Emit lint even if span for inline attribute isn't found. Fix lint docs.

Author: calebzulawski

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -590,14 +590,13 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
             && !tcx.codegen_fn_attrs(owner_id).target_features.is_empty()
         {
             if codegen_fn_attrs.inline == InlineAttr::Always {
-                if let Some(inline_span) = inline_span {
-                    tcx.emit_node_span_lint(
-                        lint::builtin::INLINE_ALWAYS_CLOSURE_IN_TARGET_FEATURE_FUNCTION,
-                        rustc_hir::CRATE_HIR_ID,
-                        inline_span,
-                        errors::InlineAlwaysClosureInTargetFeatureFunction,
-                    );
-                }
+                // Do *not* inherit target features here, that could be unsound.
+                tcx.emit_node_span_lint(
+                    lint::builtin::INLINE_ALWAYS_CLOSURE_IN_TARGET_FEATURE_FUNCTION,
+                    rustc_hir::CRATE_HIR_ID,
+                    inline_span.unwrap_or(tcx.def_span(did)),
+                    errors::InlineAlwaysClosureInTargetFeatureFunction,
+                );
             } else {
                 codegen_fn_attrs
                     .target_features

compiler/rustc_lint_defs/src/builtin.rs

@@ -5188,10 +5188,14 @@ declare_lint! {
     ///
     /// ```rust,edition2021,compile_fail
     /// #![deny(inline_always_closure_in_target_feature_function)]
+    /// #![feature(target_feature_11)]
     ///
     /// #[target_feature(enable = "avx")]
     /// fn example() {
-    ///     let closure = #[inline(always)] || {};
+    ///     let closure = {
+    ///         #[inline(always)] move || {}
+    ///     };
+    ///     closure()
     /// }
     ///
     /// ```