Rollup merge of rust-lang#128221 - calebzulawski:implied-target-features, r=Amanieu

Add implied target features to target_feature attribute

See [zulip](https://rust-lang.zulipchat.com/#narrow/stream/208962-t-libs.2Fstdarch/topic/Why.20would.20target-feature.20include.20implied.20features.3F) for some context.  Adds implied target features, e.g. `#[target_feature(enable = "avx2")]` acts like `#[target_feature(enable = "avx2,avx,sse4.2,sse4.1...")]`.  Fixes rust-lang#128125, fixes rust-lang#128426

The implied feature sets are taken from [the rust reference](https://doc.rust-lang.org/reference/attributes/codegen.html?highlight=target-fea#x86-or-x86_64), there are certainly more features and targets to add.

Please feel free to reassign this to whoever should review it.

r? ``@Amanieu``

Author: matthiaskrgr

src/attributes.rs

@@ -75,7 +75,7 @@ pub fn from_fn_attrs<'gcc, 'tcx>(
     let function_features = codegen_fn_attrs
         .target_features
         .iter()
-        .map(|features| features.as_str())
+        .map(|features| features.name.as_str())
         .collect::<Vec<&str>>();
 
     if let Some(features) = check_tied_features(

src/gcc_util.rs

@@ -65,8 +65,8 @@ pub(crate) fn global_gcc_features(sess: &Session, diagnostics: bool) -> Vec<Stri
 
             let feature = backend_feature_name(s)?;
             // Warn against use of GCC specific feature names on the CLI.
-            if diagnostics && !supported_features.iter().any(|&(v, _)| v == feature) {
-                let rust_feature = supported_features.iter().find_map(|&(rust_feature, _)| {
+            if diagnostics && !supported_features.iter().any(|&(v, _, _)| v == feature) {
+                let rust_feature = supported_features.iter().find_map(|&(rust_feature, _, _)| {
                     let gcc_features = to_gcc_features(sess, rust_feature);
                     if gcc_features.contains(&feature) && !gcc_features.contains(&rust_feature) {
                         Some(rust_feature)

src/lib.rs

@@ -486,7 +486,7 @@ pub fn target_features(
     sess.target
         .supported_target_features()
         .iter()
-        .filter_map(|&(feature, gate)| {
+        .filter_map(|&(feature, gate, _)| {
             if sess.is_nightly_build() || allow_unstable || gate.is_stable() {
                 Some(feature)
             } else {