Fix feature gate check

Author: JohnTitor

compiler/rustc_typeck/src/collect.rs

@@ -2600,15 +2600,20 @@ fn simd_ffi_check<'tcx>(
 
     // The use of SIMD types in FFI is feature-gated:
     if !tcx.features().simd_ffi {
+        let snip = tcx
+                    .sess
+                    .source_map()
+                    .span_to_snippet(ast_ty.span)
+                    .map_or_else(|_| String::new(), |s| format!("{}", s));
         tcx.sess
             .struct_span_err(
                 ast_ty.span,
                 &format!(
                     "use of SIMD type `{}` in FFI is unstable",
-                    tcx.hir().node_to_string(ast_ty.hir_id)
+                    snip
                 ),
             )
-            .help("add #![feature(simd_ffi)] to the crate attributes to enable")
+            .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
             .emit();
         return;
     }
@@ -2642,7 +2647,11 @@ fn simd_ffi_check<'tcx>(
 
     for f in features {
         if let Err(v) = simd_ffi_feature_check(target, simd_len, simd_elem_width, f.to_ident_string()) {
-            let type_str = tcx.hir().node_to_string(ast_ty.hir_id);
+            let type_str = tcx
+                    .sess
+                    .source_map()
+                    .span_to_snippet(ast_ty.span)
+                    .map_or_else(|_| String::new(), |s| format!("{}", s));
             let msg = if let Some(f) = v {
                 format!(
                     "use of SIMD type `{}` in FFI requires `#[target_feature(enable = \"{}\")]`",

src/test/ui/rfcs/rfc-2574-simd-ffi/simd-ffi-feature-gate.rs

@@ -0,0 +1,17 @@
+// only-x86_64
+
+#![feature(repr_simd)]
+#![feature(avx512_target_feature)]
+#![allow(non_camel_case_types)]
+#![cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+
+#[repr(simd)]
+struct v128(i128);
+
+extern {
+    fn foo(x: v128); //~ ERROR use of SIMD type `v128` in FFI is unstable
+    fn bar(x: i32, y: v128); //~ ERROR use of SIMD type `v128` in FFI is unstable
+    fn baz(x: i32) -> v128; //~ ERROR use of SIMD type `v128` in FFI is unstable
+}
+
+fn main() {}

src/test/ui/rfcs/rfc-2574-simd-ffi/simd-ffi-feature-gate.stderr

@@ -0,0 +1,26 @@
+error: use of SIMD type `v128` in FFI is unstable
+  --> $DIR/simd-ffi-feature-gate.rs:12:15
+   |
+LL |     fn foo(x: v128);
+   |               ^^^^
+   |
+   = help: add `#![feature(simd_ffi)]` to the crate attributes to enable
+
+error: use of SIMD type `v128` in FFI is unstable
+  --> $DIR/simd-ffi-feature-gate.rs:13:23
+   |
+LL |     fn bar(x: i32, y: v128);
+   |                       ^^^^
+   |
+   = help: add `#![feature(simd_ffi)]` to the crate attributes to enable
+
+error: use of SIMD type `v128` in FFI is unstable
+  --> $DIR/simd-ffi-feature-gate.rs:14:23
+   |
+LL |     fn baz(x: i32) -> v128;
+   |                       ^^^^
+   |
+   = help: add `#![feature(simd_ffi)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+