1 files changed, 41 insertions, 0 deletions
diff --git a/compiler/rustc_mir_transform/src/errors.rs b/compiler/rustc_mir_transform/src/errors.rs
index ad9635aae33..775f5f9a7cf 100644
--- a/compiler/rustc_mir_transform/src/errors.rs
+++ b/compiler/rustc_mir_transform/src/errors.rs
@@ -2,6 +2,7 @@ use rustc_errors::codes::*;
 use rustc_errors::{Diag, LintDiagnostic};
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_middle::mir::AssertKind;
+use rustc_middle::query::Key;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::lint::{self, Lint};
 use rustc_span::def_id::DefId;
@@ -9,6 +10,46 @@ use rustc_span::{Ident, Span, Symbol};
 
 use crate::fluent_generated as fluent;
 
+/// Emit diagnostic for calls to `#[inline(always)]`-annotated functions with a
+/// `#[target_feature]` attribute where the caller enables a different set of target features.
+pub(crate) fn emit_inline_always_target_feature_diagnostic<'a, 'tcx>(
+    tcx: TyCtxt<'tcx>,
+    call_span: Span,
+    callee_def_id: DefId,
+    caller_def_id: DefId,
+    callee_only: &[&'a str],
+) {
+    let callee = tcx.def_path_str(callee_def_id);
+    let caller = tcx.def_path_str(caller_def_id);
+
+    tcx.node_span_lint(
+        lint::builtin::INLINE_ALWAYS_MISMATCHING_TARGET_FEATURES,
+        tcx.local_def_id_to_hir_id(caller_def_id.as_local().unwrap()),
+        call_span,
+        |lint| {
+            lint.primary_message(format!(
+                "call to `#[inline(always)]`-annotated `{callee}` \
+                requires the same target features to be inlined"
+            ));
+            lint.note("function will not be inlined");
+
+            lint.note(format!(
+                "the following target features are on `{callee}` but missing from `{caller}`: {}",
+                callee_only.join(", ")
+            ));
+            lint.span_note(callee_def_id.default_span(tcx), format!("`{callee}` is defined here"));
+
+            let feats = callee_only.join(",");
+            lint.span_suggestion(
+                tcx.def_span(caller_def_id).shrink_to_lo(),
+                format!("add `#[target_feature]` attribute to `{caller}`"),
+                format!("#[target_feature(enable = \"{feats}\")]\n"),
+                lint::Applicability::MaybeIncorrect,
+            );
+        },
+    );
+}
+
 #[derive(LintDiagnostic)]
 #[diag(mir_transform_unconditional_recursion)]
 #[help]