From 4cacfc00bcb875c04318b516139d0d8cf559ff7c Mon Sep 17 00:00:00 2001
From: Jonathan Brouwer <jonathantbrouwer@gmail.com>
Date: Tue, 3 Feb 2026 15:08:00 +0100
Subject: [PATCH] Convert to inline diagnostics in `rustc_incremental`

---
 Cargo.lock                               |   2 -
 compiler/rustc_driver_impl/Cargo.toml    |   1 -
 compiler/rustc_driver_impl/src/lib.rs    |   1 -
 compiler/rustc_incremental/Cargo.toml    |   1 -
 compiler/rustc_incremental/messages.ftl  | 102 ----------------------
 compiler/rustc_incremental/src/errors.rs | 106 +++++++++++++----------
 compiler/rustc_incremental/src/lib.rs    |   2 -
 7 files changed, 62 insertions(+), 153 deletions(-)
 delete mode 100644 compiler/rustc_incremental/messages.ftl

diff --git a/Cargo.lock b/Cargo.lock
index 2be69cf0b23bf..2bcf7d52310e7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3789,7 +3789,6 @@ dependencies = [
  "rustc_hir_analysis",
  "rustc_hir_pretty",
  "rustc_hir_typeck",
- "rustc_incremental",
  "rustc_index",
  "rustc_interface",
  "rustc_lexer",
@@ -4048,7 +4047,6 @@ dependencies = [
  "rustc_ast",
  "rustc_data_structures",
  "rustc_errors",
- "rustc_fluent_macro",
  "rustc_fs_util",
  "rustc_graphviz",
  "rustc_hashes",
diff --git a/compiler/rustc_driver_impl/Cargo.toml b/compiler/rustc_driver_impl/Cargo.toml
index bdc577622b24a..f888c54cefcdd 100644
--- a/compiler/rustc_driver_impl/Cargo.toml
+++ b/compiler/rustc_driver_impl/Cargo.toml
@@ -23,7 +23,6 @@ rustc_feature = { path = "../rustc_feature" }
 rustc_hir_analysis = { path = "../rustc_hir_analysis" }
 rustc_hir_pretty = { path = "../rustc_hir_pretty" }
 rustc_hir_typeck = { path = "../rustc_hir_typeck" }
-rustc_incremental = { path = "../rustc_incremental" }
 rustc_index = { path = "../rustc_index" }
 rustc_interface = { path = "../rustc_interface" }
 rustc_lexer = { path = "../rustc_lexer" }
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index cdc9959605c14..cdf636f97d45b 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -124,7 +124,6 @@ pub static DEFAULT_LOCALE_RESOURCES: &[&str] = &[
     rustc_expand::DEFAULT_LOCALE_RESOURCE,
     rustc_hir_analysis::DEFAULT_LOCALE_RESOURCE,
     rustc_hir_typeck::DEFAULT_LOCALE_RESOURCE,
-    rustc_incremental::DEFAULT_LOCALE_RESOURCE,
     rustc_interface::DEFAULT_LOCALE_RESOURCE,
     rustc_lint::DEFAULT_LOCALE_RESOURCE,
     rustc_metadata::DEFAULT_LOCALE_RESOURCE,
diff --git a/compiler/rustc_incremental/Cargo.toml b/compiler/rustc_incremental/Cargo.toml
index db0a584188755..ae96cc62e54a3 100644
--- a/compiler/rustc_incremental/Cargo.toml
+++ b/compiler/rustc_incremental/Cargo.toml
@@ -9,7 +9,6 @@ rand = "0.9.0"
 rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
-rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_graphviz = { path = "../rustc_graphviz" }
 rustc_hashes = { path = "../rustc_hashes" }
diff --git a/compiler/rustc_incremental/messages.ftl b/compiler/rustc_incremental/messages.ftl
deleted file mode 100644
index bbc1fab05dfeb..0000000000000
--- a/compiler/rustc_incremental/messages.ftl
+++ /dev/null
@@ -1,102 +0,0 @@
-incremental_assert_loaded =
-    we asserted that an existing incremental cache directory should be successfully loaded, but it was not
-
-incremental_assert_not_loaded =
-    we asserted that the incremental cache should not be loaded, but it was loaded
-
-incremental_assertion_auto =
-    `except` specified DepNodes that can not be affected for "{$name}": "{$e}"
-
-incremental_associated_value_expected = expected an associated value
-
-incremental_associated_value_expected_for = associated value expected for `{$ident}`
-
-incremental_canonicalize_path = incremental compilation: error canonicalizing path `{$path}`: {$err}
-
-incremental_cargo_help_1 =
-    incremental compilation can be disabled by setting the environment variable CARGO_INCREMENTAL=0 (see https://doc.rust-lang.org/cargo/reference/profiles.html#incremental)
-incremental_cargo_help_2 =
-    the entire build directory can be changed to a different filesystem by setting the environment variable CARGO_TARGET_DIR to a different path (see https://doc.rust-lang.org/cargo/reference/config.html#buildtarget-dir)
-
-incremental_copy_workproduct_to_cache =
-    error copying object file `{$from}` to incremental directory as `{$to}`: {$err}
-
-incremental_corrupt_file = corrupt incremental compilation artifact found at `{$path}`. This file will automatically be ignored and deleted. If you see this message repeatedly or can provoke it without manually manipulating the compiler's artifacts, please file an issue. The incremental compilation system relies on hardlinks and filesystem locks behaving correctly, and may not deal well with OS crashes, so whatever information you can provide about your filesystem or other state may be very relevant.
-
-incremental_create_dep_graph = failed to create dependency graph at `{$path}`: {$err}
-
-incremental_create_incr_comp_dir =
-    could not create incremental compilation {$tag} directory `{$path}`: {$err}
-
-incremental_create_lock =
-    incremental compilation: could not create session directory lock file: {$lock_err}
-incremental_create_new = failed to create {$name} at `{$path}`: {$err}
-
-incremental_delete_full = error deleting incremental compilation session directory `{$path}`: {$err}
-
-incremental_delete_incompatible =
-    failed to delete invalidated or incompatible incremental compilation session directory contents `{$path}`: {$err}
-
-incremental_delete_lock =
-    error deleting lock file for incremental compilation session directory `{$path}`: {$err}
-
-incremental_delete_old = unable to delete old {$name} at `{$path}`: {$err}
-
-incremental_delete_partial = failed to delete partly initialized session dir `{$path}`: {$err}
-
-incremental_delete_workproduct = file-system error deleting outdated file `{$path}`: {$err}
-
-incremental_finalize = error finalizing incremental compilation session directory `{$path}`: {$err}
-
-incremental_finalized_gc_failed =
-    failed to garbage collect finalized incremental compilation session directory `{$path}`: {$err}
-
-incremental_hard_link_failed =
-    hard linking files in the incremental compilation cache failed. copying files instead. consider moving the cache directory to a file system which supports hard linking in session dir `{$path}`
-
-incremental_invalid_gc_failed =
-    failed to garbage collect invalid incremental compilation session directory `{$path}`: {$err}
-
-incremental_load_dep_graph = could not load dep-graph from `{$path}`: {$err}
-
-incremental_lock_unsupported =
-    the filesystem for the incremental path at {$session_dir} does not appear to support locking, consider changing the incremental path to a filesystem that supports locking or disable incremental compilation
-
-incremental_missing_depnode = missing `DepNode` variant
-
-incremental_missing_if_this_changed = no `#[rustc_if_this_changed]` annotation detected
-
-incremental_move_dep_graph = failed to move dependency graph from `{$from}` to `{$to}`: {$err}
-
-incremental_no_cfg = no cfg attribute
-
-incremental_no_path = no path from `{$source}` to `{$target}`
-
-incremental_not_clean = `{$dep_node_str}` should be clean but is not
-
-incremental_not_dirty = `{$dep_node_str}` should be dirty but is not
-
-incremental_not_loaded = `{$dep_node_str}` should have been loaded from disk but it was not
-
-incremental_ok = OK
-
-incremental_repeated_depnode_label = dep-node label `{$label}` is repeated
-
-incremental_session_gc_failed =
-    failed to garbage collect incremental compilation session directory `{$path}`: {$err}
-
-incremental_unchecked_clean = found unchecked `#[rustc_clean]` attribute
-
-incremental_undefined_clean_dirty_assertions =
-    clean/dirty auto-assertions not yet defined for {$kind}
-
-incremental_undefined_clean_dirty_assertions_item =
-    clean/dirty auto-assertions not yet defined for Node::Item.node={$kind}
-
-incremental_unknown_rustc_clean_argument = unknown `rustc_clean` argument
-
-incremental_unrecognized_depnode = unrecognized `DepNode` variant: {$name}
-
-incremental_unrecognized_depnode_label = dep-node label `{$label}` not recognized
-
-incremental_write_new = failed to write {$name} to `{$path}`: {$err}
diff --git a/compiler/rustc_incremental/src/errors.rs b/compiler/rustc_incremental/src/errors.rs
index dbc72d085be99..65109fdec03a7 100644
--- a/compiler/rustc_incremental/src/errors.rs
+++ b/compiler/rustc_incremental/src/errors.rs
@@ -4,7 +4,7 @@ use rustc_macros::Diagnostic;
 use rustc_span::{Ident, Span, Symbol};
 
 #[derive(Diagnostic)]
-#[diag(incremental_unrecognized_depnode)]
+#[diag("unrecognized `DepNode` variant: {$name}")]
 pub(crate) struct UnrecognizedDepNode {
     #[primary_span]
     pub span: Span,
@@ -12,28 +12,28 @@ pub(crate) struct UnrecognizedDepNode {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_missing_depnode)]
+#[diag("missing `DepNode` variant")]
 pub(crate) struct MissingDepNode {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_missing_if_this_changed)]
+#[diag("no `#[rustc_if_this_changed]` annotation detected")]
 pub(crate) struct MissingIfThisChanged {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_ok)]
+#[diag("OK")]
 pub(crate) struct Ok {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_no_path)]
+#[diag("no path from `{$source}` to `{$target}`")]
 pub(crate) struct NoPath {
     #[primary_span]
     pub span: Span,
@@ -42,7 +42,7 @@ pub(crate) struct NoPath {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_assertion_auto)]
+#[diag("`except` specified DepNodes that can not be affected for \"{$name}\": \"{$e}\"")]
 pub(crate) struct AssertionAuto<'a> {
     #[primary_span]
     pub span: Span,
@@ -51,7 +51,7 @@ pub(crate) struct AssertionAuto<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_undefined_clean_dirty_assertions_item)]
+#[diag("clean/dirty auto-assertions not yet defined for Node::Item.node={$kind}")]
 pub(crate) struct UndefinedCleanDirtyItem {
     #[primary_span]
     pub span: Span,
@@ -59,7 +59,7 @@ pub(crate) struct UndefinedCleanDirtyItem {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_undefined_clean_dirty_assertions)]
+#[diag("clean/dirty auto-assertions not yet defined for {$kind}")]
 pub(crate) struct UndefinedCleanDirty {
     #[primary_span]
     pub span: Span,
@@ -67,7 +67,7 @@ pub(crate) struct UndefinedCleanDirty {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_repeated_depnode_label)]
+#[diag("dep-node label `{$label}` is repeated")]
 pub(crate) struct RepeatedDepNodeLabel<'a> {
     #[primary_span]
     pub span: Span,
@@ -75,7 +75,7 @@ pub(crate) struct RepeatedDepNodeLabel<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_unrecognized_depnode_label)]
+#[diag("dep-node label `{$label}` not recognized")]
 pub(crate) struct UnrecognizedDepNodeLabel<'a> {
     #[primary_span]
     pub span: Span,
@@ -83,7 +83,7 @@ pub(crate) struct UnrecognizedDepNodeLabel<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_not_dirty)]
+#[diag("`{$dep_node_str}` should be dirty but is not")]
 pub(crate) struct NotDirty<'a> {
     #[primary_span]
     pub span: Span,
@@ -91,7 +91,7 @@ pub(crate) struct NotDirty<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_not_clean)]
+#[diag("`{$dep_node_str}` should be clean but is not")]
 pub(crate) struct NotClean<'a> {
     #[primary_span]
     pub span: Span,
@@ -99,7 +99,7 @@ pub(crate) struct NotClean<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_not_loaded)]
+#[diag("`{$dep_node_str}` should have been loaded from disk but it was not")]
 pub(crate) struct NotLoaded<'a> {
     #[primary_span]
     pub span: Span,
@@ -107,21 +107,21 @@ pub(crate) struct NotLoaded<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_unknown_rustc_clean_argument)]
+#[diag("unknown `rustc_clean` argument")]
 pub(crate) struct UnknownRustcCleanArgument {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_no_cfg)]
+#[diag("no cfg attribute")]
 pub(crate) struct NoCfg {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_associated_value_expected_for)]
+#[diag("associated value expected for `{$ident}`")]
 pub(crate) struct AssociatedValueExpectedFor {
     #[primary_span]
     pub span: Span,
@@ -129,21 +129,21 @@ pub(crate) struct AssociatedValueExpectedFor {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_associated_value_expected)]
+#[diag("expected an associated value")]
 pub(crate) struct AssociatedValueExpected {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_unchecked_clean)]
+#[diag("found unchecked `#[rustc_clean]` attribute")]
 pub(crate) struct UncheckedClean {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_delete_old)]
+#[diag("unable to delete old {$name} at `{$path}`: {$err}")]
 pub(crate) struct DeleteOld<'a> {
     pub name: &'a str,
     pub path: PathBuf,
@@ -151,7 +151,7 @@ pub(crate) struct DeleteOld<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_create_new)]
+#[diag("failed to create {$name} at `{$path}`: {$err}")]
 pub(crate) struct CreateNew<'a> {
     pub name: &'a str,
     pub path: PathBuf,
@@ -159,7 +159,7 @@ pub(crate) struct CreateNew<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_write_new)]
+#[diag("failed to write {$name} to `{$path}`: {$err}")]
 pub(crate) struct WriteNew<'a> {
     pub name: &'a str,
     pub path: PathBuf,
@@ -167,14 +167,14 @@ pub(crate) struct WriteNew<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_canonicalize_path)]
+#[diag("incremental compilation: error canonicalizing path `{$path}`: {$err}")]
 pub(crate) struct CanonicalizePath {
     pub path: PathBuf,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_create_incr_comp_dir)]
+#[diag("could not create incremental compilation {$tag} directory `{$path}`: {$err}")]
 pub(crate) struct CreateIncrCompDir<'a> {
     pub tag: &'a str,
     pub path: &'a Path,
@@ -182,96 +182,112 @@ pub(crate) struct CreateIncrCompDir<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_create_lock)]
+#[diag("incremental compilation: could not create session directory lock file: {$lock_err}")]
 pub(crate) struct CreateLock<'a> {
     pub lock_err: std::io::Error,
     pub session_dir: &'a Path,
-    #[note(incremental_lock_unsupported)]
+    #[note(
+        "the filesystem for the incremental path at {$session_dir} does not appear to support locking, consider changing the incremental path to a filesystem that supports locking or disable incremental compilation"
+    )]
     pub is_unsupported_lock: bool,
-    #[help(incremental_cargo_help_1)]
-    #[help(incremental_cargo_help_2)]
+    #[help(
+        "incremental compilation can be disabled by setting the environment variable CARGO_INCREMENTAL=0 (see https://doc.rust-lang.org/cargo/reference/profiles.html#incremental)"
+    )]
+    #[help(
+        "the entire build directory can be changed to a different filesystem by setting the environment variable CARGO_TARGET_DIR to a different path (see https://doc.rust-lang.org/cargo/reference/config.html#buildtarget-dir)"
+    )]
     pub is_cargo: bool,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_delete_lock)]
+#[diag("error deleting lock file for incremental compilation session directory `{$path}`: {$err}")]
 pub(crate) struct DeleteLock<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_hard_link_failed)]
+#[diag(
+    "hard linking files in the incremental compilation cache failed. copying files instead. consider moving the cache directory to a file system which supports hard linking in session dir `{$path}`"
+)]
 pub(crate) struct HardLinkFailed<'a> {
     pub path: &'a Path,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_delete_partial)]
+#[diag("failed to delete partly initialized session dir `{$path}`: {$err}")]
 pub(crate) struct DeletePartial<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_delete_full)]
+#[diag("error deleting incremental compilation session directory `{$path}`: {$err}")]
 pub(crate) struct DeleteFull<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_finalize)]
+#[diag("error finalizing incremental compilation session directory `{$path}`: {$err}")]
 pub(crate) struct Finalize<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_invalid_gc_failed)]
+#[diag(
+    "failed to garbage collect invalid incremental compilation session directory `{$path}`: {$err}"
+)]
 pub(crate) struct InvalidGcFailed<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_finalized_gc_failed)]
+#[diag(
+    "failed to garbage collect finalized incremental compilation session directory `{$path}`: {$err}"
+)]
 pub(crate) struct FinalizedGcFailed<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_session_gc_failed)]
+#[diag("failed to garbage collect incremental compilation session directory `{$path}`: {$err}")]
 pub(crate) struct SessionGcFailed<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_assert_not_loaded)]
+#[diag("we asserted that the incremental cache should not be loaded, but it was loaded")]
 pub(crate) struct AssertNotLoaded;
 
 #[derive(Diagnostic)]
-#[diag(incremental_assert_loaded)]
+#[diag(
+    "we asserted that an existing incremental cache directory should be successfully loaded, but it was not"
+)]
 pub(crate) struct AssertLoaded;
 
 #[derive(Diagnostic)]
-#[diag(incremental_delete_incompatible)]
+#[diag(
+    "failed to delete invalidated or incompatible incremental compilation session directory contents `{$path}`: {$err}"
+)]
 pub(crate) struct DeleteIncompatible {
     pub path: PathBuf,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_load_dep_graph)]
+#[diag("could not load dep-graph from `{$path}`: {$err}")]
 pub(crate) struct LoadDepGraph {
     pub path: PathBuf,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_move_dep_graph)]
+#[diag("failed to move dependency graph from `{$from}` to `{$to}`: {$err}")]
 pub(crate) struct MoveDepGraph<'a> {
     pub from: &'a Path,
     pub to: &'a Path,
@@ -279,14 +295,14 @@ pub(crate) struct MoveDepGraph<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_create_dep_graph)]
+#[diag("failed to create dependency graph at `{$path}`: {$err}")]
 pub(crate) struct CreateDepGraph<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_copy_workproduct_to_cache)]
+#[diag("error copying object file `{$from}` to incremental directory as `{$to}`: {$err}")]
 pub(crate) struct CopyWorkProductToCache<'a> {
     pub from: &'a Path,
     pub to: &'a Path,
@@ -294,14 +310,16 @@ pub(crate) struct CopyWorkProductToCache<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_delete_workproduct)]
+#[diag("file-system error deleting outdated file `{$path}`: {$err}")]
 pub(crate) struct DeleteWorkProduct<'a> {
     pub path: &'a Path,
     pub err: std::io::Error,
 }
 
 #[derive(Diagnostic)]
-#[diag(incremental_corrupt_file)]
+#[diag(
+    "corrupt incremental compilation artifact found at `{$path}`. This file will automatically be ignored and deleted. If you see this message repeatedly or can provoke it without manually manipulating the compiler's artifacts, please file an issue. The incremental compilation system relies on hardlinks and filesystem locks behaving correctly, and may not deal well with OS crashes, so whatever information you can provide about your filesystem or other state may be very relevant."
+)]
 pub(crate) struct CorruptFile<'a> {
     pub path: &'a Path,
 }
diff --git a/compiler/rustc_incremental/src/lib.rs b/compiler/rustc_incremental/src/lib.rs
index e750810c01193..591ade379e6a2 100644
--- a/compiler/rustc_incremental/src/lib.rs
+++ b/compiler/rustc_incremental/src/lib.rs
@@ -21,5 +21,3 @@ pub fn provide(providers: &mut Providers) {
     providers.hooks.save_dep_graph =
         |tcx| tcx.sess.time("serialize_dep_graph", || persist::save_dep_graph(tcx));
 }
-
-rustc_fluent_macro::fluent_messages! { "../messages.ftl" }