1 // Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! [Flexible target specification.](https://github.com/rust-lang/rfcs/pull/131)
13 //! Rust targets a wide variety of usecases, and in the interest of flexibility,
14 //! allows new target triples to be defined in configuration files. Most users
15 //! will not need to care about these, but this is invaluable when porting Rust
16 //! to a new platform, and allows for an unprecedented level of control over how
17 //! the compiler works.
19 //! # Using custom targets
21 //! A target triple, as passed via `rustc --target=TRIPLE`, will first be
22 //! compared against the list of built-in targets. This is to ease distributing
23 //! rustc (no need for configuration files) and also to hold these built-in
24 //! targets as immutable and sacred. If `TRIPLE` is not one of the built-in
25 //! targets, rustc will check if a file named `TRIPLE` exists. If it does, it
26 //! will be loaded as the target configuration. If the file does not exist,
27 //! rustc will search each directory in the environment variable
28 //! `RUST_TARGET_PATH` for a file named `TRIPLE.json`. The first one found will
29 //! be loaded. If no file is found in any of those directories, a fatal error
32 //! Projects defining their own targets should use
33 //! `--target=path/to/my-awesome-platform.json` instead of adding to
34 //! `RUST_TARGET_PATH`.
36 //! # Defining a new target
38 //! Targets are defined using [JSON](http://json.org/). The `Target` struct in
39 //! this module defines the format the JSON file should take, though each
40 //! underscore in the field names should be replaced with a hyphen (`-`) in the
41 //! JSON file. Some fields are required in every target specification, such as
42 //! `llvm-target`, `target-endian`, `target-pointer-width`, `data-layout`,
43 //! `arch`, and `os`. In general, options passed to rustc with `-C` override
44 //! the target's settings, though `target-feature` and `link-args` will *add*
45 //! to the list specified by the target, rather than replace.
47 use serialize::json::{Json, ToJson};
48 use std::collections::BTreeMap;
49 use std::default::Default;
50 use std::io::prelude::*;
65 mod windows_msvc_base;
67 pub type TargetResult = Result<Target, String>;
69 macro_rules! supported_targets {
70 ( $(($triple:expr, $module:ident)),+ ) => (
73 /// List of supported targets
74 const TARGETS: &'static [&'static str] = &[$($triple),*];
76 fn load_specific(target: &str) -> TargetResult {
80 let mut t = $module::target()?;
81 t.options.is_builtin = true;
83 // round-trip through the JSON parser to ensure at
84 // run-time that the parser works correctly
85 t = Target::from_json(t.to_json())?;
86 debug!("Got builtin target: {:?}", t);
90 _ => Err(format!("Unable to find target: {}", target))
94 pub fn get_targets() -> Box<Iterator<Item=String>> {
95 Box::new(TARGETS.iter().filter_map(|t| -> Option<String> {
97 .and(Ok(t.to_string()))
103 mod test_json_encode_decode {
104 use serialize::json::ToJson;
106 $(use super::$module;)*
111 // Grab the TargetResult struct. If we successfully retrieved
112 // a Target, then the test JSON encoding/decoding can run for this
113 // Target on this testing platform (i.e., checking the iOS targets
114 // only on a Mac test platform).
115 let _ = $module::target().map(|original| {
116 let as_json = original.to_json();
117 let parsed = Target::from_json(as_json).unwrap();
118 assert_eq!(original, parsed);
127 ("x86_64-unknown-linux-gnu", x86_64_unknown_linux_gnu),
128 ("i686-unknown-linux-gnu", i686_unknown_linux_gnu),
129 ("i586-unknown-linux-gnu", i586_unknown_linux_gnu),
130 ("mips-unknown-linux-gnu", mips_unknown_linux_gnu),
131 ("mips64-unknown-linux-gnuabi64", mips64_unknown_linux_gnuabi64),
132 ("mips64el-unknown-linux-gnuabi64", mips64el_unknown_linux_gnuabi64),
133 ("mipsel-unknown-linux-gnu", mipsel_unknown_linux_gnu),
134 ("powerpc-unknown-linux-gnu", powerpc_unknown_linux_gnu),
135 ("powerpc64-unknown-linux-gnu", powerpc64_unknown_linux_gnu),
136 ("powerpc64le-unknown-linux-gnu", powerpc64le_unknown_linux_gnu),
137 ("s390x-unknown-linux-gnu", s390x_unknown_linux_gnu),
138 ("arm-unknown-linux-gnueabi", arm_unknown_linux_gnueabi),
139 ("arm-unknown-linux-gnueabihf", arm_unknown_linux_gnueabihf),
140 ("arm-unknown-linux-musleabi", arm_unknown_linux_musleabi),
141 ("arm-unknown-linux-musleabihf", arm_unknown_linux_musleabihf),
142 ("armv7-unknown-linux-gnueabihf", armv7_unknown_linux_gnueabihf),
143 ("armv7-unknown-linux-musleabihf", armv7_unknown_linux_musleabihf),
144 ("aarch64-unknown-linux-gnu", aarch64_unknown_linux_gnu),
145 ("x86_64-unknown-linux-musl", x86_64_unknown_linux_musl),
146 ("i686-unknown-linux-musl", i686_unknown_linux_musl),
147 ("mips-unknown-linux-musl", mips_unknown_linux_musl),
148 ("mipsel-unknown-linux-musl", mipsel_unknown_linux_musl),
149 ("mips-unknown-linux-uclibc", mips_unknown_linux_uclibc),
150 ("mipsel-unknown-linux-uclibc", mipsel_unknown_linux_uclibc),
152 ("i686-linux-android", i686_linux_android),
153 ("arm-linux-androideabi", arm_linux_androideabi),
154 ("armv7-linux-androideabi", armv7_linux_androideabi),
155 ("aarch64-linux-android", aarch64_linux_android),
157 ("i686-unknown-freebsd", i686_unknown_freebsd),
158 ("x86_64-unknown-freebsd", x86_64_unknown_freebsd),
160 ("i686-unknown-dragonfly", i686_unknown_dragonfly),
161 ("x86_64-unknown-dragonfly", x86_64_unknown_dragonfly),
163 ("x86_64-unknown-bitrig", x86_64_unknown_bitrig),
164 ("x86_64-unknown-openbsd", x86_64_unknown_openbsd),
165 ("x86_64-unknown-netbsd", x86_64_unknown_netbsd),
166 ("x86_64-rumprun-netbsd", x86_64_rumprun_netbsd),
168 ("i686_unknown_haiku", i686_unknown_haiku),
169 ("x86_64_unknown_haiku", x86_64_unknown_haiku),
171 ("x86_64-apple-darwin", x86_64_apple_darwin),
172 ("i686-apple-darwin", i686_apple_darwin),
174 ("i386-apple-ios", i386_apple_ios),
175 ("x86_64-apple-ios", x86_64_apple_ios),
176 ("aarch64-apple-ios", aarch64_apple_ios),
177 ("armv7-apple-ios", armv7_apple_ios),
178 ("armv7s-apple-ios", armv7s_apple_ios),
180 ("x86_64-sun-solaris", x86_64_sun_solaris),
182 ("x86_64-pc-windows-gnu", x86_64_pc_windows_gnu),
183 ("i686-pc-windows-gnu", i686_pc_windows_gnu),
185 ("x86_64-pc-windows-msvc", x86_64_pc_windows_msvc),
186 ("i686-pc-windows-msvc", i686_pc_windows_msvc),
187 ("i586-pc-windows-msvc", i586_pc_windows_msvc),
189 ("le32-unknown-nacl", le32_unknown_nacl),
190 ("asmjs-unknown-emscripten", asmjs_unknown_emscripten)
193 /// Everything `rustc` knows about how to compile for a specific target.
195 /// Every field here must be specified, and has no default value.
196 #[derive(PartialEq, Clone, Debug)]
198 /// Target triple to pass to LLVM.
199 pub llvm_target: String,
200 /// String to use as the `target_endian` `cfg` variable.
201 pub target_endian: String,
202 /// String to use as the `target_pointer_width` `cfg` variable.
203 pub target_pointer_width: String,
204 /// OS name to use for conditional compilation.
205 pub target_os: String,
206 /// Environment name to use for conditional compilation.
207 pub target_env: String,
208 /// Vendor name to use for conditional compilation.
209 pub target_vendor: String,
210 /// Architecture to use for ABI considerations. Valid options: "x86",
211 /// "x86_64", "arm", "aarch64", "mips", "powerpc", and "powerpc64".
213 /// [Data layout](http://llvm.org/docs/LangRef.html#data-layout) to pass to LLVM.
214 pub data_layout: String,
215 /// Optional settings with defaults.
216 pub options: TargetOptions,
219 /// Optional aspects of a target specification.
221 /// This has an implementation of `Default`, see each field for what the default is. In general,
222 /// these try to take "minimal defaults" that don't assume anything about the runtime they run in.
223 #[derive(PartialEq, Clone, Debug)]
224 pub struct TargetOptions {
225 /// Whether the target is built-in or loaded from a custom target specification.
226 pub is_builtin: bool,
228 /// Linker to invoke. Defaults to "cc".
230 /// Archive utility to use when managing archives. Defaults to "ar".
233 /// Linker arguments that are unconditionally passed *before* any
234 /// user-defined libraries.
235 pub pre_link_args: Vec<String>,
236 /// Objects to link before all others, always found within the
238 pub pre_link_objects_exe: Vec<String>, // ... when linking an executable
239 pub pre_link_objects_dll: Vec<String>, // ... when linking a dylib
240 /// Linker arguments that are unconditionally passed after any
241 /// user-defined but before post_link_objects. Standard platform
242 /// libraries that should be always be linked to, usually go here.
243 pub late_link_args: Vec<String>,
244 /// Objects to link after all others, always found within the
246 pub post_link_objects: Vec<String>,
247 /// Linker arguments that are unconditionally passed *after* any
248 /// user-defined libraries.
249 pub post_link_args: Vec<String>,
251 /// Default CPU to pass to LLVM. Corresponds to `llc -mcpu=$cpu`. Defaults
254 /// Default target features to pass to LLVM. These features will *always* be
255 /// passed, and cannot be disabled even via `-C`. Corresponds to `llc
256 /// -mattr=$features`.
257 pub features: String,
258 /// Whether dynamic linking is available on this target. Defaults to false.
259 pub dynamic_linking: bool,
260 /// Whether executables are available on this target. iOS, for example, only allows static
261 /// libraries. Defaults to false.
262 pub executables: bool,
263 /// Relocation model to use in object file. Corresponds to `llc
264 /// -relocation-model=$relocation_model`. Defaults to "pic".
265 pub relocation_model: String,
266 /// Code model to use. Corresponds to `llc -code-model=$code_model`. Defaults to "default".
267 pub code_model: String,
268 /// Do not emit code that uses the "red zone", if the ABI has one. Defaults to false.
269 pub disable_redzone: bool,
270 /// Eliminate frame pointers from stack frames if possible. Defaults to true.
271 pub eliminate_frame_pointer: bool,
272 /// Emit each function in its own section. Defaults to true.
273 pub function_sections: bool,
274 /// String to prepend to the name of every dynamic library. Defaults to "lib".
275 pub dll_prefix: String,
276 /// String to append to the name of every dynamic library. Defaults to ".so".
277 pub dll_suffix: String,
278 /// String to append to the name of every executable.
279 pub exe_suffix: String,
280 /// String to prepend to the name of every static library. Defaults to "lib".
281 pub staticlib_prefix: String,
282 /// String to append to the name of every static library. Defaults to ".a".
283 pub staticlib_suffix: String,
284 /// OS family to use for conditional compilation. Valid options: "unix", "windows".
285 pub target_family: Option<String>,
286 /// Whether the target toolchain is like OSX's. Only useful for compiling against iOS/OS X, in
287 /// particular running dsymutil and some other stuff like `-dead_strip`. Defaults to false.
288 pub is_like_osx: bool,
289 /// Whether the target toolchain is like Solaris's.
290 /// Only useful for compiling against Illumos/Solaris,
291 /// as they have a different set of linker flags. Defaults to false.
292 pub is_like_solaris: bool,
293 /// Whether the target toolchain is like Windows'. Only useful for compiling against Windows,
294 /// only really used for figuring out how to find libraries, since Windows uses its own
295 /// library naming convention. Defaults to false.
296 pub is_like_windows: bool,
297 pub is_like_msvc: bool,
298 /// Whether the target toolchain is like Android's. Only useful for compiling against Android.
299 /// Defaults to false.
300 pub is_like_android: bool,
301 /// Whether the linker support GNU-like arguments such as -O. Defaults to false.
302 pub linker_is_gnu: bool,
303 /// The MinGW toolchain has a known issue that prevents it from correctly
304 /// handling COFF object files with more than 2^15 sections. Since each weak
305 /// symbol needs its own COMDAT section, weak linkage implies a large
306 /// number sections that easily exceeds the given limit for larger
307 /// codebases. Consequently we want a way to disallow weak linkage on some
309 pub allows_weak_linkage: bool,
310 /// Whether the linker support rpaths or not. Defaults to false.
312 /// Whether to disable linking to the default libraries, typically corresponds
313 /// to `-nodefaultlibs`. Defaults to true.
314 pub no_default_libraries: bool,
315 /// Dynamically linked executables can be compiled as position independent
316 /// if the default relocation model of position independent code is not
317 /// changed. This is a requirement to take advantage of ASLR, as otherwise
318 /// the functions in the executable are not randomized and can be used
319 /// during an exploit of a vulnerability in any code.
320 pub position_independent_executables: bool,
321 /// Format that archives should be emitted in. This affects whether we use
322 /// LLVM to assemble an archive or fall back to the system linker, and
323 /// currently only "gnu" is used to fall into LLVM. Unknown strings cause
324 /// the system linker to be used.
325 pub archive_format: String,
326 /// Is asm!() allowed? Defaults to true.
328 /// Whether the target uses a custom unwind resumption routine.
329 /// By default LLVM lowers `resume` instructions into calls to `_Unwind_Resume`
330 /// defined in libgcc. If this option is enabled, the target must provide
331 /// `eh_unwind_resume` lang item.
332 pub custom_unwind_resume: bool,
334 /// Default crate for allocation symbols to link against
335 pub lib_allocation_crate: String,
336 pub exe_allocation_crate: String,
338 /// Flag indicating whether ELF TLS (e.g. #[thread_local]) is available for
340 pub has_elf_tls: bool,
341 // This is mainly for easy compatibility with emscripten.
342 // If we give emcc .o files that are actually .bc files it
344 pub obj_is_bitcode: bool,
346 /// Maximum integer size in bits that this target can perform atomic
348 pub max_atomic_width: u64,
351 impl Default for TargetOptions {
352 /// Create a set of "sane defaults" for any target. This is still
353 /// incomplete, and if used for compilation, will certainly not work.
354 fn default() -> TargetOptions {
357 linker: option_env!("CFG_DEFAULT_LINKER").unwrap_or("cc").to_string(),
358 ar: option_env!("CFG_DEFAULT_AR").unwrap_or("ar").to_string(),
359 pre_link_args: Vec::new(),
360 post_link_args: Vec::new(),
361 cpu: "generic".to_string(),
362 features: "".to_string(),
363 dynamic_linking: false,
365 relocation_model: "pic".to_string(),
366 code_model: "default".to_string(),
367 disable_redzone: false,
368 eliminate_frame_pointer: true,
369 function_sections: true,
370 dll_prefix: "lib".to_string(),
371 dll_suffix: ".so".to_string(),
372 exe_suffix: "".to_string(),
373 staticlib_prefix: "lib".to_string(),
374 staticlib_suffix: ".a".to_string(),
377 is_like_solaris: false,
378 is_like_windows: false,
379 is_like_android: false,
381 linker_is_gnu: false,
382 allows_weak_linkage: true,
384 no_default_libraries: true,
385 position_independent_executables: false,
386 pre_link_objects_exe: Vec::new(),
387 pre_link_objects_dll: Vec::new(),
388 post_link_objects: Vec::new(),
389 late_link_args: Vec::new(),
390 archive_format: "gnu".to_string(),
391 custom_unwind_resume: false,
392 lib_allocation_crate: "alloc_system".to_string(),
393 exe_allocation_crate: "alloc_system".to_string(),
396 obj_is_bitcode: false,
403 /// Given a function ABI, turn "System" into the correct ABI for this target.
404 pub fn adjust_abi(&self, abi: Abi) -> Abi {
407 if self.options.is_like_windows && self.arch == "x86" {
417 /// Load a target descriptor from a JSON object.
418 pub fn from_json(obj: Json) -> TargetResult {
419 // While ugly, this code must remain this way to retain
420 // compatibility with existing JSON fields and the internal
421 // expected naming of the Target and TargetOptions structs.
422 // To ensure compatibility is retained, the built-in targets
423 // are round-tripped through this code to catch cases where
424 // the JSON parser is not updated to match the structs.
426 let get_req_field = |name: &str| {
428 .map(|s| s.as_string())
429 .and_then(|os| os.map(|s| s.to_string())) {
430 Some(val) => Ok(val),
432 return Err(format!("Field {} in target specification is required", name))
437 let get_opt_field = |name: &str, default: &str| {
438 obj.find(name).and_then(|s| s.as_string())
439 .map(|s| s.to_string())
440 .unwrap_or(default.to_string())
443 let mut base = Target {
444 llvm_target: get_req_field("llvm-target")?,
445 target_endian: get_req_field("target-endian")?,
446 target_pointer_width: get_req_field("target-pointer-width")?,
447 data_layout: get_req_field("data-layout")?,
448 arch: get_req_field("arch")?,
449 target_os: get_req_field("os")?,
450 target_env: get_opt_field("env", ""),
451 target_vendor: get_opt_field("vendor", "unknown"),
452 options: Default::default(),
455 // Default max-atomic-width to target-pointer-width
456 base.options.max_atomic_width = base.target_pointer_width.parse().unwrap();
459 ($key_name:ident) => ( {
460 let name = (stringify!($key_name)).replace("_", "-");
461 obj.find(&name[..]).map(|o| o.as_string()
462 .map(|s| base.options.$key_name = s.to_string()));
464 ($key_name:ident, bool) => ( {
465 let name = (stringify!($key_name)).replace("_", "-");
467 .map(|o| o.as_boolean()
468 .map(|s| base.options.$key_name = s));
470 ($key_name:ident, u64) => ( {
471 let name = (stringify!($key_name)).replace("_", "-");
474 .map(|s| base.options.$key_name = s));
476 ($key_name:ident, list) => ( {
477 let name = (stringify!($key_name)).replace("_", "-");
478 obj.find(&name[..]).map(|o| o.as_array()
479 .map(|v| base.options.$key_name = v.iter()
480 .map(|a| a.as_string().unwrap().to_string()).collect()
484 ($key_name:ident, optional) => ( {
485 let name = (stringify!($key_name)).replace("_", "-");
486 if let Some(o) = obj.find(&name[..]) {
487 base.options.$key_name = o
489 .map(|s| s.to_string() );
494 key!(is_builtin, bool);
497 key!(pre_link_args, list);
498 key!(pre_link_objects_exe, list);
499 key!(pre_link_objects_dll, list);
500 key!(late_link_args, list);
501 key!(post_link_objects, list);
502 key!(post_link_args, list);
505 key!(dynamic_linking, bool);
506 key!(executables, bool);
507 key!(relocation_model);
509 key!(disable_redzone, bool);
510 key!(eliminate_frame_pointer, bool);
511 key!(function_sections, bool);
515 key!(staticlib_prefix);
516 key!(staticlib_suffix);
517 key!(target_family, optional);
518 key!(is_like_osx, bool);
519 key!(is_like_solaris, bool);
520 key!(is_like_windows, bool);
521 key!(is_like_msvc, bool);
522 key!(is_like_android, bool);
523 key!(linker_is_gnu, bool);
524 key!(allows_weak_linkage, bool);
525 key!(has_rpath, bool);
526 key!(no_default_libraries, bool);
527 key!(position_independent_executables, bool);
528 key!(archive_format);
529 key!(allow_asm, bool);
530 key!(custom_unwind_resume, bool);
531 key!(lib_allocation_crate);
532 key!(exe_allocation_crate);
533 key!(has_elf_tls, bool);
534 key!(obj_is_bitcode, bool);
535 key!(max_atomic_width, u64);
540 /// Search RUST_TARGET_PATH for a JSON file specifying the given target
541 /// triple. Note that it could also just be a bare filename already, so also
542 /// check for that. If one of the hardcoded targets we know about, just
543 /// return it directly.
545 /// The error string could come from any of the APIs called, including
546 /// filesystem access and JSON decoding.
547 pub fn search(target: &str) -> Result<Target, String> {
549 use std::ffi::OsString;
551 use std::path::{Path, PathBuf};
554 fn load_file(path: &Path) -> Result<Target, String> {
555 let mut f = File::open(path).map_err(|e| e.to_string())?;
556 let mut contents = Vec::new();
557 f.read_to_end(&mut contents).map_err(|e| e.to_string())?;
558 let obj = json::from_reader(&mut &contents[..])
559 .map_err(|e| e.to_string())?;
560 Target::from_json(obj)
563 if let Ok(t) = load_specific(target) {
567 let path = Path::new(target);
570 return load_file(&path);
574 let mut target = target.to_string();
575 target.push_str(".json");
576 PathBuf::from(target)
579 let target_path = env::var_os("RUST_TARGET_PATH")
580 .unwrap_or(OsString::new());
582 // FIXME 16351: add a sane default search path?
584 for dir in env::split_paths(&target_path) {
585 let p = dir.join(&path);
587 return load_file(&p);
591 Err(format!("Could not find specification for target {:?}", target))
595 impl ToJson for Target {
596 fn to_json(&self) -> Json {
597 let mut d = BTreeMap::new();
598 let default: TargetOptions = Default::default();
600 macro_rules! target_val {
602 let name = (stringify!($attr)).replace("_", "-");
603 d.insert(name.to_string(), self.$attr.to_json());
605 ($attr:ident, $key_name:expr) => ( {
606 let name = $key_name;
607 d.insert(name.to_string(), self.$attr.to_json());
611 macro_rules! target_option_val {
613 let name = (stringify!($attr)).replace("_", "-");
614 if default.$attr != self.options.$attr {
615 d.insert(name.to_string(), self.options.$attr.to_json());
618 ($attr:ident, $key_name:expr) => ( {
619 let name = $key_name;
620 if default.$attr != self.options.$attr {
621 d.insert(name.to_string(), self.options.$attr.to_json());
626 target_val!(llvm_target);
627 target_val!(target_endian);
628 target_val!(target_pointer_width);
630 target_val!(target_os, "os");
631 target_val!(target_env, "env");
632 target_val!(target_vendor, "vendor");
634 target_val!(data_layout);
636 target_option_val!(is_builtin);
637 target_option_val!(linker);
638 target_option_val!(ar);
639 target_option_val!(pre_link_args);
640 target_option_val!(pre_link_objects_exe);
641 target_option_val!(pre_link_objects_dll);
642 target_option_val!(late_link_args);
643 target_option_val!(post_link_objects);
644 target_option_val!(post_link_args);
645 target_option_val!(cpu);
646 target_option_val!(features);
647 target_option_val!(dynamic_linking);
648 target_option_val!(executables);
649 target_option_val!(relocation_model);
650 target_option_val!(code_model);
651 target_option_val!(disable_redzone);
652 target_option_val!(eliminate_frame_pointer);
653 target_option_val!(function_sections);
654 target_option_val!(dll_prefix);
655 target_option_val!(dll_suffix);
656 target_option_val!(exe_suffix);
657 target_option_val!(staticlib_prefix);
658 target_option_val!(staticlib_suffix);
659 target_option_val!(target_family);
660 target_option_val!(is_like_osx);
661 target_option_val!(is_like_solaris);
662 target_option_val!(is_like_windows);
663 target_option_val!(is_like_msvc);
664 target_option_val!(is_like_android);
665 target_option_val!(linker_is_gnu);
666 target_option_val!(allows_weak_linkage);
667 target_option_val!(has_rpath);
668 target_option_val!(no_default_libraries);
669 target_option_val!(position_independent_executables);
670 target_option_val!(archive_format);
671 target_option_val!(allow_asm);
672 target_option_val!(custom_unwind_resume);
673 target_option_val!(lib_allocation_crate);
674 target_option_val!(exe_allocation_crate);
675 target_option_val!(has_elf_tls);
676 target_option_val!(obj_is_bitcode);
677 target_option_val!(max_atomic_width);
683 fn maybe_jemalloc() -> String {
684 if cfg!(feature = "jemalloc") {
685 "alloc_jemalloc".to_string()
687 "alloc_system".to_string()