From 86cb5730aea078e616de2a9ae0a5755f7ff0e80c Mon Sep 17 00:00:00 2001
From: Jacob Bramley <jacob.bramley@arm.com>
Date: Thu, 28 Sep 2023 15:14:37 +0100
Subject: [PATCH] Report missing features when skipping tests.

---
 .../stdarch/crates/simd-test-macro/src/lib.rs    | 16 +++++++++-------
 library/stdarch/crates/stdarch-test/src/lib.rs   | 12 ++++++++----
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/library/stdarch/crates/simd-test-macro/src/lib.rs b/library/stdarch/crates/simd-test-macro/src/lib.rs
index 9e089f86bf2e..73be684c474b 100644
--- a/library/stdarch/crates/simd-test-macro/src/lib.rs
+++ b/library/stdarch/crates/simd-test-macro/src/lib.rs
@@ -82,16 +82,16 @@ pub fn simd_test(
     };
     let macro_test = Ident::new(macro_test, Span::call_site());
 
-    let mut cfg_target_features = TokenStream::new();
+    let mut detect_missing_features = TokenStream::new();
     for feature in target_features {
         let q = quote_spanned! {
             proc_macro2::Span::call_site() =>
-            #macro_test!(#feature) &&
+            if !#macro_test!(#feature) {
+                missing_features.push(#feature);
+            }
         };
-        q.to_tokens(&mut cfg_target_features);
+        q.to_tokens(&mut detect_missing_features);
     }
-    let q = quote! { true };
-    q.to_tokens(&mut cfg_target_features);
 
     let test_norun = std::env::var("STDSIMD_TEST_NORUN").is_ok();
     let maybe_ignore = if test_norun {
@@ -107,11 +107,13 @@ pub fn simd_test(
         #maybe_ignore
         #(#item_attrs)*
         fn #name() {
-            if #force_test | (#cfg_target_features) {
+            let mut missing_features = ::std::vec::Vec::new();
+            #detect_missing_features
+            if #force_test || missing_features.is_empty() {
                 let v = unsafe { #name() };
                 return v;
             } else {
-                ::stdarch_test::assert_skip_test_ok(stringify!(#name));
+                ::stdarch_test::assert_skip_test_ok(stringify!(#name), &missing_features);
             }
 
             #[target_feature(enable = #enable_feature)]
diff --git a/library/stdarch/crates/stdarch-test/src/lib.rs b/library/stdarch/crates/stdarch-test/src/lib.rs
index 05298d8c644c..40128c0ad226 100644
--- a/library/stdarch/crates/stdarch-test/src/lib.rs
+++ b/library/stdarch/crates/stdarch-test/src/lib.rs
@@ -173,11 +173,15 @@ pub fn assert(shim_addr: usize, fnname: &str, expected: &str) {
     }
 }
 
-pub fn assert_skip_test_ok(name: &str) {
-    if env::var("STDARCH_TEST_EVERYTHING").is_err() {
-        return;
+pub fn assert_skip_test_ok(name: &str, missing_features: &[&str]) {
+    println!("Skipping test `{name}` due to missing target features:");
+    for feature in missing_features {
+        println!("  - {feature}");
+    }
+    match env::var("STDARCH_TEST_EVERYTHING") {
+        Ok(_) => panic!("skipped test `{name}` when it shouldn't be skipped"),
+        Err(_) => println!("Set STDARCH_TEST_EVERYTHING to make this an error."),
     }
-    panic!("skipped test `{name}` when it shouldn't be skipped");
 }
 
 // See comment in `assert-instr-macro` crate for why this exists