rustc_ast_lowering: make "yield syntax is experimental" translatable
diff --git a/compiler/rustc_ast_lowering/messages.ftl b/compiler/rustc_ast_lowering/messages.ftl
index 9e4d5a3..efee5a9 100644
--- a/compiler/rustc_ast_lowering/messages.ftl
+++ b/compiler/rustc_ast_lowering/messages.ftl
@@ -175,6 +175,8 @@
     .label = `_` not allowed here
 
 ast_lowering_use_angle_brackets = use angle brackets instead
+
+ast_lowering_yield = yield syntax is experimental
 ast_lowering_yield_in_closure =
     `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
     .suggestion = use `#[coroutine]` to make this closure a coroutine
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 124fe6b..b5d8a54 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -23,7 +23,7 @@
     ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs, ResolverAstLoweringExt,
 };
 use crate::errors::YieldInClosure;
-use crate::{FnDeclKind, ImplTraitPosition};
+use crate::{fluent_generated, FnDeclKind, ImplTraitPosition};
 
 impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] {
@@ -1540,7 +1540,6 @@ fn lower_expr_field(&mut self, f: &ExprField) -> hir::ExprField<'hir> {
         }
     }
 
-    #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
     fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
         let yielded =
             opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span));
@@ -1575,7 +1574,7 @@ fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::Expr
                         &self.tcx.sess,
                         sym::coroutines,
                         span,
-                        "yield syntax is experimental",
+                        fluent_generated::ast_lowering_yield,
                     )
                     .emit();
                 }
@@ -1587,7 +1586,7 @@ fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::Expr
                         &self.tcx.sess,
                         sym::coroutines,
                         span,
-                        "yield syntax is experimental",
+                        fluent_generated::ast_lowering_yield,
                     )
                     .emit();
                 }
diff --git a/tests/ui/coroutine/gen_block.none.stderr b/tests/ui/coroutine/gen_block.none.stderr
index 64fa2be..15123a4 100644
--- a/tests/ui/coroutine/gen_block.none.stderr
+++ b/tests/ui/coroutine/gen_block.none.stderr
@@ -73,7 +73,6 @@
    = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
    = help: add `#![feature(coroutines)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
   --> $DIR/gen_block.rs:16:16
@@ -95,7 +94,6 @@
    = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
    = help: add `#![feature(coroutines)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: aborting due to 11 previous errors
 
diff --git a/tests/ui/feature-gates/feature-gate-coroutines.none.stderr b/tests/ui/feature-gates/feature-gate-coroutines.none.stderr
index 65e7737..032d7ad 100644
--- a/tests/ui/feature-gates/feature-gate-coroutines.none.stderr
+++ b/tests/ui/feature-gates/feature-gate-coroutines.none.stderr
@@ -47,7 +47,6 @@
    = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
    = help: add `#![feature(coroutines)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
   --> $DIR/feature-gate-coroutines.rs:5:5
@@ -69,7 +68,6 @@
    = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
    = help: add `#![feature(coroutines)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: `yield` can only be used in `#[coroutine]` closures, or `gen` blocks
   --> $DIR/feature-gate-coroutines.rs:10:16