Migrate unstable-in-stable diagnostic

5 files changed, 30 insertions, 20 deletions

diff --git a/compiler/rustc_const_eval/src/errors.rs b/compiler/rustc_const_eval/src/errors.rs
new file mode 100644
index 00000000000..f19e8046d42
--- /dev/null
+++ b/compiler/rustc_const_eval/src/errors.rs
@@ -0,0 +1,21 @@
+use rustc_macros::SessionDiagnostic;
+use rustc_span::Span;
+
+#[derive(SessionDiagnostic)]
+#[error(const_eval::unstable_in_stable)]
+pub(crate) struct UnstableInStable {
+    pub gate: String,
+    #[primary_span]
+    pub span: Span,
+    #[suggestion(
+        const_eval::unstable_sugg,
+        code = "#[rustc_const_unstable(feature = \"...\", issue = \"...\")]\n",
+        applicability = "has-placeholders"
+    )]
+    #[suggestion(
+        const_eval::bypass_sugg,
+        code = "#[rustc_allow_const_fn_unstable({gate})]\n",
+        applicability = "has-placeholders"
+    )]
+    pub attr_span: Span,
+}
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index 2d42ae236ad..d65d4f7eb72 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -31,6 +31,7 @@ extern crate tracing;
 extern crate rustc_middle;
 
 pub mod const_eval;
+mod errors;
 pub mod interpret;
 pub mod transform;
 pub mod util;
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index f87de4f6a08..3dcd96df33c 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -1,6 +1,6 @@
 //! The `Visitor` responsible for actually checking a `mir::Body` for invalid operations.
 
-use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed};
+use rustc_errors::{Diagnostic, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_index::bit_set::BitSet;
@@ -24,6 +24,7 @@ use super::qualifs::{self, CustomEq, HasMutInterior, NeedsDrop, NeedsNonConstDro
 use super::resolver::FlowSensitiveAnalysis;
 use super::{ConstCx, Qualif};
 use crate::const_eval::is_unstable_const_fn;
+use crate::errors::UnstableInStable;
 
 type QualifResults<'mir, 'tcx, Q> =
     rustc_mir_dataflow::ResultsCursor<'mir, 'tcx, FlowSensitiveAnalysis<'mir, 'mir, 'tcx, Q>>;
@@ -1026,23 +1027,5 @@ fn is_int_bool_or_char(ty: Ty<'_>) -> bool {
 fn emit_unstable_in_stable_error(ccx: &ConstCx<'_, '_>, span: Span, gate: Symbol) {
     let attr_span = ccx.tcx.def_span(ccx.def_id()).shrink_to_lo();
 
-    ccx.tcx
-        .sess
-        .struct_span_err(
-            span,
-            &format!("const-stable function cannot use `#[feature({})]`", gate.as_str()),
-        )
-        .span_suggestion(
-            attr_span,
-            "if it is not part of the public API, make this function unstably const",
-            concat!(r#"#[rustc_const_unstable(feature = "...", issue = "...")]"#, '\n'),
-            Applicability::HasPlaceholders,
-        )
-        .span_suggestion(
-            attr_span,
-            "otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks",
-            format!("#[rustc_allow_const_fn_unstable({})]\n", gate),
-            Applicability::MaybeIncorrect,
-        )
-        .emit();
+    ccx.tcx.sess.emit_err(UnstableInStable { gate: gate.to_string(), span, attr_span });
 }
diff --git a/compiler/rustc_error_messages/locales/en-US/const_eval.ftl b/compiler/rustc_error_messages/locales/en-US/const_eval.ftl
new file mode 100644
index 00000000000..a022e596efb
--- /dev/null
+++ b/compiler/rustc_error_messages/locales/en-US/const_eval.ftl
@@ -0,0 +1,4 @@
+const-eval-unstable-in-stable =
+    const-stable function cannot use `#[feature({$gate})]`
+    .unstable-sugg = if it is not part of the public API, make this function unstably const
+    .bypass-sugg = otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 563d0534d8f..5a482bc5b2c 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -37,6 +37,7 @@ fluent_messages! {
     parser => "../locales/en-US/parser.ftl",
     privacy => "../locales/en-US/privacy.ftl",
     typeck => "../locales/en-US/typeck.ftl",
+    const_eval => "../locales/en-US/const_eval.ftl",
 }
 
 pub use fluent_generated::{self as fluent, DEFAULT_LOCALE_RESOURCES};