendor>
pc, apple, nvidia, ibm, etc.
<sys>
none, linux, win32, darwin, cuda, etc.
<abi>
eabi, gnu, android, macho, elf, etc.
-W help
Print 'lint' options and default settings.
-W OPT, --warn OPT
Set lint warnings.
-A OPT, --allow OPT
Set lint allowed.
-D OPT, --deny OPT
Set lint denied.
-F OPT, --forbid OPT
Set lint forbidden.
-C FLAG[=VAL], --codegen FLAG[=VAL]
Set a codegen‐related flag to the value specified. Use -C help to print available flags. See CODEGEN OPTIONS below.
-V, --version
Print version info and exit.
-v, --verbose
Use verbose output.
--remap-path-prefix from=to
Remap source path prefixes in all output, including compiler diagnostics, debug information, macro expansions, etc. The from=to parameter is scanned from right to left, so from may contain '=', but to may not.

This is useful for normalizing build products, for example by removing the current directory out of pathnames emitted into the object files. The replacement is purely textual, with no consideration of the current system's pathname syntax. For example --remap-path-prefix foo=bar will match foo/lib.rs but not ./foo/lib.rs.

--extern NAME=PATH
Specify where an external rust library is located. These should match extern declarations in the crate's source code.
--sysroot PATH
Override the system root.
-Z FLAG
Set internal debugging options. Use -Z help to print available options.
--color auto|always|never
Configure coloring of output:
auto
colorize, if output goes to a tty (default);
always
always colorize output;
never
never colorize output.

linker=/path/to/cc
Path to the linker utility to use when linking libraries, executables, and objects.
link-args='-flag1 -flag2'
A space‐separated list of extra arguments to pass to the linker when the linker is invoked.
lto
Perform LLVM link‐time optimizations.
target-cpu=help
Selects a target processor. If the value is 'help', then a list of available CPUs is printed.
target-feature='+feature1,-feature2'
A comma‐separated list of features to enable or disable for the target. A preceding '+' enables a feature while a preceding '-' disables it. Available features can be discovered through llc -mcpu=help.
passes=val
A space‐separated list of extra LLVM passes to run. A value of 'list' will cause rustc to print all known passes and exit. The passes specified are appended at the end of the normal pass manager.
llvm-args='-arg1 -arg2'
A space‐separated list of arguments to pass through to LLVM.
save-temps
If specified, the compiler will save more files (.bc, .o, .no-opt.bc) generated throughout compilation in the output directory.
rpath
If specified, then the rpath value for dynamic libraries will be set in either dynamic library or executable outputs.
no-prepopulate-passes
Suppresses pre‐population of the LLVM pass manager that is run over the module.
no-vectorize-loops
Suppresses running the loop vectorization LLVM pass, regardless of optimization level.
no-vectorize-slp
Suppresses running the LLVM SLP vectorization pass, regardless of optimization level.
soft-float
Generates software floating point library calls instead of hardware instructions.
prefer-dynamic
Prefers dynamic linking to static linking.
no-integrated-as
Force usage of an external assembler rather than LLVM's integrated one.
no-redzone
Disable the use of the redzone.
relocation-model=[pic,static,dynamic-no-pic]
The relocation model to use. (Default: pic)
code-model=[small,kernel,medium,large]
Choose the code model to use.
metadata=val
Metadata to mangle symbol names with.
extra-filename=val
Extra data to put in each output filename.
codegen-units=n
Divide crate into n units to optimize in parallel.
remark=val
Print remarks for these optimization passes (space separated, or "all").
no-stack-check
Disable checks for stack exhaustion (a memory‐safety hazard!).
debuginfo=val
Debug info emission level:
0
no debug info;
1
line‐tables only (for stacktraces and breakpoints);
2
full debug info with variable and type information.
opt-level=VAL
Optimize with possible levels 0–3, s (optimize for size), or z (for minimal size)

Some of these affect only test harness programs (generated via rustc --test); others affect all programs which link to the Rust standard library.
RUST_TEST_THREADS
The test framework Rust provides executes tests in parallel. This variable sets the maximum number of threads used for this purpose. This setting is overridden by the --test-threads option.
RUST_TEST_NOCAPTURE
If set to a value other than "0", a synonym for the --nocapture flag.
RUST_MIN_STACK
Sets the minimum stack size for new threads.
RUST_BACKTRACE
If set to a value different than "0", produces a backtrace in the output of a program which panics.

To build an executable from a source file with a main function: $ rustc -o hello hello.rs

To build a library from a source file: $ rustc --crate-type=lib hello-lib.rs

To build either with a crate (.rs) file: $ rustc hello.rs

To build an executable with debug info: $ rustc -g -o hello hello.rs

rustdoc(1)

See https://github.com/rust-lang/rust/issues for issues.

See https://github.com/rust-lang/rust/graphs/contributors or use `git log --all --format='%cN <%cE>' | sort -u` in the rust source distribution.

This work is dual‐licensed under Apache 2.0 and MIT terms. See COPYRIGHT file in the rust source distribution.
November 2020 rustc 1.48.0