Update

Author: chansuke

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -1,24 +1,24 @@
-use rustc_ast::{MetaItemInner, MetaItemKind, ast, attr};
-use rustc_attr::{InlineAttr, InstructionSetAttr, OptimizeAttr, list_contains_name};
+use rustc_ast::{ast, attr, MetaItemInner, MetaItemKind};
+use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::codes::*;
-use rustc_errors::{DiagMessage, SubdiagMessage, struct_span_code_err};
+use rustc_errors::{struct_span_code_err, DiagMessage, SubdiagMessage};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
-use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
+use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
 use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
-use rustc_hir::{LangItem, lang_items};
+use rustc_hir::{lang_items, LangItem};
 use rustc_middle::middle::codegen_fn_attrs::{
     CodegenFnAttrFlags, CodegenFnAttrs, PatchableFunctionEntry,
 };
 use rustc_middle::mir::mono::Linkage;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self as ty, TyCtxt};
 use rustc_session::parse::feature_err;
-use rustc_session::{Session, lint};
+use rustc_session::{lint, Session};
 use rustc_span::symbol::Ident;
-use rustc_span::{Span, sym};
-use rustc_target::spec::{SanitizerSet, abi};
+use rustc_span::{sym, Span};
+use rustc_target::spec::{abi, SanitizerSet};
 
 use crate::errors;
 use crate::target_features::{check_target_feature_trait_unsafe, from_target_feature_attr};
@@ -399,7 +399,16 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                                     .emit();
                                     None
                                 }
-                                _ => None,
+                                _ => {
+                                    struct_span_code_err!(
+                                        tcx.dcx(),
+                                        attr.span,
+                                        E0779,
+                                        "`[instruction_set]` attribute argument should be valid"
+                                    )
+                                    .emit();
+                                    None
+                                }
                             }
                         }
                         _ => None,

compiler/rustc_error_codes/src/error_codes/E0779.md

@@ -5,7 +5,8 @@ Erroneous code example:
 ```compile_fail,E0779
 #![feature(isa_attribute)]
 
-#[instruction_set(intel::x64)] // error: `[instruction_set]` attribute argument should be valid
+#[instruction_set(intel::x64)] // error: `[instruction_set]` attribute argument
+                               //        should be valid
 pub fn something() {}
 fn main() {}
 ```