From ead78fdfdf6692b2ecef7f47dfc934011c51fe4c Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 12 Dec 2024 11:40:36 +0000
Subject: [PATCH 1/4] Remove jobserver from Session

It is effectively a global resource and the jobserver::Client in Session
was a clone of GLOBAL_CLIENT anyway.
---
 Cargo.lock                                             |  1 -
 .../rustc_codegen_cranelift/src/concurrency_limiter.rs | 10 ++++------
 compiler/rustc_codegen_cranelift/src/driver/aot.rs     |  4 ++--
 compiler/rustc_codegen_cranelift/src/lib.rs            |  1 -
 compiler/rustc_codegen_ssa/Cargo.toml                  |  1 -
 compiler/rustc_codegen_ssa/src/back/write.rs           |  7 ++-----
 compiler/rustc_data_structures/src/jobserver.rs        |  2 +-
 compiler/rustc_session/src/session.rs                  |  6 ------
 8 files changed, 9 insertions(+), 23 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 38b009bfc7000..923d4017c0cad 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3507,7 +3507,6 @@ dependencies = [
  "cc",
  "either",
  "itertools",
- "jobserver",
  "libc",
  "object 0.36.5",
  "pathdiff",
diff --git a/compiler/rustc_codegen_cranelift/src/concurrency_limiter.rs b/compiler/rustc_codegen_cranelift/src/concurrency_limiter.rs
index 2093b49ff31a7..b5a81fc11d57b 100644
--- a/compiler/rustc_codegen_cranelift/src/concurrency_limiter.rs
+++ b/compiler/rustc_codegen_cranelift/src/concurrency_limiter.rs
@@ -1,8 +1,7 @@
 use std::sync::{Arc, Condvar, Mutex};
 
-use jobserver::HelperThread;
+use rustc_data_structures::jobserver::{self, HelperThread};
 use rustc_errors::DiagCtxtHandle;
-use rustc_session::Session;
 
 // FIXME don't panic when a worker thread panics
 
@@ -14,14 +13,13 @@ pub(super) struct ConcurrencyLimiter {
 }
 
 impl ConcurrencyLimiter {
-    pub(super) fn new(sess: &Session, pending_jobs: usize) -> Self {
+    pub(super) fn new(pending_jobs: usize) -> Self {
         let state = Arc::new(Mutex::new(state::ConcurrencyLimiterState::new(pending_jobs)));
         let available_token_condvar = Arc::new(Condvar::new());
 
         let state_helper = state.clone();
         let available_token_condvar_helper = available_token_condvar.clone();
-        let helper_thread = sess
-            .jobserver
+        let helper_thread = jobserver::client()
             .clone()
             .into_helper_thread(move |token| {
                 let mut state = state_helper.lock().unwrap();
@@ -113,7 +111,7 @@ impl Drop for ConcurrencyLimiterToken {
 }
 
 mod state {
-    use jobserver::Acquired;
+    use rustc_data_structures::jobserver::Acquired;
 
     #[derive(Debug)]
     pub(super) struct ConcurrencyLimiterState {
diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index 5bbcfc2cda7d7..4fc30b69123dd 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -679,7 +679,7 @@ pub(crate) fn run_aot(
             metadata_module: None,
             metadata,
             crate_info: CrateInfo::new(tcx, target_cpu),
-            concurrency_limiter: ConcurrencyLimiter::new(tcx.sess, 0),
+            concurrency_limiter: ConcurrencyLimiter::new(0),
         });
     };
 
@@ -711,7 +711,7 @@ pub(crate) fn run_aot(
             CguReuse::PreLto | CguReuse::PostLto => false,
         });
 
-    let concurrency_limiter = IntoDynSyncSend(ConcurrencyLimiter::new(tcx.sess, todo_cgus.len()));
+    let concurrency_limiter = IntoDynSyncSend(ConcurrencyLimiter::new(todo_cgus.len()));
 
     let modules = tcx.sess.time("codegen mono items", || {
         let mut modules: Vec<_> = par_map(todo_cgus, |(_, cgu)| {
diff --git a/compiler/rustc_codegen_cranelift/src/lib.rs b/compiler/rustc_codegen_cranelift/src/lib.rs
index 9f552b3feb950..c3a1617b49500 100644
--- a/compiler/rustc_codegen_cranelift/src/lib.rs
+++ b/compiler/rustc_codegen_cranelift/src/lib.rs
@@ -12,7 +12,6 @@
 #![warn(unused_lifetimes)]
 // tidy-alphabetical-end
 
-extern crate jobserver;
 #[macro_use]
 extern crate rustc_middle;
 extern crate rustc_abi;
diff --git a/compiler/rustc_codegen_ssa/Cargo.toml b/compiler/rustc_codegen_ssa/Cargo.toml
index c81e36dfc8d0a..450a95ae20cdd 100644
--- a/compiler/rustc_codegen_ssa/Cargo.toml
+++ b/compiler/rustc_codegen_ssa/Cargo.toml
@@ -11,7 +11,6 @@ bitflags = "2.4.1"
 cc = "1.1.23"
 either = "1.5.0"
 itertools = "0.12"
-jobserver = "0.1.28"
 pathdiff = "0.2.0"
 regex = "1.4"
 rustc_abi = { path = "../rustc_abi" }
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 501f751791936..683defcafee24 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -6,9 +6,9 @@ use std::sync::Arc;
 use std::sync::mpsc::{Receiver, Sender, channel};
 use std::{fs, io, mem, str, thread};
 
-use jobserver::{Acquired, Client};
 use rustc_ast::attr;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
+use rustc_data_structures::jobserver::{self, Acquired};
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::profiling::{SelfProfilerRef, VerboseTimingGuard};
 use rustc_errors::emitter::Emitter;
@@ -456,7 +456,6 @@ pub(crate) fn start_async_codegen<B: ExtraBackendMethods>(
     metadata_module: Option<CompiledModule>,
 ) -> OngoingCodegen<B> {
     let (coordinator_send, coordinator_receive) = channel();
-    let sess = tcx.sess;
 
     let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
     let no_builtins = attr::contains_name(crate_attrs, sym::no_builtins);
@@ -477,7 +476,6 @@ pub(crate) fn start_async_codegen<B: ExtraBackendMethods>(
         shared_emitter,
         codegen_worker_send,
         coordinator_receive,
-        sess.jobserver.clone(),
         Arc::new(regular_config),
         Arc::new(metadata_config),
         Arc::new(allocator_config),
@@ -1093,7 +1091,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
     shared_emitter: SharedEmitter,
     codegen_worker_send: Sender<CguMessage>,
     coordinator_receive: Receiver<Box<dyn Any + Send>>,
-    jobserver: Client,
     regular_config: Arc<ModuleConfig>,
     metadata_config: Arc<ModuleConfig>,
     allocator_config: Arc<ModuleConfig>,
@@ -1145,7 +1142,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
     // get tokens on `coordinator_receive` which will
     // get managed in the main loop below.
     let coordinator_send2 = coordinator_send.clone();
-    let helper = jobserver
+    let helper = jobserver::client()
         .into_helper_thread(move |token| {
             drop(coordinator_send2.send(Box::new(Message::Token::<B>(token))));
         })
diff --git a/compiler/rustc_data_structures/src/jobserver.rs b/compiler/rustc_data_structures/src/jobserver.rs
index d09f7efc8ffff..1204f2d692d6c 100644
--- a/compiler/rustc_data_structures/src/jobserver.rs
+++ b/compiler/rustc_data_structures/src/jobserver.rs
@@ -1,6 +1,6 @@
 use std::sync::{LazyLock, OnceLock};
 
-pub use jobserver_crate::Client;
+pub use jobserver_crate::{Acquired, Client, HelperThread};
 use jobserver_crate::{FromEnv, FromEnvErrorKind};
 
 // We can only call `from_env_ext` once per process
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 993d111466bed..160525cead032 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -8,7 +8,6 @@ use std::{env, fmt, io};
 
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
-use rustc_data_structures::jobserver::{self, Client};
 use rustc_data_structures::profiling::{SelfProfiler, SelfProfilerRef};
 use rustc_data_structures::sync::{
     DynSend, DynSync, Lock, Lrc, MappedReadGuard, ReadGuard, RwLock,
@@ -154,10 +153,6 @@ pub struct Session {
     /// Data about code being compiled, gathered during compilation.
     pub code_stats: CodeStats,
 
-    /// Loaded up early on in the initialization of this `Session` to avoid
-    /// false positives about a job server in our environment.
-    pub jobserver: Client,
-
     /// This only ever stores a `LintStore` but we don't want a dependency on that type here.
     pub lint_store: Option<Lrc<dyn LintStoreMarker>>,
 
@@ -1072,7 +1067,6 @@ pub fn build_session(
         incr_comp_session: RwLock::new(IncrCompSession::NotInitialized),
         prof,
         code_stats: Default::default(),
-        jobserver: jobserver::client(),
         lint_store: None,
         registered_lints: false,
         driver_lint_caps,

From 981f625ba7c8e8ddcf6e470eb54d822eaf9fb300 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 12 Dec 2024 11:45:10 +0000
Subject: [PATCH 2/4] Remove registered_lints field from Session

It only exists to pass some information from one part of the driver to
another part. We can directly pass this information to the function that
needs it to reduce the amount of mutation of the Session.
---
 compiler/rustc_driver_impl/src/lib.rs     | 8 +++++---
 compiler/rustc_interface/src/interface.rs | 1 -
 compiler/rustc_session/src/session.rs     | 4 ----
 src/librustdoc/lib.rs                     | 4 +++-
 4 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 2e01c385a6670..b8d5281087efa 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -350,6 +350,8 @@ fn run_compiler(
 
     callbacks.config(&mut config);
 
+    let registered_lints = config.register_lints.is_some();
+
     interface::run_compiler(config, |compiler| {
         let sess = &compiler.sess;
         let codegen_backend = &*compiler.codegen_backend;
@@ -365,7 +367,7 @@ fn run_compiler(
         // `--help`/`-Zhelp`/`-Chelp`. This is the earliest it can run, because
         // it must happen after lints are registered, during session creation.
         if sess.opts.describe_lints {
-            describe_lints(sess);
+            describe_lints(sess, registered_lints);
             return early_exit();
         }
 
@@ -982,7 +984,7 @@ the command line flag directly.
 }
 
 /// Write to stdout lint command options, together with a list of all available lints
-pub fn describe_lints(sess: &Session) {
+pub fn describe_lints(sess: &Session, registered_lints: bool) {
     safe_println!(
         "
 Available lint options:
@@ -1086,7 +1088,7 @@ Available lint options:
 
     print_lint_groups(builtin_groups, true);
 
-    match (sess.registered_lints, loaded.len(), loaded_groups.len()) {
+    match (registered_lints, loaded.len(), loaded_groups.len()) {
         (false, 0, _) | (false, _, 0) => {
             safe_println!("Lint tools like Clippy can load additional lints and lint groups.");
         }
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 07ae24ee6d32b..7ad893f61ab5e 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -479,7 +479,6 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             let mut lint_store = rustc_lint::new_lint_store(sess.enable_internal_lints());
             if let Some(register_lints) = config.register_lints.as_deref() {
                 register_lints(&sess, &mut lint_store);
-                sess.registered_lints = true;
             }
             sess.lint_store = Some(Lrc::new(lint_store));
 
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 160525cead032..9f6106f9cfb7e 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -156,9 +156,6 @@ pub struct Session {
     /// This only ever stores a `LintStore` but we don't want a dependency on that type here.
     pub lint_store: Option<Lrc<dyn LintStoreMarker>>,
 
-    /// Should be set if any lints are registered in `lint_store`.
-    pub registered_lints: bool,
-
     /// Cap lint level specified by a driver specifically.
     pub driver_lint_caps: FxHashMap<lint::LintId, lint::Level>,
 
@@ -1068,7 +1065,6 @@ pub fn build_session(
         prof,
         code_stats: Default::default(),
         lint_store: None,
-        registered_lints: false,
         driver_lint_caps,
         ctfe_backtrace,
         miri_unleashed_features: Lock::new(Default::default()),
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index a384c286039d2..5d82b8e309a6a 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -846,11 +846,13 @@ fn main_args(
 
     let config = core::create_config(input, options, &render_options, using_internal_features);
 
+    let registered_lints = config.register_lints.is_some();
+
     interface::run_compiler(config, |compiler| {
         let sess = &compiler.sess;
 
         if sess.opts.describe_lints {
-            rustc_driver::describe_lints(sess);
+            rustc_driver::describe_lints(sess, registered_lints);
             return;
         }
 

From ea9e8c13dc94949ab38370c39559110da33c878f Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 12 Dec 2024 13:46:16 +0000
Subject: [PATCH 3/4] Explain why an untranslatable_diagnostic occurs

---
 compiler/rustc_interface/src/interface.rs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index 7ad893f61ab5e..91f190c6a28de 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -371,7 +371,6 @@ pub(crate) fn initialize_checked_jobserver(early_dcx: &EarlyDiagCtxt) {
 
 // JUSTIFICATION: before session exists, only config
 #[allow(rustc::bad_opt_access)]
-#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
 pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Send) -> R {
     trace!("run_compiler");
 
@@ -425,7 +424,11 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
                 config.opts.unstable_opts.translate_directionality_markers,
             ) {
                 Ok(bundle) => bundle,
-                Err(e) => early_dcx.early_fatal(format!("failed to load fluent bundle: {e}")),
+                Err(e) => {
+                    // We can't translate anything if we failed to load translations
+                    #[allow(rustc::untranslatable_diagnostic)]
+                    early_dcx.early_fatal(format!("failed to load fluent bundle: {e}"))
+                }
             };
 
             let mut locale_resources = config.locale_resources;

From 3198496385cd8fdd89818e0bf14bacd8db6292d9 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Thu, 12 Dec 2024 14:44:18 +0000
Subject: [PATCH 4/4] Make dependency_formats an FxIndexMap rather than a list
 of tuples

It is treated as a map already. This is using FxIndexMap rather than
UnordMap because the latter doesn't provide an api to pick a single
value iff all values are equal, which each_linked_rlib depends on.
---
 .../rustc_codegen_cranelift/src/driver/jit.rs |  7 +---
 compiler/rustc_codegen_ssa/src/back/link.rs   | 34 +++++++------------
 compiler/rustc_codegen_ssa/src/back/linker.rs |  2 +-
 .../rustc_metadata/src/dependency_format.rs   |  2 +-
 compiler/rustc_metadata/src/rmeta/encoder.rs  |  5 +--
 .../src/middle/dependency_format.rs           |  3 +-
 src/tools/miri/src/helpers.rs                 |  5 ++-
 7 files changed, 21 insertions(+), 37 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/src/driver/jit.rs b/compiler/rustc_codegen_cranelift/src/driver/jit.rs
index d68948966eaeb..4be4291021dfa 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/jit.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/jit.rs
@@ -287,12 +287,7 @@ fn dep_symbol_lookup_fn(
 
     let mut dylib_paths = Vec::new();
 
-    let data = &crate_info
-        .dependency_formats
-        .iter()
-        .find(|(crate_type, _data)| *crate_type == rustc_session::config::CrateType::Executable)
-        .unwrap()
-        .1;
+    let data = &crate_info.dependency_formats[&rustc_session::config::CrateType::Executable].1;
     // `used_crates` is in reverse postorder in terms of dependencies. Reverse the order here to
     // get a postorder which ensures that all dependencies of a dylib are loaded before the dylib
     // itself. This helps the dynamic linker to find dylibs not in the regular dynamic library
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 35d18d0206dbb..31ac8c6e66aae 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -236,7 +236,13 @@ pub fn each_linked_rlib(
 ) -> Result<(), errors::LinkRlibError> {
     let crates = info.used_crates.iter();
 
-    let fmts = if crate_type.is_none() {
+    let fmts = if let Some(crate_type) = crate_type {
+        let Some(fmts) = info.dependency_formats.get(&crate_type) else {
+            return Err(errors::LinkRlibError::MissingFormat);
+        };
+
+        fmts
+    } else {
         for combination in info.dependency_formats.iter().combinations(2) {
             let (ty1, list1) = &combination[0];
             let (ty2, list2) = &combination[1];
@@ -252,18 +258,7 @@ pub fn each_linked_rlib(
         if info.dependency_formats.is_empty() {
             return Err(errors::LinkRlibError::MissingFormat);
         }
-        &info.dependency_formats[0].1
-    } else {
-        let fmts = info
-            .dependency_formats
-            .iter()
-            .find_map(|&(ty, ref list)| if Some(ty) == crate_type { Some(list) } else { None });
-
-        let Some(fmts) = fmts else {
-            return Err(errors::LinkRlibError::MissingFormat);
-        };
-
-        fmts
+        info.dependency_formats.first().unwrap().1
     };
 
     for &cnum in crates {
@@ -624,8 +619,7 @@ fn link_staticlib(
     let fmts = codegen_results
         .crate_info
         .dependency_formats
-        .iter()
-        .find_map(|&(ty, ref list)| if ty == CrateType::Staticlib { Some(list) } else { None })
+        .get(&CrateType::Staticlib)
         .expect("no dependency formats for staticlib");
 
     let mut all_rust_dylibs = vec![];
@@ -2355,11 +2349,10 @@ fn linker_with_args(
     // they are used within inlined functions or instantiated generic functions. We do this *after*
     // handling the raw-dylib symbols in the current crate to make sure that those are chosen first
     // by the linker.
-    let (_, dependency_linkage) = codegen_results
+    let dependency_linkage = codegen_results
         .crate_info
         .dependency_formats
-        .iter()
-        .find(|(ty, _)| *ty == crate_type)
+        .get(&crate_type)
         .expect("failed to find crate type in dependency format list");
 
     // We sort the libraries below
@@ -2738,11 +2731,10 @@ fn add_upstream_rust_crates(
     // Linking to a rlib involves just passing it to the linker (the linker
     // will slurp up the object files inside), and linking to a dynamic library
     // involves just passing the right -l flag.
-    let (_, data) = codegen_results
+    let data = codegen_results
         .crate_info
         .dependency_formats
-        .iter()
-        .find(|(ty, _)| *ty == crate_type)
+        .get(&crate_type)
         .expect("failed to find crate type in dependency format list");
 
     if sess.target.is_like_aix {
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index 4c5eb98e890e8..301b22f2be4f8 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -1749,7 +1749,7 @@ fn for_each_exported_symbols_include_dep<'tcx>(
     }
 
     let formats = tcx.dependency_formats(());
-    let deps = formats.iter().find_map(|(t, list)| (*t == crate_type).then_some(list)).unwrap();
+    let deps = &formats[&crate_type];
 
     for (index, dep_format) in deps.iter().enumerate() {
         let cnum = CrateNum::new(index + 1);
diff --git a/compiler/rustc_metadata/src/dependency_format.rs b/compiler/rustc_metadata/src/dependency_format.rs
index 641d1d8e79819..e8de0acb7c9fe 100644
--- a/compiler/rustc_metadata/src/dependency_format.rs
+++ b/compiler/rustc_metadata/src/dependency_format.rs
@@ -77,7 +77,7 @@ pub(crate) fn calculate(tcx: TyCtxt<'_>) -> Dependencies {
             verify_ok(tcx, &linkage);
             (ty, linkage)
         })
-        .collect::<Vec<_>>()
+        .collect()
 }
 
 fn calculate_type(tcx: TyCtxt<'_>, ty: CrateType) -> DependencyList {
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 5c80d24f502d1..5548406502b4e 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -2164,10 +2164,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
     fn encode_dylib_dependency_formats(&mut self) -> LazyArray<Option<LinkagePreference>> {
         empty_proc_macro!(self);
         let formats = self.tcx.dependency_formats(());
-        for (ty, arr) in formats.iter() {
-            if *ty != CrateType::Dylib {
-                continue;
-            }
+        if let Some(arr) = formats.get(&CrateType::Dylib) {
             return self.lazy_array(arr.iter().map(|slot| match *slot {
                 Linkage::NotLinked | Linkage::IncludedFromDylib => None,
 
diff --git a/compiler/rustc_middle/src/middle/dependency_format.rs b/compiler/rustc_middle/src/middle/dependency_format.rs
index a3aff9a110130..e3b40b6415784 100644
--- a/compiler/rustc_middle/src/middle/dependency_format.rs
+++ b/compiler/rustc_middle/src/middle/dependency_format.rs
@@ -7,6 +7,7 @@
 // FIXME: move this file to rustc_metadata::dependency_format, but
 // this will introduce circular dependency between rustc_metadata and rustc_middle
 
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_macros::{Decodable, Encodable, HashStable};
 use rustc_session::config::CrateType;
 
@@ -18,7 +19,7 @@ pub type DependencyList = Vec<Linkage>;
 /// A mapping of all required dependencies for a particular flavor of output.
 ///
 /// This is local to the tcx, and is generally relevant to one session.
-pub type Dependencies = Vec<(CrateType, DependencyList)>;
+pub type Dependencies = FxIndexMap<CrateType, DependencyList>;
 
 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Encodable, Decodable)]
 pub enum Linkage {
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index b57ce4e070c38..1f7c60ad1bdfe 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -149,10 +149,9 @@ pub fn iter_exported_symbols<'tcx>(
     let dependency_formats = tcx.dependency_formats(());
     // Find the dependencies of the executable we are running.
     let dependency_format = dependency_formats
-        .iter()
-        .find(|(crate_type, _)| *crate_type == CrateType::Executable)
+        .get(&CrateType::Executable)
         .expect("interpreting a non-executable crate");
-    for cnum in dependency_format.1.iter().enumerate().filter_map(|(num, &linkage)| {
+    for cnum in dependency_format.iter().enumerate().filter_map(|(num, &linkage)| {
         // We add 1 to the number because that's what rustc also does everywhere it
         // calls `CrateNum::new`...
         #[expect(clippy::arithmetic_side_effects)]