target check_consistency: ensure target feature string makes some basic sense

compiler/rustc_target/src/spec/tests/tests_impl.rs

@@ -1,5 +1,7 @@
 use std::assert_matches::assert_matches;
 
+use rustc_data_structures::fx::FxHashSet;
+
 use super::super::*;
 
 // Test target self-consistency and JSON encoding/decoding roundtrip.
@@ -170,6 +172,27 @@ impl Target {
  }
  _ => {}
  }
+
+ // Check that the given target-features string makes some basic sense.
+ if !self.features.is_empty() {
+ let mut features_enabled = FxHashSet::default();
+ let mut features_disabled = FxHashSet::default();
+ for feat in self.features.split(',') {
+ if let Some(feat) = feat.strip_prefix("+") {
+ features_enabled.insert(feat);
+ if features_disabled.contains(feat) {
+ panic!("target feature `{feat}` is both enabled and disabled");
+ }
+ } else if let Some(feat) = feat.strip_prefix("-") {
+ features_disabled.insert(feat);
+ if features_enabled.contains(feat) {
+ panic!("target feature `{feat}` is both enabled and disabled");
+ }
+ } else {
+ panic!("target feature `{feat}` is invalid, must start with `+` or `-`");
+ }
+ }
+ }
  }
 
  // Add your target to the whitelist if it has `std` library