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Exhaustively specify names and stability of --print values #148990

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f7fb38c
Extract module `rustc_session::config::print_request`
Zalathar Nov 11, 2025
40fbc36
Exhaustively specify names and stability of `--print` values
Zalathar Nov 11, 2025
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181 changes: 4 additions & 177 deletions compiler/rustc_session/src/config.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ use tracing::debug;

pub use crate::config::cfg::{Cfg, CheckCfg, ExpectedValues};
use crate::config::native_libs::parse_native_libs;
pub use crate::config::print_request::{PrintKind, PrintRequest};
use crate::errors::FileWriteFail;
pub use crate::options::*;
use crate::search_paths::SearchPath;
Expand All @@ -45,37 +46,9 @@ use crate::{EarlyDiagCtxt, HashStableContext, Session, filesearch, lint};
mod cfg;
mod externs;
mod native_libs;
mod print_request;
pub mod sigpipe;

pub const PRINT_KINDS: &[(&str, PrintKind)] = &[
// tidy-alphabetical-start
("all-target-specs-json", PrintKind::AllTargetSpecsJson),
("calling-conventions", PrintKind::CallingConventions),
("cfg", PrintKind::Cfg),
("check-cfg", PrintKind::CheckCfg),
("code-models", PrintKind::CodeModels),
("crate-name", PrintKind::CrateName),
("crate-root-lint-levels", PrintKind::CrateRootLintLevels),
("deployment-target", PrintKind::DeploymentTarget),
("file-names", PrintKind::FileNames),
("host-tuple", PrintKind::HostTuple),
("link-args", PrintKind::LinkArgs),
("native-static-libs", PrintKind::NativeStaticLibs),
("relocation-models", PrintKind::RelocationModels),
("split-debuginfo", PrintKind::SplitDebuginfo),
("stack-protector-strategies", PrintKind::StackProtectorStrategies),
("supported-crate-types", PrintKind::SupportedCrateTypes),
("sysroot", PrintKind::Sysroot),
("target-cpus", PrintKind::TargetCPUs),
("target-features", PrintKind::TargetFeatures),
("target-libdir", PrintKind::TargetLibdir),
("target-list", PrintKind::TargetList),
("target-spec-json", PrintKind::TargetSpecJson),
("target-spec-json-schema", PrintKind::TargetSpecJsonSchema),
("tls-models", PrintKind::TlsModels),
// tidy-alphabetical-end
];

/// The different settings that the `-C strip` flag can have.
#[derive(Clone, Copy, PartialEq, Hash, Debug)]
pub enum Strip {
Expand Down Expand Up @@ -1015,42 +988,6 @@ impl ExternEntry {
}
}

#[derive(Clone, PartialEq, Debug)]
pub struct PrintRequest {
pub kind: PrintKind,
pub out: OutFileName,
}

#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum PrintKind {
// tidy-alphabetical-start
AllTargetSpecsJson,
CallingConventions,
Cfg,
CheckCfg,
CodeModels,
CrateName,
CrateRootLintLevels,
DeploymentTarget,
FileNames,
HostTuple,
LinkArgs,
NativeStaticLibs,
RelocationModels,
SplitDebuginfo,
StackProtectorStrategies,
SupportedCrateTypes,
Sysroot,
TargetCPUs,
TargetFeatures,
TargetLibdir,
TargetList,
TargetSpecJson,
TargetSpecJsonSchema,
TlsModels,
// tidy-alphabetical-end
}

#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, Default)]
pub struct NextSolverConfig {
/// Whether the new trait solver should be enabled in coherence.
Expand Down Expand Up @@ -1794,14 +1731,6 @@ The default is {DEFAULT_EDITION} and the latest stable edition is {LATEST_STABLE
)
});

static PRINT_HELP: LazyLock<String> = LazyLock::new(|| {
format!(
"Compiler information to print on stdout (or to a file)\n\
INFO may be one of <{}>.",
PRINT_KINDS.iter().map(|(name, _)| format!("{name}")).collect::<Vec<_>>().join("|")
)
});

static EMIT_HELP: LazyLock<String> = LazyLock::new(|| {
let mut result =
String::from("Comma separated list of types of output for the compiler to emit.\n");
Expand Down Expand Up @@ -1868,7 +1797,7 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
opt(Stable, Opt, "", "crate-name", "Specify the name of the crate being built", "<NAME>"),
opt(Stable, Opt, "", "edition", &EDITION_STRING, EDITION_NAME_LIST),
opt(Stable, Multi, "", "emit", &EMIT_HELP, "<TYPE>[=<FILE>]"),
opt(Stable, Multi, "", "print", &PRINT_HELP, "<INFO>[=<FILE>]"),
opt(Stable, Multi, "", "print", &print_request::PRINT_HELP, "<INFO>[=<FILE>]"),
opt(Stable, FlagMulti, "g", "", "Equivalent to -C debuginfo=2", ""),
opt(Stable, FlagMulti, "O", "", "Equivalent to -C opt-level=3", ""),
opt(Stable, Opt, "o", "", "Write output to FILENAME", "<FILENAME>"),
Expand Down Expand Up @@ -2316,108 +2245,6 @@ fn should_override_cgus_and_disable_thinlto(
(disable_local_thinlto, codegen_units)
}

fn collect_print_requests(
early_dcx: &EarlyDiagCtxt,
cg: &mut CodegenOptions,
unstable_opts: &UnstableOptions,
matches: &getopts::Matches,
) -> Vec<PrintRequest> {
let mut prints = Vec::<PrintRequest>::new();
if cg.target_cpu.as_deref() == Some("help") {
prints.push(PrintRequest { kind: PrintKind::TargetCPUs, out: OutFileName::Stdout });
cg.target_cpu = None;
};
if cg.target_feature == "help" {
prints.push(PrintRequest { kind: PrintKind::TargetFeatures, out: OutFileName::Stdout });
cg.target_feature = String::new();
}

// We disallow reusing the same path in multiple prints, such as `--print
// cfg=output.txt --print link-args=output.txt`, because outputs are printed
// by disparate pieces of the compiler, and keeping track of which files
// need to be overwritten vs appended to is annoying.
let mut printed_paths = FxHashSet::default();

prints.extend(matches.opt_strs("print").into_iter().map(|req| {
let (req, out) = split_out_file_name(&req);

let kind = if let Some((print_name, print_kind)) =
PRINT_KINDS.iter().find(|&&(name, _)| name == req)
{
check_print_request_stability(early_dcx, unstable_opts, (print_name, *print_kind));
*print_kind
} else {
let is_nightly = nightly_options::match_is_nightly_build(matches);
emit_unknown_print_request_help(early_dcx, req, is_nightly)
};

let out = out.unwrap_or(OutFileName::Stdout);
if let OutFileName::Real(path) = &out {
if !printed_paths.insert(path.clone()) {
early_dcx.early_fatal(format!(
"cannot print multiple outputs to the same path: {}",
path.display(),
));
}
}

PrintRequest { kind, out }
}));

prints
}

fn check_print_request_stability(
early_dcx: &EarlyDiagCtxt,
unstable_opts: &UnstableOptions,
(print_name, print_kind): (&str, PrintKind),
) {
if !is_print_request_stable(print_kind) && !unstable_opts.unstable_options {
early_dcx.early_fatal(format!(
"the `-Z unstable-options` flag must also be passed to enable the `{print_name}` \
print option"
));
}
}

fn is_print_request_stable(print_kind: PrintKind) -> bool {
match print_kind {
PrintKind::AllTargetSpecsJson
| PrintKind::CheckCfg
| PrintKind::CrateRootLintLevels
| PrintKind::SupportedCrateTypes
| PrintKind::TargetSpecJson
| PrintKind::TargetSpecJsonSchema => false,
_ => true,
}
}

fn emit_unknown_print_request_help(early_dcx: &EarlyDiagCtxt, req: &str, is_nightly: bool) -> ! {
let prints = PRINT_KINDS
.iter()
.filter_map(|(name, kind)| {
// If we're not on nightly, we don't want to print unstable options
if !is_nightly && !is_print_request_stable(*kind) {
None
} else {
Some(format!("`{name}`"))
}
})
.collect::<Vec<_>>();
let prints = prints.join(", ");

let mut diag = early_dcx.early_struct_fatal(format!("unknown print request: `{req}`"));
#[allow(rustc::diagnostic_outside_of_impl)]
diag.help(format!("valid print requests are: {prints}"));

if req == "lints" {
diag.help(format!("use `-Whelp` to print a list of lints"));
}

diag.help(format!("for more information, see the rustc book: https://doc.rust-lang.org/rustc/command-line-arguments.html#--print-print-compiler-information"));
diag.emit()
}

pub fn parse_target_triple(early_dcx: &EarlyDiagCtxt, matches: &getopts::Matches) -> TargetTuple {
match matches.opt_str("target") {
Some(target) if target.ends_with(".json") => {
Expand Down Expand Up @@ -2842,7 +2669,7 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
));
}

let prints = collect_print_requests(early_dcx, &mut cg, &unstable_opts, matches);
let prints = print_request::collect_print_requests(early_dcx, &mut cg, &unstable_opts, matches);

// -Zretpoline-external-thunk also requires -Zretpoline
if unstable_opts.retpoline_external_thunk {
Expand Down
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