xref: /wasmtime-44.0.1/crates/cli-flags/src/lib.rs (revision 6f6a514b)
1 //! Contains the common Wasmtime command line interface (CLI) flags.
2 
3 use anyhow::{Context, Result};
4 use clap::Parser;
5 use serde::Deserialize;
6 use std::{
7     fmt, fs,
8     path::{Path, PathBuf},
9     time::Duration,
10 };
11 use wasmtime::Config;
12 
13 pub mod opt;
14 
15 #[cfg(feature = "logging")]
16 fn init_file_per_thread_logger(prefix: &'static str) {
17     file_per_thread_logger::initialize(prefix);
18     file_per_thread_logger::allow_uninitialized();
19 
20     // Extending behavior of default spawner:
21     // https://docs.rs/rayon/1.1.0/rayon/struct.ThreadPoolBuilder.html#method.spawn_handler
22     // Source code says DefaultSpawner is implementation detail and
23     // shouldn't be used directly.
24     #[cfg(feature = "parallel-compilation")]
25     rayon::ThreadPoolBuilder::new()
26         .spawn_handler(move |thread| {
27             let mut b = std::thread::Builder::new();
28             if let Some(name) = thread.name() {
29                 b = b.name(name.to_owned());
30             }
31             if let Some(stack_size) = thread.stack_size() {
32                 b = b.stack_size(stack_size);
33             }
34             b.spawn(move || {
35                 file_per_thread_logger::initialize(prefix);
36                 thread.run()
37             })?;
38             Ok(())
39         })
40         .build_global()
41         .unwrap();
42 }
43 
44 wasmtime_option_group! {
45     #[derive(PartialEq, Clone, Deserialize)]
46     #[serde(rename_all = "kebab-case", deny_unknown_fields)]
47     pub struct OptimizeOptions {
48         /// Optimization level of generated code (0-2, s; default: 2)
49         #[serde(default)]
50         #[serde(deserialize_with = "crate::opt::cli_parse_wrapper")]
51         pub opt_level: Option<wasmtime::OptLevel>,
52 
53         /// Register allocator algorithm choice.
54         #[serde(default)]
55         #[serde(deserialize_with = "crate::opt::cli_parse_wrapper")]
56         pub regalloc_algorithm: Option<wasmtime::RegallocAlgorithm>,
57 
58         /// Do not allow Wasm linear memories to move in the host process's
59         /// address space.
60         pub memory_may_move: Option<bool>,
61 
62         /// Initial virtual memory allocation size for memories.
63         pub memory_reservation: Option<u64>,
64 
65         /// Bytes to reserve at the end of linear memory for growth into.
66         pub memory_reservation_for_growth: Option<u64>,
67 
68         /// Size, in bytes, of guard pages for linear memories.
69         pub memory_guard_size: Option<u64>,
70 
71         /// Indicates whether an unmapped region of memory is placed before all
72         /// linear memories.
73         pub guard_before_linear_memory: Option<bool>,
74 
75         /// Whether to initialize tables lazily, so that instantiation is
76         /// fast but indirect calls are a little slower. If no, tables are
77         /// initialized eagerly from any active element segments that apply to
78         /// them during instantiation. (default: yes)
79         pub table_lazy_init: Option<bool>,
80 
81         /// Enable the pooling allocator, in place of the on-demand allocator.
82         pub pooling_allocator: Option<bool>,
83 
84         /// The number of decommits to do per batch. A batch size of 1
85         /// effectively disables decommit batching. (default: 1)
86         pub pooling_decommit_batch_size: Option<usize>,
87 
88         /// How many bytes to keep resident between instantiations for the
89         /// pooling allocator in linear memories.
90         pub pooling_memory_keep_resident: Option<usize>,
91 
92         /// How many bytes to keep resident between instantiations for the
93         /// pooling allocator in tables.
94         pub pooling_table_keep_resident: Option<usize>,
95 
96         /// Enable memory protection keys for the pooling allocator; this can
97         /// optimize the size of memory slots.
98         #[serde(default)]
99         #[serde(deserialize_with = "crate::opt::cli_parse_wrapper")]
100         pub pooling_memory_protection_keys: Option<wasmtime::Enabled>,
101 
102         /// Sets an upper limit on how many memory protection keys (MPK) Wasmtime
103         /// will use. (default: 16)
104         pub pooling_max_memory_protection_keys: Option<usize>,
105 
106         /// Configure attempting to initialize linear memory via a
107         /// copy-on-write mapping (default: yes)
108         pub memory_init_cow: Option<bool>,
109 
110         /// Threshold below which CoW images are guaranteed to be used and be
111         /// dense.
112         pub memory_guaranteed_dense_image_size: Option<u64>,
113 
114         /// The maximum number of WebAssembly instances which can be created
115         /// with the pooling allocator.
116         pub pooling_total_core_instances: Option<u32>,
117 
118         /// The maximum number of WebAssembly components which can be created
119         /// with the pooling allocator.
120         pub pooling_total_component_instances: Option<u32>,
121 
122         /// The maximum number of WebAssembly memories which can be created with
123         /// the pooling allocator.
124         pub pooling_total_memories: Option<u32>,
125 
126         /// The maximum number of WebAssembly tables which can be created with
127         /// the pooling allocator.
128         pub pooling_total_tables: Option<u32>,
129 
130         /// The maximum number of WebAssembly stacks which can be created with
131         /// the pooling allocator.
132         pub pooling_total_stacks: Option<u32>,
133 
134         /// The maximum runtime size of each linear memory in the pooling
135         /// allocator, in bytes.
136         pub pooling_max_memory_size: Option<usize>,
137 
138         /// The maximum table elements for any table defined in a module when
139         /// using the pooling allocator.
140         pub pooling_table_elements: Option<usize>,
141 
142         /// The maximum size, in bytes, allocated for a core instance's metadata
143         /// when using the pooling allocator.
144         pub pooling_max_core_instance_size: Option<usize>,
145 
146         /// Configures the maximum number of "unused warm slots" to retain in the
147         /// pooling allocator. (default: 100)
148         pub pooling_max_unused_warm_slots: Option<u32>,
149 
150         /// How much memory, in bytes, to keep resident for async stacks allocated
151         /// with the pooling allocator. (default: 0)
152         pub pooling_async_stack_keep_resident: Option<usize>,
153 
154         /// The maximum size, in bytes, allocated for a component instance's
155         /// `VMComponentContext` metadata. (default: 1MiB)
156         pub pooling_max_component_instance_size: Option<usize>,
157 
158         /// The maximum number of core instances a single component may contain
159         /// (default is unlimited).
160         pub pooling_max_core_instances_per_component: Option<u32>,
161 
162         /// The maximum number of Wasm linear memories that a single component may
163         /// transitively contain (default is unlimited).
164         pub pooling_max_memories_per_component: Option<u32>,
165 
166         /// The maximum number of tables that a single component may transitively
167         /// contain (default is unlimited).
168         pub pooling_max_tables_per_component: Option<u32>,
169 
170         /// The maximum number of defined tables for a core module. (default: 1)
171         pub pooling_max_tables_per_module: Option<u32>,
172 
173         /// The maximum number of defined linear memories for a module. (default: 1)
174         pub pooling_max_memories_per_module: Option<u32>,
175 
176         /// The maximum number of concurrent GC heaps supported. (default: 1000)
177         pub pooling_total_gc_heaps: Option<u32>,
178 
179         /// Enable or disable the use of host signal handlers for traps.
180         pub signals_based_traps: Option<bool>,
181 
182         /// DEPRECATED: Use `-Cmemory-guard-size=N` instead.
183         pub dynamic_memory_guard_size: Option<u64>,
184 
185         /// DEPRECATED: Use `-Cmemory-guard-size=N` instead.
186         pub static_memory_guard_size: Option<u64>,
187 
188         /// DEPRECATED: Use `-Cmemory-may-move` instead.
189         pub static_memory_forced: Option<bool>,
190 
191         /// DEPRECATED: Use `-Cmemory-reservation=N` instead.
192         pub static_memory_maximum_size: Option<u64>,
193 
194         /// DEPRECATED: Use `-Cmemory-reservation-for-growth=N` instead.
195         pub dynamic_memory_reserved_for_growth: Option<u64>,
196 
197         /// Whether or not `PAGEMAP_SCAN` ioctls are used to reset linear
198         /// memory.
199         #[serde(default)]
200         #[serde(deserialize_with = "crate::opt::cli_parse_wrapper")]
201         pub pooling_pagemap_scan: Option<wasmtime::Enabled>,
202     }
203 
204     enum Optimize {
205         ...
206     }
207 }
208 
209 wasmtime_option_group! {
210     #[derive(PartialEq, Clone, Deserialize)]
211     #[serde(rename_all = "kebab-case", deny_unknown_fields)]
212     pub struct CodegenOptions {
213         /// Either `cranelift` or `winch`.
214         ///
215         /// Currently only `cranelift` and `winch` are supported, but not all
216         /// builds of Wasmtime have both built in.
217         #[serde(default)]
218         #[serde(deserialize_with = "crate::opt::cli_parse_wrapper")]
219         pub compiler: Option<wasmtime::Strategy>,
220         /// Which garbage collector to use: `drc` or `null`.
221         ///
222         /// `drc` is the deferred reference-counting collector.
223         ///
224         /// `null` is the null garbage collector, which does not collect any
225         /// garbage.
226         ///
227         /// Note that not all builds of Wasmtime will have support for garbage
228         /// collection included.
229         #[serde(default)]
230         #[serde(deserialize_with = "crate::opt::cli_parse_wrapper")]
231         pub collector: Option<wasmtime::Collector>,
232         /// Enable Cranelift's internal debug verifier (expensive)
233         pub cranelift_debug_verifier: Option<bool>,
234         /// Whether or not to enable caching of compiled modules.
235         pub cache: Option<bool>,
236         /// Configuration for compiled module caching.
237         pub cache_config: Option<String>,
238         /// Whether or not to enable parallel compilation of modules.
239         pub parallel_compilation: Option<bool>,
240         /// Whether to enable proof-carrying code (PCC)-based validation.
241         pub pcc: Option<bool>,
242         /// Controls whether native unwind information is present in compiled
243         /// object files.
244         pub native_unwind_info: Option<bool>,
245 
246         /// Whether to perform function inlining during compilation.
247         pub inlining: Option<bool>,
248 
249         #[prefixed = "cranelift"]
250         #[serde(default)]
251         /// Set a cranelift-specific option. Use `wasmtime settings` to see
252         /// all.
253         pub cranelift: Vec<(String, Option<String>)>,
254     }
255 
256     enum Codegen {
257         ...
258     }
259 }
260 
261 wasmtime_option_group! {
262     #[derive(PartialEq, Clone, Deserialize)]
263     #[serde(rename_all = "kebab-case", deny_unknown_fields)]
264     pub struct DebugOptions {
265         /// Enable generation of DWARF debug information in compiled code.
266         pub debug_info: Option<bool>,
267         /// Configure whether compiled code can map native addresses to wasm.
268         pub address_map: Option<bool>,
269         /// Configure whether logging is enabled.
270         pub logging: Option<bool>,
271         /// Configure whether logs are emitted to files
272         pub log_to_files: Option<bool>,
273         /// Enable coredump generation to this file after a WebAssembly trap.
274         pub coredump: Option<String>,
275     }
276 
277     enum Debug {
278         ...
279     }
280 }
281 
282 wasmtime_option_group! {
283     #[derive(PartialEq, Clone, Deserialize)]
284     #[serde(rename_all = "kebab-case", deny_unknown_fields)]
285     pub struct WasmOptions {
286         /// Enable canonicalization of all NaN values.
287         pub nan_canonicalization: Option<bool>,
288         /// Enable execution fuel with N units fuel, trapping after running out
289         /// of fuel.
290         ///
291         /// Most WebAssembly instructions consume 1 unit of fuel. Some
292         /// instructions, such as `nop`, `drop`, `block`, and `loop`, consume 0
293         /// units, as any execution cost associated with them involves other
294         /// instructions which do consume fuel.
295         pub fuel: Option<u64>,
296         /// Yield when a global epoch counter changes, allowing for async
297         /// operation without blocking the executor.
298         pub epoch_interruption: Option<bool>,
299         /// Maximum stack size, in bytes, that wasm is allowed to consume before a
300         /// stack overflow is reported.
301         pub max_wasm_stack: Option<usize>,
302         /// Stack size, in bytes, that will be allocated for async stacks.
303         ///
304         /// Note that this must be larger than `max-wasm-stack` and the
305         /// difference between the two is how much stack the host has to execute
306         /// on.
307         pub async_stack_size: Option<usize>,
308         /// Configures whether or not stacks used for async futures are zeroed
309         /// before (re)use as a defense-in-depth mechanism. (default: false)
310         pub async_stack_zeroing: Option<bool>,
311         /// Allow unknown exports when running commands.
312         pub unknown_exports_allow: Option<bool>,
313         /// Allow the main module to import unknown functions, using an
314         /// implementation that immediately traps, when running commands.
315         pub unknown_imports_trap: Option<bool>,
316         /// Allow the main module to import unknown functions, using an
317         /// implementation that returns default values, when running commands.
318         pub unknown_imports_default: Option<bool>,
319         /// Enables memory error checking. (see wmemcheck.md for more info)
320         pub wmemcheck: Option<bool>,
321         /// Maximum size, in bytes, that a linear memory is allowed to reach.
322         ///
323         /// Growth beyond this limit will cause `memory.grow` instructions in
324         /// WebAssembly modules to return -1 and fail.
325         pub max_memory_size: Option<usize>,
326         /// Maximum size, in table elements, that a table is allowed to reach.
327         pub max_table_elements: Option<usize>,
328         /// Maximum number of WebAssembly instances allowed to be created.
329         pub max_instances: Option<usize>,
330         /// Maximum number of WebAssembly tables allowed to be created.
331         pub max_tables: Option<usize>,
332         /// Maximum number of WebAssembly linear memories allowed to be created.
333         pub max_memories: Option<usize>,
334         /// Force a trap to be raised on `memory.grow` and `table.grow` failure
335         /// instead of returning -1 from these instructions.
336         ///
337         /// This is not necessarily a spec-compliant option to enable but can be
338         /// useful for tracking down a backtrace of what is requesting so much
339         /// memory, for example.
340         pub trap_on_grow_failure: Option<bool>,
341         /// Maximum execution time of wasm code before timing out (1, 2s, 100ms, etc)
342         pub timeout: Option<Duration>,
343         /// Configures support for all WebAssembly proposals implemented.
344         pub all_proposals: Option<bool>,
345         /// Configure support for the bulk memory proposal.
346         pub bulk_memory: Option<bool>,
347         /// Configure support for the multi-memory proposal.
348         pub multi_memory: Option<bool>,
349         /// Configure support for the multi-value proposal.
350         pub multi_value: Option<bool>,
351         /// Configure support for the reference-types proposal.
352         pub reference_types: Option<bool>,
353         /// Configure support for the simd proposal.
354         pub simd: Option<bool>,
355         /// Configure support for the relaxed-simd proposal.
356         pub relaxed_simd: Option<bool>,
357         /// Configure forcing deterministic and host-independent behavior of
358         /// the relaxed-simd instructions.
359         ///
360         /// By default these instructions may have architecture-specific behavior as
361         /// allowed by the specification, but this can be used to force the behavior
362         /// of these instructions to match the deterministic behavior classified in
363         /// the specification. Note that enabling this option may come at a
364         /// performance cost.
365         pub relaxed_simd_deterministic: Option<bool>,
366         /// Configure support for the tail-call proposal.
367         pub tail_call: Option<bool>,
368         /// Configure support for the threads proposal.
369         pub threads: Option<bool>,
370         /// Configure support for the shared-everything-threads proposal.
371         pub shared_everything_threads: Option<bool>,
372         /// Configure support for the memory64 proposal.
373         pub memory64: Option<bool>,
374         /// Configure support for the component-model proposal.
375         pub component_model: Option<bool>,
376         /// Component model support for async lifting/lowering.
377         pub component_model_async: Option<bool>,
378         /// Component model support for async lifting/lowering: this corresponds
379         /// to the �� emoji in the component model specification.
380         pub component_model_async_builtins: Option<bool>,
381         /// Component model support for async lifting/lowering: this corresponds
382         /// to the �� emoji in the component model specification.
383         pub component_model_async_stackful: Option<bool>,
384         /// Component model support for `error-context`: this corresponds
385         /// to the �� emoji in the component model specification.
386         pub component_model_error_context: Option<bool>,
387         /// GC support in the component model: this corresponds to the �� emoji
388         /// in the component model specification.
389         pub component_model_gc: Option<bool>,
390         /// Configure support for the function-references proposal.
391         pub function_references: Option<bool>,
392         /// Configure support for the stack-switching proposal.
393         pub stack_switching: Option<bool>,
394         /// Configure support for the GC proposal.
395         pub gc: Option<bool>,
396         /// Configure support for the custom-page-sizes proposal.
397         pub custom_page_sizes: Option<bool>,
398         /// Configure support for the wide-arithmetic proposal.
399         pub wide_arithmetic: Option<bool>,
400         /// Configure support for the extended-const proposal.
401         pub extended_const: Option<bool>,
402         /// Configure support for the exceptions proposal.
403         pub exceptions: Option<bool>,
404         /// DEPRECATED: Configure support for the legacy exceptions proposal.
405         pub legacy_exceptions: Option<bool>,
406     }
407 
408     enum Wasm {
409         ...
410     }
411 }
412 
413 wasmtime_option_group! {
414     #[derive(PartialEq, Clone, Deserialize)]
415     #[serde(rename_all = "kebab-case", deny_unknown_fields)]
416     pub struct WasiOptions {
417         /// Enable support for WASI CLI APIs, including filesystems, sockets, clocks, and random.
418         pub cli: Option<bool>,
419         /// Enable WASI APIs marked as: @unstable(feature = cli-exit-with-code)
420         pub cli_exit_with_code: Option<bool>,
421         /// Deprecated alias for `cli`
422         pub common: Option<bool>,
423         /// Enable support for WASI neural network imports (experimental)
424         pub nn: Option<bool>,
425         /// Enable support for WASI threading imports (experimental). Implies preview2=false.
426         pub threads: Option<bool>,
427         /// Enable support for WASI HTTP imports
428         pub http: Option<bool>,
429         /// Number of distinct write calls to the outgoing body's output-stream
430         /// that the implementation will buffer.
431         /// Default: 1.
432         pub http_outgoing_body_buffer_chunks: Option<usize>,
433         /// Maximum size allowed in a write call to the outgoing body's output-stream.
434         /// Default: 1024 * 1024.
435         pub http_outgoing_body_chunk_size: Option<usize>,
436         /// Enable support for WASI config imports (experimental)
437         pub config: Option<bool>,
438         /// Enable support for WASI key-value imports (experimental)
439         pub keyvalue: Option<bool>,
440         /// Inherit environment variables and file descriptors following the
441         /// systemd listen fd specification (UNIX only) (legacy wasip1
442         /// implementation only)
443         pub listenfd: Option<bool>,
444         /// Grant access to the given TCP listen socket (experimental, legacy
445         /// wasip1 implementation only)
446         #[serde(default)]
447         pub tcplisten: Vec<String>,
448         /// Enable support for WASI TLS (Transport Layer Security) imports (experimental)
449         pub tls: Option<bool>,
450         /// Implement WASI Preview1 using new Preview2 implementation (true, default) or legacy
451         /// implementation (false)
452         pub preview2: Option<bool>,
453         /// Pre-load machine learning graphs (i.e., models) for use by wasi-nn.
454         ///
455         /// Each use of the flag will preload a ML model from the host directory
456         /// using the given model encoding. The model will be mapped to the
457         /// directory name: e.g., `--wasi-nn-graph openvino:/foo/bar` will preload
458         /// an OpenVINO model named `bar`. Note that which model encodings are
459         /// available is dependent on the backends implemented in the
460         /// `wasmtime_wasi_nn` crate.
461         #[serde(skip)]
462         pub nn_graph: Vec<WasiNnGraph>,
463         /// Flag for WASI preview2 to inherit the host's network within the
464         /// guest so it has full access to all addresses/ports/etc.
465         pub inherit_network: Option<bool>,
466         /// Indicates whether `wasi:sockets/ip-name-lookup` is enabled or not.
467         pub allow_ip_name_lookup: Option<bool>,
468         /// Indicates whether `wasi:sockets` TCP support is enabled or not.
469         pub tcp: Option<bool>,
470         /// Indicates whether `wasi:sockets` UDP support is enabled or not.
471         pub udp: Option<bool>,
472         /// Enable WASI APIs marked as: @unstable(feature = network-error-code)
473         pub network_error_code: Option<bool>,
474         /// Allows imports from the `wasi_unstable` core wasm module.
475         pub preview0: Option<bool>,
476         /// Inherit all environment variables from the parent process.
477         ///
478         /// This option can be further overwritten with `--env` flags.
479         pub inherit_env: Option<bool>,
480         /// Pass a wasi config variable to the program.
481         #[serde(skip)]
482         pub config_var: Vec<KeyValuePair>,
483         /// Preset data for the In-Memory provider of WASI key-value API.
484         #[serde(skip)]
485         pub keyvalue_in_memory_data: Vec<KeyValuePair>,
486         /// Enable support for WASIp3 APIs.
487         pub p3: Option<bool>,
488     }
489 
490     enum Wasi {
491         ...
492     }
493 }
494 
495 #[derive(Debug, Clone, PartialEq)]
496 pub struct WasiNnGraph {
497     pub format: String,
498     pub dir: String,
499 }
500 
501 #[derive(Debug, Clone, PartialEq)]
502 pub struct KeyValuePair {
503     pub key: String,
504     pub value: String,
505 }
506 
507 /// Common options for commands that translate WebAssembly modules
508 #[derive(Parser, Clone, Deserialize)]
509 #[serde(deny_unknown_fields)]
510 pub struct CommonOptions {
511     // These options groups are used to parse `-O` and such options but aren't
512     // the raw form consumed by the CLI. Instead they're pushed into the `pub`
513     // fields below as part of the `configure` method.
514     //
515     // Ideally clap would support `pub opts: OptimizeOptions` and parse directly
516     // into that but it does not appear to do so for multiple `-O` flags for
517     // now.
518     /// Optimization and tuning related options for wasm performance, `-O help` to
519     /// see all.
520     #[arg(short = 'O', long = "optimize", value_name = "KEY[=VAL[,..]]")]
521     #[serde(skip)]
522     opts_raw: Vec<opt::CommaSeparated<Optimize>>,
523 
524     /// Codegen-related configuration options, `-C help` to see all.
525     #[arg(short = 'C', long = "codegen", value_name = "KEY[=VAL[,..]]")]
526     #[serde(skip)]
527     codegen_raw: Vec<opt::CommaSeparated<Codegen>>,
528 
529     /// Debug-related configuration options, `-D help` to see all.
530     #[arg(short = 'D', long = "debug", value_name = "KEY[=VAL[,..]]")]
531     #[serde(skip)]
532     debug_raw: Vec<opt::CommaSeparated<Debug>>,
533 
534     /// Options for configuring semantic execution of WebAssembly, `-W help` to see
535     /// all.
536     #[arg(short = 'W', long = "wasm", value_name = "KEY[=VAL[,..]]")]
537     #[serde(skip)]
538     wasm_raw: Vec<opt::CommaSeparated<Wasm>>,
539 
540     /// Options for configuring WASI and its proposals, `-S help` to see all.
541     #[arg(short = 'S', long = "wasi", value_name = "KEY[=VAL[,..]]")]
542     #[serde(skip)]
543     wasi_raw: Vec<opt::CommaSeparated<Wasi>>,
544 
545     // These fields are filled in by the `configure` method below via the
546     // options parsed from the CLI above. This is what the CLI should use.
547     #[arg(skip)]
548     #[serde(skip)]
549     configured: bool,
550 
551     #[arg(skip)]
552     #[serde(rename = "optimize", default)]
553     pub opts: OptimizeOptions,
554 
555     #[arg(skip)]
556     #[serde(rename = "codegen", default)]
557     pub codegen: CodegenOptions,
558 
559     #[arg(skip)]
560     #[serde(rename = "debug", default)]
561     pub debug: DebugOptions,
562 
563     #[arg(skip)]
564     #[serde(rename = "wasm", default)]
565     pub wasm: WasmOptions,
566 
567     #[arg(skip)]
568     #[serde(rename = "wasi", default)]
569     pub wasi: WasiOptions,
570 
571     /// The target triple; default is the host triple
572     #[arg(long, value_name = "TARGET")]
573     #[serde(skip)]
574     pub target: Option<String>,
575 
576     /// Use the specified TOML configuration file.
577     /// This TOML configuration file can provide same configuration options as the
578     /// `--optimize`, `--codgen`, `--debug`, `--wasm`, `--wasi` CLI options, with a couple exceptions.
579     ///
580     /// Additional options specified on the command line will take precedent over options loaded from
581     /// this TOML file.
582     #[arg(long = "config", value_name = "FILE")]
583     #[serde(skip)]
584     pub config: Option<PathBuf>,
585 }
586 
587 macro_rules! match_feature {
588     (
589         [$feat:tt : $config:expr]
590         $val:ident => $e:expr,
591         $p:pat => err,
592     ) => {
593         #[cfg(feature = $feat)]
594         {
595             if let Some($val) = $config {
596                 $e;
597             }
598         }
599         #[cfg(not(feature = $feat))]
600         {
601             if let Some($p) = $config {
602                 anyhow::bail!(concat!("support for ", $feat, " disabled at compile time"));
603             }
604         }
605     };
606 }
607 
608 impl CommonOptions {
609     /// Creates a blank new set of [`CommonOptions`] that can be configured.
610     pub fn new() -> CommonOptions {
611         CommonOptions {
612             opts_raw: Vec::new(),
613             codegen_raw: Vec::new(),
614             debug_raw: Vec::new(),
615             wasm_raw: Vec::new(),
616             wasi_raw: Vec::new(),
617             configured: true,
618             opts: Default::default(),
619             codegen: Default::default(),
620             debug: Default::default(),
621             wasm: Default::default(),
622             wasi: Default::default(),
623             target: None,
624             config: None,
625         }
626     }
627 
628     fn configure(&mut self) -> Result<()> {
629         if self.configured {
630             return Ok(());
631         }
632         self.configured = true;
633         if let Some(toml_config_path) = &self.config {
634             let toml_options = CommonOptions::from_file(toml_config_path)?;
635             self.opts = toml_options.opts;
636             self.codegen = toml_options.codegen;
637             self.debug = toml_options.debug;
638             self.wasm = toml_options.wasm;
639             self.wasi = toml_options.wasi;
640         }
641         self.opts.configure_with(&self.opts_raw);
642         self.codegen.configure_with(&self.codegen_raw);
643         self.debug.configure_with(&self.debug_raw);
644         self.wasm.configure_with(&self.wasm_raw);
645         self.wasi.configure_with(&self.wasi_raw);
646         Ok(())
647     }
648 
649     pub fn init_logging(&mut self) -> Result<()> {
650         self.configure()?;
651         if self.debug.logging == Some(false) {
652             return Ok(());
653         }
654         #[cfg(feature = "logging")]
655         if self.debug.log_to_files == Some(true) {
656             let prefix = "wasmtime.dbg.";
657             init_file_per_thread_logger(prefix);
658         } else {
659             use std::io::IsTerminal;
660             use tracing_subscriber::{EnvFilter, FmtSubscriber};
661             let builder = FmtSubscriber::builder()
662                 .with_writer(std::io::stderr)
663                 .with_env_filter(EnvFilter::from_env("WASMTIME_LOG"))
664                 .with_ansi(std::io::stderr().is_terminal());
665             if std::env::var("WASMTIME_LOG_NO_CONTEXT").is_ok_and(|value| value.eq("1")) {
666                 builder
667                     .with_level(false)
668                     .with_target(false)
669                     .without_time()
670                     .init()
671             } else {
672                 builder.init();
673             }
674         }
675         #[cfg(not(feature = "logging"))]
676         if self.debug.log_to_files == Some(true) || self.debug.logging == Some(true) {
677             anyhow::bail!("support for logging disabled at compile time");
678         }
679         Ok(())
680     }
681 
682     pub fn config(&mut self, pooling_allocator_default: Option<bool>) -> Result<Config> {
683         self.configure()?;
684         let mut config = Config::new();
685 
686         match_feature! {
687             ["cranelift" : self.codegen.compiler]
688             strategy => config.strategy(strategy),
689             _ => err,
690         }
691         match_feature! {
692             ["gc" : self.codegen.collector]
693             collector => config.collector(collector),
694             _ => err,
695         }
696         if let Some(target) = &self.target {
697             config.target(target)?;
698         }
699         match_feature! {
700             ["cranelift" : self.codegen.cranelift_debug_verifier]
701             enable => config.cranelift_debug_verifier(enable),
702             true => err,
703         }
704         if let Some(enable) = self.debug.debug_info {
705             config.debug_info(enable);
706         }
707         if self.debug.coredump.is_some() {
708             #[cfg(feature = "coredump")]
709             config.coredump_on_trap(true);
710             #[cfg(not(feature = "coredump"))]
711             anyhow::bail!("support for coredumps disabled at compile time");
712         }
713         match_feature! {
714             ["cranelift" : self.opts.opt_level]
715             level => config.cranelift_opt_level(level),
716             _ => err,
717         }
718         match_feature! {
719             ["cranelift": self.opts.regalloc_algorithm]
720             algo => config.cranelift_regalloc_algorithm(algo),
721             _ => err,
722         }
723         match_feature! {
724             ["cranelift" : self.wasm.nan_canonicalization]
725             enable => config.cranelift_nan_canonicalization(enable),
726             true => err,
727         }
728         match_feature! {
729             ["cranelift" : self.codegen.pcc]
730             enable => config.cranelift_pcc(enable),
731             true => err,
732         }
733 
734         self.enable_wasm_features(&mut config)?;
735 
736         #[cfg(feature = "cranelift")]
737         for (name, value) in self.codegen.cranelift.iter() {
738             let name = name.replace('-', "_");
739             unsafe {
740                 match value {
741                     Some(val) => {
742                         config.cranelift_flag_set(&name, val);
743                     }
744                     None => {
745                         config.cranelift_flag_enable(&name);
746                     }
747                 }
748             }
749         }
750         #[cfg(not(feature = "cranelift"))]
751         if !self.codegen.cranelift.is_empty() {
752             anyhow::bail!("support for cranelift disabled at compile time");
753         }
754 
755         #[cfg(feature = "cache")]
756         if self.codegen.cache != Some(false) {
757             use wasmtime::Cache;
758             let cache = match &self.codegen.cache_config {
759                 Some(path) => Cache::from_file(Some(Path::new(path)))?,
760                 None => Cache::from_file(None)?,
761             };
762             config.cache(Some(cache));
763         }
764         #[cfg(not(feature = "cache"))]
765         if self.codegen.cache == Some(true) {
766             anyhow::bail!("support for caching disabled at compile time");
767         }
768 
769         match_feature! {
770             ["parallel-compilation" : self.codegen.parallel_compilation]
771             enable => config.parallel_compilation(enable),
772             true => err,
773         }
774 
775         let memory_reservation = self
776             .opts
777             .memory_reservation
778             .or(self.opts.static_memory_maximum_size);
779         if let Some(size) = memory_reservation {
780             config.memory_reservation(size);
781         }
782 
783         if let Some(enable) = self.opts.static_memory_forced {
784             config.memory_may_move(!enable);
785         }
786         if let Some(enable) = self.opts.memory_may_move {
787             config.memory_may_move(enable);
788         }
789 
790         let memory_guard_size = self
791             .opts
792             .static_memory_guard_size
793             .or(self.opts.dynamic_memory_guard_size)
794             .or(self.opts.memory_guard_size);
795         if let Some(size) = memory_guard_size {
796             config.memory_guard_size(size);
797         }
798 
799         let mem_for_growth = self
800             .opts
801             .memory_reservation_for_growth
802             .or(self.opts.dynamic_memory_reserved_for_growth);
803         if let Some(size) = mem_for_growth {
804             config.memory_reservation_for_growth(size);
805         }
806         if let Some(enable) = self.opts.guard_before_linear_memory {
807             config.guard_before_linear_memory(enable);
808         }
809         if let Some(enable) = self.opts.table_lazy_init {
810             config.table_lazy_init(enable);
811         }
812 
813         // If fuel has been configured, set the `consume fuel` flag on the config.
814         if self.wasm.fuel.is_some() {
815             config.consume_fuel(true);
816         }
817 
818         if let Some(enable) = self.wasm.epoch_interruption {
819             config.epoch_interruption(enable);
820         }
821         if let Some(enable) = self.debug.address_map {
822             config.generate_address_map(enable);
823         }
824         if let Some(enable) = self.opts.memory_init_cow {
825             config.memory_init_cow(enable);
826         }
827         if let Some(size) = self.opts.memory_guaranteed_dense_image_size {
828             config.memory_guaranteed_dense_image_size(size);
829         }
830         if let Some(enable) = self.opts.signals_based_traps {
831             config.signals_based_traps(enable);
832         }
833         if let Some(enable) = self.codegen.native_unwind_info {
834             config.native_unwind_info(enable);
835         }
836         if let Some(enable) = self.codegen.inlining {
837             config.compiler_inlining(enable);
838         }
839 
840         // async_stack_size enabled by either async or stack-switching, so
841         // cannot directly use match_feature!
842         #[cfg(any(feature = "async", feature = "stack-switching"))]
843         {
844             if let Some(size) = self.wasm.async_stack_size {
845                 config.async_stack_size(size);
846             }
847         }
848         #[cfg(not(any(feature = "async", feature = "stack-switching")))]
849         {
850             if let Some(_size) = self.wasm.async_stack_size {
851                 anyhow::bail!(concat!(
852                     "support for async/stack-switching disabled at compile time"
853                 ));
854             }
855         }
856 
857         match_feature! {
858             ["pooling-allocator" : self.opts.pooling_allocator.or(pooling_allocator_default)]
859             enable => {
860                 if enable {
861                     let mut cfg = wasmtime::PoolingAllocationConfig::default();
862                     if let Some(size) = self.opts.pooling_memory_keep_resident {
863                         cfg.linear_memory_keep_resident(size);
864                     }
865                     if let Some(size) = self.opts.pooling_table_keep_resident {
866                         cfg.table_keep_resident(size);
867                     }
868                     if let Some(limit) = self.opts.pooling_total_core_instances {
869                         cfg.total_core_instances(limit);
870                     }
871                     if let Some(limit) = self.opts.pooling_total_component_instances {
872                         cfg.total_component_instances(limit);
873                     }
874                     if let Some(limit) = self.opts.pooling_total_memories {
875                         cfg.total_memories(limit);
876                     }
877                     if let Some(limit) = self.opts.pooling_total_tables {
878                         cfg.total_tables(limit);
879                     }
880                     if let Some(limit) = self.opts.pooling_table_elements
881                         .or(self.wasm.max_table_elements)
882                     {
883                         cfg.table_elements(limit);
884                     }
885                     if let Some(limit) = self.opts.pooling_max_core_instance_size {
886                         cfg.max_core_instance_size(limit);
887                     }
888                     match_feature! {
889                         ["async" : self.opts.pooling_total_stacks]
890                         limit => cfg.total_stacks(limit),
891                         _ => err,
892                     }
893                     if let Some(max) = self.opts.pooling_max_memory_size
894                         .or(self.wasm.max_memory_size)
895                     {
896                         cfg.max_memory_size(max);
897                     }
898                     if let Some(size) = self.opts.pooling_decommit_batch_size {
899                         cfg.decommit_batch_size(size);
900                     }
901                     if let Some(max) = self.opts.pooling_max_unused_warm_slots {
902                         cfg.max_unused_warm_slots(max);
903                     }
904                     match_feature! {
905                         ["async" : self.opts.pooling_async_stack_keep_resident]
906                         size => cfg.async_stack_keep_resident(size),
907                         _ => err,
908                     }
909                     if let Some(max) = self.opts.pooling_max_component_instance_size {
910                         cfg.max_component_instance_size(max);
911                     }
912                     if let Some(max) = self.opts.pooling_max_core_instances_per_component {
913                         cfg.max_core_instances_per_component(max);
914                     }
915                     if let Some(max) = self.opts.pooling_max_memories_per_component {
916                         cfg.max_memories_per_component(max);
917                     }
918                     if let Some(max) = self.opts.pooling_max_tables_per_component {
919                         cfg.max_tables_per_component(max);
920                     }
921                     if let Some(max) = self.opts.pooling_max_tables_per_module {
922                         cfg.max_tables_per_module(max);
923                     }
924                     if let Some(max) = self.opts.pooling_max_memories_per_module {
925                         cfg.max_memories_per_module(max);
926                     }
927                     match_feature! {
928                         ["memory-protection-keys" : self.opts.pooling_memory_protection_keys]
929                         enable => cfg.memory_protection_keys(enable),
930                         _ => err,
931                     }
932                     match_feature! {
933                         ["memory-protection-keys" : self.opts.pooling_max_memory_protection_keys]
934                         max => cfg.max_memory_protection_keys(max),
935                         _ => err,
936                     }
937                     match_feature! {
938                         ["gc" : self.opts.pooling_total_gc_heaps]
939                         max => cfg.total_gc_heaps(max),
940                         _ => err,
941                     }
942                     if let Some(enabled) = self.opts.pooling_pagemap_scan {
943                         cfg.pagemap_scan(enabled);
944                     }
945                     config.allocation_strategy(wasmtime::InstanceAllocationStrategy::Pooling(cfg));
946                 }
947             },
948             true => err,
949         }
950 
951         if self.opts.pooling_memory_protection_keys.is_some()
952             && !self.opts.pooling_allocator.unwrap_or(false)
953         {
954             anyhow::bail!("memory protection keys require the pooling allocator");
955         }
956 
957         if self.opts.pooling_max_memory_protection_keys.is_some()
958             && !self.opts.pooling_memory_protection_keys.is_some()
959         {
960             anyhow::bail!(
961                 "max memory protection keys requires memory protection keys to be enabled"
962             );
963         }
964 
965         match_feature! {
966             ["async" : self.wasm.async_stack_zeroing]
967             enable => config.async_stack_zeroing(enable),
968             _ => err,
969         }
970 
971         if let Some(max) = self.wasm.max_wasm_stack {
972             config.max_wasm_stack(max);
973 
974             // If `-Wasync-stack-size` isn't passed then automatically adjust it
975             // to the wasm stack size provided here too. That prevents the need
976             // to pass both when one can generally be inferred from the other.
977             #[cfg(any(feature = "async", feature = "stack-switching"))]
978             if self.wasm.async_stack_size.is_none() {
979                 const DEFAULT_HOST_STACK: usize = 512 << 10;
980                 config.async_stack_size(max + DEFAULT_HOST_STACK);
981             }
982         }
983 
984         if let Some(enable) = self.wasm.relaxed_simd_deterministic {
985             config.relaxed_simd_deterministic(enable);
986         }
987         match_feature! {
988             ["cranelift" : self.wasm.wmemcheck]
989             enable => config.wmemcheck(enable),
990             true => err,
991         }
992 
993         Ok(config)
994     }
995 
996     pub fn enable_wasm_features(&self, config: &mut Config) -> Result<()> {
997         let all = self.wasm.all_proposals;
998 
999         if let Some(enable) = self.wasm.simd.or(all) {
1000             config.wasm_simd(enable);
1001         }
1002         if let Some(enable) = self.wasm.relaxed_simd.or(all) {
1003             config.wasm_relaxed_simd(enable);
1004         }
1005         if let Some(enable) = self.wasm.bulk_memory.or(all) {
1006             config.wasm_bulk_memory(enable);
1007         }
1008         if let Some(enable) = self.wasm.multi_value.or(all) {
1009             config.wasm_multi_value(enable);
1010         }
1011         if let Some(enable) = self.wasm.tail_call.or(all) {
1012             config.wasm_tail_call(enable);
1013         }
1014         if let Some(enable) = self.wasm.multi_memory.or(all) {
1015             config.wasm_multi_memory(enable);
1016         }
1017         if let Some(enable) = self.wasm.memory64.or(all) {
1018             config.wasm_memory64(enable);
1019         }
1020         if let Some(enable) = self.wasm.stack_switching {
1021             config.wasm_stack_switching(enable);
1022         }
1023         if let Some(enable) = self.wasm.custom_page_sizes.or(all) {
1024             config.wasm_custom_page_sizes(enable);
1025         }
1026         if let Some(enable) = self.wasm.wide_arithmetic.or(all) {
1027             config.wasm_wide_arithmetic(enable);
1028         }
1029         if let Some(enable) = self.wasm.extended_const.or(all) {
1030             config.wasm_extended_const(enable);
1031         }
1032         if let Some(enable) = self.wasm.exceptions.or(all) {
1033             config.wasm_exceptions(enable);
1034         }
1035         if let Some(enable) = self.wasm.legacy_exceptions.or(all) {
1036             #[expect(deprecated, reason = "forwarding CLI flag")]
1037             config.wasm_legacy_exceptions(enable);
1038         }
1039 
1040         macro_rules! handle_conditionally_compiled {
1041             ($(($feature:tt, $field:tt, $method:tt))*) => ($(
1042                 if let Some(enable) = self.wasm.$field.or(all) {
1043                     #[cfg(feature = $feature)]
1044                     config.$method(enable);
1045                     #[cfg(not(feature = $feature))]
1046                     if enable && all.is_none() {
1047                         anyhow::bail!("support for {} was disabled at compile-time", $feature);
1048                     }
1049                 }
1050             )*)
1051         }
1052 
1053         handle_conditionally_compiled! {
1054             ("component-model", component_model, wasm_component_model)
1055             ("component-model-async", component_model_async, wasm_component_model_async)
1056             ("component-model-async", component_model_async_builtins, wasm_component_model_async_builtins)
1057             ("component-model-async", component_model_async_stackful, wasm_component_model_async_stackful)
1058             ("component-model", component_model_error_context, wasm_component_model_error_context)
1059             ("threads", threads, wasm_threads)
1060             ("gc", gc, wasm_gc)
1061             ("gc", reference_types, wasm_reference_types)
1062             ("gc", function_references, wasm_function_references)
1063             ("stack-switching", stack_switching, wasm_stack_switching)
1064         }
1065 
1066         if let Some(enable) = self.wasm.component_model_gc {
1067             #[cfg(all(feature = "component-model", feature = "gc"))]
1068             config.wasm_component_model_gc(enable);
1069             #[cfg(not(all(feature = "component-model", feature = "gc")))]
1070             if enable && all.is_none() {
1071                 anyhow::bail!("support for `component-model-gc` was disabled at compile time")
1072             }
1073         }
1074 
1075         Ok(())
1076     }
1077 
1078     pub fn from_file<P: AsRef<Path>>(path: P) -> Result<Self> {
1079         let path_ref = path.as_ref();
1080         let file_contents = fs::read_to_string(path_ref)
1081             .with_context(|| format!("failed to read config file: {path_ref:?}"))?;
1082         toml::from_str::<CommonOptions>(&file_contents)
1083             .with_context(|| format!("failed to parse TOML config file {path_ref:?}"))
1084     }
1085 }
1086 
1087 #[cfg(test)]
1088 mod tests {
1089     use wasmtime::{OptLevel, RegallocAlgorithm};
1090 
1091     use super::*;
1092 
1093     #[test]
1094     fn from_toml() {
1095         // empty toml
1096         let empty_toml = "";
1097         let mut common_options: CommonOptions = toml::from_str(empty_toml).unwrap();
1098         common_options.config(None).unwrap();
1099 
1100         // basic toml
1101         let basic_toml = r#"
1102             [optimize]
1103             [codegen]
1104             [debug]
1105             [wasm]
1106             [wasi]
1107         "#;
1108         let mut common_options: CommonOptions = toml::from_str(basic_toml).unwrap();
1109         common_options.config(None).unwrap();
1110 
1111         // toml with custom deserialization to match CLI flag parsing
1112         for (opt_value, expected) in [
1113             ("0", Some(OptLevel::None)),
1114             ("1", Some(OptLevel::Speed)),
1115             ("2", Some(OptLevel::Speed)),
1116             ("\"s\"", Some(OptLevel::SpeedAndSize)),
1117             ("\"hello\"", None), // should fail
1118             ("3", None),         // should fail
1119         ] {
1120             let toml = format!(
1121                 r#"
1122                     [optimize]
1123                     opt-level = {opt_value}
1124                 "#,
1125             );
1126             let parsed_opt_level = toml::from_str::<CommonOptions>(&toml)
1127                 .ok()
1128                 .and_then(|common_options| common_options.opts.opt_level);
1129 
1130             assert_eq!(
1131                 parsed_opt_level, expected,
1132                 "Mismatch for input '{opt_value}'. Parsed: {parsed_opt_level:?}, Expected: {expected:?}"
1133             );
1134         }
1135 
1136         // Regalloc algorithm
1137         for (regalloc_value, expected) in [
1138             ("\"backtracking\"", Some(RegallocAlgorithm::Backtracking)),
1139             ("\"hello\"", None), // should fail
1140             ("3", None),         // should fail
1141             ("true", None),      // should fail
1142         ] {
1143             let toml = format!(
1144                 r#"
1145                     [optimize]
1146                     regalloc-algorithm = {regalloc_value}
1147                 "#,
1148             );
1149             let parsed_regalloc_algorithm = toml::from_str::<CommonOptions>(&toml)
1150                 .ok()
1151                 .and_then(|common_options| common_options.opts.regalloc_algorithm);
1152             assert_eq!(
1153                 parsed_regalloc_algorithm, expected,
1154                 "Mismatch for input '{regalloc_value}'. Parsed: {parsed_regalloc_algorithm:?}, Expected: {expected:?}"
1155             );
1156         }
1157 
1158         // Strategy
1159         for (strategy_value, expected) in [
1160             ("\"cranelift\"", Some(wasmtime::Strategy::Cranelift)),
1161             ("\"winch\"", Some(wasmtime::Strategy::Winch)),
1162             ("\"hello\"", None), // should fail
1163             ("5", None),         // should fail
1164             ("true", None),      // should fail
1165         ] {
1166             let toml = format!(
1167                 r#"
1168                     [codegen]
1169                     compiler = {strategy_value}
1170                 "#,
1171             );
1172             let parsed_strategy = toml::from_str::<CommonOptions>(&toml)
1173                 .ok()
1174                 .and_then(|common_options| common_options.codegen.compiler);
1175             assert_eq!(
1176                 parsed_strategy, expected,
1177                 "Mismatch for input '{strategy_value}'. Parsed: {parsed_strategy:?}, Expected: {expected:?}",
1178             );
1179         }
1180 
1181         // Collector
1182         for (collector_value, expected) in [
1183             (
1184                 "\"drc\"",
1185                 Some(wasmtime::Collector::DeferredReferenceCounting),
1186             ),
1187             ("\"null\"", Some(wasmtime::Collector::Null)),
1188             ("\"hello\"", None), // should fail
1189             ("5", None),         // should fail
1190             ("true", None),      // should fail
1191         ] {
1192             let toml = format!(
1193                 r#"
1194                     [codegen]
1195                     collector = {collector_value}
1196                 "#,
1197             );
1198             let parsed_collector = toml::from_str::<CommonOptions>(&toml)
1199                 .ok()
1200                 .and_then(|common_options| common_options.codegen.collector);
1201             assert_eq!(
1202                 parsed_collector, expected,
1203                 "Mismatch for input '{collector_value}'. Parsed: {parsed_collector:?}, Expected: {expected:?}",
1204             );
1205         }
1206     }
1207 }
1208 
1209 impl Default for CommonOptions {
1210     fn default() -> CommonOptions {
1211         CommonOptions::new()
1212     }
1213 }
1214 
1215 impl fmt::Display for CommonOptions {
1216     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1217         let CommonOptions {
1218             codegen_raw,
1219             codegen,
1220             debug_raw,
1221             debug,
1222             opts_raw,
1223             opts,
1224             wasm_raw,
1225             wasm,
1226             wasi_raw,
1227             wasi,
1228             configured,
1229             target,
1230             config,
1231         } = self;
1232         if let Some(target) = target {
1233             write!(f, "--target {target} ")?;
1234         }
1235         if let Some(config) = config {
1236             write!(f, "--config {} ", config.display())?;
1237         }
1238 
1239         let codegen_flags;
1240         let opts_flags;
1241         let wasi_flags;
1242         let wasm_flags;
1243         let debug_flags;
1244 
1245         if *configured {
1246             codegen_flags = codegen.to_options();
1247             debug_flags = debug.to_options();
1248             wasi_flags = wasi.to_options();
1249             wasm_flags = wasm.to_options();
1250             opts_flags = opts.to_options();
1251         } else {
1252             codegen_flags = codegen_raw
1253                 .iter()
1254                 .flat_map(|t| t.0.iter())
1255                 .cloned()
1256                 .collect();
1257             debug_flags = debug_raw.iter().flat_map(|t| t.0.iter()).cloned().collect();
1258             wasi_flags = wasi_raw.iter().flat_map(|t| t.0.iter()).cloned().collect();
1259             wasm_flags = wasm_raw.iter().flat_map(|t| t.0.iter()).cloned().collect();
1260             opts_flags = opts_raw.iter().flat_map(|t| t.0.iter()).cloned().collect();
1261         }
1262 
1263         for flag in codegen_flags {
1264             write!(f, "-C{flag} ")?;
1265         }
1266         for flag in opts_flags {
1267             write!(f, "-O{flag} ")?;
1268         }
1269         for flag in wasi_flags {
1270             write!(f, "-S{flag} ")?;
1271         }
1272         for flag in wasm_flags {
1273             write!(f, "-W{flag} ")?;
1274         }
1275         for flag in debug_flags {
1276             write!(f, "-D{flag} ")?;
1277         }
1278 
1279         Ok(())
1280     }
1281 }
1282