Add `rustc_fluent_macro` to decouple fluent from `rustc_macros`

Fluent, with all the icu4x it brings in, takes quite some time to
compile. `fluent_messages!` is only needed in further downstream rustc
crates, but is blocking more upstream crates like `rustc_index`. By
splitting it out, we allow `rustc_macros` to be compiled earlier, which
speeds up `x check compiler` by about 5 seconds (and even more after the
needless dependency on `serde_json` is removed from
`rustc_data_structures`).

7 files changed, 200 insertions, 194 deletions

diff --git a/tests/ui-fulldeps/fluent-messages/test.rs b/tests/ui-fulldeps/fluent-messages/test.rs
index 6ba13387b04..1dd6d211b3f 100644
--- a/tests/ui-fulldeps/fluent-messages/test.rs
+++ b/tests/ui-fulldeps/fluent-messages/test.rs
@@ -3,8 +3,8 @@
 #![feature(rustc_private)]
 #![crate_type = "lib"]
 
-extern crate rustc_macros;
-use rustc_macros::fluent_messages;
+extern crate rustc_fluent_macro;
+use rustc_fluent_macro::fluent_messages;
 
 /// Copy of the relevant `DiagnosticMessage` variant constructed by `fluent_messages` as it
 /// expects `crate::DiagnosticMessage` to exist.
diff --git a/tests/ui-fulldeps/internal-lints/diagnostics.rs b/tests/ui-fulldeps/internal-lints/diagnostics.rs
index 3aa65d53d4e..994fc26ba02 100644
--- a/tests/ui-fulldeps/internal-lints/diagnostics.rs
+++ b/tests/ui-fulldeps/internal-lints/diagnostics.rs
@@ -7,15 +7,17 @@
 #![deny(rustc::diagnostic_outside_of_impl)]
 
 extern crate rustc_errors;
+extern crate rustc_fluent_macro;
 extern crate rustc_macros;
 extern crate rustc_session;
 extern crate rustc_span;
 
 use rustc_errors::{
-    AddToDiagnostic, IntoDiagnostic, Diagnostic, DiagnosticBuilder,
-    ErrorGuaranteed, Handler, DiagnosticMessage, SubdiagnosticMessage,
+    AddToDiagnostic, Diagnostic, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, Handler,
+    IntoDiagnostic, SubdiagnosticMessage,
 };
-use rustc_macros::{fluent_messages, Diagnostic, Subdiagnostic};
+use rustc_fluent_macro::fluent_messages;
+use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::Span;
 
 fluent_messages! { "./diagnostics.ftl" }
diff --git a/tests/ui-fulldeps/internal-lints/diagnostics.stderr b/tests/ui-fulldeps/internal-lints/diagnostics.stderr
index 6f797ebc2dd..6e670c01852 100644
--- a/tests/ui-fulldeps/internal-lints/diagnostics.stderr
+++ b/tests/ui-fulldeps/internal-lints/diagnostics.stderr
@@ -1,5 +1,5 @@
 error: diagnostics should be created using translatable messages
-  --> $DIR/diagnostics.rs:41:17
+  --> $DIR/diagnostics.rs:43:17
    |
 LL |         handler.struct_err("untranslatable diagnostic")
    |                 ^^^^^^^^^^
@@ -11,13 +11,13 @@ LL | #![deny(rustc::untranslatable_diagnostic)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostics should be created using translatable messages
-  --> $DIR/diagnostics.rs:61:14
+  --> $DIR/diagnostics.rs:63:14
    |
 LL |         diag.note("untranslatable diagnostic");
    |              ^^^^
 
 error: diagnostics should only be created in `IntoDiagnostic`/`AddToDiagnostic` impls
-  --> $DIR/diagnostics.rs:78:25
+  --> $DIR/diagnostics.rs:80:25
    |
 LL |     let _diag = handler.struct_err(crate::fluent_generated::no_crate_example);
    |                         ^^^^^^^^^^
@@ -29,13 +29,13 @@ LL | #![deny(rustc::diagnostic_outside_of_impl)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostics should only be created in `IntoDiagnostic`/`AddToDiagnostic` impls
-  --> $DIR/diagnostics.rs:81:25
+  --> $DIR/diagnostics.rs:83:25
    |
 LL |     let _diag = handler.struct_err("untranslatable diagnostic");
    |                         ^^^^^^^^^^
 
 error: diagnostics should be created using translatable messages
-  --> $DIR/diagnostics.rs:81:25
+  --> $DIR/diagnostics.rs:83:25
    |
 LL |     let _diag = handler.struct_err("untranslatable diagnostic");
    |                         ^^^^^^^^^^
diff --git a/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.rs b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.rs
index ef85fada506..80ab03ab24c 100644
--- a/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.rs
+++ b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.rs
@@ -17,8 +17,10 @@ extern crate rustc_span;
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 
+extern crate rustc_fluent_macro;
 extern crate rustc_macros;
-use rustc_macros::{fluent_messages, Diagnostic, LintDiagnostic, Subdiagnostic};
+use rustc_fluent_macro::fluent_messages;
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 
 extern crate rustc_middle;
 use rustc_middle::ty::Ty;
diff --git a/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
index 3f961449566..5e1bea4e38c 100644
--- a/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
+++ b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr
@@ -1,11 +1,11 @@
 error: unsupported type attribute for diagnostic derive enum
-  --> $DIR/diagnostic-derive.rs:42:1
+  --> $DIR/diagnostic-derive.rs:44:1
    |
 LL | #[diag(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:45:5
+  --> $DIR/diagnostic-derive.rs:47:5
    |
 LL |     Foo,
    |     ^^^
@@ -13,7 +13,7 @@ LL |     Foo,
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:47:5
+  --> $DIR/diagnostic-derive.rs:49:5
    |
 LL |     Bar,
    |     ^^^
@@ -21,19 +21,19 @@ LL |     Bar,
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: expected parentheses: #[diag(...)]
-  --> $DIR/diagnostic-derive.rs:53:8
+  --> $DIR/diagnostic-derive.rs:55:8
    |
 LL | #[diag = "E0123"]
    |        ^
 
 error: `#[nonsense(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:58:1
+  --> $DIR/diagnostic-derive.rs:60:1
    |
 LL | #[nonsense(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:58:1
+  --> $DIR/diagnostic-derive.rs:60:1
    |
 LL | / #[nonsense(no_crate_example, code = "E0123")]
 LL | |
@@ -45,7 +45,7 @@ LL | | struct InvalidStructAttr {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:65:1
+  --> $DIR/diagnostic-derive.rs:67:1
    |
 LL | / #[diag("E0123")]
 LL | |
@@ -55,13 +55,13 @@ LL | | struct InvalidLitNestedAttr {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: diagnostic slug must be the first argument
-  --> $DIR/diagnostic-derive.rs:75:16
+  --> $DIR/diagnostic-derive.rs:77:16
    |
 LL | #[diag(nonsense("foo"), code = "E0123", slug = "foo")]
    |                ^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:75:1
+  --> $DIR/diagnostic-derive.rs:77:1
    |
 LL | / #[diag(nonsense("foo"), code = "E0123", slug = "foo")]
 LL | |
@@ -72,7 +72,7 @@ LL | | struct InvalidNestedStructAttr1 {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: unknown argument
-  --> $DIR/diagnostic-derive.rs:81:8
+  --> $DIR/diagnostic-derive.rs:83:8
    |
 LL | #[diag(nonsense = "...", code = "E0123", slug = "foo")]
    |        ^^^^^^^^
@@ -80,7 +80,7 @@ LL | #[diag(nonsense = "...", code = "E0123", slug = "foo")]
    = note: only the `code` parameter is valid after the slug
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:81:1
+  --> $DIR/diagnostic-derive.rs:83:1
    |
 LL | / #[diag(nonsense = "...", code = "E0123", slug = "foo")]
 LL | |
@@ -91,7 +91,7 @@ LL | | struct InvalidNestedStructAttr2 {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: unknown argument
-  --> $DIR/diagnostic-derive.rs:87:8
+  --> $DIR/diagnostic-derive.rs:89:8
    |
 LL | #[diag(nonsense = 4, code = "E0123", slug = "foo")]
    |        ^^^^^^^^
@@ -99,7 +99,7 @@ LL | #[diag(nonsense = 4, code = "E0123", slug = "foo")]
    = note: only the `code` parameter is valid after the slug
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:87:1
+  --> $DIR/diagnostic-derive.rs:89:1
    |
 LL | / #[diag(nonsense = 4, code = "E0123", slug = "foo")]
 LL | |
@@ -110,7 +110,7 @@ LL | | struct InvalidNestedStructAttr3 {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: unknown argument
-  --> $DIR/diagnostic-derive.rs:93:42
+  --> $DIR/diagnostic-derive.rs:95:42
    |
 LL | #[diag(no_crate_example, code = "E0123", slug = "foo")]
    |                                          ^^^^
@@ -118,55 +118,55 @@ LL | #[diag(no_crate_example, code = "E0123", slug = "foo")]
    = note: only the `code` parameter is valid after the slug
 
 error: `#[suggestion = ...]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:100:5
+  --> $DIR/diagnostic-derive.rs:102:5
    |
 LL |     #[suggestion = "bar"]
    |     ^^^^^^^^^^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:107:8
+  --> $DIR/diagnostic-derive.rs:109:8
    |
 LL | #[diag(no_crate_example, code = "E0456")]
    |        ^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:106:8
+  --> $DIR/diagnostic-derive.rs:108:8
    |
 LL | #[diag(no_crate_example, code = "E0123")]
    |        ^^^^^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:107:26
+  --> $DIR/diagnostic-derive.rs:109:26
    |
 LL | #[diag(no_crate_example, code = "E0456")]
    |                          ^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:106:26
+  --> $DIR/diagnostic-derive.rs:108:26
    |
 LL | #[diag(no_crate_example, code = "E0123")]
    |                          ^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:113:42
+  --> $DIR/diagnostic-derive.rs:115:42
    |
 LL | #[diag(no_crate_example, code = "E0456", code = "E0457")]
    |                                          ^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:113:26
+  --> $DIR/diagnostic-derive.rs:115:26
    |
 LL | #[diag(no_crate_example, code = "E0456", code = "E0457")]
    |                          ^^^^
 
 error: diagnostic slug must be the first argument
-  --> $DIR/diagnostic-derive.rs:118:43
+  --> $DIR/diagnostic-derive.rs:120:43
    |
 LL | #[diag(no_crate_example, no_crate::example, code = "E0456")]
    |                                           ^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:123:1
+  --> $DIR/diagnostic-derive.rs:125:1
    |
 LL | struct KindNotProvided {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -174,7 +174,7 @@ LL | struct KindNotProvided {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:126:1
+  --> $DIR/diagnostic-derive.rs:128:1
    |
 LL | / #[diag(code = "E0456")]
 LL | |
@@ -184,31 +184,31 @@ LL | | struct SlugNotProvided {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: the `#[primary_span]` attribute can only be applied to fields of type `Span` or `MultiSpan`
-  --> $DIR/diagnostic-derive.rs:137:5
+  --> $DIR/diagnostic-derive.rs:139:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
 
 error: `#[nonsense]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:145:5
+  --> $DIR/diagnostic-derive.rs:147:5
    |
 LL |     #[nonsense]
    |     ^^^^^^^^^^^
 
 error: the `#[label(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
-  --> $DIR/diagnostic-derive.rs:162:5
+  --> $DIR/diagnostic-derive.rs:164:5
    |
 LL |     #[label(no_crate_label)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `name` doesn't refer to a field on this type
-  --> $DIR/diagnostic-derive.rs:170:46
+  --> $DIR/diagnostic-derive.rs:172:46
    |
 LL |     #[suggestion(no_crate_suggestion, code = "{name}")]
    |                                              ^^^^^^^^
 
 error: invalid format string: expected `'}'` but string was terminated
-  --> $DIR/diagnostic-derive.rs:175:10
+  --> $DIR/diagnostic-derive.rs:177:10
    |
 LL | #[derive(Diagnostic)]
    |          ^^^^^^^^^^ expected `'}'` in format string
@@ -217,7 +217,7 @@ LL | #[derive(Diagnostic)]
    = note: this error originates in the derive macro `Diagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: invalid format string: unmatched `}` found
-  --> $DIR/diagnostic-derive.rs:185:10
+  --> $DIR/diagnostic-derive.rs:187:10
    |
 LL | #[derive(Diagnostic)]
    |          ^^^^^^^^^^ unmatched `}` in format string
@@ -226,19 +226,19 @@ LL | #[derive(Diagnostic)]
    = note: this error originates in the derive macro `Diagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: the `#[label(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
-  --> $DIR/diagnostic-derive.rs:205:5
+  --> $DIR/diagnostic-derive.rs:207:5
    |
 LL |     #[label(no_crate_label)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: suggestion without `code = "..."`
-  --> $DIR/diagnostic-derive.rs:224:5
+  --> $DIR/diagnostic-derive.rs:226:5
    |
 LL |     #[suggestion(no_crate_suggestion)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: invalid nested attribute
-  --> $DIR/diagnostic-derive.rs:232:18
+  --> $DIR/diagnostic-derive.rs:234:18
    |
 LL |     #[suggestion(nonsense = "bar")]
    |                  ^^^^^^^^
@@ -246,13 +246,13 @@ LL |     #[suggestion(nonsense = "bar")]
    = help: only `style`, `code` and `applicability` are valid nested attributes
 
 error: suggestion without `code = "..."`
-  --> $DIR/diagnostic-derive.rs:232:5
+  --> $DIR/diagnostic-derive.rs:234:5
    |
 LL |     #[suggestion(nonsense = "bar")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: invalid nested attribute
-  --> $DIR/diagnostic-derive.rs:241:18
+  --> $DIR/diagnostic-derive.rs:243:18
    |
 LL |     #[suggestion(msg = "bar")]
    |                  ^^^
@@ -260,13 +260,13 @@ LL |     #[suggestion(msg = "bar")]
    = help: only `style`, `code` and `applicability` are valid nested attributes
 
 error: suggestion without `code = "..."`
-  --> $DIR/diagnostic-derive.rs:241:5
+  --> $DIR/diagnostic-derive.rs:243:5
    |
 LL |     #[suggestion(msg = "bar")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: wrong field type for suggestion
-  --> $DIR/diagnostic-derive.rs:264:5
+  --> $DIR/diagnostic-derive.rs:266:5
    |
 LL | /     #[suggestion(no_crate_suggestion, code = "This is suggested code")]
 LL | |
@@ -276,79 +276,79 @@ LL | |     suggestion: Applicability,
    = help: `#[suggestion(...)]` should be applied to fields of type `Span` or `(Span, Applicability)`
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:280:24
+  --> $DIR/diagnostic-derive.rs:282:24
    |
 LL |     suggestion: (Span, Span, Applicability),
    |                        ^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:280:18
+  --> $DIR/diagnostic-derive.rs:282:18
    |
 LL |     suggestion: (Span, Span, Applicability),
    |                  ^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:288:33
+  --> $DIR/diagnostic-derive.rs:290:33
    |
 LL |     suggestion: (Applicability, Applicability, Span),
    |                                 ^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:288:18
+  --> $DIR/diagnostic-derive.rs:290:18
    |
 LL |     suggestion: (Applicability, Applicability, Span),
    |                  ^^^^^^^^^^^^^
 
 error: `#[label = ...]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:295:5
+  --> $DIR/diagnostic-derive.rs:297:5
    |
 LL |     #[label = "bar"]
    |     ^^^^^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:446:5
+  --> $DIR/diagnostic-derive.rs:448:5
    |
 LL |     #[suggestion(no_crate_suggestion, code = "...", applicability = "maybe-incorrect")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:448:24
+  --> $DIR/diagnostic-derive.rs:450:24
    |
 LL |     suggestion: (Span, Applicability),
    |                        ^^^^^^^^^^^^^
 
 error: invalid applicability
-  --> $DIR/diagnostic-derive.rs:454:69
+  --> $DIR/diagnostic-derive.rs:456:69
    |
 LL |     #[suggestion(no_crate_suggestion, code = "...", applicability = "batman")]
    |                                                                     ^^^^^^^^
 
 error: the `#[help(...)]` attribute can only be applied to fields of type `Span`, `MultiSpan`, `bool` or `()`
-  --> $DIR/diagnostic-derive.rs:521:5
+  --> $DIR/diagnostic-derive.rs:523:5
    |
 LL |     #[help(no_crate_help)]
    |     ^^^^^^^^^^^^^^^^^^^^^^
 
 error: a diagnostic slug must be the first argument to the attribute
-  --> $DIR/diagnostic-derive.rs:530:32
+  --> $DIR/diagnostic-derive.rs:532:32
    |
 LL |     #[label(no_crate_label, foo)]
    |                                ^
 
 error: invalid nested attribute
-  --> $DIR/diagnostic-derive.rs:538:29
+  --> $DIR/diagnostic-derive.rs:540:29
    |
 LL |     #[label(no_crate_label, foo = "...")]
    |                             ^^^
 
 error: invalid nested attribute
-  --> $DIR/diagnostic-derive.rs:546:29
+  --> $DIR/diagnostic-derive.rs:548:29
    |
 LL |     #[label(no_crate_label, foo("..."))]
    |                             ^^^
 
 error: `#[primary_span]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:558:5
+  --> $DIR/diagnostic-derive.rs:560:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
@@ -356,13 +356,13 @@ LL |     #[primary_span]
    = help: the `primary_span` field attribute is not valid for lint diagnostics
 
 error: `#[error(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:578:1
+  --> $DIR/diagnostic-derive.rs:580:1
    |
 LL | #[error(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:578:1
+  --> $DIR/diagnostic-derive.rs:580:1
    |
 LL | / #[error(no_crate_example, code = "E0123")]
 LL | |
@@ -374,13 +374,13 @@ LL | | struct ErrorAttribute {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: `#[warn_(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:585:1
+  --> $DIR/diagnostic-derive.rs:587:1
    |
 LL | #[warn_(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:585:1
+  --> $DIR/diagnostic-derive.rs:587:1
    |
 LL | / #[warn_(no_crate_example, code = "E0123")]
 LL | |
@@ -392,13 +392,13 @@ LL | | struct WarnAttribute {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: `#[lint(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:592:1
+  --> $DIR/diagnostic-derive.rs:594:1
    |
 LL | #[lint(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:592:1
+  --> $DIR/diagnostic-derive.rs:594:1
    |
 LL | / #[lint(no_crate_example, code = "E0123")]
 LL | |
@@ -410,19 +410,19 @@ LL | | struct LintAttributeOnSessionDiag {}
    = help: specify the slug as the first argument to the `#[diag(...)]` attribute, such as `#[diag(hir_analysis_example_error)]`
 
 error: `#[lint(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:599:1
+  --> $DIR/diagnostic-derive.rs:601:1
    |
 LL | #[lint(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `#[lint(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:599:1
+  --> $DIR/diagnostic-derive.rs:601:1
    |
 LL | #[lint(no_crate_example, code = "E0123")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:599:1
+  --> $DIR/diagnostic-derive.rs:601:1
    |
 LL | / #[lint(no_crate_example, code = "E0123")]
 LL | |
@@ -435,19 +435,19 @@ LL | | struct LintAttributeOnLintDiag {}
    = help: specify the slug as the first argument to the attribute, such as `#[diag(compiletest_example)]`
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:609:53
+  --> $DIR/diagnostic-derive.rs:611:53
    |
 LL |     #[suggestion(no_crate_suggestion, code = "...", code = ",,,")]
    |                                                     ^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:609:39
+  --> $DIR/diagnostic-derive.rs:611:39
    |
 LL |     #[suggestion(no_crate_suggestion, code = "...", code = ",,,")]
    |                                       ^^^^
 
 error: wrong types for suggestion
-  --> $DIR/diagnostic-derive.rs:618:24
+  --> $DIR/diagnostic-derive.rs:620:24
    |
 LL |     suggestion: (Span, usize),
    |                        ^^^^^
@@ -455,7 +455,7 @@ LL |     suggestion: (Span, usize),
    = help: `#[suggestion(...)]` on a tuple field must be applied to fields of type `(Span, Applicability)`
 
 error: wrong types for suggestion
-  --> $DIR/diagnostic-derive.rs:626:17
+  --> $DIR/diagnostic-derive.rs:628:17
    |
 LL |     suggestion: (Span,),
    |                 ^^^^^^^
@@ -463,13 +463,13 @@ LL |     suggestion: (Span,),
    = help: `#[suggestion(...)]` on a tuple field must be applied to fields of type `(Span, Applicability)`
 
 error: suggestion without `code = "..."`
-  --> $DIR/diagnostic-derive.rs:633:5
+  --> $DIR/diagnostic-derive.rs:635:5
    |
 LL |     #[suggestion(no_crate_suggestion)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `#[multipart_suggestion(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:640:1
+  --> $DIR/diagnostic-derive.rs:642:1
    |
 LL | #[multipart_suggestion(no_crate_suggestion)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -477,7 +477,7 @@ LL | #[multipart_suggestion(no_crate_suggestion)]
    = help: consider creating a `Subdiagnostic` instead
 
 error: `#[multipart_suggestion(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:647:5
+  --> $DIR/diagnostic-derive.rs:649:5
    |
 LL |     #[multipart_suggestion(no_crate_suggestion)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -485,13 +485,13 @@ LL |     #[multipart_suggestion(no_crate_suggestion)]
    = help: consider creating a `Subdiagnostic` instead
 
 error: unexpected end of input, unexpected token in nested attribute, expected ident
-  --> $DIR/diagnostic-derive.rs:643:24
+  --> $DIR/diagnostic-derive.rs:645:24
    |
 LL | #[multipart_suggestion()]
    |                        ^
 
 error: `#[suggestion(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:655:1
+  --> $DIR/diagnostic-derive.rs:657:1
    |
 LL | #[suggestion(no_crate_suggestion, code = "...")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -499,7 +499,7 @@ LL | #[suggestion(no_crate_suggestion, code = "...")]
    = help: `#[label]` and `#[suggestion]` can only be applied to fields
 
 error: `#[label]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:664:1
+  --> $DIR/diagnostic-derive.rs:666:1
    |
 LL | #[label]
    | ^^^^^^^^
@@ -507,31 +507,31 @@ LL | #[label]
    = help: `#[label]` and `#[suggestion]` can only be applied to fields
 
 error: `eager` is the only supported nested attribute for `subdiagnostic`
-  --> $DIR/diagnostic-derive.rs:698:7
+  --> $DIR/diagnostic-derive.rs:700:7
    |
 LL |     #[subdiagnostic(bad)]
    |       ^^^^^^^^^^^^^^^^^^
 
 error: `#[subdiagnostic = ...]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:706:5
+  --> $DIR/diagnostic-derive.rs:708:5
    |
 LL |     #[subdiagnostic = "bad"]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `eager` is the only supported nested attribute for `subdiagnostic`
-  --> $DIR/diagnostic-derive.rs:714:7
+  --> $DIR/diagnostic-derive.rs:716:7
    |
 LL |     #[subdiagnostic(bad, bad)]
    |       ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `eager` is the only supported nested attribute for `subdiagnostic`
-  --> $DIR/diagnostic-derive.rs:722:7
+  --> $DIR/diagnostic-derive.rs:724:7
    |
 LL |     #[subdiagnostic("bad")]
    |       ^^^^^^^^^^^^^^^^^^^^
 
 error: `#[subdiagnostic(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:730:5
+  --> $DIR/diagnostic-derive.rs:732:5
    |
 LL |     #[subdiagnostic(eager)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^
@@ -539,31 +539,31 @@ LL |     #[subdiagnostic(eager)]
    = help: eager subdiagnostics are not supported on lints
 
 error: expected at least one string literal for `code(...)`
-  --> $DIR/diagnostic-derive.rs:788:23
+  --> $DIR/diagnostic-derive.rs:790:23
    |
 LL |     #[suggestion(code())]
    |                       ^
 
 error: `code(...)` must contain only string literals
-  --> $DIR/diagnostic-derive.rs:796:23
+  --> $DIR/diagnostic-derive.rs:798:23
    |
 LL |     #[suggestion(code(foo))]
    |                       ^^^
 
 error: unexpected token
-  --> $DIR/diagnostic-derive.rs:796:23
+  --> $DIR/diagnostic-derive.rs:798:23
    |
 LL |     #[suggestion(code(foo))]
    |                       ^^^
 
 error: expected string literal
-  --> $DIR/diagnostic-derive.rs:805:25
+  --> $DIR/diagnostic-derive.rs:807:25
    |
 LL |     #[suggestion(code = 3)]
    |                         ^
 
 error: `#[suggestion(...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:820:5
+  --> $DIR/diagnostic-derive.rs:822:5
    |
 LL |     #[suggestion(no_crate_suggestion, code = "")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -573,67 +573,67 @@ LL |     #[suggestion(no_crate_suggestion, code = "")]
    = help: to show a variable set of suggestions, use a `Vec` of `Subdiagnostic`s annotated with `#[suggestion(...)]`
 
 error: cannot find attribute `nonsense` in this scope
-  --> $DIR/diagnostic-derive.rs:58:3
+  --> $DIR/diagnostic-derive.rs:60:3
    |
 LL | #[nonsense(no_crate_example, code = "E0123")]
    |   ^^^^^^^^
 
 error: cannot find attribute `nonsense` in this scope
-  --> $DIR/diagnostic-derive.rs:145:7
+  --> $DIR/diagnostic-derive.rs:147:7
    |
 LL |     #[nonsense]
    |       ^^^^^^^^
 
 error: cannot find attribute `error` in this scope
-  --> $DIR/diagnostic-derive.rs:578:3
+  --> $DIR/diagnostic-derive.rs:580:3
    |
 LL | #[error(no_crate_example, code = "E0123")]
    |   ^^^^^
 
 error: cannot find attribute `warn_` in this scope
-  --> $DIR/diagnostic-derive.rs:585:3
+  --> $DIR/diagnostic-derive.rs:587:3
    |
 LL | #[warn_(no_crate_example, code = "E0123")]
    |   ^^^^^ help: a built-in attribute with a similar name exists: `warn`
 
 error: cannot find attribute `lint` in this scope
-  --> $DIR/diagnostic-derive.rs:592:3
+  --> $DIR/diagnostic-derive.rs:594:3
    |
 LL | #[lint(no_crate_example, code = "E0123")]
    |   ^^^^ help: a built-in attribute with a similar name exists: `link`
 
 error: cannot find attribute `lint` in this scope
-  --> $DIR/diagnostic-derive.rs:599:3
+  --> $DIR/diagnostic-derive.rs:601:3
    |
 LL | #[lint(no_crate_example, code = "E0123")]
    |   ^^^^ help: a built-in attribute with a similar name exists: `link`
 
 error: cannot find attribute `multipart_suggestion` in this scope
-  --> $DIR/diagnostic-derive.rs:640:3
+  --> $DIR/diagnostic-derive.rs:642:3
    |
 LL | #[multipart_suggestion(no_crate_suggestion)]
    |   ^^^^^^^^^^^^^^^^^^^^
 
 error: cannot find attribute `multipart_suggestion` in this scope
-  --> $DIR/diagnostic-derive.rs:643:3
+  --> $DIR/diagnostic-derive.rs:645:3
    |
 LL | #[multipart_suggestion()]
    |   ^^^^^^^^^^^^^^^^^^^^
 
 error: cannot find attribute `multipart_suggestion` in this scope
-  --> $DIR/diagnostic-derive.rs:647:7
+  --> $DIR/diagnostic-derive.rs:649:7
    |
 LL |     #[multipart_suggestion(no_crate_suggestion)]
    |       ^^^^^^^^^^^^^^^^^^^^
 
 error[E0425]: cannot find value `nonsense` in module `crate::fluent_generated`
-  --> $DIR/diagnostic-derive.rs:70:8
+  --> $DIR/diagnostic-derive.rs:72:8
    |
 LL | #[diag(nonsense, code = "E0123")]
    |        ^^^^^^^^ not found in `crate::fluent_generated`
 
 error[E0425]: cannot find value `__code_34` in this scope
-  --> $DIR/diagnostic-derive.rs:802:10
+  --> $DIR/diagnostic-derive.rs:804:10
    |
 LL | #[derive(Diagnostic)]
    |          ^^^^^^^^^^ not found in this scope
@@ -641,7 +641,7 @@ LL | #[derive(Diagnostic)]
    = note: this error originates in the derive macro `Diagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `Hello: IntoDiagnosticArg` is not satisfied
-  --> $DIR/diagnostic-derive.rs:339:10
+  --> $DIR/diagnostic-derive.rs:341:10
    |
 LL | #[derive(Diagnostic)]
    |          ^^^^^^^^^^ the trait `IntoDiagnosticArg` is not implemented for `Hello`
diff --git a/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs b/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
index 73cc1cfc03a..1bfbb60015d 100644
--- a/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
+++ b/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.rs
@@ -12,12 +12,14 @@
 #![crate_type = "lib"]
 
 extern crate rustc_errors;
+extern crate rustc_fluent_macro;
 extern crate rustc_macros;
 extern crate rustc_session;
 extern crate rustc_span;
 
 use rustc_errors::{Applicability, DiagnosticMessage, SubdiagnosticMessage};
-use rustc_macros::{fluent_messages, Subdiagnostic};
+use rustc_fluent_macro::fluent_messages;
+use rustc_macros::Subdiagnostic;
 use rustc_span::Span;
 
 fluent_messages! { "./example.ftl" }
diff --git a/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr b/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
index 529003d90ab..fca4f506890 100644
--- a/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
+++ b/tests/ui-fulldeps/session-diagnostic/subdiagnostic-derive.stderr
@@ -1,5 +1,5 @@
 error: label without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:50:1
+  --> $DIR/subdiagnostic-derive.rs:52:1
    |
 LL | / #[label(no_crate_example)]
 LL | |
@@ -9,133 +9,133 @@ LL | | }
    | |_^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
-  --> $DIR/subdiagnostic-derive.rs:57:1
+  --> $DIR/subdiagnostic-derive.rs:59:1
    |
 LL | #[label]
    | ^^^^^^^^
 
 error: `#[foo]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:66:1
+  --> $DIR/subdiagnostic-derive.rs:68:1
    |
 LL | #[foo]
    | ^^^^^^
 
 error: `#[label = ...]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:76:1
+  --> $DIR/subdiagnostic-derive.rs:78:1
    |
 LL | #[label = "..."]
    | ^^^^^^^^^^^^^^^^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:85:9
+  --> $DIR/subdiagnostic-derive.rs:87:9
    |
 LL | #[label(bug = "...")]
    |         ^^^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
-  --> $DIR/subdiagnostic-derive.rs:85:1
+  --> $DIR/subdiagnostic-derive.rs:87:1
    |
 LL | #[label(bug = "...")]
    | ^^^^^^^^^^^^^^^^^^^^^
 
 error: unexpected literal in nested attribute, expected ident
-  --> $DIR/subdiagnostic-derive.rs:95:9
+  --> $DIR/subdiagnostic-derive.rs:97:9
    |
 LL | #[label("...")]
    |         ^^^^^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:104:9
+  --> $DIR/subdiagnostic-derive.rs:106:9
    |
 LL | #[label(slug = 4)]
    |         ^^^^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
-  --> $DIR/subdiagnostic-derive.rs:104:1
+  --> $DIR/subdiagnostic-derive.rs:106:1
    |
 LL | #[label(slug = 4)]
    | ^^^^^^^^^^^^^^^^^^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:114:9
+  --> $DIR/subdiagnostic-derive.rs:116:9
    |
 LL | #[label(slug("..."))]
    |         ^^^^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
-  --> $DIR/subdiagnostic-derive.rs:114:1
+  --> $DIR/subdiagnostic-derive.rs:116:1
    |
 LL | #[label(slug("..."))]
    | ^^^^^^^^^^^^^^^^^^^^^
 
 error: unexpected end of input, unexpected token in nested attribute, expected ident
-  --> $DIR/subdiagnostic-derive.rs:134:9
+  --> $DIR/subdiagnostic-derive.rs:136:9
    |
 LL | #[label()]
    |         ^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:143:27
+  --> $DIR/subdiagnostic-derive.rs:145:27
    |
 LL | #[label(no_crate_example, code = "...")]
    |                           ^^^^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:152:27
+  --> $DIR/subdiagnostic-derive.rs:154:27
    |
 LL | #[label(no_crate_example, applicability = "machine-applicable")]
    |                           ^^^^^^^^^^^^^
 
 error: unsupported type attribute for subdiagnostic enum
-  --> $DIR/subdiagnostic-derive.rs:161:1
+  --> $DIR/subdiagnostic-derive.rs:163:1
    |
 LL | #[foo]
    | ^^^^^^
 
 error: `#[bar]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:175:5
+  --> $DIR/subdiagnostic-derive.rs:177:5
    |
 LL |     #[bar]
    |     ^^^^^^
 
 error: `#[bar = ...]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:187:5
+  --> $DIR/subdiagnostic-derive.rs:189:5
    |
 LL |     #[bar = "..."]
    |     ^^^^^^^^^^^^^^
 
 error: `#[bar = ...]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:199:5
+  --> $DIR/subdiagnostic-derive.rs:201:5
    |
 LL |     #[bar = 4]
    |     ^^^^^^^^^^
 
 error: `#[bar(...)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:211:5
+  --> $DIR/subdiagnostic-derive.rs:213:5
    |
 LL |     #[bar("...")]
    |     ^^^^^^^^^^^^^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:223:13
+  --> $DIR/subdiagnostic-derive.rs:225:13
    |
 LL |     #[label(code = "...")]
    |             ^^^^
 
 error: diagnostic slug must be first argument of a `#[label(...)]` attribute
-  --> $DIR/subdiagnostic-derive.rs:223:5
+  --> $DIR/subdiagnostic-derive.rs:225:5
    |
 LL |     #[label(code = "...")]
    |     ^^^^^^^^^^^^^^^^^^^^^^
 
 error: the `#[primary_span]` attribute can only be applied to fields of type `Span` or `MultiSpan`
-  --> $DIR/subdiagnostic-derive.rs:252:5
+  --> $DIR/subdiagnostic-derive.rs:254:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
 
 error: label without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:249:1
+  --> $DIR/subdiagnostic-derive.rs:251:1
    |
 LL | / #[label(no_crate_example)]
 LL | |
@@ -147,13 +147,13 @@ LL | | }
    | |_^
 
 error: `#[applicability]` is only valid on suggestions
-  --> $DIR/subdiagnostic-derive.rs:262:5
+  --> $DIR/subdiagnostic-derive.rs:264:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
 error: `#[bar]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:272:5
+  --> $DIR/subdiagnostic-derive.rs:274:5
    |
 LL |     #[bar]
    |     ^^^^^^
@@ -161,13 +161,13 @@ LL |     #[bar]
    = help: only `primary_span`, `applicability` and `skip_arg` are valid field attributes
 
 error: `#[bar = ...]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:283:5
+  --> $DIR/subdiagnostic-derive.rs:285:5
    |
 LL |     #[bar = "..."]
    |     ^^^^^^^^^^^^^^
 
 error: `#[bar(...)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:294:5
+  --> $DIR/subdiagnostic-derive.rs:296:5
    |
 LL |     #[bar("...")]
    |     ^^^^^^^^^^^^^
@@ -175,7 +175,7 @@ LL |     #[bar("...")]
    = help: only `primary_span`, `applicability` and `skip_arg` are valid field attributes
 
 error: unexpected unsupported untagged union
-  --> $DIR/subdiagnostic-derive.rs:310:1
+  --> $DIR/subdiagnostic-derive.rs:312:1
    |
 LL | / union AC {
 LL | |
@@ -185,73 +185,73 @@ LL | | }
    | |_^
 
 error: a diagnostic slug must be the first argument to the attribute
-  --> $DIR/subdiagnostic-derive.rs:325:44
+  --> $DIR/subdiagnostic-derive.rs:327:44
    |
 LL | #[label(no_crate_example, no_crate::example)]
    |                                            ^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:338:5
+  --> $DIR/subdiagnostic-derive.rs:340:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:335:5
+  --> $DIR/subdiagnostic-derive.rs:337:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
 
 error: subdiagnostic kind not specified
-  --> $DIR/subdiagnostic-derive.rs:344:8
+  --> $DIR/subdiagnostic-derive.rs:346:8
    |
 LL | struct AG {
    |        ^^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:381:46
+  --> $DIR/subdiagnostic-derive.rs:383:46
    |
 LL | #[suggestion(no_crate_example, code = "...", code = "...")]
    |                                              ^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:381:32
+  --> $DIR/subdiagnostic-derive.rs:383:32
    |
 LL | #[suggestion(no_crate_example, code = "...", code = "...")]
    |                                ^^^^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:399:5
+  --> $DIR/subdiagnostic-derive.rs:401:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:396:5
+  --> $DIR/subdiagnostic-derive.rs:398:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
 error: the `#[applicability]` attribute can only be applied to fields of type `Applicability`
-  --> $DIR/subdiagnostic-derive.rs:409:5
+  --> $DIR/subdiagnostic-derive.rs:411:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
 error: suggestion without `code = "..."`
-  --> $DIR/subdiagnostic-derive.rs:422:1
+  --> $DIR/subdiagnostic-derive.rs:424:1
    |
 LL | #[suggestion(no_crate_example)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: invalid applicability
-  --> $DIR/subdiagnostic-derive.rs:432:62
+  --> $DIR/subdiagnostic-derive.rs:434:62
    |
 LL | #[suggestion(no_crate_example, code = "...", applicability = "foo")]
    |                                                              ^^^^^
 
 error: suggestion without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:450:1
+  --> $DIR/subdiagnostic-derive.rs:452:1
    |
 LL | / #[suggestion(no_crate_example, code = "...")]
 LL | |
@@ -261,25 +261,25 @@ LL | | }
    | |_^
 
 error: unsupported type attribute for subdiagnostic enum
-  --> $DIR/subdiagnostic-derive.rs:464:1
+  --> $DIR/subdiagnostic-derive.rs:466:1
    |
 LL | #[label]
    | ^^^^^^^^
 
 error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:484:39
+  --> $DIR/subdiagnostic-derive.rs:486:39
    |
 LL | #[suggestion(no_crate_example, code = "{var}", applicability = "machine-applicable")]
    |                                       ^^^^^^^
 
 error: `var` doesn't refer to a field on this type
-  --> $DIR/subdiagnostic-derive.rs:503:43
+  --> $DIR/subdiagnostic-derive.rs:505:43
    |
 LL |     #[suggestion(no_crate_example, code = "{var}", applicability = "machine-applicable")]
    |                                           ^^^^^^^
 
 error: `#[suggestion_part]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:526:5
+  --> $DIR/subdiagnostic-derive.rs:528:5
    |
 LL |     #[suggestion_part]
    |     ^^^^^^^^^^^^^^^^^^
@@ -287,7 +287,7 @@ LL |     #[suggestion_part]
    = help: `#[suggestion_part(...)]` is only valid in multipart suggestions, use `#[primary_span]` instead
 
 error: `#[suggestion_part(...)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:529:5
+  --> $DIR/subdiagnostic-derive.rs:531:5
    |
 LL |     #[suggestion_part(code = "...")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -295,7 +295,7 @@ LL |     #[suggestion_part(code = "...")]
    = help: `#[suggestion_part(...)]` is only valid in multipart suggestions
 
 error: suggestion without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:523:1
+  --> $DIR/subdiagnostic-derive.rs:525:1
    |
 LL | / #[suggestion(no_crate_example, code = "...")]
 LL | |
@@ -307,7 +307,7 @@ LL | | }
    | |_^
 
 error: invalid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:538:42
+  --> $DIR/subdiagnostic-derive.rs:540:42
    |
 LL | #[multipart_suggestion(no_crate_example, code = "...", applicability = "machine-applicable")]
    |                                          ^^^^
@@ -315,7 +315,7 @@ LL | #[multipart_suggestion(no_crate_example, code = "...", applicability = "mac
    = help: only `style` and `applicability` are valid nested attributes
 
 error: multipart suggestion without any `#[suggestion_part(...)]` fields
-  --> $DIR/subdiagnostic-derive.rs:538:1
+  --> $DIR/subdiagnostic-derive.rs:540:1
    |
 LL | / #[multipart_suggestion(no_crate_example, code = "...", applicability = "machine-applicable")]
 LL | |
@@ -326,19 +326,19 @@ LL | | }
    | |_^
 
 error: `#[suggestion_part(...)]` attribute without `code = "..."`
-  --> $DIR/subdiagnostic-derive.rs:548:5
+  --> $DIR/subdiagnostic-derive.rs:550:5
    |
 LL |     #[suggestion_part]
    |     ^^^^^^^^^^^^^^^^^^
 
 error: unexpected end of input, unexpected token in nested attribute, expected ident
-  --> $DIR/subdiagnostic-derive.rs:556:23
+  --> $DIR/subdiagnostic-derive.rs:558:23
    |
 LL |     #[suggestion_part()]
    |                       ^
 
 error: `#[primary_span]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:565:5
+  --> $DIR/subdiagnostic-derive.rs:567:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
@@ -346,7 +346,7 @@ LL |     #[primary_span]
    = help: multipart suggestions use one or more `#[suggestion_part]`s rather than one `#[primary_span]`
 
 error: multipart suggestion without any `#[suggestion_part(...)]` fields
-  --> $DIR/subdiagnostic-derive.rs:562:1
+  --> $DIR/subdiagnostic-derive.rs:564:1
    |
 LL | / #[multipart_suggestion(no_crate_example)]
 LL | |
@@ -358,121 +358,121 @@ LL | | }
    | |_^
 
 error: `#[suggestion_part(...)]` attribute without `code = "..."`
-  --> $DIR/subdiagnostic-derive.rs:573:5
+  --> $DIR/subdiagnostic-derive.rs:575:5
    |
 LL |     #[suggestion_part]
    |     ^^^^^^^^^^^^^^^^^^
 
 error: `code` is the only valid nested attribute
-  --> $DIR/subdiagnostic-derive.rs:579:23
+  --> $DIR/subdiagnostic-derive.rs:581:23
    |
 LL |     #[suggestion_part(foo = "bar")]
    |                       ^^^
 
 error: the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
-  --> $DIR/subdiagnostic-derive.rs:583:5
+  --> $DIR/subdiagnostic-derive.rs:585:5
    |
 LL |     #[suggestion_part(code = "...")]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: the `#[suggestion_part(...)]` attribute can only be applied to fields of type `Span` or `MultiSpan`
-  --> $DIR/subdiagnostic-derive.rs:586:5
+  --> $DIR/subdiagnostic-derive.rs:588:5
    |
 LL |     #[suggestion_part()]
    |     ^^^^^^^^^^^^^^^^^^^^
 
 error: unexpected end of input, unexpected token in nested attribute, expected ident
-  --> $DIR/subdiagnostic-derive.rs:576:23
+  --> $DIR/subdiagnostic-derive.rs:578:23
    |
 LL |     #[suggestion_part()]
    |                       ^
 
 error: expected `,`
-  --> $DIR/subdiagnostic-derive.rs:579:27
+  --> $DIR/subdiagnostic-derive.rs:581:27
    |
 LL |     #[suggestion_part(foo = "bar")]
    |                           ^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:594:37
+  --> $DIR/subdiagnostic-derive.rs:596:37
    |
 LL |     #[suggestion_part(code = "...", code = ",,,")]
    |                                     ^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:594:23
+  --> $DIR/subdiagnostic-derive.rs:596:23
    |
 LL |     #[suggestion_part(code = "...", code = ",,,")]
    |                       ^^^^
 
 error: `#[applicability]` has no effect if all `#[suggestion]`/`#[multipart_suggestion]` attributes have a static `applicability = "..."`
-  --> $DIR/subdiagnostic-derive.rs:623:5
+  --> $DIR/subdiagnostic-derive.rs:625:5
    |
 LL |     #[applicability]
    |     ^^^^^^^^^^^^^^^^
 
 error: expected exactly one string literal for `code = ...`
-  --> $DIR/subdiagnostic-derive.rs:671:34
+  --> $DIR/subdiagnostic-derive.rs:673:34
    |
 LL |     #[suggestion_part(code("foo"))]
    |                                  ^
 
 error: unexpected token
-  --> $DIR/subdiagnostic-derive.rs:671:28
+  --> $DIR/subdiagnostic-derive.rs:673:28
    |
 LL |     #[suggestion_part(code("foo"))]
    |                            ^^^^^
 
 error: expected exactly one string literal for `code = ...`
-  --> $DIR/subdiagnostic-derive.rs:681:41
+  --> $DIR/subdiagnostic-derive.rs:683:41
    |
 LL |     #[suggestion_part(code("foo", "bar"))]
    |                                         ^
 
 error: unexpected token
-  --> $DIR/subdiagnostic-derive.rs:681:28
+  --> $DIR/subdiagnostic-derive.rs:683:28
    |
 LL |     #[suggestion_part(code("foo", "bar"))]
    |                            ^^^^^
 
 error: expected exactly one string literal for `code = ...`
-  --> $DIR/subdiagnostic-derive.rs:691:30
+  --> $DIR/subdiagnostic-derive.rs:693:30
    |
 LL |     #[suggestion_part(code(3))]
    |                              ^
 
 error: unexpected token
-  --> $DIR/subdiagnostic-derive.rs:691:28
+  --> $DIR/subdiagnostic-derive.rs:693:28
    |
 LL |     #[suggestion_part(code(3))]
    |                            ^
 
 error: expected exactly one string literal for `code = ...`
-  --> $DIR/subdiagnostic-derive.rs:701:29
+  --> $DIR/subdiagnostic-derive.rs:703:29
    |
 LL |     #[suggestion_part(code())]
    |                             ^
 
 error: expected string literal
-  --> $DIR/subdiagnostic-derive.rs:713:30
+  --> $DIR/subdiagnostic-derive.rs:715:30
    |
 LL |     #[suggestion_part(code = 3)]
    |                              ^
 
 error: specified multiple times
-  --> $DIR/subdiagnostic-derive.rs:755:1
+  --> $DIR/subdiagnostic-derive.rs:757:1
    |
 LL | #[suggestion(no_crate_example, code = "", style = "hidden", style = "normal")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/subdiagnostic-derive.rs:755:1
+  --> $DIR/subdiagnostic-derive.rs:757:1
    |
 LL | #[suggestion(no_crate_example, code = "", style = "hidden", style = "normal")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `#[suggestion_hidden(...)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:764:1
+  --> $DIR/subdiagnostic-derive.rs:766:1
    |
 LL | #[suggestion_hidden(no_crate_example, code = "")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -480,7 +480,7 @@ LL | #[suggestion_hidden(no_crate_example, code = "")]
    = help: Use `#[suggestion(..., style = "hidden")]` instead
 
 error: `#[suggestion_hidden(...)]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:772:1
+  --> $DIR/subdiagnostic-derive.rs:774:1
    |
 LL | #[suggestion_hidden(no_crate_example, code = "", style = "normal")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -488,7 +488,7 @@ LL | #[suggestion_hidden(no_crate_example, code = "", style = "normal")]
    = help: Use `#[suggestion(..., style = "hidden")]` instead
 
 error: invalid suggestion style
-  --> $DIR/subdiagnostic-derive.rs:780:51
+  --> $DIR/subdiagnostic-derive.rs:782:51
    |
 LL | #[suggestion(no_crate_example, code = "", style = "foo")]
    |                                                   ^^^^^
@@ -496,31 +496,31 @@ LL | #[suggestion(no_crate_example, code = "", style = "foo")]
    = help: valid styles are `normal`, `short`, `hidden`, `verbose` and `tool-only`
 
 error: expected `= "xxx"`
-  --> $DIR/subdiagnostic-derive.rs:788:49
+  --> $DIR/subdiagnostic-derive.rs:790:49
    |
 LL | #[suggestion(no_crate_example, code = "", style = 42)]
    |                                                 ^
 
 error: a diagnostic slug must be the first argument to the attribute
-  --> $DIR/subdiagnostic-derive.rs:796:48
+  --> $DIR/subdiagnostic-derive.rs:798:48
    |
 LL | #[suggestion(no_crate_example, code = "", style)]
    |                                                ^
 
 error: expected `= "xxx"`
-  --> $DIR/subdiagnostic-derive.rs:804:48
+  --> $DIR/subdiagnostic-derive.rs:806:48
    |
 LL | #[suggestion(no_crate_example, code = "", style("foo"))]
    |                                                ^
 
 error: expected `,`
-  --> $DIR/subdiagnostic-derive.rs:804:48
+  --> $DIR/subdiagnostic-derive.rs:806:48
    |
 LL | #[suggestion(no_crate_example, code = "", style("foo"))]
    |                                                ^
 
 error: `#[primary_span]` is not a valid attribute
-  --> $DIR/subdiagnostic-derive.rs:816:5
+  --> $DIR/subdiagnostic-derive.rs:818:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
@@ -529,7 +529,7 @@ LL |     #[primary_span]
    = help: to create a suggestion with multiple spans, use `#[multipart_suggestion]` instead
 
 error: suggestion without `#[primary_span]` field
-  --> $DIR/subdiagnostic-derive.rs:813:1
+  --> $DIR/subdiagnostic-derive.rs:815:1
    |
 LL | / #[suggestion(no_crate_example, code = "")]
 LL | |
@@ -541,67 +541,67 @@ LL | | }
    | |_^
 
 error: cannot find attribute `foo` in this scope
-  --> $DIR/subdiagnostic-derive.rs:66:3
+  --> $DIR/subdiagnostic-derive.rs:68:3
    |
 LL | #[foo]
    |   ^^^
 
 error: cannot find attribute `foo` in this scope
-  --> $DIR/subdiagnostic-derive.rs:161:3
+  --> $DIR/subdiagnostic-derive.rs:163:3
    |
 LL | #[foo]
    |   ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:175:7
+  --> $DIR/subdiagnostic-derive.rs:177:7
    |
 LL |     #[bar]
    |       ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:187:7
+  --> $DIR/subdiagnostic-derive.rs:189:7
    |
 LL |     #[bar = "..."]
    |       ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:199:7
+  --> $DIR/subdiagnostic-derive.rs:201:7
    |
 LL |     #[bar = 4]
    |       ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:211:7
+  --> $DIR/subdiagnostic-derive.rs:213:7
    |
 LL |     #[bar("...")]
    |       ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:272:7
+  --> $DIR/subdiagnostic-derive.rs:274:7
    |
 LL |     #[bar]
    |       ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:283:7
+  --> $DIR/subdiagnostic-derive.rs:285:7
    |
 LL |     #[bar = "..."]
    |       ^^^
 
 error: cannot find attribute `bar` in this scope
-  --> $DIR/subdiagnostic-derive.rs:294:7
+  --> $DIR/subdiagnostic-derive.rs:296:7
    |
 LL |     #[bar("...")]
    |       ^^^
 
 error[E0425]: cannot find value `slug` in module `crate::fluent_generated`
-  --> $DIR/subdiagnostic-derive.rs:124:9
+  --> $DIR/subdiagnostic-derive.rs:126:9
    |
 LL | #[label(slug)]
    |         ^^^^ not found in `crate::fluent_generated`
 
 error[E0425]: cannot find value `__code_29` in this scope
-  --> $DIR/subdiagnostic-derive.rs:707:10
+  --> $DIR/subdiagnostic-derive.rs:709:10
    |
 LL | #[derive(Subdiagnostic)]
    |          ^^^^^^^^^^^^^ not found in this scope